Average Weather in Seoul South Korea
In Seoul, the summers are long, warm, muggy, wet, and partly cloudy and the winters are freezing, dry, and mostly clear. Over the course of the year, the temperature typically varies from 21°F to 85°F and is rarely below 11°F or above 91°F.
The hot season lasts for 4.0 months, from May 25 to September 25, with an average daily high temperature above 75°F. The hottest day of the year is August 4, with an average high of 85°F and low of 75°F.
The cold season lasts for 3.0 months, from December 1 to March 1, with an average daily high temperature below 44°F. The coldest day of the year is January 18, with an average low of 21°F and high of 34°F.
Average High and Low Temperature
The figure below shows you a compact characterization of the entire year of hourly average temperatures. The horizontal axis is the day of the year, the vertical axis is the hour of the day, and the color is the average temperature for that hour and day.
Average Hourly Temperature
In Seoul, 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 Seoul begins around September 10 and lasts for 5.9 months, ending around March 8. On October 20, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 71% of the time, and overcast or mostly cloudy 29% of the time.
The cloudier part of the year begins around March 8 and lasts for 6.1 months, ending around September 10. On July 14, the cloudiest day of the year, the sky is overcast or mostly cloudy 55% of the time, and clear, mostly clear, or partly cloudy 45% of the time.
Cloud Cover Categories
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days in Seoul varies significantly throughout the year.
The wetter season lasts 2.8 months, from June 18 to September 11, with a greater than 31% chance of a given day being a wet day. The chance of a wet day peaks at 53% on July 22.
The drier season lasts 9.2 months, from September 11 to June 18. The smallest chance of a wet day is 9% on January 23.
Among wet days, we distinguish between those that experience rain alone, snow alone, or a mixture of the two. Based on this categorization, the most common form of precipitation throughout the year is rain alone, with a peak probability of 53% on July 22.
Daily Chance of Precipitation
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. Seoul experiences extreme seasonal variation in monthly rainfall.
The rainy period of the year lasts for 11 months, from January 25 to December 30, with a sliding 31-day rainfall of at least 0.5 inches. The most rain falls during the 31 days centered around July 17, with an average total accumulation of 11.6 inches.
The rainless period of the year lasts for 3.7 weeks, from December 30 to January 25. The least rain falls around January 16, with an average total accumulation of 0.5 inches.
Average Monthly Rainfall
The sliding 31-day liquid-equivalent quantity of snowfall in Seoul does not vary significantly over the course of the year, staying within 0.1 inches of 0.1 inches throughout.
Average Liquid-Equivalent Monthly Snowfall
The length of the day in Seoul varies significantly over the course of the year. In 2017, the shortest day is December 22, with 9 hours, 34 minutes of daylight; the longest day is June 21, with 14 hours, 46 minutes of daylight.
Hours of Daylight and Twilight
The earliest sunrise is at 5:10 AM on June 13, and the latest sunrise is 2 hours, 37 minutes later at 7:47 AM on January 6. The earliest sunset is at 5:13 PM on December 7, and the latest sunset is 2 hours, 44 minutes later at 7:57 PM on June 28.
Daylight saving time (DST) is not observed in Seoul during 2017.
Sunrise & Sunset with Twilight
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.
Seoul experiences extreme seasonal variation in the perceived humidity.
The muggier period of the year lasts for 2.9 months, from June 17 to September 13, during which time the comfort level is muggy, oppressive, or miserable at least 24% of the time. The muggiest day of the year is August 3, with muggy conditions 91% of the time.
The least muggy day of the year is February 22, when muggy conditions are essentially unheard of.
Humidity Comfort Levels
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 Seoul experiences mild seasonal variation over the course of the year.
The windier part of the year lasts for 6.8 months, from October 25 to May 18, with average wind speeds of more than 4.3 miles per hour. The windiest day of the year is February 24, with an average hourly wind speed of 5.1 miles per hour.
The calmer time of year lasts for 5.2 months, from May 18 to October 25. The calmest day of the year is June 14, with an average hourly wind speed of 3.6 miles per hour.
Average Wind Speed
The predominant average hourly wind direction in Seoul varies throughout the year.
The wind is most often from the west for 5.4 months, from January 28 to July 9 and for 1.2 months, from October 7 to November 13, with a peak percentage of 45% on April 9. The wind is most often from the east for 1.9 months, from August 10 to October 7, with a peak percentage of 38% on September 8. The wind is most often from the north for 2.5 months, from November 13 to January 28, with a peak percentage of 44% on January 1.
Seoul 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 significant seasonal variation over the course of the year.
The time of year with warmer water lasts for 3.1 months, from July 5 to October 9, with an average temperature above 68°F. The day of the year with the warmest water is August 22, with an average temperature of 76°F.
The time of year with cooler water lasts for 3.7 months, from December 23 to April 15, with an average temperature below 47°F. The day of the year with the coolest water is February 19, with an average temperature of 39°F.
Average Water Temperature
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 significant seasonal variation over the course of the year.
The brighter period of the year lasts for 3.6 months, from April 18 to August 5, with an average daily incident shortwave energy per square meter above 5.6 kWh. The brightest day of the year is June 1, with an average of 6.5 kWh.
The darker period of the year lasts for 3.0 months, from November 5 to February 4, with an average daily incident shortwave energy per square meter below 3.2 kWh. The darkest day of the year is December 20, with an average of 2.3 kWh.
Average Daily Incident Shortwave Solar Energy
For the purposes of this report, the geographical coordinates of Seoul are 37.566 deg latitude, 126.978 deg longitude, and 171 ft elevation.
The topography within 2 miles of Seoul contains very significant variations in elevation, with a maximum elevation change of 974 feet and an average elevation above sea level of 239 feet. Within 10 miles contains very significant variations in elevation (2,651 feet). Within 50 miles contains large variations in elevation (4,954 feet).
The area within 2 miles of Seoul is covered by artificial surfaces (42%), sparse vegetation (29%), trees (15%), and bare soil (10%), within 10 miles by sparse vegetation (24%) and trees (24%), and within 50 miles by trees (35%) and water (22%).
This report illustrates the typical weather in Seoul, based on a statistical analysis of historical hourly weather reports and model reconstructions from January 1, 1980 to December 31, 2016.
Temperature and Dew Point
There are 4 weather stations near enough to contribute to our estimation of the temperature and dew point in Seoul.
For each station, the records are corrected for the elevation difference between that station and Seoul according to the International Standard Atmosphere , and by the relative change present in the MERRA-2 satellite-era reanalysis between the two locations.
The estimated value at Seoul is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Seoul and a given station.
The stations contributing to this reconstruction are: Seoul (81%, 1.0 kilometers, west); Seoul Air Base (7%, 18 kilometers, southeast); Camp Stanley / H-207 (6%, 20 kilometers, northeast); and Tonghae Radar Site (6%, 21 kilometers, north).
All data relating to the Sun's position (e.g., sunrise and sunset) are computed using astronomical formulas from the book, Astronomical Tables of the Sun, Moon and Planets , by Jean Meeus.
All other weather data, including cloud cover, precipitation, wind speed and direction, and solar flux, come from NASA's MERRA-2 Modern-Era Retrospective Analysis . This reanalysis combines a variety of wide-area measurements in a state-of-the-art global meteorological model to reconstruct the hourly history of weather throughout the world on a 50-kilometer grid.
Land Use data comes from the Global Land Cover SHARE database , published by the Food and Agriculture Organization of the United Nations.
Elevation data comes from the Shuttle Radar Topography Mission (SRTM) , published by NASA's Jet Propulsion Laboratory.
Names, locations, and time zones of places and some airports come from the GeoNames Geographical Database .
Time zones for aiports and weather stations are provided by AskGeo.com .
Maps are © Esri, with data from National Geographic, Esri, DeLorme, NAVTEQ, UNEP-WCMC, USGS, NASA, ESA, METI, NRCAN, GEBCO, NOAA, and iPC.