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May Weather in Pittsburgh Pennsylvania, United States

Daily high temperatures increase by 8°F, from 68°F to 76°F, rarely falling below 55°F or exceeding 86°F.

Daily low temperatures increase by 9°F, from 49°F to 58°F, rarely falling below 38°F or exceeding 67°F.

For reference, on July 19, the hottest day of the year, temperatures in Pittsburgh typically range from 66°F to 83°F, while on January 29, the coldest day of the year, they range from 23°F to 37°F.

Average High and Low Temperature in May in Pittsburgh

The daily average high (red line) and low (blue line) temperature, with 25th to 75th and 10th to 90th percentile bands. The thin dotted lines are the corresponding average perceived temperatures.

The figure below shows you a compact characterization of the hourly average temperatures for the quarter of the year centered on May. 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 May in Pittsburgh

Average Hourly Temperature in May in PittsburghMay112233445566778899101011111212131314141515161617171818191920202121222223232424252526262727282829293030313112 AM12 AM2 AM2 AM4 AM4 AM6 AM6 AM8 AM8 AM10 AM10 AM12 PM12 PM2 PM2 PM4 PM4 PM6 PM6 PM8 PM8 PM10 PM10 PM12 AM12 AMAprJunNowNowvery coldcoldcoolcomfortablewarm
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
The average hourly temperature, color coded into bands. The shaded overlays indicate night and civil twilight.

Tulcea, Romania (5,071 miles away); Krasnodar, Russia (5,433 miles); and Urus-Martan, Russia (5,746 miles) are the far-away foreign places with temperatures most similar to Pittsburgh (view comparison).

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The month of May in Pittsburgh experiences essentially constant cloud cover, with the percentage of time that the sky is overcast or mostly cloudy remaining about 52% throughout the month.

The clearest day of the month is May 31, with clear, mostly clear, or partly cloudy conditions 49% of the time.

For reference, on January 12, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 69%, while on August 26, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 65%.

Cloud Cover Categories in May in Pittsburgh

Cloud Cover Categories in May in PittsburghMay11223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303031310%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%AprJunMay 148%May 148%May 3149%May 3149%May 1148%May 1148%May 2148%May 2148%NowNowclearmostly clearpartly cloudymostly cloudyovercast
0% clear 20% mostly clear 40% partly cloudy 60% mostly cloudy 80% overcast 100%
The percentage of time spent in each cloud cover band, categorized by the percentage of the sky covered by clouds.

A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Pittsburgh, the chance of a wet day over the course of May is increasing, starting the month at 34% and ending it at 39%.

For reference, the year's highest daily chance of a wet day is 41% on June 15, and its lowest chance is 20% on January 30.

Probability of Precipitation in May in Pittsburgh

The percentage of days in which various types of precipitation are observed, excluding trace quantities: rain alone, snow alone, and mixed (both rain and snow fell in the same day).

Rainfall

To show variation within the month and not just the monthly total, we show the rainfall accumulated over a sliding 31-day period centered around each day.

The average sliding 31-day rainfall during May in Pittsburgh is gradually increasing, starting the month at 2.9 inches, when it rarely exceeds 4.6 inches or falls below 1.4 inches, and ending the month at 3.4 inches, when it rarely exceeds 5.1 inches or falls below 1.7 inches.

Average Monthly Rainfall in May in Pittsburgh

The average rainfall (solid line) accumulated over the course of a sliding 31-day period centered on the day in question, with 25th to 75th and 10th to 90th percentile bands. The thin dotted line is the corresponding average snowfall.

Over the course of May in Pittsburgh, the length of the day is increasing. From the start to the end of the month, the length of the day increases by 54 minutes, implying an average daily increase of 1 minute, 48 seconds, and weekly increase of 12 minutes, 36 seconds.

The shortest day of the month is May 1, with 13 hours, 58 minutes of daylight and the longest day is May 31, with 14 hours, 52 minutes of daylight.

Hours of Daylight and Twilight in May in Pittsburgh

The number of hours during which the Sun is visible (black line). From bottom (most yellow) to top (most gray), the color bands indicate: full daylight, twilight (civil, nautical, and astronomical), and full night.

The latest sunrise of the month in Pittsburgh is 6:18 AM on May 1 and the earliest sunrise is 26 minutes earlier at 5:52 AM on May 31.

The earliest sunset is 8:16 PM on May 1 and the latest sunset is 28 minutes later at 8:43 PM on May 31.

Daylight saving time is observed in Pittsburgh during 2024, but it neither starts nor ends during May, so the entire month is in standard time.

For reference, on June 20, the longest day of the year, the Sun rises at 5:49 AM and sets 15 hours, 4 minutes later, at 8:53 PM, while on December 21, the shortest day of the year, it rises at 7:39 AM and sets 9 hours, 17 minutes later, at 4:56 PM.

Sunrise & Sunset with Twilight in May in Pittsburgh

The solar day over the course of May. From bottom to top, the black lines are the previous solar midnight, sunrise, solar noon, sunset, and the next solar midnight. The day, twilights (civil, nautical, and astronomical), and night are indicated by the color bands from yellow to gray.

The figure below presents a compact representation of the sun's elevation (the angle of the sun above the horizon) and azimuth (its compass bearing) for every hour of every day in the reporting period. The horizontal axis is the day of the year and the vertical axis is the hour of the day. For a given day and hour of that day, the background color indicates the azimuth of the sun at that moment. The black isolines are contours of constant solar elevation.

Solar Elevation and Azimuth in May in Pittsburgh

Solar Elevation and Azimuth in May in PittsburghMay112233445566778899101011111212131314141515161617171818191920202121222223232424252526262727282829293030313112 AM12 AM2 AM2 AM4 AM4 AM6 AM6 AM8 AM8 AM10 AM10 AM12 PM12 PM2 PM2 PM4 PM4 PM6 PM6 PM8 PM8 PM10 PM10 PM12 AM12 AMAprJun001010202020303040405050506060700001010202030303040405050606070NowNow
northeastsouthwest
Solar elevation and azimuth over the course of May 2024. The black lines are lines of constant solar elevation (the angle of the sun above the horizon, in degrees). The background color fills indicate the azimuth (the compass bearing) of the sun. The lightly tinted areas at the boundaries of the cardinal compass points indicate the implied intermediate directions (northeast, southeast, southwest, and northwest).

The figure below presents a compact representation of key lunar data for May 2024. 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. The label associated with each bar indicates the date and time that the phase is obtained, and the companion time labels indicate the rise and set times of the Moon for the nearest time interval in which the moon is above the horizon.

Moon Rise, Set & Phases in May in Pittsburgh

Moon Rise, Set & Phases in May in PittsburghMay112233445566778899101011111212131314141515161617171818191920202121222223232424252526262727282829293030313112 AM12 AM4 AM4 AM8 AM8 AM12 PM12 PM4 PM4 PM8 PM8 PM12 AM12 AMAprJunApr 82:22 PMApr 82:22 PMApr 237:50 PMApr 237:50 PMMay 711:23 PMMay 711:23 PMMay 239:54 AMMay 239:54 AMJun 68:38 AMJun 68:38 AMJun 219:09 PMJun 219:09 PM6:45 AM6:45 AM8:06 PM8:06 PM8:07 PM8:07 PM6:35 AM6:35 AM5:38 AM5:38 AM8:15 PM8:15 PM8:07 PM8:07 PM5:35 AM5:35 AM5:26 AM5:26 AM9:35 PM9:35 PM9:11 PM9:11 PM5:54 AM5:54 AM
The time in which the moon is above the horizon (light blue area), with new moons (dark gray lines) and full moons (blue lines) indicated. The shaded overlays indicate night and civil twilight.
May 2024IlluminationMoonriseMoonsetMoonriseMeridian PassingDistance
1
50%2:55 AMESE12:37 PMWSW-7:46 AMS232,130 mi
2
38%3:28 AMESE1:53 PMWSW-8:40 AMS229,804 mi
3
27%3:56 AMESE3:08 PMWSW-9:31 AMS227,821 mi
4
17%4:21 AME4:24 PMW-10:20 AMS226,385 mi
5
9%4:45 AME5:39 PMW-11:09 AMS225,696 mi
6
3%5:10 AMENE6:56 PMWNW-11:59 AMS225,909 mi
7
0%5:38 AMENE8:15 PMWNW-12:51 PMS227,094 mi
8
1%6:10 AMENE9:33 PMWNW-1:47 PMS229,211 mi
9
4%6:50 AMNE10:47 PMNW-2:45 PMS232,106 mi
10
9%7:37 AMNE11:54 PMNW-3:44 PMS235,524 mi
11
17%8:34 AMNE--4:43 PMS239,157 mi
12
26%-12:48 AMNW9:37 AMNE5:38 PMS242,688 mi
13
35%-1:32 AMNW10:43 AMENE6:29 PMS245,839 mi
14
45%-2:07 AMWNW11:49 AMENE7:16 PMS248,394 mi
15
50%-2:35 AMWNW12:53 PMENE7:59 PMS250,208 mi
16
64%-2:58 AMWNW1:54 PMENE8:39 PMS251,212 mi
17
73%-3:18 AMW2:54 PME9:18 PMS251,406 mi
18
82%-3:37 AMW3:54 PME9:57 PMS250,847 mi
19
89%-3:56 AMW4:54 PME10:36 PMS249,640 mi
20
94%-4:16 AMWSW5:56 PMESE11:17 PMS247,925 mi
21
96%-4:38 AMWSW7:00 PMESE--
22
98%-5:04 AMWSW8:07 PMESE12:02 AMS245,854 mi
23
100%-5:35 AMWSW9:15 PMSE12:51 AMS243,583 mi
24
100%-6:15 AMSW10:21 PMSE1:45 AMS241,255 mi
25
97%-7:05 AMSW11:22 PMSE2:43 AMS238,986 mi
26
92%-8:05 AMSW-3:44 AMS236,857 mi
27
84%12:13 AMSE9:14 AMSW-4:44 AMS234,917 mi
28
75%12:56 AMESE10:28 AMWSW-5:42 AMS233,187 mi
29
65%1:30 AMESE11:43 AMWSW-6:36 AMS231,681 mi
30
50%1:59 AMESE12:57 PMWSW-7:27 AMS230,422 mi
31
41%2:24 AME2:10 PMW-8:16 AMS229,460 mi

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 chance that a given day will be muggy in Pittsburgh is rapidly increasing during May, rising from 0% to 11% over the course of the month.

For reference, on July 28, the muggiest day of the year, there are muggy conditions 40% of the time, while on November 5, the least muggy day of the year, there are muggy conditions 0% of the time.

Humidity Comfort Levels in May in Pittsburgh

Humidity Comfort Levels in May in PittsburghMay11223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303031310%0%10%10%20%20%30%30%40%40%50%50%60%60%70%70%80%80%90%90%100%100%AprJunMay 10%May 10%May 3111%May 3111%May 111%May 111%May 214%May 214%NowNowmuggymuggyhumidhumidcomfortablecomfortabledrydry
dry 55°F comfortable 60°F humid 65°F muggy 70°F oppressive 75°F miserable
The percentage of time spent at various humidity comfort levels, categorized by dew point.

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 Pittsburgh is gradually decreasing during May, decreasing from 4.8 miles per hour to 4.0 miles per hour over the course of the month.

For reference, on February 2, the windiest day of the year, the daily average wind speed is 6.5 miles per hour, while on August 3, the calmest day of the year, the daily average wind speed is 3.4 miles per hour.

Average Wind Speed in May in Pittsburgh

The average of mean hourly wind speeds (dark gray line), with 25th to 75th and 10th to 90th percentile bands.

The hourly average wind direction in Pittsburgh throughout May is predominantly from the west, with a peak proportion of 36% on May 1.

Wind Direction in May in Pittsburgh

Wind Direction in May in PittsburghMay11223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303031310%100%20%80%40%60%60%40%80%20%100%0%AprJunNowNowwestsouthnortheast
northeastsouthwest
The percentage of hours in which the mean wind direction is from each of the four cardinal wind directions, excluding hours in which the mean wind speed is less than 1.0 mph. The lightly tinted areas at the boundaries are the percentage of hours spent in the implied intermediate directions (northeast, southeast, southwest, and northwest).

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).

The growing season in Pittsburgh typically lasts for 6.5 months (200 days), from around April 12 to around October 29, rarely starting before March 26 or after April 29, and rarely ending before October 11 or after November 14.

The month of May in Pittsburgh is very likely fully within the growing season, with the chance that a given day is in the growing season gradually increasing from 92% to 100% over the course of the month.

Time Spent in Various Temperature Bands and the Growing Season in May in Pittsburgh

Time Spent in Various Temperature Bands and the Growing Season in May in Pittsburghgrowing seasonMay11223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303031310%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%AprJun92%May 192%May 1100%May 31100%May 3199%May 1199%May 11100%May 21100%May 2150%Apr 1250%Apr 12NowNowvery coldcoldcoolcomfortablewarmhotfreezing
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
The percentage of time spent in various temperature bands. The black line is the percentage chance that a given day is within the growing season.

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.

The average accumulated growing degree days in Pittsburgh are increasing during May, increasing by 387°F, from 303°F to 690°F, over the course of the month.

Growing Degree Days in May in Pittsburgh

The average growing degree days accumulated over the course of May, with 25th to 75th and 10th to 90th percentile bands.

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 in Pittsburgh is gradually increasing during May, rising by 0.7 kWh, from 5.8 kWh to 6.4 kWh, over the course of the month.

Average Daily Incident Shortwave Solar Energy in May in Pittsburgh

Average Daily Incident Shortwave Solar Energy in May in PittsburghMay11223344556677889910101111121213131414151516161717181819192020212122222323242425252626272728282929303031310 kWh0 kWh1 kWh1 kWh2 kWh2 kWh3 kWh3 kWh4 kWh4 kWh5 kWh5 kWh6 kWh6 kWh7 kWh7 kWh8 kWh8 kWh9 kWh9 kWhAprJunMay 15.8 kWhMay 15.8 kWhMay 316.4 kWhMay 316.4 kWhMay 116.0 kWhMay 116.0 kWhMay 216.2 kWhMay 216.2 kWhNowNow
The average daily shortwave solar energy reaching the ground per square meter (orange line), with 25th to 75th and 10th to 90th percentile bands.

For the purposes of this report, the geographical coordinates of Pittsburgh are 40.441 deg latitude, -79.996 deg longitude, and 758 ft elevation.

The topography within 2 miles of Pittsburgh contains significant variations in elevation, with a maximum elevation change of 535 feet and an average elevation above sea level of 887 feet. Within 10 miles also contains significant variations in elevation (663 feet). Within 50 miles contains significant variations in elevation (2,365 feet).

The area within 2 miles of Pittsburgh is covered by artificial surfaces (97%), within 10 miles by artificial surfaces (79%) and trees (18%), and within 50 miles by trees (63%) and cropland (23%).

This report illustrates the typical weather in Pittsburgh, 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 Pittsburgh.

For each station, the records are corrected for the elevation difference between that station and Pittsburgh 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 Pittsburgh is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Pittsburgh and a given station.

The stations contributing to this reconstruction are:

To get a sense of how much these sources agree with each other, you can view a comparison of Pittsburgh and the stations that contribute to our estimates of its temperature history and climate. Please note that each source's contribution is adjusted for elevation and the relative change present in the MERRA-2 data.

Other Data

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 © OpenStreetMap contributors.

Disclaimer

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.

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