An anticyclone positioned directly over Britain is expected to bring warm and stable climate before making way for the remnants of Storm Boris, which caused severe flooding in Central Europe.
The high pressure system moving across the British Isles will ensure dry and warm conditions early in the week.
However, forecasters predict the anticyclone will shift northwards, allowing rain from Storm Boris to hit southern England and Wales midweek and into the weekend.
Severe flooding in Central Europe has prompted some countries to declare a national emergency.
For now, the large anticyclone will dominate much of the UK, bringing fine, dry weather.
Most areas will remain warm, although a northerly breeze in Kent could bring occasional showers.
NetWeather meteorologist Terry Scholey said temperatures would range from 15 to 18C in the north and 20 to 22C in the south through Thursday.
By mid-week, as the anticyclone moves northwards, rain is expected to hit southern regions, while northern areas are expected to remain largely dry.
Overnight temperatures will remain cool, with a northeasterly breeze developing in the southeast, potentially bringing cloud cover, particularly along the North Sea coasts.
Scholey said: “Lower temperatures of 5-8C, but below that in some rural valleys in the north and west, perhaps giving a touch of frost again for a brief period at dawn.
“Much of the country remains in good, dry weather mid-week, but later, and more particularly at the weekend, the threat of rain from the south becomes more acute.
“An easterly or northeasterly wind will also increase, bringing fairly gusty conditions and varying amounts of cloud to the east and south.”
THE Met Office said some of the rains in the south could be heavy and thundery.
A spokesperson said: “Over the weekend, similar conditions will prevail across the north of the UK, while southern parts see an increasing chance of showers, some of which may be heavy or thundery. Over the coming week, while the threat of showers remains in the south, high pressure may well re-establish itself from the north with settled conditions becoming more prevalent once again, albeit cooler than earlier in the period.”
Tonight and tonight:
Cloud and patchy rain in the far north of Scotland. Some cloud in the south-east later, but clear spells elsewhere with patchy mist and fog, particularly in parts of north-east England. Cold in places, especially in rural areas.
Tuesday:
A good start for most, with any fog clearing by morning. Cloudier in the far north with some drizzle. Sunny elsewhere and feeling warm.
Forecast for Wednesday to Friday:
Mostly fine for most of the week, although a developing easterly breeze may introduce patchy clouds. Risk of showers through Friday in central and southern areas. Warm to sunny.