Climate and Average Weather Year Round at Incheon International Airport South Korea

At Incheon International Airport, the summers are warm, muggy, wet, and partly cloudy and the winters are freezing, snowy, windy, and mostly clear. Over the course of the year, the temperature typically varies from 21°F to 85°F and is rarely below 10°F or above 91°F.

Based on the tourism score, the best times of year to visit Incheon International Airport for warm-weather activities are from late May to early July and from late August to early October.

The warm season lasts for 3.7 months, from June 1 to September 24, with an average daily high temperature above 75°F. The hottest month of the year at Incheon International Airport is August, with an average high of 83°F and low of 72°F.

The cold season lasts for 3.0 months, from December 2 to March 3, with an average daily high temperature below 44°F. The coldest month of the year at Incheon International Airport is January, with an average low of 21°F and high of 34°F.

At Incheon International Airport, 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 at Incheon International Airport begins around September 9 and lasts for 5.9 months, ending around March 5.

The clearest month of the year at Incheon International Airport is October, during which on average the sky is clear, mostly clear, or partly cloudy 70% of the time.

The cloudier part of the year begins around March 5 and lasts for 6.1 months, ending around September 9.

The cloudiest month of the year at Incheon International Airport is July, during which on average the sky is overcast or mostly cloudy 53% 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 at Incheon International Airport varies significantly throughout the year.

The wetter season lasts 2.9 months, from June 17 to September 13, with a greater than 29% chance of a given day being a wet day. The month with the most wet days at Incheon International Airport is July, with an average of 14.9 days with at least 0.04 inches of precipitation.

The drier season lasts 9.1 months, from September 13 to June 17. The month with the fewest wet days at Incheon International Airport is January, with an average of 3.0 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 at Incheon International Airport is July, with an average of 14.9 days. Based on this categorization, the most common form of precipitation throughout the year is rain alone, with a peak probability of 50% on July 21.

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. Incheon International Airport experiences extreme seasonal variation in monthly rainfall.

Rain falls throughout the year at Incheon International Airport. The month with the most rain at Incheon International Airport is July, with an average rainfall of 10.4 inches.

The month with the least rain at Incheon International Airport is January, with an average rainfall of 0.4 inches.

Snowfall

As with rainfall, we consider the snowfall accumulated over a sliding 31-day period centered around each day of the year. Incheon International Airport experiences some seasonal variation in monthly snowfall.

The snowy period of the year lasts for 1.0 months, from January 5 to February 6, with a sliding 31-day snowfall of at least 1.0 inches. The month with the most snow at Incheon International Airport is January, with an average snowfall of 1.1 inches.

The snowless period of the year lasts for 11 months, from February 6 to January 5. The least snow falls around July 25, with an average total accumulation of 0.0 inches.

The length of the day at Incheon International Airport varies significantly over the course of the year. In 2024, the shortest day is December 21, with 9 hours, 35 minutes of daylight; the longest day is June 21, with 14 hours, 45 minutes of daylight.

The earliest sunrise is at 5:12 AM on June 13, and the latest sunrise is 2 hours, 36 minutes later at 7:49 AM on January 7. The earliest sunset is at 5:15 PM on December 6, and the latest sunset is 2 hours, 43 minutes later at 7:59 PM on June 28.

Daylight saving time (DST) is not observed at Incheon International Airport 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.

Incheon International Airport experiences extreme seasonal variation in the perceived humidity.

The muggier period of the year lasts for 3.1 months, from June 14 to September 17, during which time the comfort level is muggy, oppressive, or miserable at least 23% of the time. The month with the most muggy days at Incheon International Airport is July, with 26.0 days that are muggy or worse.

The least muggy day of the year is February 17, when muggy conditions are essentially unheard of.

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 at Incheon International Airport experiences significant seasonal variation over the course of the year.

The windier part of the year lasts for 6.3 months, from October 15 to April 25, with average wind speeds of more than 9.9 miles per hour. The windiest month of the year at Incheon International Airport is December, with an average hourly wind speed of 12.2 miles per hour.

The calmer time of year lasts for 5.7 months, from April 25 to October 15. The calmest month of the year at Incheon International Airport is June, with an average hourly wind speed of 7.5 miles per hour.

The predominant average hourly wind direction at Incheon International Airport varies throughout the year.

The wind is most often from the west for 3.8 months, from March 8 to July 3, with a peak percentage of 43% on May 29. The wind is most often from the south for 1.3 months, from July 3 to August 13, with a peak percentage of 44% on July 22. The wind is most often from the north for 5.6 months, from September 19 to March 8, with a peak percentage of 57% on January 1.

Incheon International Airport 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 8, with an average temperature above 68°F. The month of the year at Incheon International Airport with the warmest water is August, with an average temperature of 75°F.

The time of year with cooler water lasts for 3.7 months, from December 22 to April 13, with an average temperature below 46°F. The month of the year at Incheon International Airport with the coolest water is February, with an average temperature of 39°F.

To characterize how pleasant the weather is at Incheon International Airport 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 times of year to visit Incheon International Airport for general outdoor tourist activities are from late May to early July and from late August to early October, with a peak score in the third week of September.

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 Incheon International Airport for hot-weather activities is from mid July to late August, with a peak score in the second week of August.

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).

The growing season at Incheon International Airport typically lasts for 7.7 months (235 days), from around March 26 to around November 16, rarely starting before March 9 or after April 11, and rarely ending before October 31 or after December 2.

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.

Based on growing degree days alone, the first spring blooms at Incheon International Airport should appear around April 20, only rarely appearing before April 12 or after April 30.

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 17 to August 4, with an average daily incident shortwave energy per square meter above 5.7 kWh. The brightest month of the year at Incheon International Airport is June, with an average of 6.3 kWh.

The darker period of the year lasts for 2.9 months, from November 6 to February 3, with an average daily incident shortwave energy per square meter below 3.1 kWh. The darkest month of the year at Incheon International Airport is December, with an average of 2.3 kWh.

For the purposes of this report, the geographical coordinates of Incheon International Airport are 37.449 deg latitude, 126.451 deg longitude, and 112 ft elevation.

The topography within 2 miles of Incheon International Airport contains significant variations in elevation, with a maximum elevation change of 804 feet and an average elevation above sea level of 29 feet. Within 10 miles contains significant variations in elevation (853 feet). Within 50 miles contains very significant variations in elevation (2,858 feet).

The area within 2 miles of Incheon International Airport is covered by water (35%), sparse vegetation (33%), and grassland (24%), within 10 miles by water (86%), and within 50 miles by water (49%) and trees (18%).