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Thailand

Koh Samui weather in January

Is it warm? Yes. January in Koh Samui is hot: afternoons average 29°C and nights 24°C. Most days (80%) peak between 28°C and 30°C.

Hot · average high

29°C

25°C or more on almost every day.

  • Average low24°overnight
  • Sea28°average, 2022–2025
  • Rainy days6126 mm in the month
  • SkyOften cloudy64% cloud · 16% clear days

How warm it really gets

Every January afternoon from 2011–2025: 465 days. Most (80%) peaked between 28° and 30°.

Number of January days by daily high, 2011–2025.

January, year by year

The average January high in each year. The warmest, 2024, averaged 30°C; the coolest, 2011, 29°C.

Average January high by year: 2011: 28.5°C, 2012: 28.7°C, 2013: 29.5°C, 2014: 28.5°C, 2015: 28.7°C, 2016: 29.9°C, 2017: 28.7°C, 2018: 28.9°C, 2019: 29.3°C, 2020: 29.8°C, 2021: 28.7°C, 2022: 29.6°C, 2023: 29.2°C, 2024: 30.1°C, 2025: 29.1°C.

Compared with home

Average January highs. Expect rain on about 6 days (126 mm in a typical month).

  • Koh Samui29°
  • Cork9°
  • London9°
  • Dublin8°
  • Belfast8°
  • Glasgow7°
  • Manchester7°

Other months

Koh Samui all year · Where else is hot in January

Warmer in January, not much further

Flying times are estimates from Dublin; Koh Samui is about 13h.

  • Very hot in Jan

    33°C average high

    avg high · 19° at night

    25°C+ on almost every day

    The Gambia

    The Gambia

    Sea
    23°
    Rain
    0 days
    Sky
    Often cloudy
    From Dublin
    ≈ 6h

  • Hot in Jan

    31°C average high

    avg high · 25° at night

    25°C+ on almost every day

    Aruba

    Caribbean

    Sea
    27°
    Rain
    4 days
    Sky
    Some cloud
    From Dublin
    ≈ 9h 15m

  • Hot in Jan

    30°C average high

    avg high · 23° at night

    25°C+ on almost every day

    Jamaica (Montego Bay)

    Caribbean

    Sea
    28°
    Rain
    13 days
    Sky
    Some cloud
    From Dublin
    ≈ 9h 15m

Air: Copernicus ERA5-Land, 2011–2025, matched to the official averages for Koh Samui. Sea: Copernicus ERA5, 2022–2025. Rainy days = days with 1 mm of rain or more, as weather stations count them. Clear day = average cloud cover of 30% or less. These are averages of past weather, not a forecast. Methodology