The UK is set for “plenty of sunshine” in the coming days, but the dry weather will also contribute to high levels of air pollution.

       Forecasters say Tuesday has already been the warmest day of the year so far with the mercury hitting 20.5C in Northolt, west London.

       The conditions are set to be dry and sunny across the country for the next few days before colder, wetter conditions return next week, according to the Met Office.

       People at Blyth beach in Northumberland on Tuesday (Owen Humphreys/PA)

       (PA Wire)

       However, experts also say that south-easterly winds are blowing pollutants in from Europe and the settled UK weather is contributing a build-up of “high levels of air pollution” – especially in towns and cities.

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       The UK Health Security Agency (UKHSA) is advising people to “reduce physical exertion” in areas that are particularly affected and those with lung or heart problems to “avoid strenuous physical activity”.

       Becky Mitchell, senior operational meteorologist at the Met Office, told the PA news agency: “Temperatures are rising quite quickly and there’s plenty of sunshine across the whole country today.

       “Most places are staying dry and sunny and it looks very similar for much of this week – we hang on to that sunshine.”

       Ms Mitchell added that temperatures hit 20.5C in Northolt in London, making Tuesday the warmest day of the year so far after Saturday saw 20.2C in Scotland.

       But she added: “That obviously happens quite a lot – that through March we get the warmest day of the year so far.”

       A woman next to a cherry blossom tree in St James’s Park, London (Victoria Jones/PA)

       (PA Wire)

       The toastiest two days of the current sunny spell will be Tuesday and Wednesday, when temperatures are forecast to be 20C, she added.

       “Then, as the rest of the week goes on, we’ll probably just see the high teens for many areas, so temperatures not quite as high through the rest of the week but still plenty of sunshine.”

       Ms Mitchell also said conditions will start to get “a bit more cloudy” across parts of Scotland from Thursday and colder, wetter weather will return next week.

       “As we head into next week, it will probably start off sunny and dry, but we’re likely to start to see some showers as the week goes on,” she said.

       People walk by flower beds and cherry blossom at Cannon Hill Park in Birmingham (Jacob King/PA)

       (PA Wire)

       “It will be turning a little bit more unsettled and also, it will be a little bit colder as well.

       “Temperatures are way above average this week but they’ve going to be a little bit below average by the end of next week,” she added.

       Ms Mitchell also warned that air quality is “looking quite low”, especially in northern and eastern areas of the country as well as towns and cities.

       People at Blyth beach in Northumberland (Owen Humphreys/PA)

       (PA Wire)

       “High levels of air pollution (are) expected in the next few days,” she said.

       “That’s because we’ve got light south-easterly winds and that’s just dragging in pollutants from the continent.

       “And I think because we’ve got very settled weather and it’s not particularly windy, it just means pollution levels can build up over a long period of time.”

       A UKHSA spokesperson said: “Many parts of the country have recorded/are forecast to have very high levels of ambient air pollution.

       “UKHSA is advising people in those areas to reduce physical exertion, particularly when outdoors and especially if they experience symptoms such as a cough or sore throat.”

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       “Adults and children with lung problems, adults with heart problems, and older people, in areas where high levels are recorded should avoid strenuous physical activity.

       “People with asthma may find they need to use their reliever inhaler more often.”