Portsmouth weather: Hour by hour forecast amid high temperatures and Met Office thunderstorm and heat warnings

The alert covers Portsmouth, Hampshire, London and much of the south east of England. “Whilst many places will stay dry, a few thunderstorms are likely to break out on Wednesday,” the forecaster said.

“These are possible at any time, but become more likely during the afternoon and evening. Where these occur, 20 to 30 mm of rain is possible within an hour, and perhaps as much as 50 mm in two hours; the latter more likely across south east England and parts of East Anglia during the evening. Lightning will be an additional hazard.”

The thunderstorm warning is in place between 12pm today and midnight tomorrow (August 1). A yellow heat health alert will also be in place amid the rising temperatures. The Met Office said “significant impacts are possible across the health and social care sector due to the high temperatures”. BBC Weather predicts that it will be sunny with a gentle breeze.

Hour by hour Portsmouth forecast

8am - sunny intervals - 20C - 20 per cent chance of rain

9am - sunny intervals - 22C - 10 per cent chance of rain 10am - sunny intervals - 23C - 10 per cent chance of rain 11am - sunny intervals - 24C - 10 per cent chance of rain 12pm - sunny intervals - 25C - 10 per cent chance of rain

1pm - sunny intervals - 26C - 10 per cent chance of rain 2pm - sunny intervals - 26C - 5 per cent chance of rain 3pm - sunny intervals - 26C - 5 per cent chance of rain 4pm - sunny intervals - 26C - 5 per cent chance of rain 5pm - sunny intervals - 26C - 5 per cent chance of rain 6pm - sunny intervals - 25C - 5 per cent chance of rain 7pm - sunny intervals - 24C - 5 per cent chance of rain 8pm - sunny intervals - 24C - 5 per cent chance of rain 9pm - sunny intervals - 23C - 5 per cent chance of rain 10pm - sunny intervals - 22C - 10 per cent chance of rain 11pm - sunny intervals - 21C - 20 per cent chance of rain