THE Met Office has issued yellow heat health alerts for most of England - with temperatures set to hit 30C in just days.
Forecasters have warned of a likely "increase in mortality across the population" from tomorrow until Thursday.
The heat alerts will be in force for every region of England except the north east, which is covered by a green alert.
OAPs and people with health conditions are most at risk, but young people could also suffer in the heat.
Met Office expert Dan Rudman said:"Fine conditions will return today for the beginning of next week.
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"For much of the UK this will be accompanied by a boost in temperatures with many places reaching the mid-20°Cs.
"Some central and southern areas are likely to see temperatures approaching the values needed for heatwave conditions.
"Heatwave conditions need to remain in situ for three consecutive days.
"By the beginning to middle of next week it is possible that some parts of the UK could be reaching heatwave thresholds.
"Whether or not everyone experiences heatwave thresholds, most of the UK will experience the highest temperatures so far this year."
RNLI water safety boss Samantha Hughes said: "The forecasted warm weather will mean we’ll see more visitors at the coast."
Samantha added: "We at the RNLI always want people to enjoy themselves safely.
"Entering the water during warm weather can increase the risk of cold water shock due to the sudden changes in skin temperatures.
"Enter the water gradually and avoid jumping or diving straight in to reduce your risk of cold-water shock.
"If you’re planning on heading to the beach, we highly recommend you visit one that is lifeguarded.
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"Swim between the red and yellow flags - this is the safest area and is most closely monitored by lifeguards.
"If you get into trouble in the water, Float to Live. Tilt your head back with ears submerged and try to relax and control your breathing.
"Use your hands to help you stay afloat and then call for help or swim to safety if you can.
"In an emergency at the coast, call 999 or 112 and ask for the Coastguard or ask for the fire service if you are near inland waters."
