Average Weather in Phoenix Arizona, United States
In Phoenix, the temperature typically varies from 45°F to 107°F over the course of the year, and is rarely below 38°F or above 112°F.
The hot season lasts for 3.7 months, from May 29 to September 20, with an average daily high temperature above 98°F. The hottest day of the year is July 5, with an average high of 107°F and low of 84°F.
The cool season lasts for 3.2 months, from November 20 to February 27, with an average daily high temperature below 74°F. The coldest day of the year is December 28, with an average low of 45°F and high of 66°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 Phoenix varies significantly over the course of the year. In 2017, the shortest day is December 21, with 9 hours, 56 minutes of daylight; the longest day is June 21, with 14 hours, 22 minutes of daylight.
Hours of Daylight and Twilight
The earliest sunrise is at 5:17 AM on June 12, and the latest sunrise is 2 hours, 15 minutes later at 7:33 AM on January 7. The earliest sunset is at 5:20 PM on December 4, and the latest sunset is 2 hours, 22 minutes later at 7:42 PM on June 29.
Daylight saving time (DST) is not observed in Phoenix during 2017.
Sunrise & Sunset with Twilight
In Phoenix, 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 Phoenix begins around April 8 and lasts for 3.1 months, ending around July 11. On June 14, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 86% of the time, and overcast or mostly cloudy 14% of the time.
The cloudier part of the year begins around July 11 and lasts for 8.9 months, ending around April 8. On February 19, the cloudiest day of the year, the sky is overcast or mostly cloudy 38% of the time, and clear, mostly clear, or partly cloudy 62% 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 Phoenix varies throughout the year.
The wetter season lasts 8.4 months, from July 7 to March 20, with a greater than 10% chance of a given day being a wet day. The chance of a wet day peaks at 19% on August 4.
The drier season lasts 3.6 months, from March 20 to July 7. The smallest chance of a wet day is 1% on June 13.
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 19% on August 4.
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. Phoenix experiences some seasonal variation in monthly rainfall.
The rainy period of the year lasts for 8.8 months, from July 10 to April 3, with a sliding 31-day rainfall of at least 0.5 inches. The most rain falls during the 31 days centered around February 19, with an average total accumulation of 1.1 inches.
The rainless period of the year lasts for 3.2 months, from April 3 to July 10. The least rain falls around June 7, with and average total accumulation of 0.1 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.
Phoenix experiences some seasonal variation in the perceived humidity.
The muggier period of the year lasts for 2.7 months, from July 1 to September 23, during which time the comfort level is muggy, oppressive, or miserable at least 6% of the time. The muggiest day of the year is August 14, with muggy conditions 23% of the time.
The least muggy day of the year is December 3, when muggy conditions are essentially unheard of.
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 Phoenix does not vary significantly over the course of the year, remaining within 0.5 miles per hour of 3.6 miles per hour throughout.
Average Wind Speed
The predominant average hourly wind direction in Phoenix varies throughout the year.
The wind is most often from the west for 6.6 months, from March 5 to September 23, with a peak percentage of 55% on July 6. The wind is most often from the east for 5.4 months, from September 23 to March 5, with a peak percentage of 54% on December 30.
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 2.9 months, from April 19 to July 16, with an average daily incident shortwave energy per square meter above 7.4 kWh. The brightest day of the year is June 12, with an average of 8.5 kWh.
The darker period of the year lasts for 3.2 months, from November 5 to February 10, with an average daily incident shortwave energy per square meter below 4.2 kWh. The darkest day of the year is December 24, with an average of 3.1 kWh.
Average Daily Incident Shortwave Solar Energy
For the purposes of this report, the geographical coordinates of Phoenix are 33.448 deg latitude, -112.074 deg longitude, and 1,086 ft elevation.
The topography within 2 miles of Phoenix is essentially flat, with a maximum elevation change of 56 feet, and an average elevation above sea level of 1,082 feet. Within 10 miles contains very significant variations in elevation (1,722 feet). Within 50 miles contains extreme variations in elevation (6,909 feet).
The area within 2 miles of Phoenix is covered by artificial surfaces (52%) and shrubs (48%), within 10 miles by artificial surfaces (51%) and shrubs (44%), and within 50 miles by shrubs (85%).
This report illustrates the typical weather in Phoenix, 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 3 weather stations near enough to contribute to our estimation of the temperature and dew point in Phoenix.
For each station, the records are corrected for the elevation difference between that station and Phoenix 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 Phoenix is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Phoenix and a given station.
The stations contributing to this reconstruction are: Phoenix Sky Harbor International Airport (81%, 7 kilometers, east), Phoenix-Deer Valley Airport (9%, 27 kilometers, north), and Luke Air Force Base (9%, 29 kilometers, northwest).
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 .