London will join all of England in enjoying another warm day on Tuesday, then it's back to reality.
Above-normal warmth has graced London every day so far this May, including Monday, a streak that will not only continue, but also peak on Tuesday.
Temperatures on Tuesday are expected to reach 21 degrees (C, 70 degrees F) in a city where a high of 15.6 degrees (C, 60 degrees F) is more common this time of year.
All of southern England will experience highs of around 20 degrees (C, 68 degrees F) on Tuesday, while highs will range from 16 to 18 degrees (C, 61 to 64 degrees F) across the northern half of England and Wales.
Residents, however, should not get used to the warmth.
After a few showers lightly dampen parts of England Tuesday afternoon, the passage of steadier rain Tuesday night and Wednesday will open the door for cooler air to come rushing in.
Temperatures in London on Wednesday will be held to 16 degrees (C, 61 degrees F), then to 12 degrees (C, 54 degrees F) on Thursday. Brisk winds will add to Thursday's chill.
While the cooler air invades England, the opposite will take place across eastern Europe with unseasonable warmth set to expand.
Temperatures will reach or exceed 27 degrees (C, 80 degrees F) across a large portion of eastern Europe, including in Warsaw, Poland, and Kiev, Ukraine, Wednesday and/or Thursday. Moscow, Russia, will approach that mark on Friday.