The forecast of higher temperatures across some parts of the country has prompted the first Heat-Health alert of the summer.
Temperatures will peak across East Anglia, the East Midlands and south east England during Monday, where highs of 32 °C are possible.
Head of Health Forecasting at the Met Office, Patrick Sachon, said: "There is the possibility of daytime and night-time temperatures reaching trigger thresholds. These temperatures, together with high humidity, pose a risk to vulnerable people, such as those with underlying health problems."
The next few days will see varied weather across the UK, with some places having unsettled conditions and temperatures reaching the low 20s.
Chief Forecaster at the Met Office, Andy Page, added: "There is a 60% chance of some places in East Anglia, the East Midlands and south east England reaching 30 °C on Sunday and Monday. However, it is important to note that not all places will see the hot weather. Cooler weather is expected to spread across all parts of the UK by the middle of next week."