Climate and Average Weather Year Round in Ko Si Chang Thailand

In Ko Si Chang, the wet season is overcast, the dry season is partly cloudy, and it is hot and oppressive year round. Over the course of the year, the temperature typically varies from 72°F to 91°F and is rarely below 67°F or above 94°F.

Based on the beach/pool score, the best time of year to visit Ko Si Chang for hot-weather activities is from late November to early March.

The temperature in Ko Si Chang varies so little throughout the year that it is not entirely meaningful to discuss hot and cold seasons.

In Ko Si Chang, the average percentage of the sky covered by clouds experiences significant seasonal variation over the course of the year.

The clearer part of the year in Ko Si Chang begins around November 13 and lasts for 4.5 months, ending around March 27.

The clearest month of the year in Ko Si Chang is January, during which on average the sky is clear, mostly clear, or partly cloudy 55% of the time.

The cloudier part of the year begins around March 27 and lasts for 7.5 months, ending around November 13.

The cloudiest month of the year in Ko Si Chang is June, during which on average the sky is overcast or mostly cloudy 93% of the time.

A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days in Ko Si Chang varies very significantly throughout the year.

The wetter season lasts 5.8 months, from May 4 to October 29, with a greater than 37% chance of a given day being a wet day. The month with the most wet days in Ko Si Chang is September, with an average of 20.3 days with at least 0.04 inches of precipitation.

The drier season lasts 6.2 months, from October 29 to May 4. The month with the fewest wet days in Ko Si Chang is December, with an average of 1.0 days with at least 0.04 inches of precipitation.

Among wet days, we distinguish between those that experience rain alone, snow alone, or a mixture of the two. The month with the most days of rain alone in Ko Si Chang is September, with an average of 20.3 days. Based on this categorization, the most common form of precipitation throughout the year is rain alone, with a peak probability of 72% on September 24.

Rainfall

To show variation within the months and not just the monthly totals, we show the rainfall accumulated over a sliding 31-day period centered around each day of the year. Ko Si Chang experiences extreme seasonal variation in monthly rainfall.

The rainy period of the year lasts for 9.7 months, from February 14 to December 5, with a sliding 31-day rainfall of at least 0.5 inches. The month with the most rain in Ko Si Chang is September, with an average rainfall of 8.8 inches.

The rainless period of the year lasts for 2.3 months, from December 5 to February 14. The month with the least rain in Ko Si Chang is December, with an average rainfall of 0.2 inches.

The length of the day in Ko Si Chang varies over the course of the year. In 2024, the shortest day is December 21, with 11 hours, 21 minutes of daylight; the longest day is June 21, with 12 hours, 54 minutes of daylight.

The earliest sunrise is at 5:49 AM on May 31, and the latest sunrise is 55 minutes later at 6:43 AM on January 25. The earliest sunset is at 5:46 PM on November 19, and the latest sunset is 1 hour, 1 minute later at 6:47 PM on July 9.

Daylight saving time (DST) is not observed in Ko Si Chang during 2024.

The figure below presents a compact representation of key lunar data for 2024. The horizontal axis is the day, the vertical axis is the hour of the day, and the colored areas indicate when the moon is above the horizon. The vertical gray bars (new Moons) and blue bars (full Moons) indicate key Moon phases.

We base the humidity comfort level on the dew point, as it determines whether perspiration will evaporate from the skin, thereby cooling the body. Lower dew points feel drier and higher dew points feel more humid. Unlike temperature, which typically varies significantly between night and day, dew point tends to change more slowly, so while the temperature may drop at night, a muggy day is typically followed by a muggy night.

Ko Si Chang experiences significant seasonal variation in the perceived humidity.

The muggier period of the year lasts for 11 months, from January 16 to December 7, during which time the comfort level is muggy, oppressive, or miserable at least 68% of the time.

The month with the fewest muggy days in Ko Si Chang is December, with 19.5 days that are muggy or worse.

This section discusses the wide-area hourly average wind vector (speed and direction) at 10 meters above the ground. The wind experienced at any given location is highly dependent on local topography and other factors, and instantaneous wind speed and direction vary more widely than hourly averages.

The average hourly wind speed in Ko Si Chang experiences significant seasonal variation over the course of the year.

The windier part of the year lasts for 6.9 months, from February 8 to September 5, with average wind speeds of more than 8.2 miles per hour. The windiest month of the year in Ko Si Chang is July, with an average hourly wind speed of 9.9 miles per hour.

The calmer time of year lasts for 5.1 months, from September 5 to February 8. The calmest month of the year in Ko Si Chang is October, with an average hourly wind speed of 6.8 miles per hour.

The predominant average hourly wind direction in Ko Si Chang varies throughout the year.

The wind is most often from the south for 5.0 months, from January 15 to June 14 and for 2.0 weeks, from September 29 to October 13, with a peak percentage of 86% on March 26. The wind is most often from the west for 3.5 months, from June 14 to September 29, with a peak percentage of 65% on August 16. The wind is most often from the north for 2.1 months, from October 19 to December 21, with a peak percentage of 49% on December 2.

Ko Si Chang is located near a large body of water (e.g., ocean, sea, or large lake). This section reports on the wide-area average surface temperature of that water.

The average water temperature experiences some seasonal variation over the course of the year.

The time of year with warmer water lasts for 2.4 months, from April 10 to June 23, with an average temperature above 86°F. The month of the year in Ko Si Chang with the warmest water is May, with an average temperature of 87°F.

The time of year with cooler water lasts for 2.1 months, from December 10 to February 13, with an average temperature below 82°F. The month of the year in Ko Si Chang with the coolest water is January, with an average temperature of 81°F.

To characterize how pleasant the weather is in Ko Si Chang throughout the year, we compute two travel scores.

The tourism score favors clear, rainless days with perceived temperatures between 65°F and 80°F. Based on this score, the best time of year to visit Ko Si Chang for general outdoor tourist activities is from early December to late January, with a peak score in the last week of December.

The beach/pool score favors clear, rainless days with perceived temperatures between 75°F and 90°F. Based on this score, the best time of year to visit Ko Si Chang for hot-weather activities is from late November to early March, with a peak score in the last week of January.

Methodology

For each hour between 8:00 AM and 9:00 PM of each day in the analysis period (1980 to 2016), independent scores are computed for perceived temperature, cloud cover, and total precipitation. Those scores are combined into a single hourly composite score, which is then aggregated into days, averaged over all the years in the analysis period, and smoothed.

Our cloud cover score is 10 for fully clear skies, falling linearly to 9 for mostly clear skies, and to 1 for fully overcast skies.

Our precipitation score, which is based on the three-hour precipitation centered on the hour in question, is 10 for no precipitation, falling linearly to 9 for trace precipitation, and to 0 for 0.04 inches of precipitation or more.

Our tourism temperature score is 0 for perceived temperatures below 50°F, rising linearly to 9 for 65°F, to 10 for 75°F, falling linearly to 9 for 80°F, and to 1 for 90°F or hotter.

Our beach/pool temperature score is 0 for perceived temperatures below 65°F, rising linearly to 9 for 75°F, to 10 for 82°F, falling linearly to 9 for 90°F, and to 1 for 100°F or hotter.

Definitions of the growing season vary throughout the world, but for the purposes of this report, we define it as the longest continuous period of non-freezing temperatures (≥ 32°F) in the year (the calendar year in the Northern Hemisphere, or from July 1 until June 30 in the Southern Hemisphere).

Temperatures in Ko Si Chang are sufficiently warm year round that it is not entirely meaningful to discuss the growing season in these terms. We nevertheless include the chart below as an illustration of the distribution of temperatures experienced throughout the year.

Growing degree days are a measure of yearly heat accumulation used to predict plant and animal development, and defined as the integral of warmth above a base temperature, discarding any excess above a maximum temperature. In this report, we use a base of 50°F and a cap of 86°F.

This section discusses the total daily incident shortwave solar energy reaching the surface of the ground over a wide area, taking full account of seasonal variations in the length of the day, the elevation of the Sun above the horizon, and absorption by clouds and other atmospheric constituents. Shortwave radiation includes visible light and ultraviolet radiation.

The average daily incident shortwave solar energy experiences some seasonal variation over the course of the year.

The brighter period of the year lasts for 2.0 months, from January 27 to March 28, with an average daily incident shortwave energy per square meter above 5.7 kWh. The brightest month of the year in Ko Si Chang is February, with an average of 5.9 kWh.

The darker period of the year lasts for 5.4 months, from May 6 to October 20, with an average daily incident shortwave energy per square meter below 4.5 kWh. The darkest month of the year in Ko Si Chang is September, with an average of 4.2 kWh.

For the purposes of this report, the geographical coordinates of Ko Si Chang are 13.164 deg latitude, 100.805 deg longitude, and 89 ft elevation.

The topography within 2 miles of Ko Si Chang contains significant variations in elevation, with a maximum elevation change of 597 feet and an average elevation above sea level of 31 feet. Within 10 miles contains significant variations in elevation (1,024 feet). Within 50 miles contains very significant variations in elevation (2,743 feet).

The area within 2 miles of Ko Si Chang is covered by water (90%), within 10 miles by water (91%), and within 50 miles by water (48%) and cropland (41%).