Daily high temperatures are around 71°F, rarely falling below 65°F or exceeding 76°F. The lowest daily average high temperature is 70°F on January 6.
Daily low temperatures are around 44°F, rarely falling below 37°F or exceeding 50°F. The lowest daily average low temperature is 43°F on January 13.
For reference, on May 9, the hottest day of the year, temperatures in Arenal typically range from 55°F to 79°F, while on January 13, the coldest day of the year, they range from 43°F to 70°F.
Cochabamba, Bolivia (3,381 miles away) is the far-away foreign place with temperatures most similar to Arenal (view comparison).
The month of January in Arenal experiences gradually decreasing cloud cover, with the percentage of time that the sky is overcast or mostly cloudy decreasing from 43% to 37%.
The clearest day of the month is January 31, with clear, mostly clear, or partly cloudy conditions 63% of the time.
For reference, on September 14, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 89%, while on February 24, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 68%.
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Arenal, the chance of a wet day over the course of January is essentially constant, remaining around 5% throughout.
For reference, the year's highest daily chance of a wet day is 79% on July 3, and its lowest chance is 3% on December 13.
The average sliding 31-day rainfall during January in Arenal is essentially constant, remaining about 0.3 inches throughout, and rarely exceeding 0.7 inches or falling below -0.0 inches.
The highest average 31-day accumulation is 0.3 inches on January 29.
Over the course of January in Arenal, the length of the day is gradually increasing. From the start to the end of the month, the length of the day increases by 18 minutes, implying an average daily increase of 36 seconds, and weekly increase of 4 minutes, 9 seconds.
The shortest day of the month is January 1, with 10 hours, 59 minutes of daylight and the longest day is January 31, with 11 hours, 17 minutes of daylight.
The earliest sunrise of the month in Arenal is 7:09 AM on January 1 and the latest sunrise is 2 minutes, 53 seconds later at 7:12 AM on January 18.
The earliest sunset is 6:09 PM on January 1 and the latest sunset is 19 minutes later at 6:27 PM on January 31.
Daylight saving time is observed in Arenal during 2019, but it neither starts nor ends during January, so the entire month is in standard time.
For reference, on June 21, the longest day of the year, the Sun rises at 6:58 AM and sets 13 hours, 18 minutes later, at 8:16 PM, while on December 22, the shortest day of the year, it rises at 7:05 AM and sets 10 hours, 58 minutes later, at 6:03 PM.
The chance that a given day will be muggy in Arenal is essentially constant during January, remaining around 0% throughout.
For reference, on August 14, the muggiest day of the year, there are muggy conditions 0% of the time, while on January 1, the least muggy day of the year, there are muggy conditions 0% of the time.
The average hourly wind speed in Arenal is essentially constant during January, remaining within 0.2 miles per hour of 4.9 miles per hour throughout.
For reference, on March 13, the windiest day of the year, the daily average wind speed is 5.5 miles per hour, while on May 31, the calmest day of the year, the daily average wind speed is 4.0 miles per hour.
The hourly average wind direction in Arenal throughout January is predominantly from the south, with a peak proportion of 40% on January 27.
While it does not do so every year, freezing temperatures are seen in Arenal over some winters. The day least likely to be in the growing season is January 13, with a 73% chance.
The average accumulated growing degree days in Arenal are increasing during January, increasing by 238°F, from 0°F to 238°F, over the course of the month.
The average daily incident shortwave solar energy in Arenal is gradually increasing during January, rising by 0.6 kWh, from 5.1 kWh to 5.7 kWh, over the course of the month.
For the purposes of this report, the geographical coordinates of Arenal are 19.381 deg latitude, -98.943 deg longitude, and 7,431 ft elevation.
The topography within 2 miles of Arenal contains very significant variations in elevation, with a maximum elevation change of 994 feet and an average elevation above sea level of 7,558 feet. Within 10 miles contains very significant variations in elevation (2,228 feet). Within 50 miles contains large variations in elevation (14,675 feet).
The area within 2 miles of Arenal is covered by artificial surfaces (92%), within 10 miles by artificial surfaces (49%) and cropland (32%), and within 50 miles by cropland (40%) and trees (22%).
This report illustrates the typical weather in Arenal year round, based on a statistical analysis of historical hourly weather reports and model reconstructions from January 1, 1980 to December 31, 2016.
There are 3 weather stations near enough to contribute to our estimation of the temperature and dew point in Arenal.
For each station, the records are corrected for the elevation difference between that station and Arenal 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 Arenal is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Arenal and a given station.
The stations contributing to this reconstruction are: Benito Juárez International Airport (85%, 15 kilometers, northwest); Hermanos Serdán International Airport (10%, 65 kilometers, east); and Tulancingo (5%, 99 kilometers, northeast).