Last week The Met Office published two yellow-level weather alerts for Monday August 10 and Tuesday August 11.
These warnings are in place for most of the UK, including Portsmouth and Hampshire.
On Sunday two more weather warnings were issued for Wednesday and Thursday, with each alert in place for the whole of each day.
On its website, the Met Office says: ‘Some places are likely to see severe thunderstorms early next week - but there is significant uncertainty in location and timing.’
However the forecasting service warns the storms could potentially affect all parts of the UK at some points during this period.
It also warns that there is a small chance that homes and businesses could be flooded quickly, public transport could be affected, and there is the possibility of difficult driving conditions and power cuts.
The thunderstorms would follow the heatwave which is set to last the rest of the weekend.
Temperatures of more than 30C were recorded in Portsmouth on Saturday as large numbers of people headed to the seafront.