Average Weather in Porterville California, United States
In Porterville, the temperature typically varies from 38°F to 97°F over the course of the year, and is rarely below 30°F or above 103°F.
The hot season lasts for 3.6 months, from June 4 to September 23, with an average daily high temperature above 88°F. The hottest day of the year is July 18, with an average high of 97°F and low of 66°F.
The cool season lasts for 3.2 months, from November 20 to February 25, with an average daily high temperature below 65°F. The coldest day of the year is December 30, with an average low of 38°F and high of 57°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
The length of the day in Porterville varies significantly over the course of the year. In 2017, the shortest day is December 21, with 9 hours, 42 minutes of daylight; the longest day is June 21, with 14 hours, 37 minutes of daylight.
Hours of Daylight and Twilight
The earliest sunrise is at 5:38 AM on June 12, and the latest sunrise is 1 hour, 43 minutes later at 7:22 AM on November 4. The earliest sunset is at 4:41 PM on December 5, and the latest sunset is 3 hours, 36 minutes later at 8:17 PM on June 28.
Daylight saving time (DST) is observed in Porterville 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
In Porterville, 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 Porterville begins around May 9 and lasts for 5.7 months, ending around November 1. On August 9, 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 November 1 and lasts for 6.3 months, ending around May 9. On February 21, the cloudiest day of the year, the sky is overcast or mostly cloudy 49% of the time, and clear, mostly clear, or partly cloudy 51% 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 Porterville varies throughout the year.
The wetter season lasts 5.2 months, from November 9 to April 15, with a greater than 12% chance of a given day being a wet day. The chance of a wet day peaks at 23% on February 21.
The drier season lasts 6.8 months, from April 15 to November 9. The smallest chance of a wet day is 0% on August 1.
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 23% on February 21.
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 in the year. Porterville experiences significant seasonal variation in monthly rainfall.
The rainy period of the year lasts for 6.6 months, from October 15 to May 3, with a sliding 31-day rainfall of at least 0.5 inches. The most rain falls during the 31 days centered around January 2, with an average total accumulation of 2.2 inches.
The rainless period of the year lasts for 5.4 months, from May 3 to October 15. The least rain falls around August 3, with and average total accumulation of 0.0 inches.
Average Monthly Rainfall
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.
The perceived humidity level in Porterville, 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, staying within 1% of 1% throughout.
Humidity Comfort Levels
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 Porterville does not vary significantly over the course of the year, remaining within 0.5 miles per hour of 2.7 miles per hour throughout.
Average Wind Speed
The predominant average hourly wind direction in Porterville varies throughout the year.
The wind is most often from the west for 7.7 months, from February 27 to October 17, with a peak percentage of 67% on July 20. The wind is most often from the east for 4.4 months, from October 17 to February 27, with a peak percentage of 51% on December 31.
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 very significant seasonal variation over the course of the year.
The brighter period of the year lasts for 3.6 months, from May 3 to August 23, with an average daily incident shortwave energy per square meter above 7.4 kWh. The brightest day of the year is June 22, with an average of 8.7 kWh.
The darker period of the year lasts for 3.4 months, from November 4 to February 15, with an average daily incident shortwave energy per square meter below 3.9 kWh. The darkest day of the year is December 22, with an average of 2.6 kWh.
Average Daily Incident Shortwave Solar Energy
For the purposes of this report, the geographical coordinates of Porterville are 36.065 deg latitude, -119.017 deg longitude, and 463 ft elevation.
The topography within 2 miles of Porterville contains only modest variations in elevation, with a maximum elevation change of 318 feet, and an average elevation above sea level of 465 feet. Within 10 miles contains very significant variations in elevation (1,936 feet). Within 50 miles contains extreme variations in elevation (13,547 feet).
The area within 2 miles of Porterville is covered by artificial surfaces (62%), cropland (20%), and grassland (12%), within 10 miles by cropland (53%) and grassland (40%), and within 50 miles by cropland (39%) and grassland (23%).
This report illustrates the typical weather in Porterville, 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 2 weather stations near enough to contribute to our estimation of the temperature and dew point in Porterville.
For each station, the records are corrected for the elevation difference between that station and Porterville 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 Porterville is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Porterville and a given station.
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 .