The temperature in southern England could hit 27C (81F)
later this week making it the highest temperature recorded in April since 2018.
Warmth and sunshine will develop widely across most areas of
the UK as high pressure gradually builds.
Lack of rainfall however, will again raise concerns about
potential wildfires.
The last time the temperature rose to 27C in April was in
2018 in Cambridge.
How widespread will the warmth be?
Runners of the London and Manchester marathons will likely
tell you that it was already warm on Sunday, with the those pounding the
streets of the capital experiencing the fourth-warmest London Marathon in its
history.
The week begins with temperatures across England and Wales
already hitting 19-24C, with much of Scotland and Northern Ireland around
16-19C under slightly cloudier conditions. Some patchy rain likely in
north-west Scotland, too.
However, as sunny skies develop more widely, the combination
of strong sunshine and light winds will help temperatures to peak on either
Wednesday or Thursday, and be the highest of the year so far in each of the
four nations.
23C is the expected high in parts of Scotland and Northern
Ireland, 25C in Wales and 27C in England.
London, the Home Counties and Cambridgeshire are the areas
expected to record the warmest of the conditions.
With sea temperatures around the UK still relatively low at
the moment, coastal areas where sea breezes develop will feel cooler, but UV
levels will remain high.
Is this a heatwave?
Whilst the upcoming spell of warmth is significant, with a
number of areas seeing temperatures 10 degrees above what we'd usually expect,
it is not technically going to be a heatwave in meteorological
terms.
For this, we would need to see at least three consecutive
days at or above the "heatwave threshold" which varies depending on
where you are in the UK.
Do be prepared for high levels of UV, as the sun
is as strong this time of year as it is in August.
If you're a hay fever sufferer, another feature of the warm
and sunny weather will be an increase in pollen levels.
How unsual is the warmth?
While this will be the warmest weather of the year so far
and the warmest since early September, April can bring big swings in
temperature and it is not unusual to see this type of hot spell during spring.
The highest April temperature ever recorded is 29.4C which
was reached in London on 16 April 1949.
As our climate continues to warm though, we expect this type
of spring heat to occur more often. Recent analysis found that spring is
the fastest-warming season in the United Kingdom.
Concerns surround the lack of rain
Despite some occasional downpours, spring has been
incredibly dry so far this year for a number of areas.
In a large swathe of central southern England many have seen
only around a fifth of the rainfall they would normally expect to receive since
the start of March.
For inland areas of North Yorkshire there has been close to
a quarter of the normal rainfall which has had an impact on river levels.
According to the latest rainfall and river flow
summary, external by the Environment Agency, river levels quite
widely across the north-eastern quarter of England are classed as "notably
low" or "exceptionally low".
The ongoing dry conditions also mean that fire services
across the UK will be on high alert for further wildfires.
A study of satellite data by the OceanNewsUK shows that the area of
the UK burnt by wildfires so far this year is already higher than the total for
any year in more than a decade.
Another potential drawback to the warm, sunny and calm
conditions will be the build up of pollutants in the atmosphere. Defra and Met
Office air pollution forecasts, external for the week
shows moderate pollution levels quite widely across the UK by Wednesday,
especially for England and Wales.
How long will it last?
With the May Bank Holiday on the horizon I think you may
know the answer to this one.
Later in the week, as high pressure gradually diminishes a
shift in wind direction to the north or north-west will bring cooler air
southwards for the start of the weekend.
However, while temperatures will drop for all, they will
still remain at or above average for the time of the year. At the moment, the
start of the weekend looks dry to, but there are hints that low pressure could
bring showers and cooler conditions by the end of the long weekend.
