The Met Office has confirmed Horsham, Crawley and Midhurst will experience a heatwave during the new few days.
A heatwave is regarded as three consecutive days that top 27 degrees Celsius.
The weather predicted for Tuesday looks set to top 30, while Wednesday could be a bit cooler at 28 degree Celsius before it goes back up to 31 degree Celsius on Thursday.
Tomorrow (Tuesday) the area could experience 99 per cent humidity in the early hours, making for an uncomfortable night's sleep.
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The Met Office has also said there will be a high UV count on the three days, with residents urged to make sure they wear sunscreen.
During a heatwave, residents are advised to stay out of the sun; cover up with suitable clothing and sunglasses; take extra care with children; keep your home as cool as possible – shading windows and shutting them during the day may help - and open windows when it is cooler at night.
You should also keep drinking fluids and if there's anybody you know, for example an older person living on their own, who might be at special risk, make sure they know what to do.