A bus stop collapsed in Bangkok on April 27, 2018, amid heavy rain.

BANGKOK — Fifty-six provinces including Bangkok will face thunderstorms over the next 24 hours, the Meteorological Department said in a forecast on Thursday.

As storms better the country, waves in the Andaman Sea will be as high as two meters, according to the forecast. A climate expert said the severe weather is a sure sign of the beginning of monsoon season.

“We’re transitioning into the rainy season,” explained Seree Supratid of Rangsit University’s Climate Change & Disaster Center over the phone. “We should expect to see heavy rain – even flooding – in August.”

Rain and thunderstorms are set to cover 40 percent of the northern region, which includes provinces like Chiang Mai, Lampang, Tak and Phrae, until Friday morning.

40 percent of Isaan and central provinces will also experience thunderstorms, which will fall mostly in provinces such as Udon Thani, Khon Kaen, Nakhon Ratchasima and Surin. Kanchanaburi, Nakhin Sawan, Chon Buri and Trad are among provinces that will be affected in the heartlands.

The capital will see thunderstorms cover a third of the city until 6am tomorrow, with lows of 26 degrees celsius.

60 percent of the south will be battered with rain and waves up to two metres high. Provinces affected include tourist areas such as Phuket, Krabi, Phang Nga and Trang.

Additional reporting Asaree Thaitrakulpanich