Ko Samui
Thailand
Long-term weather forecast
Long-term weather forecast

May weather forecast and climate
Ko Samui, Thailand

The scenic view of the striking Angthong National Marine Park in Ko Samui, Thailand, calm clear water all around
The scenic view of the striking Angthong National Marine Park in Ko Samui, Thailand, calm clear water all around
The last month of the spring, May, is another tropical month in Ko Samui, Thailand, with temperature in the range of an average high of 32.5°C (90.5°F) and an average low of 25.7°C (78.3°F).

Temperature

In May, the average high-temperature is practically the same as in April - a still hot 32.5°C (90.5°F). In May, the average low-temperature is 25.7°C (78.3°F).

Heat index

In May, the average heat index is calculated to a burning hot 46.2°C (115.2°F). Be wary - heat exhaustion and heat cramps are highly anticipated. With continued activity, heatstroke is very likely.
Take into consideration that the heat index values are calculated for shade and light wind conditions. Exposure to direct sunshine can increase heat index values by up to 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'felt air temperature', 'real feel', 'feels like', or 'apparent temperature', is a measure of how hot it feels when the actual air humidity is factored in. This effect is subjective, depending on the activity and individual's heat perception influenced by various reasons (wind, metabolic differences, clothing). Be aware that direct exposure to sunlight increases heat impact, and may raise the heat index additionally, by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are especially crucial for babies and toddlers. Children are often less aware of the need to rest and re-hydrate. Thirst is a late sign of dehydration - it is vital to remain hydrated, particularly during prolonged physical activities.
To prevent overheating and help regulate its internal temperature, the human body sweat and rely on the evaporation to cool down. With a lot of moisture in the air, the evaporation process is not as effective, and the body does not cool down as efficiently, creating a perception of overheating. If the body can not disperse the excessive heat and body temperature reaches conditions of hyperthermia, above 37.5°C (99.5°F) to 38.3°C (100.9°F), thermal conditions are potentially life-threatening.

Humidity

In Ko Samui, the average relative humidity in May is 80%.

Rainfall

In May, in Ko Samui, the rain falls for 16 days. Throughout May, 155.9mm (6.1") of precipitation is accumulated. In Ko Samui, during the entire year, the rain falls for 160 days and collects up to 1960.1mm (77.2") of precipitation.

Sea temperature

The month with the warmest seawater is May, with an average sea temperature of 30.1°C (86.2°F).
Note: The surface water temperatures above 30°C (86°F) are arguably considered as unpleasant for swimming, and any intense water activity, as the refreshing effect of water is missing.

Daylight

In May, the average length of the day in Ko Samui is 12.6h.

Sunshine

Months with the least sunshine in Ko Samui are May through December, with an average of 6h of sunshine.

UV index

Months with the highest UV index are February through October, with an average maximum UV index of 12. A UV Index estimate of 11, and higher, represents an extreme health hazard from the exposure to the Sun's UV rays for ordinary individuals.
Note: In May, the average maximum UV index of 12 translate into the following recommendations:
Practice all-important precautions. Light skin people may get burned in less than 5 minutes. Seek shade and minimize exposure to direct Sun in a period between 10 a.m. and 4 p.m. when UV radiation is most intense; keep in mind that shade structures like parasols or canopies do not provide perfect sun protection. On bright days sunglasses that block both UVA and UVB rays should be worn. A hat with a wide brim is extremely helpful, as it can prevent roughly 50% of UV radiation from reaching the eyes. A broad-spectrum sunscreen of SPF 30+ should be liberally applied and re-applied every two hours, and immediately after an outdoor workout or a swim. Beware! The strength of the UV rays is significantly increased by the reflection of the water and sand.

What is the temperature in May in Ko Samui?

In Ko Samui, Thailand, in May, the average high-temperature is 32.5°C (90.5°F), and the average low-temperature is 25.7°C (78.3°F). The average heat index (a.k.a. 'real feel', 'felt air temperature'), that factores the actual air temperature with the relative humidity, in May is calculated to 46.2°C (115.2°F).

What is the average humidity in May in Ko Samui?

The average relative humidity in May in Ko Samui, Thailand, is 80%.

How much does it rain in Ko Samui in May?

In Ko Samui, in May, during 16 rainfall days, 155.9mm (6.1") of precipitation is typically accumulated.

When is the sea warmest in Ko Samui?

The month with the warmest seawater in Ko Samui, Thailand, is May, with an average sea temperature of 30.1°C (86.2°F).

How warm is the water in May in Ko Samui?

In Ko Samui, in May, the average water temperature is 30.1°C (86.2°F). The water temperature above 30°C (86°F) is arguably regarded as unpleasant. The primary purpose of entering the water - cooling down from sunshine and high temperatures - is lost.

What is the average length of the day in May in Ko Samui?

In Ko Samui, the average length of the day in May is 12.6h.

What is the month with the least sunshine in Ko Samui?

Months with the least sunshine in Ko Samui, Thailand, are May through December, with an average of 6h of sunshine.

How long on average sun shines in May in Ko Samui?

In May, the average sunshine is 6h.

What are the months with the highest UV index in Ko Samui?

February through October, with an average maximum UV index of 12, are months with the highest UV index in Ko Samui, Thailand.

What is the UV index intensity in May in Ko Samui?

The average daily maximum UV index in May is 12. A UV Index reading of 11, and higher, represents an excessive health risk from the exposure to the Sun's UV radiation.
Average temperature in May - Ko Samui, Thailand
  • Average high temperature in May: 32.5°C

The warmest month (with the highest average high temperature) is April (32.6°C).
The month with the lowest average high temperature is January (29°C).

  • Average low temperature in May: 25.7°C

The month with the highest average low temperature is April (26.1°C).
The coldest month (with the lowest average low temperature) is December (23.9°C).

Average humidity in May - Ko Samui, Thailand
  • Average humidity in May: 80%

Months with the highest relative humidity are October and November (85%).
Months with the lowest relative humidity are June, July and August (78%).

Average rainfall in May - Ko Samui, Thailand
  • Average rainfall in May: 155.9mm

The wettest month (with the highest rainfall) is November (506.6mm).
The driest month (with the lowest rainfall) is February (54.4mm).

Average rainfall days in May - Ko Samui, Thailand
  • Average rainfall days in May: 16 days

Months with the highest number of rainy days are October and November (20 days).
The month with the lowest number of rainy days is March (4 days).

Average sea temperature in May - Ko Samui, Thailand
  • Average sea temperature in May: 30.1°C

The best month for swimming (with the highest average sea temperature) is May (30.1°C).
The coldest month (with the lowest average sea temperature) is January (27.8°C).

Average daylight in May / Average sunshine in May - Ko Samui, Thailand
  • Average daylight in May: 12.6h

The month with the longest days is June (Average daylight: 12.7h).
Months with shortest days are January and December (Average daylight: 11.6h).

  • Average sunshine in May: 6h

The month with most sunshine is February (Average sunshine: 9h).
Months with least sunshine are May, June, July, August, September, October, November and December (Average sunshine: 6).

Average UV index in May - Ko Samui, Thailand
  • Average UV index in May: 12

Months with the highest UV index are February, March, April, May, June, July, August, September and October (UV index 12).
The month with the lowest UV index is December (UV index 10).