Fall Weather in Petersburg United States

Daily high temperatures decrease by 28°F, from 85°F to 57°F, rarely falling below 45°F or exceeding 93°F.

Daily low temperatures decrease by 29°F, from 65°F to 36°F, rarely falling below 24°F or exceeding 73°F.

For reference, on July 19, the hottest day of the year, temperatures in Petersburg typically range from 70°F to 90°F, while on January 29, the coldest day of the year, they range from 30°F to 49°F.

The figure below shows you a compact characterization of the hourly average fall temperatures. 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.

Polýkastro, Greece (5,048 miles away) and Luoqiao, China (7,917 miles) are the far-away foreign places with temperatures most similar to Petersburg (view comparison).

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The fall in Petersburg experiences increasing cloud cover, with the percentage of time that the sky is overcast or mostly cloudy increasing from 38% to 46%. The lowest chance of overcast or mostly cloudy conditions is 35% on October 11.

The clearest day of the fall is October 11, with clear, mostly clear, or partly cloudy conditions 65% of the time.

For reference, on December 25, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 52%, while on October 8, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 65%.

A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Petersburg, the chance of a wet day over the course of the fall is decreasing, starting the season at 29% and ending it at 24%.

For reference, the year's highest daily chance of a wet day is 42% on August 4, and its lowest chance is 21% on October 19.

Over the course of the fall in Petersburg, the chance of a day with only rain decreases from 29% to 22%, the chance of a day with mixed snow and rain remains an essentially constant 1% throughout, and the chance of a day with only snow remains an essentially constant 0% throughout.

Rainfall

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

The average sliding 31-day rainfall during the fall in Petersburg is decreasing, starting the season at 3.7 inches, when it rarely exceeds 7.8 inches or falls below 1.1 inches, and ending the season at 3.0 inches, when it rarely exceeds 5.2 inches or falls below 1.1 inches.

Over the course of the fall in Petersburg, the length of the day is very rapidly decreasing. From the start to the end of the season, the length of the day decreases by 3 hours, 9 minutes, implying an average daily decrease of 2 minutes, 6 seconds, and weekly decrease of 14 minutes, 41 seconds.

The shortest day of the fall is November 30, with 9 hours, 48 minutes of daylight and the longest day is September 1, with 12 hours, 57 minutes of daylight.

The latest sunrise of the fall in Petersburg is 7:35 AM on November 2 and the earliest sunrise is 59 minutes earlier at 6:36 AM on November 3.

The latest sunset is 7:37 PM on September 1 and the earliest sunset is 2 hours, 45 minutes earlier at 4:52 PM on November 30.

Daylight saving time (DST) starts at 1:00 AM on November 3, 2024, shifting sunrise and sunset to be an hour later.

For reference, on June 20, the longest day of the year, the Sun rises at 5:49 AM and sets 14 hours, 44 minutes later, at 8:33 PM, while on December 21, the shortest day of the year, it rises at 7:20 AM and sets 9 hours, 36 minutes later, at 4:56 PM.

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.

The figure below presents a compact representation of key lunar data for the fall of 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.

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 Petersburg is very rapidly decreasing during the fall, falling from 48% to 0% over the course of the season.

For reference, on July 23, the muggiest day of the year, there are muggy conditions 74% of the time, while on January 27, the least muggy day of the year, there are muggy conditions 0% of the time.

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 Petersburg is increasing during the fall, increasing from 4.0 miles per hour to 5.1 miles per hour over the course of the season.

For reference, on February 26, the windiest day of the year, the daily average wind speed is 6.1 miles per hour, while on August 10, the calmest day of the year, the daily average wind speed is 3.8 miles per hour.

The wind direction in Petersburg during the fall is predominantly out of the north from September 1 to November 17 and the west from November 17 to November 30.

Petersburg is located near a large body of water (e.g., ocean, sea, or large lake). This section reports on the wide-area average surface temperature of that water.

The average surface water temperature in Petersburg is very rapidly decreasing during the fall, falling by 24°F, from 77°F to 53°F, over the course of the season.

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 Petersburg typically lasts for 6.8 months (207 days), from around April 3 to around October 27, rarely starting before March 13 or after April 20, and rarely ending before October 11 or after November 12.

During the fall in Petersburg, the chance that a given day is within the growing season is very rapidly decreasing falling from 100% to 1% over the course of the 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 Petersburg are very rapidly increasing during the fall, increasing by 1,073°F, from 3,553°F to 4,626°F, over the course of the season.

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 Petersburg is very rapidly decreasing during the fall, falling by 3.2 kWh, from 5.6 kWh to 2.5 kWh, over the course of the season.

For the purposes of this report, the geographical coordinates of Petersburg are 37.228 deg latitude, -77.402 deg longitude, and 66 ft elevation.

The topography within 2 miles of Petersburg contains only modest variations in elevation, with a maximum elevation change of 164 feet and an average elevation above sea level of 80 feet. Within 10 miles also contains only modest variations in elevation (325 feet). Within 50 miles contains only modest variations in elevation (886 feet).

The area within 2 miles of Petersburg is covered by artificial surfaces (89%), within 10 miles by trees (60%) and artificial surfaces (26%), and within 50 miles by trees (70%) and cropland (18%).