Average Weather in January in San Marcos California, United States
Daily high temperatures are around 64°F, rarely falling below 56°F or exceeding 75°F.
Daily low temperatures are around 46°F, rarely falling below 39°F or exceeding 53°F.
For reference, on August 24, the hottest day of the year, temperatures in San Marcos typically range from 65°F to 81°F, while on December 27, the coldest day of the year, they range from 45°F to 64°F.
Average High and Low Temperature in January
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
Rabat, Morocco (5,969 miles away); Cape Town, South Africa (9,910 miles); and Kruisfontein, South Africa (10,267 miles) are the far-away foreign places with temperatures most similar to San Marcos (view comparison).
The month of January in San Marcos experiences essentially constant cloud cover, with the percentage of time that the sky is overcast or mostly cloudy remaining about 38% throughout the month.
The clearest day of the month is January 21, with clear, mostly clear, or partly cloudy conditions 63% of the time.
For reference, on February 20, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 43%, while on September 7, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 90%.
Cloud Cover Categories in January
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In San Marcos, the chance of a wet day over the course of January is essentially constant, remaining around 15% throughout.
For reference, the year's highest daily chance of a wet day is 21% on February 22, and its lowest chance is 1% on June 26.
Probability of Precipitation in January
The average sliding 31-day rainfall during January in San Marcos is essentially constant, remaining about 2.3 inches throughout, and rarely exceeding 6.4 inches.
Average Monthly Rainfall in January
Over the course of January in San Marcos, the length of the day is increasing. From the start to the end of the month, the length of the day increases by 34 minutes, implying an average daily increase of 1 minute, 9 seconds, and weekly increase of 8 minutes, 1 second.
The shortest day of the month is January 1, with 10 hours, 1 minute of daylight and the longest day is January 31, with 10 hours, 35 minutes of daylight.
Hours of Daylight and Twilight in January
The latest sunrise of the month in San Marcos is 6:52 AM on January 7 and the earliest sunrise is 8 minutes earlier at 6:44 AM on January 31.
The earliest sunset is 4:52 PM on January 1 and the latest sunset is 27 minutes later at 5:19 PM on January 31.
Daylight saving time is observed in San Marcos during 2018, 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 5:40 AM and sets 14 hours, 21 minutes later, at 8:00 PM, while on December 21, the shortest day of the year, it rises at 6:48 AM and sets 9 hours, 58 minutes later, at 4:45 PM.
Sunrise & Sunset with Twilight in January
The chance that a given day will be muggy in San Marcos is essentially constant during January, remaining around 0% throughout.
For reference, on August 27, the muggiest day of the year, there are muggy conditions 7% of the time, while on November 3, the least muggy day of the year, there are muggy conditions 0% of the time.
Humidity Comfort Levels in January
The average hourly wind speed in San Marcos is essentially constant during January, remaining within 0.1 miles per hour of 7.0 miles per hour throughout.
For reference, on April 11, the windiest day of the year, the daily average wind speed is 7.4 miles per hour, while on September 8, the calmest day of the year, the daily average wind speed is 5.4 miles per hour.
The lowest daily average wind speed during January is 6.9 miles per hour on January 23.
Average Wind Speed in January
Wind Direction in January
San Marcos 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 Marcos is essentially constant during January, remaining around 59°F throughout.
Average Water Temperature in January
Temperatures in San Marcos 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 January
The average accumulated growing degree days in San Marcos are gradually increasing during January, increasing by 173°F, from 0°F to 173°F, over the course of the month.
Growing Degree Days in January
The average daily incident shortwave solar energy in San Marcos is gradually increasing during January, rising by 0.6 kWh, from 3.1 kWh to 3.8 kWh, over the course of the month.
Average Daily Incident Shortwave Solar Energy in January
For the purposes of this report, the geographical coordinates of San Marcos are 33.143 deg latitude, -117.166 deg longitude, and 705 ft elevation.
The topography within 2 miles of San Marcos contains significant variations in elevation, with a maximum elevation change of 778 feet and an average elevation above sea level of 685 feet. Within 10 miles contains significant variations in elevation (2,077 feet). Within 50 miles contains large variations in elevation (8,258 feet).
The area within 2 miles of San Marcos is covered by artificial surfaces (71%) and shrubs (28%), within 10 miles by artificial surfaces (43%) and shrubs (39%), and within 50 miles by shrubs (44%) and water (33%).
This report illustrates the typical weather in San Marcos 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 are 4 weather stations near enough to contribute to our estimation of the temperature and dew point in San Marcos.
For each station, the records are corrected for the elevation difference between that station and San Marcos 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 San Marcos is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between San Marcos and a given station.
The stations contributing to this reconstruction are: McClellan–Palomar Airport (58%, 11 kilometers, west); Ramona Airport (19%, 26 kilometers, southeast); Miramar Marine Corps Air Station (20%, 31 kilometers, south); and Palm Springs International Airport (3.7%, 97 kilometers, northeast).
Time zones for aiports and weather stations are provided by AskGeo.com .