England, east Wales, and eastern Scotland look most at risk of thunderstorms.
The Met Office has issued another thunderstorm warning for those areas, with 30-40mm of rain possible in less than an hour – and perhaps as much as 80mm.
Localised surface water flooding is possible, with frequent lightning and hail.
Tuesday looks fresher but there will be further showers, although they should be lighter than Monday.
From the middle of the week, it looks like northern areas will be mainly dry, while southern parts will keep the risk of showers.
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Increasing heat and humidity into the weekend in the south may bring the chance of thunderstorms again.
Into the following week, settled conditions could become more widespread – but only a few days ago this week was looking more settled so things may change.
From around the middle of the month, a mobile westerly wind is more likely, with spells of wind and rain possible.
Northern and western parts are likely to be wettest, while the south and east are set to be driest.
But that is a long way off meteorologically speaking.
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