Temperatures are expected to hit 35C in parts of England on Monday, in an “unprecedented” May heatwave.

The Met Office is already predicting that records will be broken. A spokesperson said: “Today will be the hottest day in May in the UK in our temperature records, with highs of 35C expected. The current May record is 32.8C. Records are usually only broken by tenths of a degree, making this heatwave unprecedented for the time of year.”

The last time a monthly maximum record was broken was in January 2024, by 1.6C. The 40.3C in July 2022 exceeded the previous record by 1.6C. If the forecasted temperature of 35C is hit, this will be a big jump of 2.2C.

Much of England will have faced disturbed sleep on Sunday night, as a new overnight record for temperature was hit, at 19.4C at Kenley in Greater London. This means London residents narrowly avoided a “tropical night”, which is when temperatures overnight do not drop below 20C. This has not happened before in May. There are two “tropical nights” forecast for Monday night and Tuesday night, before temperatures ease off on Wednesday.

Sunday was the UK’s hottest May day for at least 79 years, and Kew Gardens in west London recorded 32.3C (90.1F).

Many areas of England are officially in a heatwave, with the first to meet the criteria being Santon Downham in Suffolk on Sunday. The other areas officially in heatwave conditions are Heathrow, Kew Gardens and Northolt in London, Benson in Oxfordshire, Brooms Barn in Suffolk, and High Beach and Writtle in Essex.

More heatwaves are likely this summer as a “super El Niño” is due to hit. This phenomenon supercharges weather events and makes them more extreme, for example by making heatwaves hotter. The effects are due to build up to hit in 2027, making it likely to break global heat records, but it is expected to begin emerging this summer.

El Niño is characterised by warming of the ocean surface in the central and eastern tropical Pacific Ocean. It is one of three states scientists observe; La Niña, conversely, happens when sea surface temperatures are below average, and neutral conditions are defined when neither El Niño or La Niña are present and surface temperatures are about average.

While temperatures of 30C were once unusual in the UK, even in the height of summer, they are becoming more common. Hot temperatures are likely to be here to stay in the UK and Europe. According to the latest European State of the Climate report, Europe is the fastest-warming continent in the world.

The UK generally experiences its hottest temperatures at the end of July or the beginning of August, so forecasters expect things to get even hotter by the end of summer.