The heavy storm hit the city and its adjacent provinces at 10.30pm and lasted about 45 minutes. Trees were felled and motorcyclists pulled over until the storm passed.

FM91 traffic radio station reported 29 car accidents on Praditmanutham Road and Kaset Nawamin flyover but no serious injuries were reported.

There were blackouts in several areas around Din Daeng, Ratchadapisek and Nonthaburi's Muang district and the winds also caused the People's Alliance for Democracy rally at Government House to end early.

A police tent at Government House was blown onto the compound's fence, causing masonry to collapse from a support pillar. The incident frightened protesters near the scene, but no one was injured.

Meteorological Department weather forecaster Charoon Laohakertchai said the storm was caused by a high-pressure system clashing with a cold front from China. The strong winds first hit the Northeast and moved southward to the Central region and Bangkok, he said.

 "It's a normal storm for this time of year. It might affect Bangkok for another two days," he said.

The northern meteorological office warned that rain, high winds and hail have been forecast to hit the North since yesterday and will last until the weekend. Areas likely to be affected are Chiang Rai and Chiang Mai.