Average Weather in San José Costa Rica
In San José, the temperature typically varies from 63°F to 81°F over the course of the year, and is rarely below 60°F or above 84°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
The length of the day in San José does not vary substantially over the course of the year, staying within 42 minutes of 12 hours throughout. In 2017, the shortest day is December 21, with 11 hours, 33 minutes of daylight; the longest day is June 21, with 12 hours, 42 minutes of daylight.
Hours of Daylight and Twilight
The earliest sunrise is at 5:14 AM on May 28, and the latest sunrise is 45 minutes later at 5:58 AM on January 27. The earliest sunset is at 5:10 PM on November 16, and the latest sunset is 51 minutes later at 6:01 PM on July 11.
Daylight saving time (DST) is not observed in San José during 2017.
Sunrise & Sunset with Twilight
In San José, the average percentage of the sky covered by clouds experiences extreme seasonal variation over the course of the year.
The clearer part of the year in San José begins around November 24 and lasts for 136 days, ending around April 9. On January 2, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 64% of the time, and overcast or mostly cloudy 36% of the time.
The cloudier part of the year begins around April 9 and lasts for 229 days, ending around November 24. On June 5, the cloudiest day of the year, the sky is overcast or mostly cloudy 96% of the time, and clear, mostly clear, or partly cloudy 4% 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 San José varies significantly throughout the year.
The wetter season lasts 210 days, from May 3 to November 29, with a greater than 29% chance of a given day being a wet day. The chance of a wet day peaks at 51% on October 7.
The drier season lasts 155 days, from November 29 to May 3. The smallest chance of a wet day is 7% on March 13.
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 51% on October 7.
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 in the year. San José experiences very significant seasonal variation in monthly rainfall.
Rain falls throughout the year in San José. The most rain falls during the 31 days centered around October 11, with an average total accumulation of 6.5 inches.
The least rain falls around March 16, with and average total accumulation of 0.7 inches.
Average Monthly Rainfall
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.
San José experiences very significant seasonal variation in the perceived humidity.
The muggier period of the year lasts for 237 days, from April 14 to December 7, during which time the comfort level is muggy, oppressive, or miserable at least 17% of the time. The muggiest day of the year is June 2, with muggy conditions 58% of the time.
The least muggy day of the year is January 24, with muggy conditions 3% of the time.
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 San José does not vary significantly over the course of the year, remaining within 0.5 miles per hour of 1.4 miles per hour throughout.
Average Wind Speed
The predominant average hourly wind direction in San José varies throughout the year.
The wind is most often from the west for 51 days, from September 6 to October 27, with a peak percentage of 51% on October 2. The wind is most often from the east for 314 days, from October 27 to September 6, with a peak percentage of 72% on March 1.
San José 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 does not vary significantly over the course of the year, remaining within 1°F of 83°F throughout.
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 72 days, from February 2 to April 15, with an average daily incident shortwave energy per square meter above 6.2 kWh. The brightest day of the year is March 22, with an average of 6.8 kWh.
The darker period of the year lasts for 181 days, from May 20 to November 17, with an average daily incident shortwave energy per square meter below 4.4 kWh. The darkest day of the year is October 11, with an average of 3.7 kWh.
Average Daily Incident Shortwave Solar Energy
For the purposes of this report, the geographical coordinates of San José are 9.933 deg latitude, -84.083 deg longitude, and 3,757 ft elevation (map ).
The topography within 2 miles of San José contains only modest variations in elevation, with a maximum elevation change of 466 feet, and an average elevation above sea level of 3,759 feet. Within 10 miles contains extreme variations in elevation (5,571 feet). Within 50 miles also contains extreme variations in elevation (12,303 feet).
The area within 2 miles of San José is covered by grassland (53%), trees (37%), and artificial surfaces (10%), within 10 miles by grassland (42%) and trees (42%), and within 50 miles by trees (53%) and grassland (17%).
This report illustrates the typical weather in San José, 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 is only a single weather station, Juan Santamaría International Airport, in our network suitable to be used as a proxy for the historical temperature and dew point records of San José.
At a distance of 15 kilometers from San José, closer than our threshold of 150 kilometers, this station is deemed sufficiently nearby to be relied upon as our primary source for temperature and dew point records.
The station records are corrected for the elevation difference between the station and San José according to the International Standard Atmosphere , and by the relative change present in the MERRA-2 satellite-era reanalysis between the two locations.
Please note that the station records themselves may additionally have been back-filled using other nearby stations or the MERRA-2 reanalysis.
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 .