Power is expected to be restored late on Friday to an industrial estate in Chachoengsao blacked out since Wednesday, when a storm brought down 19 high voltage electricity poles along 500 metres of road in Plaeng Yao district.
More than 100 workers were brought in to repair the damage .
The repair work has caused traffic congestion on Highway No.331 Kabin Buri- Sattahip heading to Phanat Nikhom district in Chon Buri.
Power was expected to be back on by midnight Friday, electricitry authority officials said.
In Buriram, officials were still estimating the final cost of damage cause by hail and thunderstorms which damaged more than 100 houses and rice barns in Satuk district on Wdnesday, injuring four people.
Three schools where students are sitting final exams were also damaged by trees brought down by the gusting winds which battered tambons Krasang and Thung Wang in the district - Ban Krasang School, Ban Nong Krok School and Ban Khok Ar Thot.
No students or school staff were injured.
In tambon Thung Wang, four people received minor injuries when hit by falling debris in a house where they sheltered from the storm.
Local authorities were providing assistance.
The Meteorological Department forecast is for more hot weather in upper Thailand, with more thunderstorms likely in areas of the Northeast, the Central Plains and the East through to Monday.
Rain is also predicted in the southern region over the same period, with rough seas and winds slowing weakening.
Residents in the upper part of the region were warned to brace for thunderstorms next Tuesday and Wednesday.