Thailand's weather can change quickly, especially in the rainy season, which officially runs from mid-May to mid-October. A few well-chosen apps tell you when rain is coming, whether the sea is calm enough for a boat trip, and whether the air is clean enough for a day outdoors.
We checked every app below on the Thai App Store (iPhone) in September 2026, but not on Android. On Google Play, search for the same app name and check the publisher before you install.
Start with the official source: the Thai Meteorological Department
The Thai Meteorological Department (TMD) issues Thailand's official forecasts and weather warnings. It has two current apps, and both are free:
- Thai Weather: TMD's official app, with current weather, forecasts, the paths of tropical storms, radar, satellite images and earthquake reports. It was last updated in April 2026. See Thai Weather on the App Store.
- TMD พยากรณ์ (TMD Forecast): the newer app, released in March 2025 and updated in September 2026, with forecasts, radar, satellite images, and weather and earthquake reports. See TMD พยากรณ์ on the App Store.
On the App Store, both apps list English as an app language, so you can use them without reading Thai. Skip the older "Thai Weather Radio by TMD" app, which has not been updated since 2020.
The TMD website has 7-day forecasts, radar, satellite images, PM2.5 readings and heavy-rain warnings, and the TMD weather hotline is 1182. When another app and TMD disagree about a storm or heavy rain, follow TMD: it issues the official warnings.
International weather apps worth installing
These apps were all listed on the Thai App Store in September 2026. Prices and features can change, so check the store before you pay for anything.
| App | Price (Thai App Store) | Notes |
|---|---|---|
| AccuWeather | Free to download | A general daily forecast |
| Windy.com | Free to download | Wind and weather maps |
| CARROT Weather | Free to download | Forecasts, alerts and radar |
| RainViewer | Free to download | Live rain radar |
| Windfinder | Free to download | Wind for beach and boat days |
| IQAir AirVisual | Free to download | Air quality |
| Weather Underground | Free | Still listed, but not updated since June 2025 |
| WeatherPro | 29 THB | A paid forecast app |
The first six were all updated in 2026, a sign that they are still maintained. Weather Underground's iPhone app was last updated on 30 June 2025, so choose a different app as your main one. To be sure you install the right app, check the publisher: AccuWeather International (AccuWeather), Windyty (Windy.com), Grailr (CARROT Weather), MeteoLab (RainViewer) and DTN Germany GmbH (WeatherPro, no longer MeteoGroup as older guides say).
You do not need all of them. One general forecast app, one radar app and one air-quality app cover most trips. Add a wind app if you plan boat trips or island hopping.
Rain radar and sea conditions
In the rainy season, a daily forecast tells you that it will rain; a radar app such as RainViewer, or the radar in the TMD apps, shows you when. Check the radar before you leave your hotel, see which way the rain is moving, and plan the next hour or two around it.
Rain does not usually fall all day: even in September, Bangkok's wettest month, there are on average about 18 days with 1 mm of rain or more, so many days stay partly dry. Plan outdoor sightseeing for the morning and keep indoor options, such as museums or malls, for later in the day.
Before boat trips and ferries, check the wind in Windy.com or Windfinder. The Marine Department's 24-hour hotline, 1199, covers boats and piers. Rough-sea closures vary, so always confirm with your boat operator on the day.
Some marine parks also close every year, whatever the forecast says:
- Similan Islands: open 15 October to 15 May, and closed from 16 May to 14 October for the south-west monsoon. The 2026-27 season opens on 15 October 2026.
- Maya Bay (Koh Phi Phi Le): closed every year from 1 August to 30 September for reef recovery, and reopens on 1 October 2026. Phi Phi boat tours keep running but may not enter the bay.
Air-quality apps for March and April
In March and April, air quality in the north can matter as much as rain. On 1 April 2026, PM2.5 in some Chiang Mai districts went above 300 micrograms per cubic metre. On 4 April 2026, Chiang Mai, Lamphun and Phayao provinces, and the districts of Pai and Mae Sariang, were declared emergency disaster zones for air pollution.
Three free apps show you the air before you plan a day outdoors:
- Air4Thai, from Thailand's Pollution Control Department: hourly air-quality readings from the department's stations, with 7-day graphs and maps. See Air4Thai on the App Store.
- เช็คฝุ่น (Check Dust), from the Thai government agency GISTDA. See เช็คฝุ่น on the App Store.
- IQAir AirVisual: an international air-quality app.
In the north in March or April, check PM2.5 every morning, and on bad days swap hikes and viewpoints for indoor plans.
Emergency alerts: T-Alert and Thai Disaster Alert
T-Alert is Thailand's national cell-broadcast warning system, run by the Department of Disaster Prevention and Mitigation (DDPM). It was built after the floods and mudslides in the north in September 2024, and official tests began on 2 May 2025. A T-Alert message pops up on phones in the affected area with an 8-second alarm; on 5 November 2025, for example, it carried Chao Phraya flood warnings. If one appears on your phone, follow its instructions.
DDPM also runs the Thai Disaster Alert app. Install it as a second source, so you do not depend on one channel. The DDPM disaster hotline is 1784.
Setting up your apps before you land
- Install before you fly: one of the TMD apps, one radar app, one air-quality app and Thai Disaster Alert.
- Add every place on your route, including islands and parks, so you can compare them quickly.
- Turn on notifications for severe weather and rain.
- Plan for mobile data, because radar maps need a connection. Smile Taxi Service gives a free 500 MB Thailand eSIM with an airport pickup, on request (ask when you book).
- Save the emergency numbers from the table below in your phone.
What to check in each season
TMD defines three official seasons.
Rainy season (mid-May to mid-October). In 2026 it officially started on 15 May. TMD expected the heaviest rain and the highest flash-flood risk in August and September, and the rains in upper Thailand to end about mid-October 2026. Check the radar each morning, TMD's heavy-rain warnings, and the wind before any boat trip.
Cool season (mid-October to mid-February). On the Gulf side of the south (Koh Samui, Nakhon Si Thammarat, Songkhla) the rain continues until December, and Koh Samui is wettest in November. In late November 2025, floods from Cyclone Senyar hit Songkhla (Hat Yai) hardest. If you travel there from October to December, watch TMD warnings and leave extra days in your plans.
Hot season (mid-February to mid-May). Typical highs reach 35-39 C, and the hottest days go above 40 C. Check the midday temperature, and PM2.5 in the north. Drink water often and rest in the shade or air conditioning at midday. For heat stroke (confusion, hot and dry skin), call 1669.
The Andaman coast follows its own pattern: Phuket is wettest from August to October and driest in February. Koh Samui, on the Gulf side, is largely the opposite: February to September is its drier part of the year.
Weather and travel days
Heavy rain slows the roads and makes waiting outside for a bus or taxi unpleasant. If rain is forecast for your arrival or a long transfer, a pre-booked car that meets you at the airport or your hotel door is easier.
Smile Taxi Service fares are fixed per vehicle, one way, with expressway tolls included. From Suvarnabhumi Airport to Pattaya, a sedan costs 1,200 THB, an SUV 1,500 THB and a van 1,800 THB (book a sedan from Suvarnabhumi to Pattaya). Airport pickups include 60 minutes of free waiting from the actual landing time. You pay the driver in cash (THB) at the end of the trip; if you can only pay by card, message the team for a PayPal payment link (a 5% fee is added). Cancellation is free up to 24 hours before pickup. After that, a cancellation or change costs 25% (less than 24 h), 35% (less than 12 h) or 50% (less than 2 h) of the price, and a no-show 100%, also when you pay the driver in cash (details). See all routes and fares.
Emergency numbers to save
| Service | Number |
|---|---|
| TMD weather hotline | 1182 |
| DDPM disaster hotline | 1784 |
| Marine Department (boats and piers) | 1199 |
| Tourist Police | 1155 |
| Police and general emergency | 191 |
| Medical emergency | 1669 |
FAQ
What is Thailand's official weather app? TMD's "Thai Weather" and its newer "TMD พยากรณ์" app. Both are free and list English as an app language.
Which app shows air pollution in Chiang Mai? Air4Thai, from the Pollution Control Department, or IQAir AirVisual. Both are free.
Will I get emergency alerts on my phone in Thailand? The T-Alert system, run by DDPM, sends warnings to phones in the affected area and has been tested since May 2025. Install the Thai Disaster Alert app as well.
Does it rain all day in the rainy season? Not usually. Even in September, Bangkok's wettest month, many days stay partly dry. A radar app shows when the next shower is coming.
For a door-to-door transfer on a rainy day, message us on WhatsApp or LINE, or use the Smile Taxi Service booking page.