Parts of the UK will be as hot as Barcelona this week as the Indian Summer continues after temperatures temporarily dropped below freezing in places yesterday.
The Met Office predicts that temperatures will rise to 24C in London on Saturday afternoon, making it as hot as Barcelona.
The mercury will gradually creep up over the next few days, from 19C today, to 20C tomorrow and 22C on Thursday and Friday, according to Weather Online.
The majority of the country will enjoy unseasonably sunny weather, although there could still be flooding in some areas as well as mist and fog.
The warm weather is a welcome relief from last night's rather chilly conditions, with temperatures dropping to -0.1C in Hexham, Northumberland, yesterday .
However, the weather will not be perfect for the whole country today, as the Environment Agency has warned of possible flooding along East Yorkshire's North Sea coast and the Humber estuary.
Fog and mist is also expected on Friday morning in Northern Ireland, west Scotland, north Wales and north-east, north-west, central and East England.
A spokesman for netweather.tv said: "By Thursday, instead of the high teens being the max, some parts at least will head up into the low-twenties.
"Not too bad for the second half of September. One thing we'll have to watch out for all week, and particularly from Wednesday night onwards is the threat of some mist and fog patches developing. A few of these may be slow to clear into the mornings too.
"One exception to the fine, dry rule will be the far north and north-west of Scotland, as fronts just brush in at times bringing some extra cloud and mostly patchy rain. Even here the picture should improve after midweek though."
A Met Office spokesman said: "High pressure will dominate this week bringing warm days but chilly nights. Through midweek some rain will affect Scotland but later in the week the high drifts eastwards dragging in warmer air in time for the weekend."
Temperatures peaked at 26.5C in Cambridge last September, according to the Met Office.
Met Office five-day weather forecast
After a chilly start, most of the UK will have a dry day with light winds and a lot of sunny spells. The only showers will be in the Northern Isles, though even here the overnight wind will die down.
Much of the country will have another dry and clear night though low temperatures will cause a few mist patches to form. Cloud and rain will move into northern Scotland.
Wednesday will start off chilly, but once again warm sunshine will dominate for the rest of the day. Skies will be cloudier in northern Scotland with some outbreaks of rain.
Outlook for Thursday to Saturday:
The UK will have more fine weather over the coming days with chilly nights and warm days. Rain and stronger winds may move into western parts at the weekend.