Many of us will have found it unbearably humid at night over the past few days – here’s exactly why. The UK’s national forecaster said a number of reasons have led to the current humid spell.
Part of the recent heat is because soil has been dry, with Spring producing 50 per cent less rainfall than average, in some parts of the country. And when soil gets wet part of the sun’s energy goes into evaporating moisture. But when it’s dry, more of that energy goes directly into heating the air, making temperatures soar.
Another reason however are sea surface temperatures, which are ‘without a shadow of a doubt’ the result of global warming, according to Jim Dales of the British Weather Services. This is because seas surrounding the country are currently significantly warmer than average.
This warm water helps to keep the air warmer, especially when winds bring air in from over the sea. It’s worth noting the UK tends to be more humid than other inland areas as we’re an island, but the heightened temperatures mean the air carries more moisture.
And when there is more moisture in the air, sweat doesn’t evaporate as much and it’s therefore harder for our bodies to cool down. More terrifyingly, as the climate gets hotter, the atmosphere will be able to hold more water vapour, increasing the likelihood of both extreme heat and high humidity.
When will the humid nights end?
Although the humid nights are going to be intermittent, we won’t have long spells of cool evenings until Autumn, Jim Dales added. He said: “In terms of this week, the south will dip in and out of the showers for the most part.
“But the humidity wont go too far too quickly in terms of the south simply because we don’t get a northerly wind at all, and we stay with the showers on occasions for the most part. Progressively it will get less humid than it is now because the low pressure will eventually move away and we’ll get a slight more push for the Atlantic.
2The humidity will temporarily die down as the week goes on, the south lagging behind and will be the last to get the humid nights out of the way..”
London weather
Tonight: Any lingering showers soon dying out to leave brief evening sunny spells. Further heavy, perhaps thundery, showers arriving in southern parts, spreading north overnight. Rather breezy on southern coasts. Minimum temperature 14 °C.
Monday: A cloudy start with heavy showers, thundery at times. Brighter spells developing, particularly in the west, as showers become confined to eastern areas during the afternoon. Windy on southern coasts. Maximum temperature 25 °C.
Outlook for Tuesday to Thursday: A mixture of drier periods with sunny spells but also scattered showers or spells of rain. There is a risk showers could be heavy, thundery and slow-moving at times.
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Today (Saturday, July 19) – H23C L17C, yellow weather warning.
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Sunday, July 20 – H24C L16C, heavy rain changing to sunny intervals in the afternoon.
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Monday, July 21 – H25C L17C, yellow weather warning.
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Tuesday, July 22 – H24C L16C, sunny intervals changing to cloudy by late morning.
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Wednesday, July 23 – cloudy changing to light showers by late morning.
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Thursday, July 24 – H25C L17C, sunny intervals.
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Friday, July 25 – H27C L17C, sunny intervals.
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