A yellow weather warning has been issued for thunderstorms for parts of northern England and Scotland on Sunday. The Met Office said the storms could cause localised flooding and in some places hail up to 3cm in diameter along with strong, gusty winds. The warning is from 1pm to 9pm on Sunday. The Met Office said: “Whilst there remains some uncertainty in whether thunderstorms develop as cooler conditions follow from the west, there is a chance that an organised line of thunderstorms could develop across northern Britain during Sunday afternoon before clearing east into the North Sea during the evening. “This is more likely to happen across eastern parts of the warning area including north-east England and eastern Scotland.” A weekend heat health warning from the UK Health Security Agency and the Met Office has been issued that covers most of England. It will be in place until Monday at 9am. The warning urges people to “watch out for those who might struggle to keep cool in the hot weather”. It was issued as temperatures were expected to soar to 32C (89.6F). The warning covers London, the south-east, the south-west, east Midlands, West Midlands, east of England, Yorkshire and the Humber. London is expected to be the hottest part of the UK, with potential highs of 31C or 32C, while temperatures will be in the high 20s for large parts of England. The blast of hot weather has come as Glastonbury festivalgoers descended on Worthy Farm in Somerset to watch acts including Sir Elton John and the Arctic Monkeys. The Met Office said much of southern, central and eastern England would experience a rise in temperatures through the weekend. Temperatures could peak at 32C in the far south-east on Sundayand rise into the high 20s elsewhere in the south and east. The Met Office chief meteorologist Matthew Lehnert described the prospect of thunderstorms developing as “finely balanced”. He said: “It’s worth noting the temperatures in the south will remain quite high overnight this weekend, so it’s important to look out for those who may be more vulnerable to heat. “There are some marked contrasts in the UK’s weather this weekend, with some potentially impactful thunderstorms developing affecting the northern half of the UK on Sunday, while further south it will become hot. “For those in the north, there is a chance of thunderstorms developing as we see a change to cooler conditions with a chance that these could become organised with heavy rain, hail, lightning and gusty winds.”