← Weather & seasons in Thailand
On the thirty-year normal, Rayong’s driest and coolest month is December (7.5 mm, 22.1°C mean daily minimum) — the same month tops both records, which most Thai stations do not share. Wettest is September (268.8 mm) and hottest is April (34.0°C mean daily maximum). Separately, Rayong sits inside the government’s Eastern Economic Corridor alongside Chachoengsao and Chon Buri — an economic zoning decision, not a climate one.
The season bands, honestly
Rayong sits on the same stretch of Gulf coast as Pattaya but carries noticeably more rain across the year. The bands below are built from the four extreme months in the thirty-year normal, not a full monthly table.
| Window | Measured conditions | What that means here |
|---|---|---|
| Dec | Driest AND coolest month at once (7.5 mm, 22.1°C mean daily minimum). | The single best window on the numbers — most Thai stations split their driest and coolest months, Rayong's land on the same one. |
| Jan – Feb | Dry season continuing. | Good general-purpose weather for both the mainland city and Koh Samet. |
| Mar – Apr | Heating toward the year's peak. | April is the hottest month on the normal; Songkran (mid-April) falls here too. |
| May – Aug | Rain building. | The southwest monsoon arrives gradually; crossings to Koh Samet get choppier as the season goes on. |
| Sep | Wettest month (268.8 mm). | Wetter than Pattaya's own wettest month (224.5 mm, October) despite sitting on the same stretch of Gulf coast. |
| Oct – Nov | Rain easing. | Shoulder season — improving weather, thinner crowds on Koh Samet. |
All figures are 1991–2020 normals for WMO station 48478 (Rayong). The “what that means here” column is our own reading against the Koh Samet ferry season, not a separate data source.
Why Rayong isn't a purely tourism-driven coast
Rayong is one of three provinces — alongside Chachoengsao and Chon Buri — inside the Thai government’s Eastern Economic Corridor (EEC), a designated development zone rather than a tourism board. The Eastern Economic Corridor Office names U-Tapao International Airport and the Eastern Aviation City, plus the Map Ta Phut Industrial Port Phase 3 expansion, as flagship projects tied to the corridor — both are in Rayong province, alongside the separate Laem Chabang Port Phase 3 expansion over the provincial line in Chon Buri. That combination of heavy industry, a growing airport and a working port is genuinely different from Pattaya or Hua Hin's tourism-first economies, and it is worth weighing alongside the weather if you are comparing where in the region to live.
None of that changes the climate normals on this page — the EEC is an economic and infrastructure designation, not a weather pattern — but it does explain why Rayong's population and property market are shaped as much by industrial employment and the province's role as Bangkok's nearest fast beach as by tourism alone.
Why April is the month to plan around
April is Rayong’s hottest month on the thirty-year normal, at a 34.0°C mean daily maximum — a degree hotter than Pattaya's own April peak (33.0°C), despite the two provinces sharing the same stretch of Gulf coast. Songkran (mid-April) falls in the same stretch, and it sits at the tail end of the dry season described in the bands above, just before the rains start building toward September.
What we could not confirm
- A full monthly rainfall or temperature table beyond the four extreme months. The archive that would supply every other month could not be reached from this run.
- A province-wide open-burning ban for Rayong, of the kind Chiang Mai and Chiang Rai provinces have announced for 2026. We found no equivalent order for Rayong in an official source — its air-quality concerns, where they exist, are tied to industrial and vehicle emissions around Map Ta Phut rather than seasonal agricultural burning. See our Rayong air quality page for what is tracked locally.
- Current EEC investment or population figures specific to Rayong. The EECO's own site names the flagship projects but this run did not confirm an investment total or a province-level population figure against an official publication, so none is printed here.
Frequently asked questions
December, on the thirty-year normal. It is both the driest month (7.5 mm) and the coolest (a 22.1°C mean daily minimum) — most Thai stations split those two records across different months, but Rayong's land on the same one, which makes December an unusually clean best-case window for both the mainland city and a Koh Samet trip.
Wetter, on every figure this site has checked. Rayong's annual normal is 1,406.7 mm over 90.8 rain days against Pattaya's 1,105.8 mm over 82.2 days — around 27% more rain a year on the same coastline. Rayong's wettest month, September at 268.8 mm, is also well above Pattaya's own peak (224.5 mm in October).
No — the EEC is an economic development zone covering Chachoengsao, Chon Buri and Rayong provinces, not a climate designation. It explains why Rayong carries more heavy industry and infrastructure (U-Tapao Airport and Eastern Aviation City, the Map Ta Phut Industrial Port) than a typical beach province, which is worth knowing if you're choosing between Rayong and a purely tourism-driven coast — but it has no bearing on the rainfall and temperature normals on this page.
The same window the mainland climate data points to: the driest and calmest months run roughly December through February, tapering into a still-manageable dry season through April. Crossings from Ban Phe pier get rougher as the southwest monsoon builds from May, peaking around Rayong's own wettest month, September.
Those are province-specific agricultural open-burning bans tied to the north's dry-season haze. We found no equivalent province-wide burning-ban order for Rayong — its air-quality profile is shaped more by heavy industry and vehicle traffic around the Map Ta Phut estate than by seasonal field burning. See the honest gap below.
Related guides
- Best time to visit Pattaya — the neighbouring coast, drier on every figure checked.
- Island hopping from Rayong — Ban Phe pier to Koh Samet, Koh Talu and the Koh Man turtle islands.
- Air quality in Thailand — the PM2.5 standard and how burning-ban provinces differ from industrial ones.
- Compare Thai cities — the same normals for twelve stations, side by side.
- Rayong — the city guide.
- Explore Thailand — the section this guide sits in.
Timed your visit. Now time the move.
If Rayong is more than a trip, see what is actually listed here before the next dry season sets your calendar.
Sources & References
- WMO Climatological Standard Normals 1991–2020 — Thailand station data sheets (NCEI Accession 0253808), Rayong station 48478: annual rainfall of 1,406.7 mm over 90.8 rain days, wettest month September (268.8 mm), driest month December (7.5 mm), hottest month April at a 34.0°C daily-maximum mean, coolest month December at a 22.1°C daily-minimum mean, annual sunshine 2,334.0 hours
- Eastern Economic Corridor Office (EECO) — official programme overview: the EEC covers Chachoengsao, Chon Buri and Rayong provinces; flagship infrastructure named for the corridor includes U-Tapao International Airport and the Eastern Aviation City, the Map Ta Phut Industrial Port Phase 3 expansion, and Laem Chabang Port Phase 3 in neighbouring Chon Buri
Primary and official sources are cited above. Government rules, fees and procedures in Thailand change over time and vary by office; always confirm current requirements with the relevant authority before relying on them. BAANLYY never takes paid placement in editorial content.
