A ‘pollen bomb’ is set to strike the UK this weekend with hayfever sufferers being warned to keep any necessary medication close by.

A yellow heat health alert has been issued by the UK Health Security Agency as temperatures could nudge close to 30C in some areas by Saturday as a result of a warm plume of air being driven in from France.

However the sudden onset of very warm weather – which is predicted to bring with it some thundery showers – could combine to create uncomfortable and potentially dangerous conditions for those who suffer from pollen allergies and asthma.

Grass pollen is now in peak season, says the Met Office with counts expected to reach ‘very high’ levels as the air temperature warms up over the coming days.

Red, sore, watery, itchy eyes, a runny or blocked nose, sneezing and coughing are all symptoms for allergy sufferers - while those with hayfever and asthma may also notice shortness of breath and wheezing.

Asthma UK says around 95% of people’s hay fever is triggered by the current grass pollen, which tends to be highest between mid-May and July.

But high pollen levels, warm weather and the addition of thunderstorms, can pose a triple threat for people with asthma and puts them at greater risk of having a life-threatening attack.

Met Office spokesman Grahame Madge told the PA news agency there were some uncomfortable days ahead for sufferers.

He said: “We are now getting into grass season. With it being so dry across the UK, it means grasses are able to shed pollen.

“For sufferers, hay fever has been a feature of the last few days and will continue to be a feature for sufferers over the next few days and weeks.”

Only significant and heavy rainfall, he says, would wash such high pollen levels from the atmosphere and until then sufferers should continue to take all necessary precautions.