Average Weather in Tempe Arizona, United States
In Tempe, the summers are sweltering and dry, the winters are cool, and it is mostly clear year round. Over the course of the year, the temperature typically varies from 44°F to 106°F and is rarely below 36°F or above 111°F.
Based on the beach/pool score, the best times of year to visit Tempe for hot-weather activities are from late May to early July and from late August to late September.
The hot season lasts for 3.7 months, from May 28 to September 19, with an average daily high temperature above 98°F. The hottest day of the year is July 2, with an average high of 106°F and low of 83°F.
The cool season lasts for 3.2 months, from November 20 to February 26, with an average daily high temperature below 73°F. The coldest day of the year is December 27, with an average low of 44°F and high of 65°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
frigid 15°F freezing 32°F very cold 45°F cold 55°F cool 65°F comfortable 75°F warm 85°F hot 95°F sweltering
In Tempe, 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 Tempe begins around April 7 and lasts for 3.0 months, ending around July 8. On June 13, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 85% of the time, and overcast or mostly cloudy 15% of the time.
The cloudier part of the year begins around July 8 and lasts for 9.0 months, ending around April 7. 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.
Cloud Cover Categories
0% clear 20% mostly clear 40% partly cloudy 60% mostly cloudy 80% overcast 100%
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days in Tempe varies throughout the year.
The wetter season lasts 8.3 months, from July 5 to March 14, with a greater than 11% chance of a given day being a wet day. The chance of a wet day peaks at 21% on August 3.
The drier season lasts 3.7 months, from March 14 to July 5. The smallest chance of a wet day is 1% on June 12.
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 21% on August 3.
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. Tempe experiences some seasonal variation in monthly rainfall.
The rainy period of the year lasts for 9.0 months, from July 6 to April 4, 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 1.2 inches.
The rainless period of the year lasts for 3.0 months, from April 4 to July 6. The least rain falls around June 6, with an average total accumulation of 0.1 inches.
Average Monthly Rainfall
The length of the day in Tempe varies significantly over the course of the year. In 2020, the shortest day is December 21, with 9 hours, 56 minutes of daylight; the longest day is June 20, with 14 hours, 22 minutes of daylight.
Hours of Daylight and Twilight
The earliest sunrise is at 5:17 AM on June 11, and the latest sunrise is 2 hours, 15 minutes later at 7:32 AM on January 8. The earliest sunset is at 5:19 PM on December 3, and the latest sunset is 2 hours, 22 minutes later at 7:41 PM on June 29.
Daylight saving time (DST) is not observed in Tempe during 2020.
Sunrise & Sunset with Twilight
The figure below presents a compact representation of key lunar data for 2020. The horizontal axis is the day, the vertical axis is the hour of the day, and the colored areas indicate when the moon is above the horizon. The vertical gray bars (new Moons) and blue bars (full Moons) indicate key Moon phases.
Moon Rise, Set & Phases
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.
Tempe experiences some seasonal variation in the perceived humidity.
The muggier period of the year lasts for 2.8 months, from June 28 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 4, with muggy conditions 24% of the time.
The least muggy day of the year is December 2, when muggy conditions are essentially unheard of.
Humidity Comfort Levels
dry 55°F comfortable 60°F humid 65°F muggy 70°F oppressive 75°F miserable
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 Tempe experiences mild seasonal variation over the course of the year.
The windier part of the year lasts for 9.5 months, from September 27 to July 11, with average wind speeds of more than 6.6 miles per hour. The windiest day of the year is April 29, with an average hourly wind speed of 7.5 miles per hour.
The calmer time of year lasts for 2.5 months, from July 11 to September 27. The calmest day of the year is August 15, with an average hourly wind speed of 5.7 miles per hour.
Average Wind Speed
The predominant average hourly wind direction in Tempe varies throughout the year.
The wind is most often from the west for 6.5 months, from March 7 to September 21, with a peak percentage of 54% on July 5. The wind is most often from the east for 5.5 months, from September 21 to March 7, with a peak percentage of 54% on January 1.
Best Time of Year to Visit
To characterize how pleasant the weather is in Tempe throughout the year, we compute two travel scores.
The tourism score favors clear, rainless days with perceived temperatures between 65°F and 80°F. Based on this score, the best times of year to visit Tempe for general outdoor tourist activities are from early April to early June and from late September to late October, with a peak score in the last week of April.
The beach/pool score favors clear, rainless days with perceived temperatures between 75°F and 90°F. Based on this score, the best times of year to visit Tempe for hot-weather activities are from late May to early July and from late August to late September, with a peak score in the second week of June.
For each hour between 8:00 AM and 9:00 PM of each day in the analysis period (1980 to 2016), independent scores are computed for perceived temperature, cloud cover, and total precipitation. Those scores are combined into a single hourly composite score, which is then aggregated into days, averaged over all the years in the analysis period, and smoothed.
Our cloud cover score is 10 for fully clear skies, falling linearly to 9 for mostly clear skies, and to 1 for fully overcast skies.
Our precipitation score, which is based on the three-hour precipitation centered on the hour in question, is 10 for no precipitation, falling linearly to 9 for trace precipitation, and to 0 for 0.04 inches of precipitation or more.
Our tourism temperature score is 0 for perceived temperatures below 50°F, rising linearly to 9 for 65°F, to 10 for 75°F, falling linearly to 9 for 80°F, and to 1 for 90°F or hotter.
Our beach/pool temperature score is 0 for perceived temperatures below 65°F, rising linearly to 9 for 75°F, to 10 for 82°F, falling linearly to 9 for 90°F, and to 1 for 100°F or hotter.
Definitions of the growing season vary throughout the world, but for the purposes of this report, we define it as the longest continuous period of non-freezing temperatures (≥ 32°F) in the year (the calendar year in the Northern Hemisphere, or from July 1 until June 30 in the Southern Hemisphere).
Temperatures in Tempe 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
frigid 15°F freezing 32°F very cold 45°F cold 55°F cool 65°F comfortable 75°F warm 85°F hot 95°F sweltering
Growing degree days are a measure of yearly heat accumulation used to predict plant and animal development, and defined as the integral of warmth above a base temperature, discarding any excess above a maximum temperature. In this report, we use a base of 50°F and a cap of 86°F.
Growing Degree Days
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 extreme seasonal variation over the course of the year.
The brighter period of the year lasts for 2.9 months, from April 18 to July 14, with an average daily incident shortwave energy per square meter above 7.4 kWh. The brightest day of the year is June 11, with an average of 8.5 kWh.
The darker period of the year lasts for 3.2 months, from November 4 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 23, with an average of 3.1 kWh.
Average Daily Incident Shortwave Solar Energy
For the purposes of this report, the geographical coordinates of Tempe are 33.415 deg latitude, -111.909 deg longitude, and 1,181 ft elevation.
The topography within 2 miles of Tempe contains only modest variations in elevation, with a maximum elevation change of 269 feet and an average elevation above sea level of 1,179 feet. Within 10 miles contains only modest variations in elevation (1,588 feet). Within 50 miles contains very significant variations in elevation (6,877 feet).
The area within 2 miles of Tempe is covered by artificial surfaces (71%) and shrubs (29%), within 10 miles by artificial surfaces (57%) and shrubs (36%), and within 50 miles by shrubs (84%).
This report illustrates the typical weather in Tempe, 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 Tempe.
For each station, the records are corrected for the elevation difference between that station and Tempe 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 Tempe is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Tempe and a given station.
The stations contributing to this reconstruction are: Phoenix Sky Harbor International Airport (64%, 9 kilometers, west); Chandler Municipal Airport (22%, 19 kilometers, southeast); and Scottsdale Airport (14%, 23 kilometers, north).
All data relating to the Sun's position (e.g., sunrise and sunset) are computed using astronomical formulas from the book, Astronomical Algorithms 2nd Edition , 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 airports and weather stations are provided by AskGeo.com .
Maps are © Esri, with data from National Geographic, Esri, DeLorme, NAVTEQ, UNEP-WCMC, USGS, NASA, ESA, METI, NRCAN, GEBCO, NOAA, and iPC.
The information on this site is provided as is, without any assurances as to its accuracy or suitability for any purpose. Weather data is prone to errors, outages, and other defects. We assume no responsibility for any decisions made on the basis of the content presented on this site.
We draw particular cautious attention to our reliance on the MERRA-2 model-based reconstructions for a number of important data series. While having the tremendous advantages of temporal and spatial completeness, these reconstructions: (1) are based on computer models that may have model-based errors, (2) are coarsely sampled on a 50 km grid and are therefore unable to reconstruct the local variations of many microclimates, and (3) have particular difficulty with the weather in some coastal areas, especially small islands.
We further caution that our travel scores are only as good as the data that underpin them, that weather conditions at any given location and time are unpredictable and variable, and that the definition of the scores reflects a particular set of preferences that may not agree with those of any particular reader.