Average Weather in Jamestown California, United States
In Jamestown, the summers are hot, arid, and mostly clear and the winters are cold, wet, and partly cloudy. Over the course of the year, the temperature typically varies from 38°F to 91°F and is rarely below 30°F or above 98°F.
The hot season lasts for 3.4 months, from June 8 to September 21, with an average daily high temperature above 83°F. The hottest day of the year is July 18, with an average high of 91°F and low of 64°F.
The cool season lasts for 3.3 months, from November 20 to February 28, with an average daily high temperature below 60°F. The coldest day of the year is December 30, with an average low of 38°F and high of 52°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
In Jamestown, the average percentage of the sky covered by clouds experiences significant seasonal variation over the course of the year.
The clearer part of the year in Jamestown begins around May 16 and lasts for 5.3 months, ending around October 26. On July 29, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 91% of the time, and overcast or mostly cloudy 9% of the time.
The cloudier part of the year begins around October 26 and lasts for 6.7 months, ending around May 16. On February 21, the cloudiest day of the year, the sky is overcast or mostly cloudy 55% of the time, and clear, mostly clear, or partly cloudy 45% 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 Jamestown varies significantly throughout the year.
The wetter season lasts 5.6 months, from October 31 to April 19, with a greater than 16% chance of a given day being a wet day. The chance of a wet day peaks at 31% on February 20.
The drier season lasts 6.4 months, from April 19 to October 31. The smallest chance of a wet day is 0% on August 19.
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 31% on February 20.
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 of the year. Jamestown experiences extreme seasonal variation in monthly rainfall.
The rainy period of the year lasts for 8.1 months, from September 26 to May 29, with a sliding 31-day rainfall of at least 0.5 inches. The most rain falls during the 31 days centered around February 16, with an average total accumulation of 4.3 inches.
The rainless period of the year lasts for 3.9 months, from May 29 to September 26. The least rain falls around August 9, with an average total accumulation of 0.0 inches.
Average Monthly Rainfall
The length of the day in Jamestown varies significantly over the course of the year. In 2017, the shortest day is December 21, with 9 hours, 32 minutes of daylight; the longest day is June 21, with 14 hours, 48 minutes of daylight.
Hours of Daylight and Twilight
The earliest sunrise is at 5:38 AM on June 13, and the latest sunrise is 1 hour, 52 minutes later at 7:30 AM on November 4. The earliest sunset is at 4:42 PM on December 6, and the latest sunset is 3 hours, 46 minutes later at 8:28 PM on June 27.
Daylight saving time (DST) is observed in Jamestown during 2017, starting in the spring on March 12, lasting 7.8 months, and ending in the fall on November 5.
Sunrise & Sunset with Twilight and Daylight Saving Time
The perceived humidity level in Jamestown, as measured by the percentage of time in which the humidity comfort level is muggy, oppressive, or miserable, does not vary significantly over the course of the year, remaining a virtually constant 0% throughout.
Humidity Comfort Levels
Average Wind Speed
The predominant average hourly wind direction in Jamestown varies throughout the year.
The wind is most often from the south for 3.9 weeks, from February 20 to March 19, with a peak percentage of 34% on February 20. The wind is most often from the west for 6.9 months, from March 19 to October 16, with a peak percentage of 60% on July 14. The wind is most often from the east for 4.1 months, from October 16 to February 20, with a peak percentage of 47% on January 1.
The average daily incident shortwave solar energy experiences extreme seasonal variation over the course of the year.
The brighter period of the year lasts for 3.5 months, from May 8 to August 24, with an average daily incident shortwave energy per square meter above 7.3 kWh. The brightest day of the year is June 27, with an average of 8.6 kWh.
The darker period of the year lasts for 3.5 months, from November 3 to February 18, with an average daily incident shortwave energy per square meter below 3.5 kWh. The darkest day of the year is December 22, with an average of 2.3 kWh.
Average Daily Incident Shortwave Solar Energy
For the purposes of this report, the geographical coordinates of Jamestown are 37.953 deg latitude, -120.423 deg longitude, and 1,552 ft elevation.
The topography within 2 miles of Jamestown contains very significant variations in elevation, with a maximum elevation change of 899 feet and an average elevation above sea level of 1,585 feet. Within 10 miles contains very significant variations in elevation (3,632 feet). Within 50 miles also contains extreme variations in elevation (11,568 feet).
The area within 2 miles of Jamestown is covered by shrubs (57%) and grassland (43%), within 10 miles by shrubs (45%) and grassland (40%), and within 50 miles by grassland (26%) and trees (25%).
This report illustrates the typical weather in Jamestown, 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 6 weather stations near enough to contribute to our estimation of the temperature and dew point in Jamestown.
For each station, the records are corrected for the elevation difference between that station and Jamestown 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 Jamestown is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Jamestown and a given station.
The stations contributing to this reconstruction are: Modesto City-County Airport (27%, 59 kilometers, southwest); Castle Airport (26%, 65 kilometers, south); Placerville Airport (19%, 90 kilometers, north); Bridgeport Sonora Junction (7%, 91 kilometers, northeast); Sacramento Mather Airport (15%, 103 kilometers, northwest); and Lake Tahoe Airport (7%, 112 kilometers, north).
Time zones for aiports and weather stations are provided by AskGeo.com .