Updated 17th January
Covering the period 23rd January - 14th February
Mean temperatures will be between 1 and 2C above the 1981-2010 average across much of the country, but East Anglia and south-east England may end up less than 1C above.
Rainfall totals will be below normal in the east of both Scotland and England, and above normal in Northern Ireland, and near average rainfall is most likely elsewhere.
Sunshine totals will be below normal in Northern Ireland and a little below normal also in Wales and south-west England, and above normal in eastern England, while elsewhere close to average sunshine is most likely.
Monday 23rd January - Sunday 29th January
This will feature generally high pressure to the east of Britain and Atlantic weather systems making only slow headway against the blocking high. However, some of these systems will make it across the British Isles, resulting in a wetter and less settled week than the previous week.
On the 23rd and 24th a frontal system with associated cloud and rain will move slowly eastwards across the British Isles, but by the time it reaches eastern England on the 24th, rainfall amounts will generally be small. Elsewhere, however, the slow-moving tendency of the rain belt will result in fairly large rainfall totals, about 10-20mm quite widely. Higher ground (above about 300m) can expect mostly snow from this system. To the east of the front it will be dry, cloudy and quite cold, whereas to the west it will be sunny with near average temperatures.
Following a dry and sunny interlude, frontal systems will again make slow progress in from the west between the 25th and 27th, again with some snow over high ground. However, the end of the week will be much milder with a south-westerly flow. High pressure will remain close to the south-east, keeping the weather relatively dry for central, southern and eastern England and south and east Wales, but for much of Northern Ireland, Scotland and north-west England, weather systems will bring frequent cloud and rain off the North Atlantic.
Mean temperatures will be about 1C above the 1981-2010 long-term average for much of the country, due to the mild end to the week (until the 26th temperatures will if anything be a little below average).
Rainfall totals will be below normal in the north and east of Scotland and close to or rather below normal in eastern England, but generally above normal elsewhere, mainly due to the slow-moving nature of some of the frontal systems.
Sunshine totals will generally be rather below normal, the clearer interlude between weather systems on the 24th-26th providing the only significant sunshine this week.
Monday 30th January - Sunday 5th February
This period will begin with changeable south-westerlies, but with high pressure often close to the south-east. As the week progresses, the high pressure will tend to extend further north, resulting in quieter conditions spreading northwards and to a lesser extent westwards across the British Isles. It will be generally mild with south-westerly winds, and rain belts will frequently affect north Wales, Scotland, Northern Ireland and north-west England, although rainfall amounts to the east of high ground will tend to be small.
Mean temperatures will be 2 to 3C above the long-term normal in most parts of the UK, but the north and west of Scotland and Northern Ireland will be nearer 1C above and there is also a chance of some colder continental air spreading into south-eastern Britain towards the end of the week, resulting in an anomaly nearer 1C in south-east England.
Rainfall totals will be above normal in northern and western Scotland, Northern Ireland and Cumbria, and near average over much of Northern Ireland, Wales and western England, but for central and eastern England and eastern Scotland it will be drier than normal.
Sunshine totals will tend to be below normal in the west, particularly Northern Ireland, but above normal in central and eastern parts of England.
Rest of the month
Monday 6th February - Tuesday 14th February
Southerly winds will be frequent this week, with high pressure remaining extensive to the east but the chances are that the weather will turn more changeable and wet from the west towards mid-February. These southerly winds won't necessarily be particularly warm because they will pull some colder air in off the continental European land mass, and so temperatures early in the week are likely to be close to or just below normal in central and eastern Britain, with some overnight fog and frost. As we pick up a stronger North Atlantic influence late in the period, it will become mild again.
The mean temperature for this period will be about 2C above average in many western parts of the UK but less than 1C above in eastern England. Although rainfall amounts will be small early in the period, it may turn rather wet towards mid-February and so there is significant uncertainty over rainfall anomalies, but broadly speaking it will most likely be drier than average in the east, but with close to or rather above average rainfall over Northern Ireland, Wales and western parts of England, and near or rather below average rainfall in western Scotland. Sunshine totals are expected to be mostly above normal except in Northern Ireland, Wales and south-west England.