Average Weather in September in San Rafael Costa Rica
In San Rafael, the month of September is characterized by essentially constant daily high temperatures, with daily highs around 78°F throughout the month, rarely exceeding 82°F or dropping below 74°F.
Daily low temperatures are around 64°F, rarely falling below 61°F or exceeding 66°F.
For reference, on April 3, the hottest day of the year, temperatures in San Rafael typically range from 65°F to 82°F, while on September 19, the coldest day of the year, they range from 64°F to 78°F.
Average High and Low Temperature in September
The figure below shows you a compact characterization of the hourly average temperatures for the quarter of the year centered on September. 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 September
The month of September in San Rafael experiences essentially constant cloud cover, with the percentage of time that the sky is overcast or mostly cloudy remaining about 94% throughout the month. The highest chance of overcast or mostly cloudy conditions is 94% on September 29.
The clearest day of the month is September 11, with clear, mostly clear, or partly cloudy conditions 7% of the time.
For reference, on June 5, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 95%, while on January 2, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 64%.
Cloud Cover Categories in September
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In San Rafael, the chance of a wet day over the course of September is gradually increasing, starting the month at 46% and ending it at 50%.
For reference, the year's highest daily chance of a wet day is 51% on October 7, and its lowest chance is 6% on March 16.
Probability of Precipitation in September
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 September in San Rafael is increasing, starting the month at 5.8 inches, when it rarely exceeds 10.4 inches or falls below 2.1 inches, and ending the month at 6.5 inches, when it rarely exceeds 12.1 inches or falls below 2.5 inches.
Average Monthly Rainfall in September
Over the course of September in San Rafael, the length of the day is gradually decreasing. From the start to the end of the month, the length of the day decreases by 16 minutes, implying an average daily decrease of 32 seconds, and weekly decrease of 3 minutes, 47 seconds.
The shortest day of the month is September 30, with 12 hours, 2 minutes of daylight and the longest day is September 1, with 12 hours, 18 minutes of daylight.
Hours of Daylight and Twilight in September
The latest sunrise of the month in San Rafael is 5:27 AM on September 1 and the earliest sunrise is 2 minutes, 10 seconds earlier at 5:25 AM on September 30.
The latest sunset is 5:45 PM on September 1 and the earliest sunset is 18 minutes earlier at 5:27 PM on September 30.
Daylight saving time is not observed in San Rafael during 2017.
For reference, on June 21, the longest day of the year, the Sun rises at 5:17 AM and sets 12 hours, 42 minutes later, at 5:59 PM, while on December 21, the shortest day of the year, it rises at 5:48 AM and sets 11 hours, 33 minutes later, at 5:21 PM.
Sunrise & Sunset with Twilight in September
The chance that a given day will be muggy in San Rafael is increasing during September, rising from 53% to 61% over the course of the month.
The highest chance of a muggy day during September is 61% on September 28.
For reference, on June 2, the muggiest day of the year, there are muggy conditions 63% of the time, while on January 24, the least muggy day of the year, there are muggy conditions 3% of the time.
Humidity Comfort Levels in September
The average hourly wind speed in San Rafael is essentially constant during September, remaining within 0.1 miles per hour of 2.0 miles per hour throughout.
For reference, on February 10, the windiest day of the year, the daily average wind speed is 3.5 miles per hour, while on June 14, the calmest day of the year, the daily average wind speed is 1.9 miles per hour.
Average Wind Speed in September
Wind Direction in September
San Rafael 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 San Rafael is essentially constant during September, remaining around 83°F throughout.
Average Water Temperature in September
Temperatures in San Rafael are sufficiently warm year round that it is not entirely meaningful to discuss the growing season in these terms. We nevertheless include the chart below as an illustration of the distribution of temperatures experienced throughout the year.
Time Spent in Various Temperature Bands and the Growing Season in September
The average accumulated growing degree days in San Rafael is rapidly increasing during September, increasing by 558°F, from 5,044°F to 5,602°F, over the course of the month.
Growing Degree Days in September
The average daily incident shortwave solar energy in San Rafael is essentially constant during September, remaining within 0.1 kWh of 3.9 kWh throughout.
Average Daily Incident Shortwave Solar Energy in September
For the purposes of this report, the geographical coordinates of San Rafael are 9.928 deg latitude, -84.137 deg longitude, and 3,599 ft elevation.
The topography within 2 miles of San Rafael contains very significant variations in elevation, with a maximum elevation change of 1,719 feet and an average elevation above sea level of 3,643 feet. Within 10 miles contains very significant variations in elevation (6,138 feet). Within 50 miles also contains extreme variations in elevation (11,447 feet).
The area within 2 miles of San Rafael is covered by grassland (60%), artificial surfaces (21%), and trees (14%), within 10 miles by grassland (48%) and trees (37%), and within 50 miles by trees (50%) and water (18%).
This report illustrates the typical weather in San Rafael year round, 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 Rafael.
At a distance of 11 kilometers from San Rafael, 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 Rafael 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.
Time zones for aiports and weather stations are provided by AskGeo.com .