People with Asthma are being warned they are at high risk of having an attack this week as the weather heats up again.
The humid weather is the perfect growing conditions for deadly fungal spores.
Those with asthma are being warned to keep up their medications and speak to their doctors about taking an antihistamine too.
Research has shown that moulds and fungi can have a big impact on asthma symptoms, with 42 per cent of asthmatics finding mould spores a trigger for them.
Dr Andy Whittamore, Clinical Lead at Asthma UK and a practising GP told Sun Online: “High levels of mould and fungal spores in the air this week could affect more than two million people with asthma, triggering a potentially life-threatening asthma attack.
“Mould, which is common in autumn as it grows on rotting logs and fallen leaves and because of the damp weather, can be released into the air and trigger asthma symptoms for those allergic to it such as cause coughing, sneezing or watery eyes.
“If you have asthma that is triggered by mould make sure you take your preventer inhaler (usually brown) as prescribed and keep your reliever inhaler (usually blue) with you at all times.”
The weather is set to be changeable today, with rain across the country, but temperatures are set to soar back to 23C at the weekend.
East and central England are expected to be hardest hit by downpours today as rainfall lashes large swathes of the country.
However, sunshine is likely nearly everywhere tomorrow and Wednesday should bring another bright day, with the exception of Scotland where showers and cloud are probable.
Wales and south, south-east, south-west, central and east England will bask in sunshine on Thursday morning, while Northern Ireland is also set to enjoy the rays in the afternoon.
Friday is set to be another sunny treat as the mercury shoots up to 21C.
However, temperatures will peak on Saturday and Sunday, reaching 23C on both days, according to Weather Online.
Met Office five-day weather forecast
Low cloud will edge southwards across southern areas, with patchy light rain and drizzle. Cooler conditions following, with scattered showers in the far north. The showers could be heavy at times and it will be windy across northeast Scotland.
The low cloud and drizzle will slowly clear southern England. Isolated fog and low cloud will follow but there will be clear spells elsewhere, with a patchy rural grass frost.
Any fog will clear to a widely sunny day, with light winds. It will be sunniest in the south and southwest but there will be showers in the far north.
Outlook for Wednesday to Friday:
Staying mostly settled, with light winds and sunny spells. Some rain and drizzle in the north at times and chilly nights. Becoming warmer, but with increasing morning mist and fog.