Coastguard teams are searching for a man in the water at Bournemouth Beach as the country saw its hottest day so far this year.

In a statement, the Maritime and Coastguard Agency (MCA) said: “HM Coastguard is currently co-ordinating the search for a male, following a report of a person in the water at Bournemouth Beach.

“The Poole and Southbourne Coastguard Rescue Teams, a Coastguard helicopter, Poole RNLI lifeboat and Dorset Police are currently on scene.”

It comes after the Met Office said the hottest temperature recorded on Monday was 28.3C in Wisley, Surrey, with more warmer weather and likely heatwaves forecast for parts of the UK this week.

This was the warmest temperature recorded so far this year, overtaking a 27.5C reading taken in Chertsey, also in Surrey, in May.

London saw a peak recording of 27.4C at St James’s Park, while temperatures rose to 26.9C in Aberdeenshire, and reached 25C in Northern Ireland.

Temperatures in London are forecast to hit peaks of 31C on Wednesday, with much of south-east England basking in the mid-20s for the first half of the week.

It marks a break from the rainy spring, which saw 32% more rainfall than the average in England and Wales according to the Met Office, and hampered businesses reliant on tourism or high street foot traffic.

Oli Claydon, a Met Office spokesperson, said “it won’t be sunshine for everyone”, but will still be warm even where there is cloud cover during the week.

“We might see the occasional shower in parts of Northern Ireland and Scotland, where there will be a little bit of cloud through (Tuesday), but otherwise clearer skies in the South East and that’s where we’re going to see the highest temperatures,” he added.

The heatwave threshold is met when a location records at least three consecutive days with maximum temperatures exceeding a designated value, according to the Met Office.

This is 25C for most of the UK, but rises to 28C in London and its surrounding area, where temperatures are typically higher.

The UK Health Security Agency (UKHSA) has issued yellow heat-health alerts for most of England, warning the warm conditions could pose a risk to vulnerable individuals.

However, the heat is only expected to last until Wednesday with heavy showers, thunderstorms and persistent rain possibly returning in the west as the week goes on.

“There will be a little bit of rain and cloud through Thursday,” Mr Claydon said.

“But it’ll actually be quite pleasant, although temperatures will still be a little cooler and closer to average – the weather will still be fine and there will be a lot of dry weather around.”