People are being urged to take extra care to avoid setting field fires during hot weather, with some farmers saying they have lost thousands of pounds worth of crops.
The National Farmers Union (NFU) said fires were one of the biggest risks farmers faced during heat waves.
A farmer told the BBC he lost around £40,000 worth of crops when one of his fields caught fire last week.
England has experienced the driest start to the year since 1976.
The highest temperature ever in the UK was recorded last Tuesday, with thermometers reaching 40.3°C in Lincolnshire and more than 30 places reaching temperatures above the previous record.
David Exwood, vice president of the NFU, said that even as the weather turns colder, the lack of rain has increased the risk of fires in the countryside.
“There has to be extreme care when people are out in the field because anything can catch fire in this weather,” he said.
Andy Barr, owner of an 800-acre farm in Lenham, Kent, had a 50-acre barley field destroyed by fire last Saturday.
Although he hopes to make an insurance claim, Barr said the crop was worth around £40,000.
He said it was a huge shock to see his hard work go up in flames.
“You spend a year growing it and you really like to see the fruits of your labor at this time of year. That was very disappointing,” he said.
“But now I’m over the shock and we only have the slightly worrying moments to see what insurers come up with.”
Mr. Barr also thanked the firefighters and neighbors who helped stop the spread of the fire by plowing up crops that had not yet burned to make a fire break.
Rural insurer NFU Mutual said most farmers insured their buildings, machinery and crops, saying it had seen a “marked increase” in farm fire claims during the heatwave in recent weeks.
Last year it estimated the cost of farm fire claims to be in excess of £70m.
He urged people not to throw away used matches or cigarettes, not to use disposable barbecues on lawns or wastelands, and not to litter, as discarded bottles can focus sunlight and start a fire.
The NFU’s David Exwood said the hot, dry weather was also reducing the yields and quality of some crops, including potatoes, sugar beets and corn.
He said this could lead to short-term shortages of some products on store shelves and higher prices for customers.
The longer the dry weather continues, the greater the impact, he added.
At his own farm in Sussex, Exwood said his corn was struggling due to lack of rain and he was expecting a “drastically reduced yield”, which could cost him tens of thousands of pounds.
Hannah Buisman, who works on her parents’ farm near St Albans in Hertfordshire, said they had also seen reduced hay and cereal crop yields due to the heat.
She said this was taking a financial toll on the farm, at a time when costs for things like energy were rising.
Ms. Buisman said the family had also postponed the crop mix last week because they felt it was too dangerous in the hot weather. If harvesters hit a bottle left in a field or flint, they can ignite a flame and start a fire, she explained.
He urged people not to leave litter in the fields, adding that a neighboring farm had lost 240 acres of crops to a fire.
“It’s the worst nightmare, especially in years as volatile as these,” he said.