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Average Weather in Atenas Costa Rica

In Atenas, the wet season is warm, muggy, and overcast and the dry season is hot and partly cloudy. Over the course of the year, the temperature typically varies from 68°F to 89°F and is rarely below 65°F or above 92°F.

Average High and Low Temperature

The daily average high (red line) and low (blue line) temperature, with 25th to 75th and 10th to 90th percentile bands. The thin dotted lines are the corresponding average perceived temperatures.

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

Average Hourly Temperature in Atenas12 AM4 AM8 AM12 PM4 PM8 PM12 AMJanFebMarAprMayJunJulAugSepOctNovDeccomfortablewarmhot
The average hourly temperature, color coded into bands: frigid < 15°F < freezing < 32°F < chilly < 45°F < cold < 55°F < cool < 65°F < comfortable < 75°F < warm < 85°F < hot < 95°F < sweltering. The shaded overlays indicate night and civil twilight.

Clouds

In Atenas, 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 Atenas begins around November 23 and lasts for 4.5 months, ending around April 9. On January 1, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 65% of the time, and overcast or mostly cloudy 35% of the time.

The cloudier part of the year begins around April 9 and lasts for 7.5 months, ending around November 23. On June 5, the cloudiest day of the year, the sky is overcast or mostly cloudy 94% of the time, and clear, mostly clear, or partly cloudy 6% of the time.

Cloud Cover

Cloud Cover in Atenasclearerclearercloudier0%10%20%30%40%50%60%70%80%90%100%JanFebMarAprMayJunJulAugSepOctNovDecJun 594%Jun 594%Jan 135%Jan 135%Nov 2365%Nov 2365%Apr 965%Apr 965%overcastmostly cloudypartly cloudymostly clearclear
The percentage of time spent in each cloud cover band, categorized by the percentage of the sky covered by clouds: clear < 20% < mostly clear < 40% < partly cloudy < 60% < mostly cloudy < 80% < overcast.

Precipitation

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

The wetter season lasts 6.5 months, from May 6 to November 22, with a greater than 27% chance of a given day being a wet day. The chance of a wet day peaks at 50% on October 7.

The drier season lasts 5.5 months, from November 22 to May 6. The smallest chance of a wet day is 4% on January 26.

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 50% on October 7.

Daily Chance of Precipitation

Daily Chance of Precipitation in Atenaswetdrydry0%10%20%30%40%50%60%70%80%90%100%JanFebMarAprMayJunJulAugSepOctNovDecOct 750%Oct 750%Jan 264%Jan 264%Jan 19%Jan 19%May 627%May 627%Nov 2228%Nov 2228%rain
The percentage of days in which various types of precipitation are observed, excluding trace quantities: rain alone, snow alone, and mixed (both rain and snow fell in the same day).

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. Atenas experiences extreme seasonal variation in monthly rainfall.

The rainy period of the year lasts for 9.6 months, from March 26 to January 14, with a sliding 31-day rainfall of at least 0.5 inches. The most rain falls during the 31 days centered around September 29, with an average total accumulation of 6.7 inches.

The rainless period of the year lasts for 2.4 months, from January 14 to March 26. The least rain falls around February 5, with an average total accumulation of 0.4 inches.

Average Monthly Rainfall

The average rainfall (solid line) accumulated over the course of a sliding 31-day period centered on the day in question, with 25th to 75th and 10th to 90th percentile bands. The thin dotted line is the corresponding average liquid-equivalent snowfall.

Sun

The length of the day in Atenas 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, 43 minutes of daylight.

Hours of Daylight and Twilight

The number of hours during which the Sun is visible (black line). From bottom (most yellow) to top (most gray), the color bands indicate: full daylight, twilight (civil, nautical, and astronomical), and full night.

The earliest sunrise is at 5:15 AM on May 29, and the latest sunrise is 45 minutes later at 6:00 AM on January 27. The earliest sunset is at 5:12 PM on November 15, and the latest sunset is 51 minutes later at 6:03 PM on July 11.

Daylight saving time (DST) is not observed in Atenas during 2017.

Sunrise & Sunset with Twilight

Sunrise & Sunset with Twilight in Atenas12 AM2 AM4 AM6 AM8 AM10 AM12 PM2 PM4 PM6 PM8 PM10 PMJanFebMarAprMayJunJulAugSepOctNovDecMay 295:15 AMMay 295:15 AM6:03 PMJul 116:03 PMJul 11Nov 155:12 PMNov 155:12 PM6:00 AMJan 276:00 AMJan 27daynightnightnightnight
The solar day over the course of the year 2017. From bottom to top, the black lines are the previous solar midnight, sunrise, solar noon, sunset, and the next solar midnight. The day, twilights (civil, nautical, and astronomical), and night are indicated by the color bands from yellow to gray.

Humidity

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.

Atenas experiences extreme seasonal variation in the perceived humidity.

The muggier period of the year lasts for 8.1 months, from April 13 to December 15, during which time the comfort level is muggy, oppressive, or miserable at least 27% of the time. The muggiest day of the year is June 4, with muggy conditions 86% of the time.

The least muggy day of the year is February 2, with muggy conditions 7% of the time.

Humidity Comfort Levels

Humidity Comfort Levels in Atenasmuggy0%10%20%30%40%50%60%70%80%90%100%JanFebMarAprMayJunJulAugSepOctNovDecFeb 27%Feb 27%86%Jun 486%Jun 4Apr 1327%Apr 1327%Dec 1527%Dec 1527%miserablemiserableoppressiveoppressivemuggymuggyhumidhumidcomfortablecomfortabledrydry
The percentage of time spent at various humidity comfort levels, categorized by dew point: dry < 55°F < comfortable < 60°F < humid < 65°F < muggy < 70°F < oppressive < 75°F < miserable.

Wind

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 Atenas does not vary significantly over the course of the year, remaining within 0.5 miles per hour of 1.8 miles per hour throughout.

Average Wind Speed

Average Wind Speed in Atenas0.0 mph0.5 mph1.0 mph1.5 mph2.0 mph2.5 mph3.0 mph3.5 mphJanFebMarAprMayJunJulAugSepOctNovDecFeb 252.2 mphFeb 252.2 mphJun 161.3 mphJun 161.3 mph
The average of mean hourly wind speeds (dark gray line), with 25th to 75th and 10th to 90th percentile bands.

The predominant average hourly wind direction in Atenas varies throughout the year.

The wind is most often from the west for 3.1 weeks, from May 22 to June 13 and for 1.9 months, from September 1 to October 29, with a peak percentage of 48% on September 30. The wind is most often from the east for 2.6 months, from June 13 to September 1 and for 6.8 months, from October 29 to May 22, with a peak percentage of 53% on July 23.

Wind Direction

Wind Direction in AtenasEWEWE0%20%40%60%80%100%JanFebMarAprMayJunJulAugSepOctNovDecwestsoutheastnorth
The percentage of hours in which the mean wind direction is from each of the four cardinal wind directions (north, east, south, and west), excluding hours in which the mean wind speed is less than 1 mph. The lightly tinted areas at the boundaries are the percentage of hours spent in the implied intermediate directions (northeast, southeast, southwest, and northwest).

Water Temperature

Atenas 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

The daily average water temperature (purple line), with 25th to 75th and 10th to 90th percentile bands.

Solar Energy

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 2.4 months, from January 30 to April 13, with an average daily incident shortwave energy per square meter above 6.2 kWh. The brightest day of the year is March 21, with an average of 6.9 kWh.

The darker period of the year lasts for 5.9 months, from May 18 to November 15, 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 3.8 kWh.

Average Daily Incident Shortwave Solar Energy

Average Daily Incident Shortwave Solar Energy in Atenasbrightdark0 kWh1 kWh2 kWh3 kWh4 kWh5 kWh6 kWh7 kWh8 kWhJanFebMarAprMayJunJulAugSepOctNovDecMar 216.9 kWhMar 216.9 kWhOct 113.8 kWhOct 113.8 kWhJan 306.2 kWhJan 306.2 kWhMay 184.4 kWhMay 184.4 kWhNov 154.4 kWhNov 154.4 kWh
The average daily shortwave solar energy reaching the ground per square meter (orange line), with 25th to 75th and 10th to 90th percentile bands.

Topography

For the purposes of this report, the geographical coordinates of Atenas are 9.975 deg latitude, -84.379 deg longitude, and 2,195 ft elevation.

The topography within 2 miles of Atenas contains very significant variations in elevation, with a maximum elevation change of 1,667 feet and an average elevation above sea level of 2,226 feet. Within 10 miles contains very significant variations in elevation (4,764 feet). Within 50 miles also contains extreme variations in elevation (11,283 feet).

The area within 2 miles of Atenas is covered by grassland (57%) and trees (34%), within 10 miles by grassland (45%) and trees (35%), and within 50 miles by trees (43%) and water (24%).

Data Sources

This report illustrates the typical weather in Atenas, 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 Atenas.

At a distance of 19 kilometers from Atenas, 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 Atenas 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.

Other Data

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.