An amber extreme heat warning issued by the Met Office has been extended, with forecasters now expecting temperatures in parts of England to climb as high as 38C (100F) next week.
The updated alert will run from 01:00 BST on Monday until 23:59 BST on Thursday, as confidence grows that very hot and humid conditions will persist through midweek.
The warning covers large parts of England and Wales, although northern areas are only included from Wednesday into Thursday.
Officials say the alert signals likely widespread disruption, including serious risks to health, strain on infrastructure, and significant impacts on daily life.
Daytime highs are expected to surpass 30C (86F) across much of the affected region, with some locations potentially peaking at about 38C (100F).
Night-time temperatures are also forecast to remain unusually high, particularly in urban centres where values may not drop below 20–21C (68–70F), creating so-called tropical nights.
The hot spell is being driven by a surge of heat moving north from continental Europe, where an intense heatwave has developed.
In western France, temperatures could reach 43–44C (109–111F) in the coming days, while Paris may hit 40C (104F), a level described as unprecedented for June.
Heatwave conditions intensify
A heatwave is formally declared when temperatures exceed a location-specific threshold—typically between 25–28C (77–82F)—for at least three consecutive days.
An amber warning already in place for Monday and Tuesday will take effect early Monday across parts of England and Wales, with expected highs in the low to mid-30Cs.
The alert will expand further on Wednesday and Thursday, extending northwards into areas including Manchester and north Wales, as well as westwards towards Plymouth.
By Tuesday, mid-30C temperatures are expected to become more widespread, with some regions also experiencing overnight readings above 20C.
Residents can view detailed local forecasts via the BBC Weather website and app.
High UV and pollen levels are also expected across many areas.
Widespread disruption expected
According to the Met Office, adverse health effects are likely not only for vulnerable groups but across the wider population.
It warned that significant adjustments to working conditions and daily routines may be necessary, while heat-sensitive systems and infrastructure could also be affected.
Transport networks and energy demand are expected to come under pressure, and authorities have raised concerns about increased water-related incidents as more people seek relief at beaches, rivers and lakes.
The UK Health Security Agency has also issued heat-health alerts across parts of England.
How long will it last?
Hot conditions are forecast to continue at least until Thursday across much of England and Wales.
In some areas, temperatures above 30C may persist for several days, with overnight warmth remaining unusually high.
The Met Office says cooler air may begin to move in from the west later next week, though the timing and extent of any change remains uncertain.
Scientists continue to link the growing frequency and severity of such heatwaves in the UK to human-driven climate change.
Pollen levels also high
Very high and high pollen levels are expected across much of the UK over the coming days.
Wales, the Midlands and southern England are likely to experience very high grass and weed pollen counts, while northern England and Northern Ireland will see generally high levels. Scotland is expected to remain comparatively lower.
The Met Office noted, “has no data to support the claim that pollen is ‘worse’ this year”, adding that pollen levels vary depending on seasonal timing and the types of pollen currently in circulation.
