May 2016: rather mild with average rain

A stunning first week of weather in May 2016 probably led a few people into believing that we were in for a glorious start to the summer. But the second Sunday in the month when temperatures reached 27.1C under 13 hours of sunshine was about as good as it got.

May 10th 2016 looking toward Crown Hill from Dunton in Essex

The warm first week helped maintain the mean temperature to finish above average: 14.3 which is 1.2C warmer than average, the warmest May for five years.

Though on paper rainfall looked a little under average 44 per cent of the monthly total fell on the last day. Some 43.4mm fell during the course of the month, that’s 85% of what we can expect during a normal May.

Sunshine was about average. Some 184.5 hours were were recorded, 101% of what we can expect to see during an average May.

The wettest day occurred during the meteorological 24hrs of the 30th (09-09 31st) with 14.7mm, rain associated with a depression in the North Sea. Incessant cloud held temperatures down to 12.6C, the coldest May 31st for 36 years!

A conveyor belt of rain brought the coldest May 31st for 36 years

Air frosts: 0, Ground frosts: 5

So what has June got in store weatherwise? The models on the 1st suggest only slow changes in the next 3-4 days. These changes revolve around the release of low pressure from Europe towards high pressure later next week. This process begins as high pressure also begins to build down from the north at the weekend with several days of fine and increasingly warm conditions as the cool NE’ly flow is lost to warmer winds from the SE or south. Then next week with higher pressure over Europe and low pressure drifting slowly north or NE towards the west of the UK it could become very warm and humid in places and as that low to the west pushes troughs towards us from the SW it could feed some thundery rain and storms up from the SW at some stage by midweek. The pattern thereafter appears quite mixed. GFS suggests a more traditional pattern of low pressure to the NW and higher pressure to the SE with SW bringing rain at times to the north and west while the south and east see the best of prolonged dry and warm periods between intermittent rain.

High pressure to the north of Scotland brought often miserable, overcast weather to our region

Beyond the grasp of the models my long range outlook method suggests an average to rather mild month. The highest probability is 29% for something a little above average and rather mild. A little below average and mild both come in at 14% probability. Something cool or very cool comes in at 7%. If you combine the first two probabilities together something just over average would come in at 58%

A dryer than average month looks most likely at 57% probability. Sunshine probably about average.

So to sum up: mean 16.9C (0.8C above average), rainfall 38mm, sunshine 178 hours.

My May outlook for temperature was poor. I predicted a mean of 12.8C (outcome: 14.3C). Rainfall was also poor: 58mm (outcome: 43mm). Sunshine was good: 184.5 hours (outcome: 179 hours).


Here follows the full weather diary for May…Full stats for the month here:

1st: Sunny start though with cirro cumulus around. Cloud tended to thicken up through the day to leave overcast late afternoon. A warm night followed.
2nd: Cloudy with spits and spots of rain to start. Some bright spells late morning but then overcast and some rain at 6.40pm – a decaying front gave little rain. Clearing overnight and cold.
3rd: Sunny with fair weather cumulus developing.
4th: Sunny, gin clear start with just a few fair weather cumulus developing. Clear and cold overnight.
5th: Sunny and warm, some hazy cloud in the afternoon.
6th: Sunny start though turned much more hazy than yesterday. Feeling humid.
7th: Hazy sunshine to start with high level strato-cumulus bringing cloudier periods.
8th Sunny start with just a few clouds. Air much clearer than yesterday and hot by mid afternoon on Canary Wharf.
9th: Cloudy start but became sunny late morning. Rain arrived 5pm, turning moderate 7.30pm and outbreaks through the night.
10th: Light rain to start, this turning moderate at times throughout the day, though petering out at 2.30pm.
11th: Dull, damp start that went into 11am. Heavy showers developing that lasted until late afternoon.
12th: Sunny start though with a fair bit of cirro cumulus floating around. Feeling very warm.
13th: Sunny start with spotted cirro cumulus. A pleasant day.
14th: Bright start with sunny spells into the morning. Cold wind took edge off sunshine.
15th: Sunny and cool with a cool breeze.
16th: Sunny start but quickly clouded over. Bright spells into the afternoon.
17th: Sunny start but cloud soon filled in. Sunny periods around lunchtime before more cloud arrived.
18th: Cloudy start after recent light rain. Bursts of rain at 11.20am, turning heavy at 12.30pm. Some more rain at midnight.
19th: Cloudy with brief sunny intervals before noon. Then cloudy.
20th: A Cloudy and breezy day. Feeling humid.
21st: Cloudy and breezy through the day though mild. Brief shower at 6pm while driving back from Broadstairs.
22nd: Sunny start though cloud increased during the day to fill in by 2.30pm. Showers, one moderate, from 6pm.
23rd: Sunny start but lots of cloud bubbled up. A lot of threatening cloud to west and east with funnel cloud spotted over Leighton Buzzard. Cleared overnight to leave cold night.
24th: Sunny start quickly clouded over by 11am, then just sunny intervals
25th: Cloudy and cool all day thanks to HP bringing drift off North Sea.
26th: Sunny start with sunny spells though the day
27th: Cloudy start though with sunny spells developing at lunchtime and a clearance around 1pm – 2pm. More convective cloud bubbled up however, to leave a humid evening. Rain developing at 7am.
28th: Cloudy, damp start though with a little brightness at 11am. Some sunny intervals in the afternoon though much cloud.
29th: Cloudy and cool start. Hazy sunny spells in early afternoon, though still much cloud around.
30th: Cloudy with just two sunny intervals that momentarily lifted the temperature. Rain started at 7.30am and was heavy at times up to obs time. Elderly man killed on crossing, possibly due to the bad weather
31st: Rain to start. Outbreaks lasted up until 1315z then stayed cloudy, damp and chilly into the evening and night.



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