Rain is expected to subside over the next four days before returning to cover most areas of the country from Wednesday to Friday, according to the Meteorological Department.
Showers will be heaviest in the northeastern, eastern and southern provinces, deputy director-general Songkran Aksorn told FM100.5 radio on Saturday.
He added that beachgoers should exercise caution and visitors planning to travel by boat from the mainland to islands off the Andaman coast should closely monitor the weather forecast.
Andaman coastal provinces from Ranong to Phangnga, Phuket, Krabi and Trang are braced for downpours until Sunday with high tides rising to at least two metres, the agency reported.
Rain covered more than half of the country including Bangkok on Friday. One of the worst-hit areas was Nakhon Phanom, where a four-hour downpour flooded some roads in the provincial town up to 50 centimetres.
Phannga, Surat Thani, Ratchaburi, Chanthaburi, Tak and Bangkok were among the provinces hit hardest by heavy rain since Thursday, according to the department.
In Nakhon Ratchasima, the rain was believed to have been a factor in the death of a man at a workers' camp. Mitchai Wongkul, 42, was found dead in a tent on Saturday, covered by plastic sheets.
Pol Capt Anuwat Rattanajeena, an investigator at the Pho Klang police station in Muang district, said it appeared the man had died of suffocation as a preliminary examination showed no signs of violence.
Assanai Wongkul, his grandson who first alerted police about the death, said Mitchai had been using plastic sheets to protect the tent from the downpour before he left to go to his makeshift sleeping quarters nearby.
Heavy rain was a blessing for the people of Wang Thong district in Phetchabun as the increasing water level of the Khek River prompted residents to start making makeshift rafts with expectations that tourists will start to arrive soon for rafting trips.
Pongsak Palatyos, the Moo 1 village chief, said the rafting season was expected to get under way in earnest over the next two weeks.
Despite the heavy rain, water levels in major reservoirs remained low, at an average of 44% of their capacity, according to data the Hydro and Agro Informatics Institute.
Only the reservoirs at the Ratchapraba dam in Surat Thani and Srinagarind dam in Kanchanaburi were filled above half their capacity, it added.