Much of the UK is braced for another heatwave, with little rain expected to help relieve the threat of drought which has prompted hosepipe bans and fire warnings.

The Met Office said temperatures are likely to rise into the low to mid-30s in central and southern parts of the UK – but will not be as extreme as the record-breaking heat in July when the thermometer climbed above 40C.

Heatwave thresholds – which are met at different temperatures in different parts of the country – are likely to be hit in much of the UK.

Outside the hottest areas, much of England and Wales and south-east Scotland could see temperatures widely in the high 20s, with a chance of a few spots seeing temperatures into the low 30s, the Met Office said.

Scotland and Northern Ireland will also see temperatures in the high 20s and could reach official heatwave criteria by Friday, the forecasters said.

The UK Health Security Agency has issued a heat health alert for southern and central England from Tuesday to Saturday, with experts advising people to look out for those who are older or with existing health conditions, and young children.

With the latest heatwave coming after months of low rain, which have left the countryside and urban parks and gardens tinder-dry, households in some areas are being urged not to light fires or have barbecues.

Essex County Fire and Rescue Service is urging people not to light barbecues or bonfires, or let off fireworks or sky lanterns, after a large blaze which damaged gardens, sheds and trees was started by a chiminea.

The Country Land and Business Association (CLA), which represents 28,000 farmers and landowners in England and Wales, has demanded retailers follow the lead of Marks & Spencer and ban the sale of disposable barbecues across the UK this summer to reduce the risk of wildfires in the dry conditions.

The Met Office’s fire severity index (FSI), an assessment of how severe a fire could become if one were to start, is very high for most of England and Wales, and will reach “exceptional” for a swathe of England by the weekend.

Two water companies have already announced hosepipe bans and others have warned they may need to follow suit, following the driest eight months from November to June since 1976, and the driest July on record for parts of southern and eastern England.

Scientists warn that the likelihood of droughts occurring is becoming higher due to climate change, driven by greenhouse gas emissions from burning fossil fuels and other human activities.

Climate change is also making heatwaves more intense, frequent and likely – with last month’s record temperatures made at least 10 times more likely because of global warming, and “virtually impossible” without it, research shows.

The Met Office recently raised the temperatures that have to be reached for an official heatwave for eight English counties, to reflect the warming conditions in the UK.

Met Office deputy chief meteorologist Tony Wardle said: “Heatwave criteria look likely to be met for large areas of the UK later this week, with the hottest areas expected in central and southern England and Wales on Friday and Saturday.

“Temperatures could peak at 35C, or even an isolated 36C on Saturday.

“Elsewhere will see temperatures widely into the high 20s and low 30s Celsius later this week as temperatures build day on day through the week due to an area of high pressure extending over much of the UK.

“Coupled with the high daytime temperatures will be continued warm nights, with the mercury expected to drop to only around low 20s Celsius for some areas in the south.”

The Met Office said there is little rain in the forecast, with only the North West likely to see any short-lived showers.

Mr Wardles said: “Further south, which has seen little rain for some time now, dryness will continue through the week and provide no relief for parched land, especially in the South East.”

Richard Allan, professor of climate science at the University of Reading, said there are many reasons why drought events become worse as a result of human-driven climate change.

A warmer atmosphere is thirstier and dries out the ground, while heatwaves exacerbate the development of drought conditions, and, because continents are warming so fast, ocean winds cannot blow enough moisture over the land.

Uneven global warming can also disrupt weather patterns, and make periods of more persistent wet or dry conditions more common.

“Human caused warming of climate is intensifying the global water cycle and disrupting weather patterns leading to more severe droughts but also more serious flooding events across the globe,” said Prof Allan.

Dr Leslie Mabon, lecturer in environmental systems at The Open University, said: “Above all else, the drought risk we are seeing in the UK is a reminder that we urgently need to tackle the problem at source: this means reducing emissions from fossil fuels to limit the extent of harmful climate change we will face.

“Moreover, countries like the UK, which have traditionally had more a more temperate climate and have less experience of managing the prolonged effects of hot, dry spells, need to plan now to adapt to hotter weather.

“More than encouraging individuals to save water, this also means looking at our water infrastructure and considering where investments are made to ensure we are better prepared for managing water in hot spells.”