Ko Samui Weather in May

NASA POWER reanalysis for the half-degree grid cell around Ko Samui, 1991-2020; a grid cell is an area average and can differ from a thermometer in town by several degrees

Average highs run from 30°C on May 1 to 30°C on May 31, and lows from 28°C to 28°C. Normal precipitation for the month is 164 mm over about 28 wet days.

May day by day

The normal high and low for each date, in °C.

Normal low
Normal high
Reanalysis extreme high
Reanalysis extreme low

May at a glance

Average high: 30°C
Average low: 28°C
Precipitation: 164 mm
Reanalysis high: 33°CMay 11, 2016
Reanalysis low: 27°CMay 26, 1999
Daylight: 12 h 27 min to 12 h 38 min
Cloud cover: 82%
Humidity: 78%
Dew point: 25°C
Wind: 13.3 km/h

Every day of the month

A wet day has at least 1 mm of precipitation in the reanalysis.

Date	Normal high	Normal low	Reanalysis high	Reanalysis low	Chance wet
May 1	30°C	28°C	32°C 2016	27°C 1999	68%
May 2	30°C	28°C	32°C 2019	27°C 1999	70%
May 3	30°C	29°C	32°C 1998	27°C 1996	72%
May 4	30°C	28°C	31°C 2016	27°C 2009	74%
May 5	30°C	28°C	32°C 2015	27°C 2008	76%
May 6	30°C	28°C	33°C 2016	27°C 1999	77%
May 7	30°C	28°C	32°C 2010	27°C 1999	78%
May 8	30°C	28°C	33°C 2010	27°C 1999	79%
May 9	30°C	28°C	32°C 2010	27°C 2008	79%
May 10	30°C	28°C	32°C 2016	27°C 2008	81%
May 11	30°C	28°C	33°C 2016	27°C 1995	83%
May 12	30°C	28°C	33°C 2016	27°C 2008	84%
May 13	30°C	28°C	33°C 2016	27°C 2000	84%
May 14	30°C	28°C	32°C 2016	27°C 1995	86%
May 15	30°C	28°C	32°C 2016	27°C 1993	87%
May 16	30°C	28°C	32°C 2016	27°C 2007	88%
May 17	30°C	28°C	32°C 1998	27°C 2007	89%
May 18	30°C	28°C	32°C 1998	27°C 2000	89%
May 19	30°C	28°C	32°C 2016	27°C 1999	89%
May 20	30°C	28°C	32°C 2004	27°C 2005	89%
May 21	30°C	28°C	32°C 1998	27°C 1994	90%
May 22	30°C	28°C	31°C 1998	27°C 1994	91%
May 23	30°C	28°C	31°C 1998	27°C 1999	91%
May 24	30°C	28°C	32°C 1998	27°C 1999	92%
May 25	30°C	28°C	31°C 1998	27°C 1999	92%
May 26	30°C	28°C	31°C 1998	27°C 1999	92%
May 27	30°C	28°C	32°C 1998	27°C 2004	93%
May 28	30°C	28°C	32°C 1998	27°C 2004	94%
May 29	30°C	28°C	31°C 1997	27°C 1999	94%
May 30	30°C	28°C	31°C 1992	27°C 1999	93%
May 31	30°C	28°C	31°C 1992	27°C 1999	91%

Chance of rain

Chance of a wet day

Sunrise and sunset

Times for 2026, local time (GMT+7).

May 1: sunrise 6:04 AM, sunset 6:31 PM
May 31: sunrise 5:59 AM, sunset 6:37 PM

Every day of May: sun and moon

Other months

Sources

Cloud, humidity, wind and sunshine, and temperature and precipitation: NASA POWER (MERRA-2, CERES and GEWEX SRB), 1991-2020. The data was obtained from the National Aeronautics and Space Administration (NASA) Langley Research Center's Prediction Of Worldwide Energy Resources (POWER) project funded through the NASA Earth Science Division: POWER Daily API v2, accessed 2026-09-24. Sun and moon: computed with the NOAA solar equations and Meeus.