April 2015 summary

After a damp and breezy start, April was dominated by two periods of high pressure resulting in a lot of settled and dry weather – the rainfall total was 16.4mm, our second driest April on record and our third driest month overall. The wettest day of the month was the 25th, the day when high pressure finally departed, but the total for that day was just 4.4mm.

It was a quiet month too: after a gust of 29kts on the 2nd, winds fell light as high pressure established itself on the 5th. There followed a good deal of warm sunshine once morning mists had cleared, although nights were chilly under clear skies.

The high pressure system moved away on the 11th, allowing a cold front from a low to the north of Scotland to deposit 1.8mm of rain. However, another high became established over the following days bringing a return to settled weather and sunshine. The 15th was an exception – while the rest of southern England basked in sunshine, a sea mist filled the Somerset Levels and the best we could manage was 12.6C. We got our turn the following day, though, with the thermometer reaching 21.2C on the 16th – our second-highest reading for April. A cool easterly airflow brought the lowest temperature of the month, 1.7C, only a few days later, but there were no air frosts. Between 4th and 24 April we recorded less than 3mm of rain.

The high pressure moved off again on the 24th and Atlantic lows took over. Although the airflow was south-westerly, it was polar air drawn down by lows the north of Scotland – hence temperatures dropped, making it feel particularly cold after all the sunshine. The last week of April brought 10mm or rain.

The average temperature for April was a little above normal at 10.1C – the last week took the edge off temperatures after the warm spell in the middle of the month. The average pressure for the month was 1021.4hPa and the maximum was 1038.0hPa, both new April highs for this station reflecting the two spells of anticyclonic weather.

March 2015 summary

Early March was cold and blustery with rain and a little wet snow, thanks to a collection of low pressure systems north of Scotland. High pressure formed to the south of the UK on the 4th and brought clear skies and an air frost (just) early on the 5th. Daytime temperatures rose in the sunshine, and the 7th saw what turned out to be the highest temperature of the month at 16.5°C.

A deep low on the 9th generated 100kt winds in Scotland, but nothing more than a blustery shower here as the cold front passed though. The following two weeks were generally quiet with high pressure over Scandinavia, but that system drew in a cold easterly which kept temperatures down with a second air frost on the 23rd.

The settled spell came to an end on the 28th as another group of lows approached Scotland, and the 29th was a day of wind and rain.  A total of 12.6mm made this the wettest day of the month with wind gusting to 40kts. Another deep low crossed Scotland on the night of the 30th/31st with a gust of 43.5kts at 0232 – not far off the speeds reached during the St Valentine’s Day storm of 2014. The wind continued for most of the 31st.

The average temperature of 7°C and rainfall total (49mm) were both normal for March, and the gales of thelast few days offset the quiet spell in the middle of March, to give an average wind run too.

New average wind speed record

Overnight wind speeds reached a peak at about 0230 today, with a gust of 43.5kts and an average wind speed of 32.3kts.

We have seen higher gusts. 46.1kts was recorded early on 15 February last year and 44kts back in December 2008, so this morning’s gust is our third-highest. The average speed of 32.3kts is a new record for this station, though – the previous record was 30.6kts, also back in February 2014.

It’s still blowing out there now, although the peak has passed. Hold on to your hat!

 

Partial eclipse

For this morning’s partial eclipse we were right on the edge of a blanket of cloud, which I guess might have spoiled things for those in the South East. After a misty morning it was touch-and-go how thick the cloud here would be at the time of the eclipse, but in the end we got a good view through a thin layer of cloud – not thick enough to spoil an image projected onto a piece of card.

During the eclipse light levels dropped to give a watery and rather eerie effect, and it felt quite chilly as the sun dimmed. The air temperature dropped from 5.4C at the start of the eclipse to 5C at maximum, at a time when it would normally be rising as the sun gained strength. As the sun reappeared the thermometer rose quite rapidly while light (and heat) levels got back to normal. Not a big air temperature change, then, and well within the range of variation that we might see due to other causes, but there was certainly a drop in temperature which coincided with the eclipse and which was not due to air movement – it was calm.

Looks like a bright, sunny day today – enjoy!

February 2015 summary

The first half of February was dry and cold and the second half was wet and windy, with a good deal of unsettled weather.

The month began with a cold, dry airstream from the north drawn down by a low to the north of Scotland, and although daytime temperatures were above freezing it felt much colder in the low humidity. As the low moved off to Scandinavia it was replaced by an area of high pressure, which ensured the cold weather continued – night frosts were frequent, but no rain fell in the first 12 days of the month.

The high moved off on the 13th to be replaced by the the first of a series of Atlantic lows and the first rain of the month. Except for a short break on the 17th/18th, when high pressure to our south brought quiet weather, the second half of February was dominated by these lows. The wettest day was the 19th with 14mm of rain, and a particularly unstable low pressure system on the 23rd generated thunder and some wet snow, with a gust of 33.9kts being recorded early on the 24th.

The rainfall total for the month was 64.6mm, out second highest February total, and all of this fell in the second half February. The average temperature was 4.8C, a little below normal.

Winter 2014/5 was our second-wettest on record with a total of 236mm, and the average temperature was an unremarkable 5.7C. There were no exceptional frosts, but there was record high of 15.2C on 9 January. The maximum wind gust was 41.7kts in January, but there was no repeat of last year’s damaging gales.

January 2015 summary

January was wet and blustery, with temperatures a little above average. The highest temperature of the month was a remarkable (for January) 15.2C on the 9th: that’s a new record high for us, not just for January but for any winter month since the station was set up in 2007. Exeter Airport was the warmest spot in the country that day, reaching a balmy 16.5C as low pressure to the north of the UK sucked in warm air from the south: but that low pressure system also brought damaging gales to Scotland, leaving thousands of homes without power. The average temperature for January was 5.9C, a little above normal at but not exceptional.

Total rainfall was 108mm, making this our second-wettest January but a long way off last year’s January total of 157.8mm. This year it rained on 25 out of 31 days, the wettest being the 3rd with 18mm. There were some snow flurries and a couple of falls of snow granules (snow coated in ice), but the ground was too warm for it to settle – the hilltops were white for a while.

This was our second windiest January on record with a wind run of 3235nm. A complex collection of lows passed north of Scotland on 28 January, and during the morning two lively cold fronts passed in quick succession – the first produced a squally downpour and a gust of 33.9kts at 0906, and the second at 1030 brought even more torrential rain, a gust of 41.7kts at 1030 and a jump in pressure of 1.3hPa in the space of 10 minutes.

The end of January saw the wind veering from a mild south-westerly to a north-westerly. Although temperatures remained above freezing, it felt much colder in the dry polar air. As that colder air met (relatively) warm North Atlantic water there was a good deal of snowfall in the north of the UK, and a small but lively low pressure system driven by the temperature difference was formed off Scotland on the 29th. This tracked rapidly down the west coast of the UK before moving inland across Wales, losing strength as it was cut off from the warm water. This low generated thunderstorms over Ireland and some high wind speeds, and although we were some way from the centre we saw a rapid pressure dip overnight on the 29th/30th and winds gusting to 36.5kts.

The month ended with a chillier feel, but so far this has not been a cold winter. February can be just as cold as January, though, so it’s too early to guess how things may look in four weeks time.

Winter arrives with a bang!

Well, perhaps not arrives exactly – we’re already over halfway through winter, but if the forecasters are right then the coming week may see some seasonal cold weather.

The low pressure systems that will be drawing cold polar air across the UK for the next few days have active cold fronts associated with them, and two passed through in spectacular fashion earlier this morning. Overnight temperatures were mild, and rose as the night went on, reaching a peak of 10.6C at 0830 today under grey skies with occasional glimpses of blue sky. About half an hour later, cold front no. 1 arrived bringing heavy rainfall which severely limited visibility, wind gusting to 39kts and a 2C drop in temperature.

The blustery wind stayed with us as cold front no.2 approached. That front arrived here at 1020 with an even stronger gust of 42kts, 1.4mm or rain in about 10 minutes and a temperature drop of 3.3C.

That 42kt gust is equal-third in our records – we recorded 46kts in the St Valentine’s day storm of lst year, and 44 kts way back in December 2008. We’re into the clear air behind the cold front now, but the wind will soon be pulling in showers along with the polar air. Radar showed snow falling on the Welsh mountains earlier this morning, and the question is how far south it will come. Winter is here.

Snow pellets blocking the rain collector

If anyone is wondering why the weather station is reporting sleet while the sun is shining, we had some moderate falls of snow pellets known as “graupel” earlier this morning – snow that has become covered in super-cooled ice and so falls as soft ice granules. This ice blocked the rain collector, and is now melting so the rain gauge is reporting that sleet is falling. This problem always crops up with snow, and quite often when a heavy overnight frost melts in the morning sun.

Despite the overnight weather this has been a mild January so far, even milder than January 2014. The average temperature to date is 7.7C which well above normal for this time of year, but of course there is still plenty of time for that to change. The high of 15.2C last week is a new record, though.

Record temperatures for January

As the north of the UK takes another pounding from a deep low pressure system, we’re seeing some unusual conditions down here as well – though nothing as dramatic as the gales in Scotland.

At 1525 yesterday the temperature here reached 15.2C, by far our highest January temperature – the previous record was 14C in January 2011. Exeter airport recorded an even more extraordinary 16.5C. The average daytime (0600-1800) temperature yesterday was 12.9C, which is our highest daytime average since January 2008, and the temperature hardly dropped overnight – the 1800-0600 average for 9/10 Jan was 12.6C, the warmest January night since 2008.

It didn’t feel all that warm in the WSW wind that has continued for 24 hours, and that wind peaked at 34kts at 0935 today as a cold front passed through and dropped the temperature to a more seasonable 9.5C. That is the highest gust recorded here since February 2014, when the memorable St Valentine’s Day storm generated a gust of 46.1kts.

There are more low pressure systems on their way during the coming week, and we probably haven’t seen the last of the wind. Hang on to your hat!

December and year summary for 2014

December brought an ordinary end to an exceptional year. The average temperature for the month was 6.4C making it our third-warmest December, and the maximum (13.4C) and minimum (-5.3C) temperatures were in the normal range. Rainfall was about average at 63.4mm with no particularly wet days – the highest daily total was 12.4mm on the 12th. Windrun was 2964nm with no exceptional wind speeds.

The only unusual feature of December was an intense area of high pressure that brought a cold, clear spell at the end of the month. The barometer reached a high of 1042.9hPa on 29 December, our second highest pressure since the station was set up (the record is 1043.9hPa in February 2012). The same day saw the lowest temperature of the month with -5.3C recorded at 0725, but there was none of the snow that affected the north of the UK, and for a couple of days it was almost completely calm.

Much of the earlier part of the month was spent in a mild south-westerly airstream, hence that slightly above-average temperature, but most of the Atlantic low pressure systems passed well to our north and we avoided the heavy rain and gales that affected northern areas. One exception was a particularly deep low that tracked south-east across Wales on Boxing Day – at one point it was heading on our direction, but in the event it moved off across the midlands and the only effect here was a blustery wind.

If December was uneventful, the same cannot be said of 2014. The year started with the wettest winter on record here, and January’s total of 157.8mm makes that by far our wettest month. The winter of 2013/4 followed a wet autumn, and generated the floods that brought so much misery to the Levels. The low pressure systems that led to all the rain also generated some spectacular gales, with perhaps the most memorable being the St Valentine’s Day storm – that brought our highest-ever gust of 46.1kts early on the 15th February.

The apparently unending procession of deep lows of that winter had another effect, which attracted little attention with all the damage caused by wind and rain – the air was warm as well as wet, and the winter of 2013/4 was the mildest we have recorded here. January saw only two air frosts and February none at all, and a mimimum of -1.2C recorded in March was the lowest temperature of the year until November.

Spring 2014 was warm and wet, and by the end of June it was already an exceptional year – the rainfall total was double what we would expect at the halfway mark, and each of the first five months of 2014 was the second-warmest on record here. June capped that by being our warmest June on record, so it was already on the cards that 2014 might be an unusually warm year. July didn’t quite match 2013’s high temperatures but it was another very warm month with some spectacular thunderstorms – and then came August.

August was thoroughly miserable, with the lowest average temperature for the month and the second-highest August rainfall adding to 2014’s already high total. Normal service was soon resumed, though, with September and October both producing record high average temperatures. September was remarkably calm thanks to persistent high pressure, but October produced another rainfall total over the 100mm mark – by now it was clear that 2014 likely to be a record-breaking year in several respects.

November was on the wet side but nothing exceptional and, as we have seen above, December was unexceptional. Although rainfall totals ran high for most of the year, the annual total of 973.6mm fell some way short of 2012’s record 1008.2mm: but the average temperature for 2014 came out at 11.6C, and that is a new record and about 1C above the average for this station – but it is only 0.1C above the previous record set in 2011.

With floods and gales, thunderstorms and heatwaves – it may be a while before we seen other year like 2014.

The cold spell continues

Following yesterday’s low average temperature, last night set a new record as coldest night of this year with an average of -2.8C from 1800-0600. Daytime today was colder than yesterday, with an average of 0.4C from 0600-1800 – along with clear blue skies and another splendid sunset.

The barometer is creeping up again as I’m writing this, and currently reads 1042.8 hPa. That’s by far the highest pressure we’ve seen this year, but we need another 1.1 hPa for a new station record.

Hardly a breath of wind today, thanks to the high pressure. Enjoy it while it lasts!

Coldest day of the year

Today has been the coldest of the year so far, with an average temperature of 2.9C from 0600 to 1800. Pressure is high across the UK with a new year-to-date record of 1038.9hPa a few minutes ago – by the time you read this, that record will probably have been broken again as the barometer is still rising.

As a consequence of the high pressure we have clear skies (with a spectacular sunset this afternoon), and the thermometer is dropping sharply this evening. Already we have a new low for this year of -2.2C, and there is a good chance that we will have the coolest night (1800-0600) of 2014 to follow the coldest day.

None of these temperatures are exceptional for December, but this has been a mild year so we are seeing new records set during this chilly spell. 2014 still looks set to be the warmest year were have recorded here, though – we’ll know in a few days.

November 2014 summary

November was a little warmer that average and a little wetter, but also very quiet with little in the way of wind. The total wind run for the month was 730.7nm, which is about a third of the average for November.

The average temperature was 9.1C which is at the top end of the “normal” range but not exceptional – it is the third-warmest November we have recorded here. The minimum of -1.6C on the 25th is not unusual for November, but it is the lowest temperature we have seen so far this year – because of the very mild (but wet!) start to 2014.

We recorded 101mm of rain which is above average but, again, not exceptional. The wettest day was the 8th with 13.2mm, and we recorded rain on 27 days out of 30 – though one of those was frost melt (which still counts as precipitation).

So far, 2014 is still our wettest year on record with a total of 910.2mm: the equivalent figure in 2012 was 898.6mm. However December 2012 brought 109.6mm of rain, with a total for that year of 1008.2mm, so whether that record will be broken in 2014 is still anyone’s guess at the moment.

Finally, a chilly spell toward the end of November reduced the average temperature for autumn to 12.8C, making it our second warmest autumn behind 2011 (13C). Nonetheless 2014 is still set to be our warmest year yet, with our year-to-date average currently at 12.1C – about a degree higher than we would expect at this point.

Our lowest temperature so far, in a record-breaking year

This morning’s minimum temperature of -1.3C, recorded shortly after 0700, was our first air frost of this autumn. A low of -1.3C is nothing out of the ordinary for November, but what is exceptional is that it is also the lowest temperature we have seen so far this year – the previous low was -1.2C back in January, during a winter which saw only about a third of the number of frosts we would usually expect. The temperature did not fall below freezing at all during February.

What we did get in January and February was rain, of course, and our year-to-date rainfall total still reflects that. So far this year we have recorded 902.6mm, and 2014 is still in the running to be the wettest year we have recorded here – the current total is higher than at this point in the very soggy years of 2012 and 2008. The current month has been wet with 93.2m so far, but we would need a wet December as well if we are to exceed 2012’s total of 1008.2mm.

As well as being in the running for our wettest year, 2014 is almost certain to be our warmest. The average temperature so far in 2014 is 12.3C, compared with an average of about 11C for the first 11 months of previous years – the previous high was 11.3C in 2009, a full degree cooler than this year. This is the year that has seen our mildest winter, our warmest spring, our second-warmest summer (only missing joint-warmest by 0.1C) and, very shortly, our warmest autumn. Just for good measure, February 2014 saw our highest wind gust of 46kts and the highest average wind-speed of 30.6kts.

This has been an extraordinary year, and it isn’t over yet.

October 2014 summary

October can be summarised as warm, wet and (for one day at least) windy. This follows our warmest September on record: but whereas September was dominated by high pressure, October saw a more normal procession of Atlantic lows which often drew warm air up from the south – hence the mildness, as well as the rain.

The average temperature for October was 13.2C making it the joint warmest October on record here with October 2011, although we didn’t match the maximum of 28C that was recorded that month. The highest temperature recorded in October this year was 21.4C on the third which is not exceptional. The minimum temperature was 4.2C on the 12th, and that is unusual – it is the highest October minimum we have seen here, in a month which often sees the first air frost of the autumn.

We had a total of 113.4mm of rain, with rain recorded on 21 days. That total might have been higher had the thunderstorms that caused flooding in Devon on the 16th made it across Exmoor: but as it was, although thunder could be heard as the remnants of the storm made its way across the Levels, we had no heavy rain. The wettest day was the 4th with 21.8mm.

This was the third October in a row with a rainfall total exceeding 100mm, and it was the wettest month since January of this year. Our year-to-date total is 809.2mm, the highest total we have recorded at this point in the year. The equivalent figure for 2008 was 796.4mm, and for 2012 it was 758.2mm: but the last two months of 2012 also produced high totals, making that our wettest year on record with 1008.2mm. We would need two more unusually wet months to beat that figure.

The windiest day of the month was the 21st with a gust of 32.2kts, as a low pressure system that had once been Hurricane Gonzalo passed by. Overall, though, October was not an exceptional month for wind.

With above-average temperatures in September and October, this is shaping up to be a warm autumn – but there’s another month to go.