The strong winds and heavy rain, which lasted about half an hour, sent the crowds into a panic and triggered traffic jams on the Sirindhorn-Chong Mek Road.
Pattaya Noi Beach near the Sirindhorn Dam is a popular Songkran party site in the Northeast.
The storm also damaged more than 10 floating restaurants, though no casualties were reported.
The Thai Meteorological Department had warned on Saturday of a moderate high-pressure system moving from upper Vietnam to the Northeast and the South China Sea. The system is expected to bring storms, gusty winds, hail and thunder to several provinces in upper Thailand on Saturday and Sunday.
Meanwhile, temperatures in the rest of the country will surge due to prevailing southerly and southeasterly winds. The North, Northeast and Central regions may face sizzling temperatures of 38 to 42 degrees Celsius, while the East and South will record 34-37 degrees Celsius.
People in areas hit by storms are advised to remain indoors and stay away from big trees and unsecured billboards. People are also advised against wearing metallic items and using mobile phones during thunderstorms. Farmers are also advised to secure their crops and livestock.