The weather system, now moving towards Myanmar, has triggered alerts in Lampang, Sukhothai, Kamphaeng Phet, Lamphun, Chiang Mai, Tak and Mae Hong Son.
Authorities have urged residents in low-lying and foothill areas to remain vigilant.
In Khon Kaen, a flash flood inundated more than 100 homes overnight, while in Chiang Mai, strong winds felled a tree onto power lines. In Phitsanulok, rising water in the Khek River damaged farmland and forced red-flag warnings.