First 36 Degree Minimum Temperature in the Autumn

Date of first 36 degree minimum temperature in the Autumn.

This may be useful as a proxy for when the average first frost occurs. However, a few caveats are involved in using it in this way:

1) 36F at 2m height (standard observation/sensor height) is about when we see the near-ground temps able to get down to freezing. So, by extension frost can occur when the observed temperature is 36F or lower. 

2) It needs to be calm and mainly clear. Otherwise frost is much less likely at 33-36F.

3) Freezes can occur even without frost forming. This is especially possible when it's windy or there are sufficient clouds to prevent frost, typically after an early-season cold front has moved through.

4) Co-operative Observation Sites are not required to report frost.

5) Automated sites do not report frost.

Station, Date of mean first 36 F deg min temp in autumn,Lat,Lon, Start of period of record
Altoona, 10/02,40.5167,-78.3667,1948
Bear Gap, 10/08,40.8167,-76.5000,2008
Biglerville, 10/09,39.9333,-77.2500,1972
Bradford Airport, 09/06,41.8030,-78.6400,1957
Bradford 4 SW, 09/11,41.9000,-78.7167,1942
Chambersburg 1 ESE, 10/03,39.9306,-77.6511,1894
Clearfield Lawrence Airport, 09/30,41.0491,-78.4152,2000
Clermont 1 NW, 09/22,41.7000,-78.4833,2001
Confluence 1 SW, 09/30,39.8000,-79.3667,1946
Coudersport 1 SW, 09/24,41.7833,-78.0500,2002
Cowanesque Dam, 10/03,41.9833,-77.1500,1994
Dushore, 09/20,41.5215,-76.4044,2004
Ebensburg, 09/15,40.4667,-78.7333,1964
Emporium, 09/28,41.5000,-78.2333,1969
Everett, 09/26,40.0167,-78.3667,1944
Glen Hazel, 09/30,41.5667,-78.6000,2004
Hanover 4 SW, 10/08,39.7667,-77.0333,1994
Johnstown Murtha Airport, 10/10,40.3156,-78.8347,2001
Harrisburg, 10/17,40.1923,-76.7570,1888
Harrisburg 1 NE, 10/14,40.2833,-76.8667,1999
Kane 1 NNE, 08/30,41.6833,-78.8000,1940
Lancaster Airport, 10/16,40.1224,-76.2944,2000
Lancaster Filter Plant, 10/10,40.0500,-76.2667,1977
Landisville, 09/30,40.1167,-76.4333,1952
Laporte, 10/03,41.4167,-76.5000,1995
Laurel Summit, 10/08,40.1667,-79.1333,2001
Lebanon 2 W, 10/07,40.3333,-76.4667,1966
Lewisburg, 10/11,40.9500,-76.8833,1997
Lewistown, 10/07 ,40.5833,-77.5667,1939
Lock Haven, 10/05,41.1167,-77.4500,1980
Mahanoy City, 10/08,40.8333,-76.1333,2010
Meyersdale, 09/23,39.7833,-79.0333,2000
Millheim, 09/23,40.8833,-77.4667,2000
New Holland, 10/15,40.0833,-76.0667,1993
Octoraro Lake, 10/05,39.8000,-76.0500,1978
Philipsburg 2 S, 09/25,40.8667,-78.2167,1998
Port Allegany, 09/27,41.8167,-78.2833,2000
Prince Gallitzin State Park, 09/22,40.6500,-78.5500,1983
Raystown, 10/07,40.3833,-78.0833,1974
Renovo, 10/02,41.3333,-77.7333,1961
Ridgway, 09/15,41.4167,-78.7500,1913
Safe Harbor, 11/02,39.9000,-76.4000,1995
Selinsgrove Airport, 10/04,40.7833,-76.8667,1998
Shippensburg, 10/07,40.0500,-77.5167,1933
South Mountain, 10/06,39.8500,-77.4833,2000
State College, 10/02,40.8000,-77.8667,1893
Stevenson Dam, 10/06,41.4000,-78.0167,1970
Tioga Hammond Dam, 10/02,41.9000,-77.1500,2008
Warren, 09/25,41.8500,-79.1500,1896
Wellsboro 4 SW, 09/17,41.7000,-77.3833,1926
Williamsport, 10/04,41.2457,-76.9218,1895
Williamsport 2 E, 10/11,41.2333,-77.0000,1999
Wolfsburg, 10/05,40.0500,-78.5333,2004
York Airport, 10/08,39.9170,-76.8730,1998