The UK could officially enter its third heatwave of the year within days, with temperatures forecast to climb to 30C in parts of southern England this weekend.
A large area of high pressure is currently expanding from the Azores towards Portugal and Spain, helping to drive warmer conditions across western Europe and the UK.
Forecasters expect temperatures to rise steadily over France and southern Britain in the coming days, with some areas likely to reach official heatwave thresholds by the end of the weekend.
The latest forecasts come after England recorded its warmest June on record, while the UK experienced its second warmest June overall, according to provisional figures from the Met Office.
Heatwave criteria vary across the country. In London and the South East, temperatures must reach at least 28C for three consecutive days, while northern regions require highs of 25C.
Most parts of the UK are expected to remain below those levels during the remainder of this week, but temperatures in Greater London and the Home Counties could approach 28C by Friday.
By Sunday, some areas may see highs of 30C, potentially making it the earliest date that a new heatwave could be declared in parts of England.
Conditions are expected to become increasingly warmer next week, with southern Britain likely to experience temperatures close to or above 30C on several days.
Initially, westerly winds are forecast to dominate, which may prevent the extreme heat experienced during the latter half of June from returning.
However, forecasters say a shift to southerly winds later next week could push temperatures even higher, although there remains considerable uncertainty.
The UK Health Security Agency has already issued yellow heat-health alerts covering London, the South East, South West, East Midlands and East of England, warning that high temperatures could pose increased health risks to vulnerable people.
Unlike previous hot spells, the air is expected to remain less humid, at least initially, meaning conditions may feel more comfortable despite the heat.
Northern parts of the UK are not expected to reach heatwave levels in the near future. Scotland, Northern Ireland and northern England could continue to experience fresher Atlantic air and occasional showers due to their closer proximity to the jet stream.
Temperatures in cities including Belfast, Liverpool and Glasgow are forecast to remain between 20C and 24C.