Groundhog Day Climate and History

Around the fifth century, the European Celts believed that animals had certain supernatural powers on special days that were half-way between the Winter Solstice and Spring Equinox.  Folklore from Germany and France indicated that when marmots and bears came out of their winter dens too early, they were frightened by their shadow and retreated back inside for four to six weeks.  This was adopted by the Romans as Hedgehog Day.  When Christianity came into being, the formerly pagan observance also came to be called Candlemas. The earliest known American reference to Groundhog Day can be found at the Historical Society of Berks County in Reading, Pa.  The reference was made Feb. 4, 1841 in Morgantown, Berks County (Pennsylvania) storekeeper James Morris’ diary:  Last Tuesday, the 2nd, was Candlemas day, the day on which, according to the Germans, the Groundhog peeps out of his winter quarters and if he sees his shadow he pops back for another six weeks nap, but if the day be cloudy he remains out, as the weather is to be moderate.

In 2009, Former Meteorologist In Charge Rich Kane was inducted into the Punxsutawney Weather Discovery Center's Meteorologist Hall of Fame.

In western countries in the Northern Hemisphere the official first day of Spring is about six weeks after Groundhog Day, on March 20 or 21.  About 1,000 years ago, before the adoption of the Gregorian calendar when the date of the equinox drifted in the Julian calendar, the spring equinox fell on March 16 instead.  This was exactly six weeks after February 2.  Assuming that the equinox marked the first day of spring in certain medieval cultures, as it does now in western countries, Groundhog Day occurred exactly six weeks before spring. Therefore, if the groundhog saw his shadow on Groundhog Day there would be six more weeks of winter. If he didn’t, there would be 42 more days of winter. In other words, the Groundhog Day tradition may have begun as a bit of folk humor.

Regardless, the annual prognostication occurs in Punxsutawney, Pennsylvania.  According to the Punxsutawney Groundhog Club, 1886 was the first year that Groundhog Day in the city's newspaper.  The first official prediction occurred the following year, with Phil seeing his shadow and predicting 6 more weeks of winter.  He has been making forecasts ever since. 

Groundhog Climate Statistics:
 

Below are some Groundhog Day weather statistics for Pittsburgh, PA, Morgantown, WV and Zanesville, OH.

Pittsburgh, PA:

The following statistics comprises 151 years of data. From 1871 through June 1945, the data came from various locations in downtown Pittsburgh.  From July 1945 through mid-September 1952, the data came from the Allegheny County Airport.  Since then, the data has been gathered at the Pittsburgh International Airport.

The odds of having any precipitation at all on Groundhog Day is 75.7% (115 out of 151).  There has been measurable (0.01" or greater) precipitation on 74 Groundhog Days (48.7%) and trace amounts (less than 0.01") of precipitation on 41 Groundhog Days (27.0%). 

Since 1880, it has snowed on 80 out of 142 (56.3%) Groundhog Days.  Measurable snow (0.1" or greater) has fallen on 42 Groundhog Days (29.6%) and trace of snow (a dusting) has fallen on another 38 Groundhog Days (26.8%)

Since 1948, residents have woken up with measurable snow (1/2" or greater) on the ground 35 out of 75 times (46.7%), trace amounts (less than a 1/2" inch) 12 times (16.0%), and no snow 28 times (37.3%).

The odds of having a maximum temperature at or below freezing (32°F) on Groundhog Day is 35.8% (53 out of 148), and the odds of having a minimum temperature at or below freezing is 83.8% (124 out of 148).  The odds of having a minimum temperature at or below 0°F on Groundhog Day is 4.1% (6 out of 148).

In 2023, the high temperature was 36°F and the low temperature was 15°F.  A trace of precipitation fell, with a trace of snow.  There was 1" of snow on the ground at 7 AM.  The average wind speed was 7.5 mph, with a maximum speed of 16 mph out of the southwest.

Morgantown, WV:

The following statistics comprises 149 years of data. From 1873 through July 1946, the data came from a cooperative observer in the Morgantown area with occasional periods of missing data. Since then, the data has come from the Morgantown Municipal Airport-Walter L. Bill Hart Field.

The odds of having any precipitation at all on Groundhog Day is 60.4% (81 out of 134).  There has been measurable (0.01" or greater) precipitation on 56 Groundhog Days (41.8%) and trace amounts (less than 0.01") of precipitation on 25 Groundhog Days (18.7%). 

The odds of having a maximum temperature at or below freezing (32°F) on Groundhog Day is 28.7% (39 out of 136), and the odds of having a minimum temperature at or below freezing is 76.5% (104 out of 136).  The odds of having a minimum temperature at or below 0°F on Groundhog Day is 3.7% (5 out of 136).

In 2023, the high temperature was 36°F and the low temperature was 21°F.  No precipitation was recorded. The average wind speed was 5.5 mph, with a maximum speed of 13 mph from the southwest.

Zanesville, OH:

The following statistics comprises 126 years of data. From 1896 through July 1946, the data came from a cooperative observer in the Zanesville area with occasional periods of missing data. Since then, the data has come from the Zanesville Municipal Airport.

The odds of having any precipitation at all on Groundhog Day is 62.7% (79 out of 126).  There has been measurable (0.01" or greater) precipitation on 56 Groundhog Days (44.4%) and trace amounts (less than 0.01") of precipitation on 23 Groundhog Days (18.3%). 

The odds of having a maximum temperature at or below freezing (32°F) on Groundhog Day is 31.7% (40 out of 126), and the odds of having a minimum temperature at or below freezing is 80.2% (101 out of 126).  The odds of having a minimum temperature at or below 0°F on Groundhog Day is 7.9% (10 out of 126).

In 2023, the high temperature was 47°F and the low temperature was 33°F.  A total of 0.07" of precipitation fell.  The average wind speed was 6.0 mph, with a maximum wind speed of 15 mph out of the west.

Groundhog Weather History:

Below are some weather events that took place on this day:

• In 1904, a strong arctic cold front moved caused temperature to plunge across the region, with many sites seeing their largest diurnal temperature difference for the day on record.  This includes Pittsburgh, PA falling from 44°F to 5°F; Zanesville, OH, falling from 46°F to 4°F; Morgantown, WV falling from 45°F to 0°F; and Cambridge, OH falling from 48°F to -5°F.  The largest difference was recorded near Oakland, MD where the temperature fell from 46°F to -13°F, a 59 degree change!
• In 1958, a nor'easter produced heavy snow across the higher terrain of West Virginia and Maryland.  A COOP site 3 miles southeast of Parson, WV saw a record 7.5" of snow for the day, with Canaan Valley, WV receiving 8". 
• In 1961, a secondary arctic front dropped out of the Great Lakes into northwest Pennsylvania, dropping temperature in the area to record low values for the day.  This includes -26°F 3 miles southeast of Indiana and 3 miles southwest of Clarion; -24°F 2 miles southweast of Tionesta Lake; -21°F 1 mile north of New Castle, 4 miles south of Ford City Dam, and 2 miles southeast of Putneyville Dam; and -20°F in Franklin.
• In 1966, widespread snow fell across the region.  In PA: near Natrona Lock (6"), near Braddock Lock (5"), Vandergrift (5"), Sagamore (4"), Mckeesport (3").  In OH: Senecaville Lake (5"), Norwich (4"), Summerfield (4").  In WV: Terra Alta (7.5"), Rowlesburg (6.5"), Parsons (6"), Canaan Valley (4").  In MD: Savage River Dam (5"), Bittinger (3.5").
• In 1971, arctic air kept area temperature well below freezing, with most sites staying below 20 degrees and many recording the lowest max temperature for the date. This includes Terra Alta, WV (2°F), Dubois, PA (3°F), Tionesta Lake, PA (4°F), Franklin, PA (7°F), Pittsburgh, PA (10°F), and Morgantown, WV (11°F). 
• In 1981, deepening low pressure over the Central Plains caused warm, moist air to surge over the region, leading to widespread heavy rains.  Hannibal Locks and Dam in OH saw 1.88" of rain while Roseville, OH saw 1.68", both of which were daily records.  Other sites setting a daily record include Mckeesport, PA (1.39"); Lake Lynn, WV (1.25"); and Franklin, PA (1.21").
• In 1985, the combination of a deep continental trough and surface low pressure moving up the Atlantic coast help to produce widespread snowfall, favoring the higher terrain.  Daily record snowfall accumulations were set in Fairmont, WV (6.5"), the Point Marion Lock, PA (6.1"), and Oakland, MD (6.0").  Other notable totals include 8" in McHenry, MD, Uniontown, PA, and Brandonvile, WV; and 7" in Canaan Valley, WV and Chalk Hill, PA.
• In 1988, widespread heavy rain ahead of a passing cold front led to 1 to 2" accumulations over much of southeastern Ohio into western Pennsylvania.  Among the daily rainfall records set include: the Braddock Lock, PA (2.30"), near Indiana, PA (2.09"), Cambridge, OH (1.83"), Beaver Falls, PA (1.48"), Steubenville, OH (1.32"), and Zanesville, OH (1.22").
• Three of the four highest daily snowfall accumulations at any site in the region occurred between 2017-2019.  They are 9.1" near Davis, WV in 2017; 8.5" near Mountain Lake Park, MD in 2019; and 8.0" at Laurel Summit, PA in 2018.