The Meteorological Department has warned of thunderstorms in the upper part of the country between Friday and Monday and forecast rainfall for Bangkok throughout the week.

In its seven-day forecast, the department said thunderstorms are predicted in the northern and northeastern regions. Hail, strong winds, heavy rain and lightning are also forecast in certain areas between May 9 and 12. Low-lying areas may experience flash floods and runoff.

The department said that rainfall in Bangkok is forecast to continue for the whole week.

For the southern region, rainfall is predicted to decrease between Wednesday and Friday but will increase between Saturday and Monday with heavy rain in some areas.

Heavy rain could trigger flash floods and runoff, while fishermen are advised to avoid sailing during this period as waves could be more than two metres high.