Updated 18th April 2017 - Covering the period 24th April - 16th May
Mean temperatures will be about 0.5C above the 1981-2010 normal over most of the country but nearer 1C above in Northern Ireland, Wales and western England.
Rainfall totals will be near normal over most parts of the UK, with a dry start to the period offset by wetter conditions late on, but in northern Scotland the reverse will be true, with a relatively wet start and drier conditions setting in later in the period. Northern Ireland, however, will generally be wetter than normal.
Sunshine totals will be near to slightly above normal in most parts of the UK, owing to plentiful sunshine during late April and the first few days of May, but in Northern Ireland, north Wales and
north-west England there will be a slight shortage of sunshine.
Monday 24th April to Sunday 30th April
This will be a mostly cool week with northerly and north-westerly winds, but it will turn warmer towards the end of the week with high pressure building across the south of Britain.
Fronts will move southwards across the UK at infrequent intervals between the 24th and 28th, interspersed with cold bright weather with northerly and north-westerly winds. There will be some scattered rain and hail showers mainly for eastern and northern parts of the UK, and there will be snow over high ground in Scotland and northern England but it is unlikely to get cold enough for widespread snowfall on low ground. Sunshine will be quite plentiful, especially in western parts of the country. Following a very warm first half of the spring, gardeners should take care due to the possibility of some damaging late frosts.
By the 29th and 30th we can expect high pressure to build across southern Britain with a changeable westerly type affecting the north, chiefly the northern half of Scotland, and this will bring near-normal temperatures, probably rising a little above normal by day in the south, but with southern areas also prone to chilly nights and some ground frost.
Temperatures during this period will be 1 to 2C below the 1981-2010 long-term average over much of the country, but less than 1C below in Northern Ireland and in the south-west.
It will be drier than average except in northern and eastern Scotland, where rainfall totals will be close to or just above normal. Some eastern parts of England will have close to average rainfall. It will be much drier than normal in the south-west.
Sunshine will be below normal in northern Scotland but generally above normal elsewhere, especially in the west.
Monday 1st May to Sunday 7th May
It will start dry and settled for most with high pressure in charge, although frontal systems moving around the northern flank of the high will bring cloudier conditions and occasional light rain at times for north-west Scotland. Later in the week it will turn more unsettled from the west but it will be generally warm with southerly winds blowing more frequently than usual. Eastern areas will have the longest periods of dry bright weather, with a marked Atlantic trough bringing frequent cloud and rain to Northern Ireland, north-west England and western Scotland.
Mean temperatures will be about 2C above the long-term average across much of the country. It will be drier than normal in eastern Britain, especially so in north-east Scotland, but rainfall totals will be close to or rather above normal in most western areas. Sunshine totals will generally be above normal in the east but near to slightly below in the west, with the totals generally boosted by a sunny start to the week.
Monday 8th May to Tuesday 16th May
Southerly winds will continue to blow more frequently than usual during this period, but towards mid-May easterly winds are expected to feature prominently, especially in the north. Temperatures will tend to be closer to normal during this period, typically about 1C above in most parts of the UK but very close to normal along North Sea coasts due to frequent onshore winds. Rainfall totals are expected to be above normal in most parts of the UK with low pressure and fronts often close by, and the possibility of some thundery outbreaks in the south as well. However, it is expected to be drier than normal in the northern half of Scotland and near North Sea coasts. Sunshine will mostly be a little below normal but sunshine totals will be above normal in north-west Scotland.