THE Met Office has issued a weather warning for Portsmouth and much of the south today.
Slow moving thundery showers may lead to torrential downpours with the risk of frequent lightning.
It is due to warm, moist air spreading up from the continent.
The Met Office warning said some locations could see 30 to 40 milimeters in an hour.
Where this falls on urban areas or main roads it could cause disruption to transport and possibly to power.
The main risk period is during the afternoon and early evening, though a few thunderstorms are likely to rumble on into the night.
While many places will miss them, there is the risk of flash flooding.