Southern Thailand heavy rain alert runs to 13 November

Southern Thailand heavy rain is forecast to continue from 9 to 13 November, with isolated very heavy downpours, flash-flood risk in low-lying areas and waves above two metres, the Thai Meteorological Department (TMD) said in an advisory reported by The Nation Thailand on Monday morning.

The warning, issued at 5am on 9 November, covers much of the peninsula. Phuket is named for heavy rain on Thursday, 12 November, alongside Krabi, Trang, Ranong and Satun on the Andaman side. At the same time, a cold air mass from China is set to bring noticeably cooler weather to the upper half of the country.

Southern Thailand heavy rain: day-by-day outlook

The TMD has split its forecast by day, and the pattern shifts during the week. The heaviest falls start on the Gulf coast and lower south, then spread west towards the Andaman provinces later in the week.

• Monday 9 November: very heavy rain possible in Nakhon Si Thammarat, Phatthalung, Songkhla, Pattani and Narathiwat; heavy rain in Chumphon, Surat Thani, Yala, Krabi, Trang and Satun.
• Tuesday 10 November: heavy rain in Chumphon, Surat Thani, Nakhon Si Thammarat, Phatthalung, Songkhla, Pattani, Yala and Narathiwat.
• Wednesday 11 November: heavy rain in Chumphon, Surat Thani, Nakhon Si Thammarat, Phatthalung and Songkhla.
• Thursday 12 November: very heavy rain in Chumphon, Surat Thani and Nakhon Si Thammarat; heavy rain in Phuket, Ranong, Krabi, Trang, Satun and five lower southern provinces.
• Friday 13 November: very heavy rain in Surat Thani and Nakhon Si Thammarat; heavy rain extending from Phetchaburi and Prachuap Khiri Khan down to Phang Nga, Krabi and Satun.

Phuket itself is not listed on Friday, but neighbouring Phang Nga and Krabi are. Residents and visitors should treat the whole Andaman coast as unsettled for the second half of the week.

Why the weather is changing now

According to the TMD, a relatively strong high-pressure system is moving down from China over upper Thailand and the South China Sea. That cold air mass strengthens easterly winds across the country and the Gulf of Thailand, pushing moisture onto the southern peninsula.

The same system will cool the north and north-east. The department expects temperatures in the Northeast to drop by 3 to 5 degrees Celsius over the five days, with a smaller fall of 1 to 3 degrees in the North, Central and Eastern regions. People there have been told to look after their health in the cooler, windy conditions, and farmers to protect crops from damage.

The advisory follows an earlier warning for the region. Phuket Times reported last week on the Phuket heavy rain warning for 7 to 9 November, when roads in parts of the island flooded. The new advisory effectively extends that unsettled period into the rest of the week.

Sea conditions and travel advice

For boat operators and island-hoppers, the marine warning matters as much as the rainfall. The TMD says waves in both the Gulf of Thailand and the Andaman Sea could exceed two metres in areas with thundershowers. Mariners on both coasts have been told to sail with caution and keep clear of storm cells.

Rough seas can lead to cancelled or rescheduled speedboat tours, so travellers with bookings for Phi Phi, the Similans or other islands later this week should check with their operator the evening before, and keep plans flexible. Our guide to Phuket weather in November explains why the month often swings between calm days and heavy squalls.

On land, the main risks named by the TMD are flash floods and fast runoff on slopes near waterways and in low-lying districts. In practice, that means:

• avoiding fords, underpasses and roads that flood quickly during cloudbursts;
• taking extra care on hill roads where runoff can carry mud and debris;
• checking forecasts before trekking to waterfalls or riverside spots;
• keeping phones charged and following local official announcements.

Heavy rain also adds pressure to services that are already stretched. Phuket is still dealing with the closure of its main waste site, covered in our report on the Phuket landfill closure, and prolonged downpours can worsen drainage and rubbish problems in built-up areas.

What happens next

The TMD said its next update was scheduled for 5pm on 9 November. Forecasts for later in the week may change as the cold air mass develops, so the day-by-day list above should be read as a guide rather than a guarantee. The department publishes advisories on its website and official Facebook page, and its 1182 hotline runs around the clock.

For now, the message for the south is to plan around Southern Thailand heavy rain until at least Friday, and for the north to prepare for the first proper cool spell of the season. Phuket Times will update readers if warnings for Phuket or the Andaman coast are raised.

The forecast was reported by The Nation Thailand, based on the Thai Meteorological Department advisory issued on 9 November.

Photo: Flooding in Hat Yai, used here to illustrate the risk from Southern Thailand heavy rain (Government of Thailand via Wikimedia Commons, CC BY 2.0).