"The damages are huge, even though farmers have tried to battle the heat using water sprinklers," Chiang Mai Longan Farmers Cooperative chairman Adulchai Intakhao said yesterday.
According to Adulchai, Chiang Mai has more than 20,000 rai of lychee plantations.
Lychee trees provide a good yield when the temperature ranges between 20 and 30 degrees Celsius.
Lately, however, the mercury has hovered near 40C.
"Water sprinklers have helped a bit, but there is also a risk of water pressure damaging the fruit," he said.
The hot weather has caused serious concerns in many areas.
In Uttaradit's Tha Pla district yesterday, locals were still trying to get to grips with the sudden splitting open of a reinforced concrete road.
The crack in Ban Khai-Tha Pla Road was about 15 centimetres deep.
"Locals are demoralised," Moo 7 village head Pattanasak Nuanmuak said. "So, we plan to hold a ceremony to dispel bad luck and bless the locals."
Tha Pla district chief Prasong Uraivorn said he planned to turn this crisis into an opportunity by using the public focus on the heat to campaign for environmental conservation.
"Available evidence suggests that the road split under intense heat. People should be aware of just how big the threat of global warming is," he said.
According to Uttaradit Provincial Administrative Organisation deputy chairman Rachan Mahawan, the road may have split due to wear and tear.
"We will check on 57 other reinforced concrete roads in the province," he said.
In Phitsanulok's Nakhon Thai district, officials yesterday continued to test the air quality at a site where a subterranean fire was reported.
"The amount of sulphur dioxide here is many times higher than the safe limit," said Winai Thongchub, an academic working at Disease Control Office 9.
He said monitoring would continue because some gases that are harmful to health had been detected.
The spot first came to local people's attention when dogs burned to death after wandering into the spot.
Some local residents were also injured, prompting officials to investigate and cordon off the site.
Some people thought it had something to do with the continued sweltering heat of summer.