A battle between a "Bermuda" heat dome and stirring Atlantic storms will trigger an eruption of thundery downpours.
A huge high-pressure system nudging Britain, the "Azores High" also called the "Bermuda High", is at war with cyclonic lows spinning near the coast.
Usually the trigger for clear skies and soaring temperatures, this high pressure is being stifled by storm-spawning sea waters.
Britain will instead turn into a steamy hot tub with rising humidity and temperatures in the mid-20Cs.
Low pressure to the west battles the high
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Met Office meteorologist Tom Morgan said: “The best of the weather on Tuesday looks like being across the northwest of Scotland where we should have a largely dry day, otherwise there is a lot of cloud across the UK with outbreaks of rain and drizzle spreading south.
“We could spark off some fairly heavy showers and perhaps the odd thunderstorm, but it will certainly be a very humid day, particularly in the south, and in the sunshine, it will be quite warm with temperatures in the 20Cs.
“We are going to see the weather settle down, and that is due to a large area of high pressure, the Azores High, ridging towards the UK.”
The Azores High, the driver of heatwaves through the start of summer, is ebbing and flowing off the UK southwest coast.
Warmth and humidity rises from the west
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To the northwest, weather fronts trailing from low-pressure storm systems are battling it into retreat.
Sun-seekers hoping for a heatwave in the next week will be disappointed with a changeable picture promised.
Jim Dale, meteorologist for British Weather Services and co-author of ‘Surviving Extreme Weather’, said: “The Azores High is still stuck to the west of the UK, but we are just on the edge of it, so it is not going to bring anything in the way of real heat.
“We would need the Azores High to be further over the UK to bring the dry and hot weather that we saw earlier in the month.
“Instead, the outlook is for cloudy and humid conditions and temperatures in the 20Cs through this week.
“There will also be a risk of some rain or perhaps heavier downpours, and with the humidity, a risk of thunder.”
Temperatures across southern Britain will hover in the mid-20Cs this week and slightly lower further north.
Cloudy skies and humidity will make it feel warm and muggy with the risk of heavy downpours mid-week.
A battle between a 'Bermuda' heat dome and stirring Atlantic storms will trigger an eruption of thundery downpours
|NETWEATHER
Met Office meteorologist Ellie Glaisyer said: “It is quite a cloudy and damp start, particularly across the northwest on Tuesday morning.
“An area of rain continues to slip south and eastwards as we go through the morning, and it turns more showery as we go through the afternoon, and we could see some heavier downpours.
“Temperatures will be 23C or 24C in the south, but with more cloud and moisture around it will feel more humid and more muggy.
“There are further showers and longer spells of rain on the cards as we go through this week.”