January Weather in Osan South Korea
Daily high temperatures are around 35°F, rarely falling below 24°F or exceeding 46°F. The lowest daily average high temperature is 35°F on January 12.
Daily low temperatures are around 17°F, rarely falling below 5°F or exceeding 30°F. The lowest daily average low temperature is 16°F on January 19.
For reference, on August 4, the hottest day of the year, temperatures in Osan typically range from 73°F to 86°F, while on January 19, the coldest day of the year, they range from 16°F to 35°F.
Average High and Low Temperature in January in Osan
The figure below shows you a compact characterization of the hourly average temperatures for the quarter of the year centered on January. The horizontal axis is the day, 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 January in Osan
frigid 15°F freezing 32°F very cold 45°F cold 55°F cool 65°F comfortable 75°F warm 85°F hot 95°F sweltering
The month of January in Osan experiences essentially constant cloud cover, with the percentage of time that the sky is overcast or mostly cloudy remaining about 35% throughout the month.
The clearest day of the month is January 1, with clear, mostly clear, or partly cloudy conditions 66% of the time.
For reference, on July 13, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 56%, while on October 20, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 71%.
Cloud Cover Categories in January in Osan
0% clear 20% mostly clear 40% partly cloudy 60% mostly cloudy 80% overcast 100%
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Osan, the chance of a wet day over the course of January is essentially constant, remaining around 9% throughout.
For reference, the year's highest daily chance of a wet day is 52% on July 26, and its lowest chance is 8% on January 22.
Over the course of January in Osan, the chance of a day with only rain remains an essentially constant 5% throughout, the chance of a day with mixed snow and rain remains an essentially constant 2% throughout, and the chance of a day with only snow remains an essentially constant 2% throughout.
Probability of Precipitation in January in Osan
To show variation within the month and not just the monthly total, we show the rainfall accumulated over a sliding 31-day period centered around each day.
The average sliding 31-day rainfall during January in Osan is essentially constant, remaining about 0.5 inches throughout, and rarely exceeding 1.6 inches.
The lowest average 31-day accumulation is 0.5 inches on January 16.
Average Monthly Rainfall in January in Osan
As with rainfall, we consider the snowfall accumulated over a sliding 31-day period centered around each day.
The average sliding 31-day snowfall during January in Osan is essentially constant, remaining about 1.3 inches throughout, and rarely exceeding 4.4 inches or falling to 0.0 inches.
The highest average 31-day accumulation is 1.4 inches on January 18.
Average Monthly Snowfall in January in Osan
Over the course of January in Osan, the length of the day is increasing. From the start to the end of the month, the length of the day increases by 39 minutes, implying an average daily increase of 1 minute, 19 seconds, and weekly increase of 9 minutes, 10 seconds.
The shortest day of the month is January 1, with 9 hours, 39 minutes of daylight and the longest day is January 31, with 10 hours, 19 minutes of daylight.
Hours of Daylight and Twilight in January in Osan
The latest sunrise of the month in Osan is 7:45 AM on January 7 and the earliest sunrise is 10 minutes earlier at 7:35 AM on January 31.
The earliest sunset is 5:24 PM on January 1 and the latest sunset is 30 minutes later at 5:54 PM on January 31.
Daylight saving time is not observed in Osan during 2023.
For reference, on June 21, the longest day of the year, the Sun rises at 5:11 AM and sets 14 hours, 43 minutes later, at 7:55 PM, while on December 22, the shortest day of the year, it rises at 7:41 AM and sets 9 hours, 36 minutes later, at 5:18 PM.
Sunrise & Sunset with Twilight in January in Osan
The figure below presents a compact representation of the sun's elevation (the angle of the sun above the horizon) and azimuth (its compass bearing) for every hour of every day in the reporting period. The horizontal axis is the day of the year and the vertical axis is the hour of the day. For a given day and hour of that day, the background color indicates the azimuth of the sun at that moment. The black isolines are contours of constant solar elevation.
Solar Elevation and Azimuth in January in Osan
The figure below presents a compact representation of key lunar data for January 2023. 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. The label associated with each bar indicates the date and time that the phase is obtained, and the companion time labels indicate the rise and set times of the Moon for the nearest time interval in which the moon is above the horizon.
Moon Rise, Set & Phases in January in Osan
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.
The chance that a given day will be muggy in Osan is essentially constant during January, remaining around 0% throughout.
For reference, on August 2, the muggiest day of the year, there are muggy conditions 95% of the time, while on November 25, the least muggy day of the year, there are muggy conditions 0% of the time.
Humidity Comfort Levels in January in Osan
dry 55°F comfortable 60°F humid 65°F muggy 70°F oppressive 75°F miserable
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 Osan is essentially constant during January, remaining within 0.1 miles per hour of 9.2 miles per hour throughout.
For reference, on February 24, the windiest day of the year, the daily average wind speed is 9.4 miles per hour, while on June 14, the calmest day of the year, the daily average wind speed is 6.6 miles per hour.
Average Wind Speed in January in Osan
The hourly average wind direction in Osan throughout January is predominantly from the north, with a peak proportion of 48% on January 9.
Wind Direction in January in Osan
Osan 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 surface water temperature in Osan is decreasing during January, falling by 4°F, from 46°F to 41°F, over the course of the month.
Average Water Temperature in January in Osan
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 in Osan typically lasts for 6.8 months (207 days), from around April 5 to around October 29, rarely starting before March 22 or after April 20, and rarely ending before October 15 or after November 14.
The month of January in Osan is reliably fully outside of the growing season.
Time Spent in Various Temperature Bands and the Growing Season in January in Osan
frigid 15°F freezing 32°F very cold 45°F cold 55°F cool 65°F comfortable 75°F warm 85°F hot 95°F sweltering
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.
The average accumulated growing degree days in Osan are essentially constant during January, remaining around 0°F throughout.
Growing Degree Days in January in Osan
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 in Osan is gradually increasing during January, rising by 0.7 kWh, from 2.3 kWh to 3.0 kWh, over the course of the month.
Average Daily Incident Shortwave Solar Energy in January in Osan
For the purposes of this report, the geographical coordinates of Osan are 37.152 deg latitude, 127.071 deg longitude, and 72 ft elevation.
The topography within 2 miles of Osan contains only modest variations in elevation, with a maximum elevation change of 443 feet and an average elevation above sea level of 128 feet. Within 10 miles contains only modest variations in elevation (1,680 feet). Within 50 miles contains very significant variations in elevation (4,032 feet).
The area within 2 miles of Osan is covered by trees (34%), cropland (27%), sparse vegetation (21%), and grassland (18%), within 10 miles by trees (35%) and cropland (33%), and within 50 miles by trees (33%) and cropland (20%).
This report illustrates the typical weather in Osan, 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 3 weather stations near enough to contribute to our estimation of the temperature and dew point in Osan.
For each station, the records are corrected for the elevation difference between that station and Osan 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 Osan is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Osan and a given station.
The stations contributing to this reconstruction are:
To get a sense of how much these sources agree with each other, you can view a comparison of Osan and the stations that contribute to our estimates of its temperature history and climate. Please note that each source's contribution is adjusted for elevation and the relative change present in the MERRA-2 data.
All data relating to the Sun's position (e.g., sunrise and sunset) are computed using astronomical formulas from the book, Astronomical Algorithms 2nd Edition , 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 airports and weather stations are provided by AskGeo.com .
Maps are © OpenStreetMap contributors.
The information on this site is provided as is, without any assurances as to its accuracy or suitability for any purpose. Weather data is prone to errors, outages, and other defects. We assume no responsibility for any decisions made on the basis of the content presented on this site.
We draw particular cautious attention to our reliance on the MERRA-2 model-based reconstructions for a number of important data series. While having the tremendous advantages of temporal and spatial completeness, these reconstructions: (1) are based on computer models that may have model-based errors, (2) are coarsely sampled on a 50 km grid and are therefore unable to reconstruct the local variations of many microclimates, and (3) have particular difficulty with the weather in some coastal areas, especially small islands.
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