Heat in Pennsylvania, December 31, 2001

Name: Heat in Pennsylvania, December 31, 2001
Start: 2001-12-31T23:59
End: 2001-12-31T23:59
Location: Pennsylvania

December 31, 2001 · NWS PHI · 10 events in 10 counties and zones

December 2001 was an unseasonably warm month across Eastern Pennsylvania. At both the Philadelphia and Lehigh Valley International Airports, it was the 3rd warmest December on record.

Where it happened

Every event with a place to put it; 7 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.

Tornadoes
Tropical storms and surge
Floods
Wind
Hail
Winter weather
Heat and drought
Cold
Fire, smoke and dust
Marine and coastal
Other

Open the live radar over this ground

The toll

Deaths: 0
Injuries: 0
Property damage: None recorded
Crop damage: None recorded
Events: 10

Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.

What happened

The episode as NWS PHI wrote it up.

December 2001 was an unseasonably warm month across Eastern Pennsylvania. At both the Philadelphia and Lehigh Valley International Airports, it was the 3rd warmest December on record. The monthly mean temperature at the Philadelphia International Airport was 43.7 degrees and was 7.9 degrees above normal. The monthly mean temperature at the Lehigh Valley International Airport was 38.2 degrees and was 6.4 degrees above normal. The monthly mean temperature at Reading Regional Airport was 39.9 degrees and was 6.9 degrees above normal.

What forecasters said that day

The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Philadelphia/Mount Holly wrote its last area forecast discussion before the first event at Dec 31, 1:53 PM EST, 10 hours 6 minutes earlier.

Area forecast discussion, Dec 31, 1:53 PM EST, 10 hours 6 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MOUNT HOLLY NJ
153 PM EST MON DEC 31 2001

AFTER COOR...WE DECIDED TO PUT CHC OF SNOW INTO THE AREAS PHL E AND
S FOR THU DUE TO THE SYSTEM MOVING BY TO THE S. OBVIOUSLY...THE
AREAS ARND PHL AND IN CENTRAL NJ...HAVE THE LEAST CHC WHILE DELMARVA
HAS THE HIGHEST CHC OF ANY SNOW. THE AVN WAS GENLY THE MODEL OF
CHOICE. IT DOES REPRESENT THE HIGHEST CHC OF PCPN VS OTHER MODELS
BUT MODEL TREND HAS BEEN FARTHER N/W WITH TIME.

FOR SUN...ANOTHER WINTRY PATN POTENTIAL WHICH LOOKS MORE
CLIMATOLOGICAL WITH R/S DISTRIBUTION.

SHORT TERM...NOT MUCH EXCEPT A SHORT WAVE TUE AFTN THAT COULD CAUSE
FLURRIES NORTH. OTHERWISE DRY THROUGH WED.

GUIDANCE TEMPS GENLY OK.

MPO    9  27  11  28 /   0   0   0   0
ABE   14  31  14  33 /   0   0   0   0
RDG   15  32  15  35 /   0   0   0   0
PHL   20  35  23  36 /   0   0   0   0
12N   11  29  13  30 /   0   0   0   0
SMQ   15  34  17  35 /   0   0   0   0
TTN   16  34  18  35 /   0   0   0   0
MIV   12  36  14  36 /   0   0   0   0
ACY   22  36  25  36 /   0   0   0   0
ILG   16  35  19  36 /   0   0   0   0
DOV   17  35  20  36 /   0   0   0   0
GED   17  35  20  36 /   0   0   0   0
ESN   17  35  20  36 /   0   0   0   0

.PHI...
DE...NONE.
MD...NONE.
NJ...NONE.
PA...NONE.
MARINE...WILL KEEP SCA FOR SANDY HOOK TO LITTLE EGG NJ ONLY.

RNS

The radar

The national radar mosaic for the moment the first event began.

Open the radar archive at this moment

Event by event

10 heat. Local standard time, as filed.

Heat, Berks

When: December 31, 11:59 PM EST
Where: Berks forecast zone
Reported by: AWOS,ASOS,MESONET,ETC
Coordinates: 40.416, -75.926 (the zone’s center; the record gives no point)

Heat, Bucks

When: December 31, 11:59 PM EST
Where: Bucks forecast zone
Reported by: AWOS,ASOS,MESONET,ETC

Heat, Carbon

When: December 31, 11:59 PM EST
Where: Carbon forecast zone
Reported by: AWOS,ASOS,MESONET,ETC
Coordinates: 40.918, -75.709 (the zone’s center; the record gives no point)

Heat, Chester

When: December 31, 11:59 PM EST
Where: Chester forecast zone
Reported by: AWOS,ASOS,MESONET,ETC

Heat, Delaware

When: December 31, 11:59 PM EST
Where: Delaware forecast zone
Reported by: AWOS,ASOS,MESONET,ETC
Coordinates: 39.917, -75.399 (the zone’s center; the record gives no point)

Heat, Lehigh

When: December 31, 11:59 PM EST
Where: Lehigh forecast zone
Reported by: AWOS,ASOS,MESONET,ETC
Coordinates: 40.613, -75.592 (the zone’s center; the record gives no point)

Heat, Monroe

When: December 31, 11:59 PM EST
Where: Monroe forecast zone
Reported by: AWOS,ASOS,MESONET,ETC
Coordinates: 41.058, -75.339 (the zone’s center; the record gives no point)

Heat, Montgomery

When: December 31, 11:59 PM EST
Where: Montgomery forecast zone
Reported by: AWOS,ASOS,MESONET,ETC

Heat, Northampton

When: December 31, 11:59 PM EST
Where: Northampton forecast zone
Reported by: AWOS,ASOS,MESONET,ETC
Coordinates: 40.754, -75.307 (the zone’s center; the record gives no point)

Heat, Philadelphia

When: December 31, 11:59 PM EST
Where: Philadelphia forecast zone
Reported by: AWOS,ASOS,MESONET,ETC
Coordinates: 40.008, -75.134 (the zone’s center; the record gives no point)

What these are

Heat: Heat below excessive heat criteria that still caused deaths, injuries or significant impacts.

After NWS Directive 10-1605, the rules offices file Storm Data by.

The same day elsewhere

Every storm in Pennsylvania in 2001 Every state in 2001 This day in weather history Warnings in Pennsylvania, December 2001

Sources

NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 5273484, 5273485, 5273486, 5273487, 5273488, 5273489, 5273490, 5273491, 5273492, 5273493.