Don't mention the drought!

At the time of writing it only needs one thundery downpour to make this the wettest April for well over 100 years. Looking at the 10 wettest Aprils since 1900 there are hints that wet Aprils do not bode well for the following summers.
10th wettest April, 1907, was followed by a persistently cool summer with no temperatures exceeding 25C. June was wet but the other summer months were drier than average although the weather remained unsettled.
9th wettest April, 1918, was followed by a cool June, a fairly cool and very wet July, and a rather dry August with temperatures only slightly below average.
8th wettest April , 1981, was followed by a cool, but rather dry June, a rather cool but fairly wet July, and a reasonably dry and warm August.
7th wettest April, 1964, was followed by a cool and wet June, a decent July and an average August.
6th wettest April, 1998, was followed by a wet June with near average temperatures, a dry, but rather cool July, but a dry and warm August.
5th wettest April, 1924, was followed by a cool and wet summer with June and July being particularly wet.
4th wettest April, 1966, was followed by a near average June but the rest of the summer was mostly cool and wet.
3rd wettest April, 1931, was followed by a reasonable June but a poor July and a poor and particularly wet August.
2nd wettest April. 1983, was followed by a good summer with plenty of dry weather and an outstandingly warm July.
Wettest April was 2000  and was followed by a pleasant June, a cool July and a reasonable August.
Overall, out of the 10 years there were only 3 acceptable summers, although one of these was exceptionally good.
   
    

A cold April for a change

It's now half way through the month and there is every indication that we are in for a colder than average April. In fact it could be the coldest April since 1989 although a lot can happen in 2 weeks! In recent years we have had many warm Aprils. Last year there was record-breaking warmth during April and, excluding this month, the 3 warmest Aprils since 1900 have occurred in the last 5 years. Looking at the top 10 coldest Aprils in this area since 1900 the only ones in fairly recent years that have featured are 1986 and 1978. Most of the top 10 (6 entries) are made up of Aprils from the first 30 years of the 20th century. The coldest April of all was 1917. To put that April into perspective, the mean temperature was 6.0 Celsius, compared with 8.2 Celsius so far this month (last April, 2011, we had a mean temperature of 13.6 Celsius). It looks as if both the April of 1917 and this month were/are showery months, but it was noticeable that up on Hampstead Heath there were 13 days when sleet or snow was observed and grass frost occurred on 26 nights. So, the air was obviously cold, and in that year the temperature didn't rise above 15 Celsius until the very last day of the month. We' already had 16C!!

How bad is the 'drought'?

Now the hose-pipe ban been implemented the rain has started to fall, albeit in small amounts, so far! Comparisons have been made with the 'drought' of 1975/6. Comparing the rainfall figures for Kew in 1975 and Morden 2011 the totals are as follows:- Annual total Kew 1975 was 558mm. Annual total Morden 2011 was 510mm. Total from July to December (Kew) 1975 (6 months) 263mm (this included 51mm in just 1 day during September!). Total from July to December (Morden) 2011 (6 months) 268mm. For the last 3 months of 1975 the total was 108mm, in 2011 it was 123mm. The first 3 months of 1976 produced just 46mm. January to March this year has given 73mm. The '75/76 drought did not really become serious until the summer months of 1976 when days of unbroken sunshine accompanied by brisk winds, heat and low humidity conspired to reduce reservoir levels dramatically. Yes, some of the reservoirs this year are down below 50% capacity, and yes leaks from pipes are unacceptably high, but it remains to be seen if the the widespread ban on hoses is a justified precaution against water shortages, or a cynical political ploy to soften us up for the compulsory use of water meters!

Mildest March?

At the moment this is the 6th mildest March since 1900 and by the end of the month it may climb to number 4. However, the 3 mildest Marches are unlikely to be bettered this year so, at best, it will be the mildest March since 1997. In that year it was dry, drier than this March, with only 11mm of rain. The highest temperature was only 17.5C and there were 9 days when the temperature was 15C or higher; this year there have been 10 days above 15C already. In 1997 there were no days in March with maxima under 10C, this year there have been 4 so far. There were no air frosts in March 1957 and there have been 2 so far this month. And April 1997? Unfortunately it was another dry month with 12mm of rain and no significant rain from 25th March to 17th April (24 days). The other 2 very mild Marches were firstly 1957, a rather dry month with the temperature rising to 19C and with only a couple of slight frosts. This was also followed by a very dry April; and secondly the other mild March was in 1938. The highest temperature was 18C and it was a very dry month followed by an even drier April. In that year no rain fell between 2nd and 24th March (23 days) and between 4th and 23rd April (20 days). Statistically it doesn't look good for when the hose-pipe ban commences!

Spring - Full steam ahead

Just when it looked as Spring was going to be late this year the weather changed and Spring is accelerating forward. It has not been unusual in recent years for nature to get a big boost from March warmth. In the last 23 years the mean temperature for March has been 8.0 Celsius. Prior to 1989 this figure had been exceeded on only 13 occasions since the year 1900. Since 1989 there have been 14 occasions when March has had a mean temperature higher than 8.0 Celsius. So far this March (excluding today) the mean temperature has been 8.2 Celsius but the forecast charts suggest it may eventually be much higher than that. To claim a 'top ten' position the mean temperaturee has to be 8.7 Celsius or higher. This figure was last exceeded in March 2003 with a mean temperature of 9.0 Celsius. This placed March 2003 at number 6 in the list dating back to 1900. The one to beat is March 1957 (9.9C). On this day in 1957 the temperature in London exceeded 19 Celsius and even the coldest day of the month had a maximum temperature above 9 Celsius. The month was not frost-free, though. On the morning of the 4th a temperature of minus 1 Celsius was recorded.

Where are those mild early spring days?

The daffodils are in bud but so far this year there has been a shortage of those soft late winter days. In recent years it has been possible to feel pleasantly warm in the garden at some time in the late winter. Indeed, in 14 out of the last 23 Januaries there have been maximum temperatures above 13 Celsius and only 5 of the last 22 Februaries have had maximum temperatures under 13 Celsius. So far this year just one day, the 12th January, has had a temperature above 13 Celsius. This month has not had any temperatures above 12 Celsius yet, although that should all change over the next few days. A steady rise of temperature should ensure maxima in the mid to high teens around Thursday or Friday, a welcome change after the cold weather of early February. Will records be broken? Unlikely. In 3 out of the last 22 years maxima have exceeded 17 Celsius in February and on 23rd February 1990 the temperature here in Morden reached 19.0 Celsius. This exceptionally mild day in 1990 appears to be the record to beat, although the last day of February 1959 also had temperatures close to 19 Celsius in other parts of Greater London.

Not as bad as over there

Our media have been extracting the best adjectives from mothballs to describe the rather inclement weather we have been having over the last few days. True, the night before last was the coldest in February for 21 years. True, we had a burst pipe, but compared to the near continent this has been almost summery! It would be unfair to compare minima between urban areas and rural frost hollows, but here is an idea of the night-time temperatures that have been experienced at some of the airports that serve European Capitals. The lowest temperature experienced at Heathrow Airport this month has been minus 7 Celsius. Paris (Charle de Gaulle Airport) had minus 11 Celsius. Amsterdam had minus 19 Celsius...no wonder they're skating on the canals! Berlin had minus 20 Celsius, Vienna had minus 15 Celsius and Prague had minus 21 Celsius. It wasn't just central and northern Europe that had the low minima. Madrid had minus 6 Celsius, Rome had minus 3 Cel;sius and even Malta had 4 Celsius, plus 4 that is!. As the cold spell slowly comes to an end here, and even more slowly across the Channel, it can be assumed that the flowery language from the newspapers will be put to bed for another year.