The Met Office said it reached 31C on the south coast, and thousands of people made the most of the hot weather by heading to the beach and parks.
As lockdown restrictions have been eased, it has meant Portsmouth’s seafront has become busier as sunseekers try to make the most of the heatwave.
But will the sunny weather continue this week?
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The Met Office has issued yellow-level weather warnings for thunderstorms over the next four days, which could cause some localised flooding and travel disruption.
But although the warnings cover the whole of the country, forecasters have warned that there is ‘significant uncertainty in location and timing’.
In Portsmouth, there is little sign of the weather cooling down over the next few days.
On Monday temperatures could reach 28C, with the hottest day likely to be Wednesday when it could be 30C.
Because of the high humidity it is even more important to pack suncream and water if you are heading out.
Looking further ahead it will get slightly cooler later in the week with some cloudy weather expected, but temperatures will still be more than 20C.
Speaking about the end of this week, a Met Office spokesperson said: ‘A mixture of sunny spells and showers is expected, with a risk of some heavy downpours and thunderstorms.
‘Over the weekend and into the following week, more settled, drier conditions will probably become established, although some thundery showers may still affect the southeast at first and there is a chance of thicker cloud bringing outbreaks of rain to the northwest at times.
‘Fog patches are possible overnight for many although these will quickly clear through the mornings.
‘Temperatures are likely to be warm for most parts of the UK well into the middle of August.’