Amber heat health alerts have been issued for the bank holiday weekend as record-breaking May temperatures as high as 33C (91F) are expected in parts of the UK.

The alerts – which indicate a possible risk to life as well as potential damage to properties, significant travel delays and power cuts – were announced for the East Midlands, West Midlands, the east of England, London and the south-east, and will be in effect from 2pm on Friday until 5pm on Wednesday.

Yellow alerts were also issued for the north-east and north-west of England, Yorkshire and Humber, and south-west England, indicating potentially significant impacts on health and social services as well as risk of life to anyone who is over the age of 75 or has existing health conditions.

The UK is forecast to have its hottest ever day in May over the long weekend, marginally exceeding the 32.8C recorded around parts of London, West Sussex and Kent more than 80 years ago, on 29 May 1944. Friday marked the hottest day of the year so far, as temperatures reached 26.9C at Heathrow in the early afternoon, the Met Office said.

The hotter weather is being attributed to a change in wind direction, with strong jet-stream winds shifting north and bringing warmer air from hotter places. It follows one of central and southern England’s driest Aprils on record, which left river levels below normal.

The peak temperature in the UK, which is predicted to occur in southern England or the Midlands on Monday, is likely to be hotter than many parts of the Mediterranean, including Rome, Athens and Barcelona.

The Met Office deputy chief forecaster, Steve Kocher, said: “Temperatures will climb through the weekend, especially in the south, where 30C is likely to be recorded on Saturday and 32C on Sunday. Temperatures are forecast to peak on Monday, when we could see 33C recorded in southern England and the Midlands.

“It is likely that the May and spring UK temperature records will be broken over the bank holiday weekend, with forecast temperatures surpassing the existing record of 32.8C. As well as it being hot, there will be lots of dry and sunny weather for much of the UK. There will, however, be more cloud and some showers in Northern Ireland and western Scotland through the weekend. With relatively low sea surface temperatures, there is also likely to be some low cloud and sea fog clinging closely to western coasts.”

The public are advised to stay hydrated and not spend too much time in direct sunlight, especially between 11am and 3pm. They are also advised to wear sunglasses, and avoid alcohol, caffeine and hot drinks where possible. Windows should be closed during the day and opened at night in order to let cooler air in.