Is it raining now in Koh Samui?
Moderate rain
13 NovEnds at 08:30.
Last update: 07:30, 13 Nov 2026
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Live Koh Samui rain radar | RainViewer
Plan your Chaweng beach day and Nathon ferry. Live Koh Samui rain radar, updated every 5 min. Free on iOS & Android.
Rain in Koh Samui: What You Need to Know
Koh Samui keeps the wet season when most of Thailand is drying out: its heaviest rain comes from October to December, while the Andaman beaches of Phuket enjoy their sunshine. Rain arrives off the Gulf of Thailand in squalls, and a Koh Samui rain radar shows whether one is heading for Chaweng or already passing Nathon. Hyperlocal radar shows where the rain is and where it is heading.
The island is a granite dome with Khao Pom rising in the middle, and the northeast monsoon pushes moist air against the north and east coasts first. Chaweng and Bophut take the squalls head-on, while the sheltered west side near Taling Ngam can stay dry. A standard forecast for Surat Thani province averages that difference away, which is the gap a live radar fills.
RainViewer shows precipitation over Koh Samui with data from the Thai Meteorological Department, the national weather service. The live rain map refreshes about every 5 minutes, so it shows whether a squall over the Gulf is closing on the island or sliding past towards Koh Phangan.
RainViewer Radar Coverage in Koh Samui
RainViewer shows Thai precipitation using data from the Thai Meteorological Department (TMD), the national weather service, which operates a network of weather radars across the country. The map refreshes with each new scan, about every 5 minutes. From Koh Samui the map also covers Surat Thani, Koh Phangan and the Gulf coast.
Northeast monsoon season (October to December)
November is usually the wettest month, with heavy showers, rough seas and cancelled Raja and Lomprayah ferries. Roads such as the ring road around Chaweng and the hill to Lamai get slick, and beach clubs close their sunbed fronts.
Transition months (January to February, and May to June)
The monsoon changes direction and showers become patchy. A clear morning can end in a stormy afternoon, which is hard on island-hopping plans.
Dry and hot season (March to September)
Rain is occasional and the sea is calm, so most visits and dive trips fall here. The southwest monsoon months bring only short afternoon showers to the island.
Why You Need a Rain Radar in Koh Samui
Chaweng beach and Fisherman's Village visitors
Chaweng Beach has little cover when a squall comes through, and the Bophut Fisherman's Village night market closes its stalls fast. Watch the cell and pick the dry hour.
Ferry passengers at Nathon and Mae Nam piers
Ferries from Nathon and Mae Nam to the mainland and Koh Phangan are delayed in heavy rain and rough sea. Check the radar before heading to the pier.
Scooter riders on the ring road
The ring road and the hills to Lamai and Hin Ta Hin Yai are dangerous on a scooter in the wet. Wait for the cell to clear.
Big Buddha and Namuang waterfall tourists
The Big Buddha terrace at Bophut and the Na Muang waterfalls are the island's open-air attractions. Watch the weather over Khao Pom and plan the trip for the gap.
Samui airport arrivals
Flights into the open-air airport near Bophut are delayed by storms on the northeast approach. The radar shows whether a squall will clear before the boarding call.
Koh Samui Rain Radar: Frequently Asked Questions
- How does rain affect ferries from Koh Samui?
Heavy rain and rough sea delay or cancel ferries from Nathon and Mae Nam to the mainland and Koh Phangan, most often from October to December. Squalls cross open water fast. RainViewer shows whether one is on the route.
- Does rain affect the ring road on Koh Samui?
Yes, heavy rain makes the ring road around Chaweng and the hills to Lamai slick, and scooter accidents rise in the wet. Surface water collects at low junctions. Check the radar before riding.
- Does Koh Samui flood when it rains?
Yes, heavy rain can flood the low roads around Chaweng, Bophut and Nathon, and streams run high below Khao Pom. Drains fill in the first hour. Avoid the beach roads and wait for the cell to pass.
- When is the best time to visit Koh Samui to avoid rain?
March to September is the driest period and the best for Chaweng, Lamai and day trips to Ang Thong. October to December is the wettest, with November the worst. January is a good compromise.
- Why does it rain on one side of Koh Samui but not the other?
Khao Pom splits the island, and the northeast monsoon pushes squalls against the north and east coasts first. Chaweng can be soaked while the west near Taling Ngam stays dry. A hyperlocal radar shows that split.
- How does RainViewer's radar work on Koh Samui?
RainViewer shows live precipitation over Koh Samui using Thai Meteorological Department radar data, refreshed about every 5 minutes. It shows rain as it falls, not a modelled prediction, and is a hyperlocal radar for the island.
- Can RainViewer warn me before rain hits Koh Samui?
Yes, a rain alert warns you minutes before rain reaches a saved place, such as Nathon pier or Chaweng Beach. The 5-minute forecast timeline shows the next two hours. That settles whether to board the ferry now.
Track Rain in Koh Samui in Real Time
A Chaweng beach day and a Nathon ferry both depend on a dry gap, and RainViewer shows the next one.
Rain reaches Koh Samui in squalls that cross open water, and the break between two squalls is the window that matters.
RainViewer Essential gives you:
2-hour forecast in 5-minute slices
Two hours of 5-minute steps let you time the ride from Chaweng to the Nathon pier.
Rain alerts before arrival
Put an alert on Nathon pier. RainViewer warns you minutes ahead, which settles whether to catch the boat now or wait.
Direction arrows on the map
In the northeast monsoon rain reaches Samui from the north-east, so the arrows show whether a squall heads for Chaweng.
48 hours of radar history
The 48-hour history shows what fell on Khao Pom, which explains why the Na Muang waterfall is in flood.
Multiple locations
Track Chaweng, Lamai and Nathon at once.
Your weather app says showers for Koh Samui this afternoon. A live hyperlocal radar shows the squall is already over Bophut while Lamai is dry, and that decides the ferry.
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