Record envelope, standing records and threshold days for Mercer (USC00365651), Pennsylvania, United States, with 61 years of record.
Key Facts for Mercer
Mercer (USC00365651) is a weather station in Pennsylvania, United States at 41.22 latitude and -80.23 longitude, 372 m (1,220 ft) above sea level.
The station reports from 1950 to 2010, 61 years of record.
1,464 records set at Mercer still stand.
Records are tracked for tmax, tmin, prcp, snow, snwd: an element needs 30 years of data to be eligible.
Mercer tied a daily record snow depth of 25.4 cm (10.0 in) on 12 February 2010.
About the Station
Location: Pennsylvania, United States, 41.22 latitude, -80.23 longitude.
Elevation: 372 m (1,220 ft).
Period of record: 1950 to 2010, 61 years.
Eligible elements: tmax, tmin, prcp, snow, snwd.
Daily Record Envelope and 2026
0 days at or beyond a record
Record highRecord low2026 daily maximum2026 daily minimum
The band shows the record high and record low for each calendar day at Mercer. The lines show the 2026 daily maximum and minimum. 0 days in 2026 matched or passed a record. Temperatures are in degrees Celsius.
Daily record high and record low at Mercer, with 2026 drawn through them
Month
Highest record high
Lowest record low
2026 highest maximum
2026 lowest minimum
Jan
20.0 C (68.0 F)
-35.6 C (-32.1 F)
n/a
n/a
Feb
23.3 C (73.9 F)
-33.3 C (-27.9 F)
n/a
n/a
Mar
27.8 C (82.0 F)
-25.0 C (-13.0 F)
n/a
n/a
Apr
31.1 C (88.0 F)
-11.7 C (10.9 F)
n/a
n/a
May
32.2 C (90.0 F)
-7.2 C (19.0 F)
n/a
n/a
Jun
36.7 C (98.1 F)
-2.2 C (28.0 F)
n/a
n/a
Jul
37.8 C (100.0 F)
0.6 C (33.1 F)
n/a
n/a
Aug
37.8 C (100.0 F)
-0.6 C (30.9 F)
n/a
n/a
Sep
38.3 C (100.9 F)
-5.0 C (23.0 F)
n/a
n/a
Oct
31.1 C (88.0 F)
-9.4 C (15.1 F)
n/a
n/a
Nov
27.2 C (81.0 F)
-18.3 C (-0.9 F)
n/a
n/a
Dec
22.8 C (73.0 F)
-28.3 C (-18.9 F)
n/a
n/a
Which Years Hold Standing Records
1,464 standing records
Year with most
1,464 records at Mercer still stand. 1991 holds the most, with 47.
Standing records at Mercer by the year they were set
Year set
Standing records
1950
21
1952
35
1953
39
1954
20
1955
19
1956
19
1957
20
1958
32
1959
37
1960
37
1961
28
1962
37
1963
41
1964
30
1965
23
1966
32
1967
31
1968
23
1969
17
1970
25
1971
27
1972
24
1973
19
1974
23
1975
26
1976
28
1977
40
1978
17
1979
35
1980
24
1981
16
1982
27
1983
17
1984
20
1985
23
1986
22
1987
17
1988
40
1989
22
1990
35
1991
47
1992
14
1993
21
1994
33
1995
13
1996
25
1997
16
1998
18
1999
14
2000
31
2001
17
2002
22
2003
17
2004
18
2005
15
2006
20
2007
34
2008
16
2009
5
All-Time Record Progression
4 new records
4 all-time records were set at Mercer between 5 July 1990 and 9 September 2004. Each dot is a new record.
When Mercer set new all-time records
Date
Kind
Detail
1990-07-05
Record high minimum temperature
Record high minimum temperature 23.9 C (75.0 F)
1992-07-03
Record high minimum temperature
Record high minimum temperature 24.4 C (75.9 F)
1994-01-19
Record low minimum temperature
Record low minimum temperature -35.6 C (-32.1 F)
2004-09-09
Record daily precipitation
Record daily precipitation 113.5 mm (4.5 in)
Wettest Day of Each Month
Sep: 113.5 mm (4.5 in)
The wettest day on record for each calendar month at Mercer. The most was 113.5 mm (4.5 in) on 9 September 2004.
Record daily precipitation for each month at Mercer
Month
Record daily precipitation (mm)
Date
Jan
68.3 mm (2.7 in)
30 January 2002
Feb
50.8 mm (2.0 in)
10 February 1959
Mar
50.3 mm (2.0 in)
31 March 1987
Apr
55.9 mm (2.2 in)
20 April 1963
May
60.5 mm (2.4 in)
12 May 1974
Jun
83.6 mm (3.3 in)
12 June 1986
Jul
86.9 mm (3.4 in)
29 July 1999
Aug
101.6 mm (4.0 in)
11 August 1955
Sep
113.5 mm (4.5 in)
9 September 2004
Oct
64.5 mm (2.5 in)
19 October 1968
Nov
70.4 mm (2.8 in)
5 November 1985
Dec
45.0 mm (1.8 in)
3 December 1991
Period of Record Coverage
1950 to 2010
Complete yearUnder 90 percent of days
60 years of record at Mercer, 1950 to 2010. 11 years have data for under 90 percent of days and are left out of rankings: 1950, 1952, 1954, 1955, 1964, 1965, 1993, 2005 and others.
Cooler than the station meanWarmer than the station mean
One stripe for each of 44 complete years at Mercer, 1953 to 2007. Blue stripes are years cooler than the station's own mean of 9.1 C (48.4 F); red stripes are warmer. The coolest year was 2003, at 7.5 C (45.5 F), and the warmest was 1991, at 10.9 C (51.7 F). The strongest colour marks a difference of 1.9 C (3.4 F).
Annual mean temperature at Mercer as warming stripes, 1953 to 2007
Year
Annual mean temperature
Difference from the station mean
1953
10.8 C
+1.65 C
1956
8.5 C
-0.61 C
1957
9.4 C
+0.28 C
1958
7.8 C
-1.36 C
1959
9.3 C
+0.14 C
1960
8.1 C
-0.99 C
1961
8.8 C
-0.35 C
1963
7.8 C
-1.29 C
1966
8.8 C
-0.36 C
1968
8.8 C
-0.29 C
1969
9.0 C
-0.17 C
1970
9.6 C
+0.51 C
1971
9.5 C
+0.36 C
1972
8.9 C
-0.25 C
1973
10.4 C
+1.25 C
1974
9.5 C
+0.36 C
1975
9.9 C
+0.81 C
1976
8.6 C
-0.50 C
1977
9.3 C
+0.21 C
1978
8.3 C
-0.86 C
1980
8.6 C
-0.52 C
1981
8.6 C
-0.52 C
1982
9.0 C
-0.12 C
1983
9.6 C
+0.51 C
1984
9.4 C
+0.31 C
1985
9.4 C
+0.23 C
1986
9.9 C
+0.82 C
1987
10.0 C
+0.89 C
1988
9.3 C
+0.18 C
1989
8.7 C
-0.38 C
1990
10.7 C
+1.57 C
1991
10.9 C
+1.81 C
1992
8.7 C
-0.39 C
1993
8.6 C
-0.55 C
1994
8.0 C
-1.14 C
1996
8.5 C
-0.64 C
1997
8.2 C
-0.97 C
1998
9.5 C
+0.35 C
1999
9.8 C
+0.69 C
2000
9.0 C
-0.09 C
2002
9.0 C
-0.13 C
2003
7.5 C
-1.61 C
2006
10.1 C
+0.95 C
2007
9.4 C
+0.27 C
The fitted trend in annual mean temperature here over 1953 to 2007 is 0.04 C (-0.13 to 0.20) per decade. The interval includes zero, so the trend is not clearly different from zero. In Fahrenheit: 0.1 F (-0.2 to 0.4) per decade. The slope is a straight line fitted to 44 complete years; the brackets give its 95 percent interval.
Fitted temperature trends per decade at Mercer
Measure
Per decade (C)
Per decade (F)
Period
Complete years
Reading
Annual mean temperature
0.04 C (-0.13 to 0.20) per decade
0.1 F (-0.2 to 0.4) per decade
1953 to 2007
44
Not clearly different from zero
Mean daily maximum
0.1 C (-0.1 to 0.3) per decade
0.2 F (-0.1 to 0.5) per decade
1953 to 2007
44
Not clearly different from zero
Mean daily minimum
-0.03 C (-0.29 to 0.22) per decade
-0.1 F (-0.5 to 0.4) per decade
1953 to 2007
44
Not clearly different from zero
A year is complete when all 12 months have at least 20 days of both daily maximum and daily minimum readings. The annual mean is the mean of the monthly means. The trend describes this one station over this period; it does not say what caused the change.
Extremes by Year
1950 to 2010
Yearly extremes at Mercer: the record and the median year
Measure
Record
Year of the record
Median year
Years with a value
Hottest day (TXx)
38.3 C (100.9 F)
1953
32.8 C (91.0 F)
60
Coldest night (TNn)
-35.6 C (-32.1 F)
1994
-23.3 C (-9.9 F)
60
Wettest day (Rx1day)
113.5 mm (4.5 in)
2004
53.3 mm (2.1 in)
60
Wettest five days (Rx5day)
147.4 mm (5.8 in)
1955
82.9 mm (3.3 in)
60
Longest dry spell (CDD)
48 days
2010
14 days
60
Hottest day (TXx)
The hottest day of the year at Mercer, 1950 to 2010. The record is 38.3 C (100.9 F) in 1953, marked on the chart; the median year is 32.8 C (91.0 F).
Hottest day (TXx) at Mercer by year
Year
Hottest day (TXx)
1950
33.3 C (91.9 F)
1952
36.7 C (98.1 F)
1953
38.3 C (100.9 F)
1954
37.8 C (100.0 F)
1955
35.0 C (95.0 F)
1956
31.7 C (89.1 F)
1957
32.8 C (91.0 F)
1958
31.7 C (89.1 F)
1959
33.9 C (93.0 F)
1960
31.1 C (88.0 F)
1961
32.2 C (90.0 F)
1962
32.8 C (91.0 F)
1963
32.8 C (91.0 F)
1964
33.9 C (93.0 F)
1965
33.9 C (93.0 F)
1966
35.6 C (96.1 F)
1967
32.2 C (90.0 F)
1968
32.8 C (91.0 F)
1969
32.8 C (91.0 F)
1970
32.8 C (91.0 F)
1971
34.4 C (93.9 F)
1972
32.8 C (91.0 F)
1973
32.8 C (91.0 F)
1974
32.8 C (91.0 F)
1975
34.4 C (93.9 F)
1976
31.1 C (88.0 F)
1977
33.9 C (93.0 F)
1978
32.8 C (91.0 F)
1979
31.7 C (89.1 F)
1980
33.9 C (93.0 F)
1981
32.8 C (91.0 F)
1982
32.2 C (90.0 F)
1983
35.0 C (95.0 F)
1984
32.2 C (90.0 F)
1985
33.3 C (91.9 F)
1986
32.2 C (90.0 F)
1987
32.2 C (90.0 F)
1988
37.2 C (99.0 F)
1989
32.2 C (90.0 F)
1990
33.3 C (91.9 F)
1991
35.0 C (95.0 F)
1992
31.1 C (88.0 F)
1993
35.0 C (95.0 F)
1994
33.9 C (93.0 F)
1995
35.6 C (96.1 F)
1996
32.2 C (90.0 F)
1997
32.2 C (90.0 F)
1998
32.2 C (90.0 F)
1999
33.9 C (93.0 F)
2000
31.1 C (88.0 F)
2001
34.4 C (93.9 F)
2002
33.3 C (91.9 F)
2003
30.0 C (86.0 F)
2004
30.6 C (87.1 F)
2005
26.7 C (80.1 F)
2006
33.9 C (93.0 F)
2007
34.4 C (93.9 F)
2008
32.2 C (90.0 F)
2009
31.7 C (89.1 F)
2010
4.4 C (39.9 F)
Coldest night (TNn)
The coldest night of the year at Mercer, 1950 to 2010. The record is -35.6 C (-32.1 F) in 1994, marked on the chart; the median year is -23.3 C (-9.9 F).
Coldest night (TNn) at Mercer by year
Year
Coldest night (TNn)
1950
-16.7 C (1.9 F)
1952
-12.8 C (9.0 F)
1953
-15.6 C (3.9 F)
1954
-16.7 C (1.9 F)
1955
-17.8 C (0.0 F)
1956
-22.8 C (-9.0 F)
1957
-28.3 C (-18.9 F)
1958
-24.4 C (-11.9 F)
1959
-22.8 C (-9.0 F)
1960
-26.7 C (-16.1 F)
1961
-27.8 C (-18.0 F)
1962
-23.3 C (-9.9 F)
1963
-33.3 C (-27.9 F)
1964
-25.6 C (-14.1 F)
1965
-10.6 C (12.9 F)
1966
-25.6 C (-14.1 F)
1967
-25.0 C (-13.0 F)
1968
-22.8 C (-9.0 F)
1969
-20.6 C (-5.1 F)
1970
-26.1 C (-15.0 F)
1971
-23.3 C (-9.9 F)
1972
-24.4 C (-11.9 F)
1973
-22.2 C (-8.0 F)
1974
-16.7 C (1.9 F)
1975
-25.0 C (-13.0 F)
1976
-22.8 C (-9.0 F)
1977
-26.7 C (-16.1 F)
1978
-23.9 C (-11.0 F)
1979
-27.8 C (-18.0 F)
1980
-20.6 C (-5.1 F)
1981
-23.3 C (-9.9 F)
1982
-28.3 C (-18.9 F)
1983
-27.8 C (-18.0 F)
1984
-26.1 C (-15.0 F)
1985
-33.3 C (-27.9 F)
1986
-23.9 C (-11.0 F)
1987
-21.7 C (-7.1 F)
1988
-21.7 C (-7.1 F)
1989
-28.3 C (-18.9 F)
1990
-15.0 C (5.0 F)
1991
-18.9 C (-2.0 F)
1992
-18.9 C (-2.0 F)
1993
-23.3 C (-9.9 F)
1994
-35.6 C (-32.1 F)
1995
-25.0 C (-13.0 F)
1996
-24.4 C (-11.9 F)
1997
-26.1 C (-15.0 F)
1998
-18.9 C (-2.0 F)
1999
-25.0 C (-13.0 F)
2000
-21.1 C (-6.0 F)
2001
-17.2 C (1.0 F)
2002
-20.0 C (-4.0 F)
2003
-27.2 C (-17.0 F)
2004
-28.3 C (-18.9 F)
2005
-27.2 C (-17.0 F)
2006
-16.7 C (1.9 F)
2007
-21.1 C (-6.0 F)
2008
-20.0 C (-4.0 F)
2009
-25.0 C (-13.0 F)
2010
-22.8 C (-9.0 F)
Wettest day (Rx1day)
The wettest day of the year at Mercer, 1950 to 2010. The record is 113.5 mm (4.5 in) in 2004, marked on the chart; the median year is 53.3 mm (2.1 in).
Wettest day (Rx1day) at Mercer by year
Year
Wettest day (Rx1day)
1950
41.1 mm (1.6 in)
1952
40.6 mm (1.6 in)
1953
43.9 mm (1.7 in)
1954
59.4 mm (2.3 in)
1955
101.6 mm (4.0 in)
1956
82.6 mm (3.3 in)
1957
61.0 mm (2.4 in)
1958
61.5 mm (2.4 in)
1959
50.8 mm (2.0 in)
1960
43.2 mm (1.7 in)
1961
43.2 mm (1.7 in)
1962
76.2 mm (3.0 in)
1963
55.9 mm (2.2 in)
1964
43.2 mm (1.7 in)
1965
63.8 mm (2.5 in)
1966
34.8 mm (1.4 in)
1967
34.3 mm (1.4 in)
1968
64.5 mm (2.5 in)
1969
73.9 mm (2.9 in)
1970
44.5 mm (1.8 in)
1971
59.9 mm (2.4 in)
1972
59.9 mm (2.4 in)
1973
48.8 mm (1.9 in)
1974
60.5 mm (2.4 in)
1975
56.9 mm (2.2 in)
1976
39.4 mm (1.6 in)
1977
84.8 mm (3.3 in)
1978
40.4 mm (1.6 in)
1979
39.6 mm (1.6 in)
1980
54.6 mm (2.1 in)
1981
51.6 mm (2.0 in)
1982
41.1 mm (1.6 in)
1983
58.4 mm (2.3 in)
1984
45.0 mm (1.8 in)
1985
70.4 mm (2.8 in)
1986
83.6 mm (3.3 in)
1987
65.0 mm (2.6 in)
1988
50.3 mm (2.0 in)
1989
46.2 mm (1.8 in)
1990
80.0 mm (3.1 in)
1991
45.2 mm (1.8 in)
1992
70.9 mm (2.8 in)
1993
48.5 mm (1.9 in)
1994
72.1 mm (2.8 in)
1995
45.7 mm (1.8 in)
1996
54.4 mm (2.1 in)
1997
36.3 mm (1.4 in)
1998
51.6 mm (2.0 in)
1999
86.9 mm (3.4 in)
2000
53.8 mm (2.1 in)
2001
49.3 mm (1.9 in)
2002
101.6 mm (4.0 in)
2003
58.9 mm (2.3 in)
2004
113.5 mm (4.5 in)
2005
34.8 mm (1.4 in)
2006
64.0 mm (2.5 in)
2007
47.8 mm (1.9 in)
2008
40.6 mm (1.6 in)
2009
52.8 mm (2.1 in)
2010
10.4 mm (0.4 in)
Wettest five days (Rx5day)
The wettest five days of the year at Mercer, 1950 to 2010. The record is 147.4 mm (5.8 in) in 1955, marked on the chart; the median year is 82.9 mm (3.3 in).
Wettest five days (Rx5day) at Mercer by year
Year
Wettest five days (Rx5day)
1950
67.0 mm (2.6 in)
1952
94.9 mm (3.7 in)
1953
58.6 mm (2.3 in)
1954
83.5 mm (3.3 in)
1955
147.4 mm (5.8 in)
1956
97.8 mm (3.9 in)
1957
95.3 mm (3.8 in)
1958
116.6 mm (4.6 in)
1959
76.2 mm (3.0 in)
1960
104.3 mm (4.1 in)
1961
82.0 mm (3.2 in)
1962
76.2 mm (3.0 in)
1963
78.8 mm (3.1 in)
1964
64.0 mm (2.5 in)
1965
78.6 mm (3.1 in)
1966
84.2 mm (3.3 in)
1967
58.0 mm (2.3 in)
1968
66.0 mm (2.6 in)
1969
82.1 mm (3.2 in)
1970
82.9 mm (3.3 in)
1971
84.1 mm (3.3 in)
1972
89.4 mm (3.5 in)
1973
82.7 mm (3.3 in)
1974
84.9 mm (3.3 in)
1975
79.0 mm (3.1 in)
1976
71.9 mm (2.8 in)
1977
118.1 mm (4.6 in)
1978
60.4 mm (2.4 in)
1979
69.1 mm (2.7 in)
1980
67.1 mm (2.6 in)
1981
90.8 mm (3.6 in)
1982
67.0 mm (2.6 in)
1983
81.2 mm (3.2 in)
1984
88.9 mm (3.5 in)
1985
124.3 mm (4.9 in)
1986
95.5 mm (3.8 in)
1987
99.1 mm (3.9 in)
1988
95.8 mm (3.8 in)
1989
73.4 mm (2.9 in)
1990
98.0 mm (3.9 in)
1991
79.9 mm (3.1 in)
1992
120.7 mm (4.8 in)
1993
86.4 mm (3.4 in)
1994
125.7 mm (4.9 in)
1995
88.8 mm (3.5 in)
1996
92.9 mm (3.7 in)
1997
72.5 mm (2.9 in)
1998
69.9 mm (2.8 in)
1999
99.3 mm (3.9 in)
2000
75.9 mm (3.0 in)
2001
82.8 mm (3.3 in)
2002
118.3 mm (4.7 in)
2003
116.8 mm (4.6 in)
2004
120.4 mm (4.7 in)
2005
81.7 mm (3.2 in)
2006
95.0 mm (3.7 in)
2007
81.0 mm (3.2 in)
2008
63.3 mm (2.5 in)
2009
82.8 mm (3.3 in)
2010
17.8 mm (0.7 in)
Longest dry spell (CDD)
The longest dry spell of the year at Mercer, 1950 to 2010. The record is 48 days in 2010, marked on the chart; the median year is 14 days.
Longest dry spell (CDD) at Mercer by year
Year
Longest dry spell (CDD)
1950
14 days
1952
19 days
1953
22 days
1954
15 days
1955
22 days
1956
13 days
1957
13 days
1958
12 days
1959
11 days
1960
16 days
1961
14 days
1962
13 days
1963
27 days
1964
27 days
1965
10 days
1966
17 days
1967
14 days
1968
12 days
1969
18 days
1970
12 days
1971
13 days
1972
14 days
1973
14 days
1974
9 days
1975
14 days
1976
14 days
1977
17 days
1978
18 days
1979
15 days
1980
16 days
1981
12 days
1982
14 days
1983
22 days
1984
12 days
1985
12 days
1986
11 days
1987
11 days
1988
14 days
1989
14 days
1990
13 days
1991
14 days
1992
12 days
1993
14 days
1994
14 days
1995
23 days
1996
13 days
1997
12 days
1998
19 days
1999
13 days
2000
17 days
2001
16 days
2002
11 days
2003
12 days
2004
14 days
2005
16 days
2006
13 days
2007
18 days
2008
13 days
2009
37 days
2010
48 days
Each chart shows one value per year; the dot marks the record year. TXx is the hottest daily maximum, TNn the coldest daily minimum, Rx1day and Rx5day the largest one-day and five-day rain totals, and CDD the longest run of days with less than 1 mm of rain. A year with missing days can understate an extreme.
Frost Dates and Growing Season
44 years with a frost
Across 44 years with a frost, the median last spring frost at Mercer falls on 17 May and the median first autumn frost on 29 September, which leaves a median of 136 days between them.
Fitted over all years, the growing season changes by +2.4 days per decade at this station.
Frost dates and growing season at Mercer
Measure
Median, all years
Earliest period
Recent period (1973 to 2007)
Recent against earliest
Fitted trend
Last spring frost
17 May
n/a
16 May
n/a
-0.7 days per decade
First autumn frost
29 September
n/a
29 September
n/a
+1.7 days per decade
Growing days
136 days
n/a
139 days
n/a
+2.4 days per decade
A frost day is a day with a daily minimum at or below 0 C (32 F). The last spring frost and the first autumn frost are the last and first such days of the cold season, and growing days are the days between them. A negative trend for the last spring frost means it comes earlier.
Rainfall Return Levels
51 years, 1953 to 2007
A day with at least 54.2 mm (2.1 in) of rain is expected about once in 2 years. A day with at least 119.4 mm (4.7 in) of rain is expected about once in 100 years.
Rainfall return levels at Mercer: the daily rain expected about once in a given number of years
Expected about once in
A day with at least
Note
2 years
54.2 mm (2.1 in)
5 years
69.3 mm (2.7 in)
10 years
80.3 mm (3.2 in)
25 years
95.1 mm (3.7 in)
50 years
106.9 mm (4.2 in)
100 years
119.4 mm (4.7 in)
Longer than the 51 years of record
The levels come from a generalised extreme value (GEV) distribution fitted by L-moments to the wettest-day total of each year, 51 years of values from 1953 to 2007.
A return level is an estimate. It is least reliable for the long periods, 50 and 100 years, and for any period longer than the record behind the fit, where the fit has to reach past the largest day actually observed. It is not a forecast.
The largest wettest-day totals in the fit: 113.5 mm (4.5 in) in 2004; 101.6 mm (4.0 in) in 2002; 86.9 mm (3.4 in) in 1999.
Station Changes
No change in the annual mean temperature of this station was found against its neighbours.
Download the Data
Data for Mercer standing records by year: CSV or JSON. Field meanings are on the data page.
Data for Mercer threshold days by year: CSV or JSON. Field meanings are on the data page.
Source: NOAA National Centers for Environmental Information, Global Historical Climatology Network Daily (GHCN-Daily). Records are computed by World Extreme Weather Monitor and are not official NOAA products. (US Government open data (NOAA NCEI)) Data as of 2026-10-15 (15 October 2026). Records are computed by this site and are not official.