Temperatures hit 26C on Saturday, wrapping up the sunniest spring on record before the UK officially goes into the summer season.

Heathrow in west London enjoyed the hottest weather at 26.7C, about 8C higher than the average for the time of year, while levels of grass pollen were very high in the south-east of England.Provisional figures from the Met Office show 630 hours of sunshine were clocked up across the country between 1 March and 27 May. However, forecasters have also warned about the possibility of wind and rain.

A Met Office meteorologist, Tom Morgan, said: “It’s the last day of meteorological spring today but it’ll actually feel more like midsummer for some southern and eastern areas.

“It’s fairly warm in that sunshine, particularly across more eastern and south-eastern parts of the UK, with temperatures in the mid-20s.”

Morgan added it has been a “different story” in the north-west, where people had seen cooler and more showery weather.

On Sunday, temperatures will reach about 22C, and another band of rain will arrive in the north-west of the UK. There is a better chance of dry weather in southern and eastern parts, with some areas staying completely dry. Monday, in the first full week of meteorological summer, is likely to be the driest day of the week.

Low pressure in the middle of the week will probably result in cloud and showers, according to another Met Office meteorologist, Alex Deakin.

“Looking pretty unsettled through the middle of next week,” he said, adding that winds coming in from the Atlantic are likely to bring moisture and showers, particularly in western areas.

There may be a “hint of a change” towards the end of next week, with wetter conditions becoming more confined to northern parts.

He added that winds would keep temperatures down, and would also bring rain – especially in the west.