Ko Samui Island weather and climate in 2025
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April
May
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Ko Samui Island weather and climate in 2025
January
February
March
April
May
June
July
August
September
October
November
December
Overview
July
< June
Overview
August >
Day
33 °C
Night
24 °C
Sea
30 °C
Precipitation
109 mm
in month
Rainy days
20 days
in month
Daylight
13 hours
average
Sunshine
6 hours
average
Humidity
77 %
Day
33 °C
Night
24 °C
Sea
30 °C
Precipitation
109 mm
in month
Rainy days
20 days
in month
Daylight
13 hours
average
Sunshine
6 hours
average
Humidity
77 %
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Weather overview for Ko Samui Island
Weather overview
Ko Samui Island, located in Thailand, enjoys a tropical climate with highly distinct seasonal variations. Throughout the year, daytime temperatures hover between 30 °C (85 °F) and 34 °C (94 °F), peaking in April. Nighttime temperatures are coolest in February, reaching as low as 22 °C (72 °F), and are warmest in May at 24 °C (75 °F). Visitors can expect the dry season to peak in February, with the least precipitation covering only 5. As the calendar turns to October, the island experiences its zenith of rainfall, with upwards of 22. The annual cycle of sea temperatures also sees a range, with 28 °C (82 °F) marking January's lows, and May's waters delicately warming to 30 °C (86 °F).
January weather
The tourist season in Ko Samui Island starts up as the dry season begins. Sea temperatures are at their minimal for the year, a still-pleasant 28 °C (82 °F), while the day temperature experiences a rise to 31 °C (88 °F). The frequency of rainy days continues its downward trend from the prior month, resting at 9. There is also an uptick in sun hours, with a value of 7 hours.
February weather
The tourist season is drawing closer to its climax on Ko Samui Island. Sea temperatures progressively increase, paralleling the rise in the daytime temperature, now at 32 °C (90 °F). The fewest rainy days of the year are observed this month, corroborated by a low figure of 5. This month also showcases the least rainfall overall, measured at 45 mm (1.77 in). February nights are particularly cool and the zenith of sunny hours, unobstructed by clouds, can be seen with a statistic of 8 hours.
March weather
March maintains the pending high tourist season in Ko Samui Island, alongside a continued dry spell. The upward trend of the daytime temperature is notable, registering at 34 °C (92 °F), while the sea temperature also ascends. Rainy days are on the rise once more, amounting to 6, and there is an increase in the measurement of rainfall, totaling 94 mm (3.69 in).
April weather
Tourism in Ko Samui Island continues with full vigour in April. The pinnacle of the daytime temperature can be observed, fixed at 34 °C (94 °F), and a similar rise in the sea temperature is witnessed, marked at 30 °C (86 °F). The accumulation of rainy days escalates modestly in comparison to the previous month, noted at 10. The beginning of a decrease in sun hours sans clouds is also noted, with a measure of 8 hours.
May weather
As May commences, a slight decline in daytime temperatures is recorded, now at 34 °C (92 °F) in Ko Samui Island, while sea temperatures reach their pinnacle. Notably, the frequency of rainy days begins an upward trajectory, logged at 19. The month also marks the beginning of an increase in rainfall amounts. Maximum nighttime temperatures are registered, peaking at 24 °C (75 °F). Less sunshine hours are recorded, now tallying 6 hours.
June weather
Continuing the trend of the previous month, June sees a further drop in daytime temperatures, averaging 33 °C (91 °F) in Ko Samui Island. The rainfall amount also begins to decrease, now measured at 107 mm (4.20 in). The sun hours keep on their declining path, reaching 6 hours, and a dip in humidity is recorded during this month. The longest days of the year are enjoyed in June.
July weather
The onset of the wet season is marked in Ko Samui Island during the month of July. The tally of rainy days begins to ascend, documented at 20. An increase in wind speed can also be observed, rated at 3 m/s.
August weather
August in Ko Samui Island is characterized by the prevailing wet season. Signifying the start of increased rainfall, measurements reach 116 mm (4.58 in), and wind speeds are at their highest for the year, showing 3 m/s.
September weather
Ko Samui Island sees a continued increase in rainy days, which in September amount to 21, and a similar rise in rainfall is noted, reading 145 mm (5.72 in). The wet season is underway, and the minimum number of sun hours sans clouds is evident, with a value of 6 hours. A trend toward cooler nights begins within this month.
October weather
The wet season continues to make its presence known in Ko Samui Island, with the rainiest days peaking at 22. The rainfall similarly escalates, with the current month's tally at 264 mm (10.41 in). The downward trend in daytime temperatures is observable, now at 31 °C (88 °F). Gentle wind speeds persist as they reach their lowest point.
November weather
The apex of the wet season draws near in Ko Samui Island. The daytime temperature continues its downward trend, now displayed at 30 °C (86 °F), and the decrease in sea temperatures can be noticed. The peak in rainfall amounts reaches 371 mm (14.60 in), while the onset of declining rainy days is seen in November. The peak in humidity at this time represents a measure of 84 %.
December weather
As the year concludes, Ko Samui Island gradually welcomes the tourist season. The lowest daytime temperatures of the year are now apparent, marked at 30 °C (85 °F). Concurrently, a decline in sea temperatures is noticed, registering at 28 °C (82 °F). The downfall in rainy days continues as previously, observed at 13, and a decrease in rainfall is also noted. The commencement of an increase in sunny hours is also documented.
FAQs
What might the daytime temperature be on Ko Samui Island in January?
January in Ko Samui Island presents an average daytime temperature of 31 °C (88 °F), which is ideal for relaxing beside the sea.
Does the temperature on Ko Samui Island in February feel warm?
Indeed, the daytime temperature in Ko Samui Island during February reaches a warm 32 °C (90 °F).
During March, what would the sea temperature be around Ko Samui Island?
In March, the sea around Ko Samui Island is comfortably warm with temperatures around 29 °C (84 °F).
Are April's climatic conditions conducive for a visit to Ko Samui Island?
April beckons with ideal climatic conditions for a holiday in Ko Samui Island, exhibiting sea temperatures of a delightful 30 °C (86 °F).
Is May considered to be part of the wet season in Ko Samui Island?
In May, while not officially the wet season, Ko Samui Island typically experiences 19 of rain throughout the month.
What is the range of nighttime temperatures in Ko Samui Island throughout June?
June nights in Ko Samui Island usually bring an average temperature of around 24 °C (74 °F), which contributes to pleasant evenings.
What is the typical humidity level in Ko Samui Island during July?
Expect a humidity of around 77 % during July in Ko Samui Island, which is a bit higher than usual.
How many hours of sunshine can be expected in Ko Samui Island during August?
In Ko Samui Island throughout August, approximately 6 hours of sunshine are usual.
What is the rainfall pattern in Ko Samui Island during September?
Rainy days are a common occurrence in September within Ko Samui Island, with an average of 21 of rainfall.
What is the general wind situation during October in Ko Samui Island?
October in Ko Samui Island tends to have gentle breezes, with wind speeds averaging around 1 m/s.
Does Ko Samui Island experience a dry season in the month of November?
November in Ko Samui Island is not identified by a dry season; one should expect rain on roughly 20.
How many days of precipitation can typically be expected in December in Ko Samui Island?
December generally brings about 13 of rainfall in Ko Samui Island.
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