Mostly cold, dry and sunny except for the SW

At present we have high pressure developing on top of Britain. Thus after a cold bright day on the 1st with a scattering of wintry showers, most parts can expect plenty more sunshine on the 2nd, 3rd and 4th, with sharp night frosts but with daytime temperatures rising to between 7 and 10C in most places, with 11-12C locally. However, south-east England and East Anglia will be cooler with some patchy cloud on the 3rd and 4th due to a light easterly off the North Sea. Ireland will become cloudy and wet on the 3rd due to an Atlantic system moving slowly east, and this will bring some more cloud into south-west Wales and south-west England for a time, but it will fizzle out on the 4th.

A low will move down the North Sea on the 5th bringing cloud and rain down the eastern side of Britain, but it will remain dry and quite sunny in the west, with some high cloud from the frontal system to the east. Central areas will be cloudy and dry. On the 6th and 7th there will be a brief easterly incursion over England, which will bring some snow and hail showers into East Anglia and the southeast, though significant accumulations of snow are expected to be confined to Kent and Sussex. Elsewhere it will be dry and sunny, top temperatures between 5 and 8C for most, but only 3-5C over East Anglia and the southeast.

The second week will see high pressure gradually retreat north-westwards, so the early part of the week will stay dry, sunny and cold in western areas but it will become cloudy in the east with a chilly northerly wind. The latter part of the week will see colder air spread down from the Arctic with a scattering of hail, sleet and snow showers for central, northern and eastern regions.

I expect Atlantic systems to push up from the south-west during the third week. Northern Scotland should hold onto cold bright weather for most of the week but I expect an abrupt rise in temperature elsewhere, and large amounts of rain in the south-west in particular. Although the emphasis is likely to be on cloudy murky south-westerlies, I expect a brief interlude of mild sunny weather in much of eastern England as high pressure briefly builds to the SE, bringing temperatures into the mid teens.

Into the 4th week I expect this milder interlude to be replaced with a return of colder, quieter weather with high pressure nearby promising dry weather and increasing amounts of sunshine. I predict a March 2010 CET of 5.6C, which will make it the 4th consecutive month with below average temperatures. Temperatures are likely to range from 2C below the long-term mean in parts of Scotland to 0.5C above locally in the south-west, with most intervening areas about 1C below.

Most parts of the country will have a dry sunny month, with sunshine excesses of 50-70% in western Scotland and Cumbria, and rainfall deficits of 40-60% in north-west Scotland. However, rainfall will be up to 40% above average in southern England, particularly the south-west, and I envisage a 10-20% shortage of sunshine in south-west England and south Wales. Averaged nationally rainfall will be about 20-30% below normal and sunshine about 30% above.

Forecast update issued by Ian Simpson (aka Thundery wintry showers) on 2 March 2010.