Record envelope, standing records and threshold days for Conowingo Dam (USC00182060), Maryland, United States, with 91 years of record.
Key Facts for Conowingo Dam
Conowingo Dam (USC00182060) is a weather station in Maryland, United States at 39.66 latitude and -76.17 longitude, 12 m (40 ft) above sea level.
The station reports from 1936 to 2026, 91 years of record.
1,464 records set at Conowingo Dam still stand.
Records are tracked for tmax, tmin, prcp, snow, snwd: an element needs 30 years of data to be eligible.
Conowingo Dam tied a daily record high minimum temperature of 22.8 C (73.0 F) on 7 August 2026.
About the Station
Location: Maryland, United States, 39.66 latitude, -76.17 longitude.
Elevation: 12 m (40 ft).
Period of record: 1936 to 2026, 91 years.
Eligible elements: tmax, tmin, prcp, snow, snwd.
Daily Record Envelope and 2026
4 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 Conowingo Dam. The lines show the 2026 daily maximum and minimum. 4 days in 2026 matched or passed a record. Temperatures are in degrees Celsius.
Daily record high and record low at Conowingo Dam, with 2026 drawn through them
Month
Highest record high
Lowest record low
2026 highest maximum
2026 lowest minimum
Jan
23.3 C (73.9 F)
-22.8 C (-9.0 F)
13.9 C (57.0 F)
-17.2 C (1.0 F)
Feb
25.0 C (77.0 F)
-23.3 C (-9.9 F)
15.0 C (59.0 F)
-15.6 C (3.9 F)
Mar
32.2 C (90.0 F)
-15.6 C (3.9 F)
27.2 C (81.0 F)
-4.4 C (24.1 F)
Apr
35.0 C (95.0 F)
-7.2 C (19.0 F)
32.2 C (90.0 F)
0.6 C (33.1 F)
May
37.2 C (99.0 F)
-1.7 C (28.9 F)
35.6 C (96.1 F)
5.6 C (42.1 F)
Jun
42.8 C (109.0 F)
5.0 C (41.0 F)
35.0 C (95.0 F)
8.9 C (48.0 F)
Jul
41.1 C (106.0 F)
6.7 C (44.1 F)
37.8 C (100.0 F)
15.6 C (60.1 F)
Aug
40.0 C (104.0 F)
4.4 C (39.9 F)
32.8 C (91.0 F)
14.4 C (57.9 F)
Sep
37.2 C (99.0 F)
0.0 C (32.0 F)
22.2 C (72.0 F)
15.6 C (60.1 F)
Oct
34.4 C (93.9 F)
-6.7 C (19.9 F)
n/a
n/a
Nov
28.3 C (82.9 F)
-12.8 C (9.0 F)
n/a
n/a
Dec
25.0 C (77.0 F)
-18.9 C (-2.0 F)
n/a
n/a
Which Years Hold Standing Records
1,464 standing records
Year with most
1,464 records at Conowingo Dam still stand. 1991 holds the most, with 37.
Standing records at Conowingo Dam by the year they were set
Year set
Standing records
1936
28
1937
21
1938
19
1939
16
1940
28
1941
1
1942
5
1943
9
1944
1
1945
11
1946
6
1947
10
1948
12
1949
13
1950
22
1951
13
1952
16
1953
22
1954
18
1955
14
1956
18
1957
13
1958
15
1959
17
1960
25
1961
19
1962
18
1963
24
1964
28
1965
19
1966
13
1967
21
1968
11
1969
10
1970
19
1971
9
1972
18
1973
13
1974
23
1975
11
1976
27
1977
17
1978
13
1979
28
1980
13
1981
16
1982
18
1983
17
1984
22
1985
12
1986
10
1987
13
1988
20
1989
24
1990
19
1991
37
1992
1
1993
17
1994
19
1995
24
1996
15
1997
18
1998
30
1999
11
2000
18
2001
17
2002
35
2003
5
2004
3
2005
13
2006
14
2007
28
2008
14
2009
8
2010
14
2011
15
2012
8
2013
8
2014
21
2015
32
2016
9
2017
15
2018
23
2019
10
2020
14
2021
13
2022
9
2023
12
2024
16
2025
10
2026
10
All-Time Record Progression
10 new records
10 all-time records were set at Conowingo Dam between 14 February 1979 and 24 January 2016. Each dot is a new record.
When Conowingo Dam set new all-time records
Date
Kind
Detail
1979-02-14
Record low minimum temperature
Record low minimum temperature -23.3 C (-9.9 F)
1986-07-06
Record high maximum temperature
Record high maximum temperature 40.0 C (104.0 F)
1987-09-08
Record daily precipitation
Record daily precipitation 144.0 mm (5.7 in)
1988-06-21
Record high maximum temperature
Record high maximum temperature 42.8 C (109.0 F)
1993-07-08
Record high minimum temperature
Record high minimum temperature 26.1 C (79.0 F)
1993-07-09
Record high minimum temperature
Record high minimum temperature 26.7 C (80.1 F)
1994-01-19
Record low maximum temperature
Record low maximum temperature -13.9 C (7.0 F)
1994-06-25
Record high minimum temperature
Record high minimum temperature 27.2 C (81.0 F)
1999-09-16
Record daily precipitation
Record daily precipitation 209.6 mm (8.3 in)
2016-01-24
Record daily snowfall
Record daily snowfall 50.8 cm (20.0 in)
Wettest Day of Each Month
Sep: 209.6 mm (8.3 in)
The wettest day on record for each calendar month at Conowingo Dam. The most was 209.6 mm (8.3 in) on 16 September 1999.
Record daily precipitation for each month at Conowingo Dam
Month
Record daily precipitation (mm)
Date
Jan
97.8 mm (3.9 in)
10 January 2024
Feb
54.6 mm (2.1 in)
23 February 2003
Mar
93.0 mm (3.7 in)
20 March 1958
Apr
66.3 mm (2.6 in)
15 April 1983
May
144.8 mm (5.7 in)
1 May 2014
Jun
109.7 mm (4.3 in)
22 June 1972
Jul
141.0 mm (5.6 in)
8 July 1952
Aug
127.8 mm (5.0 in)
27 August 1971
Sep
209.6 mm (8.3 in)
16 September 1999
Oct
149.9 mm (5.9 in)
1 October 2010
Nov
84.6 mm (3.3 in)
25 November 1950
Dec
83.3 mm (3.3 in)
5 December 1993
Period of Record Coverage
1936 to 2026
Complete yearUnder 90 percent of days
91 years of record at Conowingo Dam, 1936 to 2026. 26 years have data for under 90 percent of days and are left out of rankings: 1941, 1942, 1943, 1944, 1945, 1946, 1947, 1948 and others.
Cooler than the station meanWarmer than the station mean
One stripe for each of 56 complete years at Conowingo Dam, 1936 to 2025. Blue stripes are years cooler than the station's own mean of 12.2 C (54.0 F); red stripes are warmer. The coolest year was 1940, at 10.4 C (50.7 F), and the warmest was 1998, at 14.9 C (58.8 F). The strongest colour marks a difference of 2.7 C (4.9 F).
Annual mean temperature at Conowingo Dam as warming stripes, 1936 to 2025
Year
Annual mean temperature
Difference from the station mean
1936
11.6 C
-0.67 C
1937
11.6 C
-0.62 C
1938
12.0 C
-0.19 C
1939
11.9 C
-0.33 C
1940
10.4 C
-1.82 C
1949
12.6 C
+0.39 C
1950
11.4 C
-0.87 C
1951
11.9 C
-0.36 C
1952
12.3 C
+0.04 C
1953
12.7 C
+0.46 C
1954
12.2 C
+0.00 C
1955
12.2 C
-0.03 C
1956
11.8 C
-0.47 C
1957
12.3 C
+0.04 C
1958
11.1 C
-1.15 C
1959
12.6 C
+0.37 C
1960
11.5 C
-0.71 C
1961
11.7 C
-0.58 C
1962
11.2 C
-0.99 C
1963
11.2 C
-1.08 C
1965
11.6 C
-0.62 C
1966
11.5 C
-0.78 C
1967
11.0 C
-1.22 C
1968
11.9 C
-0.38 C
1969
11.8 C
-0.48 C
1970
11.8 C
-0.43 C
1971
12.1 C
-0.15 C
1974
11.7 C
-0.50 C
1975
12.2 C
+0.01 C
1981
11.0 C
-1.25 C
1983
12.3 C
+0.09 C
1984
12.0 C
-0.22 C
1986
12.1 C
-0.16 C
1987
11.8 C
-0.46 C
1988
11.3 C
-0.96 C
1989
11.3 C
-0.89 C
1995
13.2 C
+0.95 C
1996
12.6 C
+0.34 C
1997
13.3 C
+1.03 C
1998
14.9 C
+2.68 C
2001
13.2 C
+0.94 C
2002
13.6 C
+1.32 C
2007
13.3 C
+1.02 C
2011
13.2 C
+0.94 C
2014
10.5 C
-1.70 C
2015
11.6 C
-0.66 C
2016
12.3 C
+0.10 C
2017
12.2 C
+0.01 C
2018
12.4 C
+0.15 C
2019
13.4 C
+1.17 C
2020
14.0 C
+1.77 C
2021
13.9 C
+1.65 C
2022
13.2 C
+0.97 C
2023
13.9 C
+1.69 C
2024
14.1 C
+1.85 C
2025
12.8 C
+0.60 C
The annual mean temperature here has risen by 0.2 C (0.1 to 0.3) per decade over 1936 to 2025. In Fahrenheit: 0.3 F (0.2 to 0.5) per decade. The slope is a straight line fitted to 56 complete years; the brackets give its 95 percent interval.
Fitted temperature trends per decade at Conowingo Dam
Measure
Per decade (C)
Per decade (F)
Period
Complete years
Reading
Annual mean temperature
0.2 C (0.1 to 0.3) per decade
0.3 F (0.2 to 0.5) per decade
1936 to 2025
56
Rise
Mean daily maximum
0.2 C (0.1 to 0.3) per decade
0.3 F (0.1 to 0.5) per decade
1936 to 2025
56
Rise
Mean daily minimum
0.2 C (0.1 to 0.3) per decade
0.4 F (0.2 to 0.6) per decade
1936 to 2025
56
Rise
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
1936 to 2026
Yearly extremes at Conowingo Dam: the record and the median year
Measure
Record
Year of the record
Median year
Years with a value
Hottest day (TXx)
42.8 C (109.0 F)
1988
36.7 C (98.1 F)
91
Coldest night (TNn)
-23.3 C (-9.9 F)
1979
-15.6 C (3.9 F)
91
Wettest day (Rx1day)
209.6 mm (8.3 in)
1999
71.6 mm (2.8 in)
91
Wettest five days (Rx5day)
248.4 mm (9.8 in)
2006
99.3 mm (3.9 in)
91
Longest dry spell (CDD)
38 days
2024
17 days
91
Hottest day (TXx)
The hottest day of the year at Conowingo Dam, 1936 to 2026. The record is 42.8 C (109.0 F) in 1988, marked on the chart; the median year is 36.7 C (98.1 F).
Hottest day (TXx) at Conowingo Dam by year
Year
Hottest day (TXx)
1936
39.4 C (102.9 F)
1937
34.4 C (93.9 F)
1938
35.0 C (95.0 F)
1939
35.6 C (96.1 F)
1940
37.2 C (99.0 F)
1941
22.8 C (73.0 F)
1942
25.6 C (78.1 F)
1943
27.8 C (82.0 F)
1944
20.0 C (68.0 F)
1945
31.1 C (88.0 F)
1946
23.9 C (75.0 F)
1947
33.9 C (93.0 F)
1948
36.1 C (97.0 F)
1949
36.7 C (98.1 F)
1950
34.4 C (93.9 F)
1951
33.9 C (93.0 F)
1952
37.8 C (100.0 F)
1953
37.8 C (100.0 F)
1954
38.9 C (102.0 F)
1955
37.8 C (100.0 F)
1956
36.1 C (97.0 F)
1957
37.8 C (100.0 F)
1958
33.9 C (93.0 F)
1959
36.7 C (98.1 F)
1960
33.3 C (91.9 F)
1961
34.4 C (93.9 F)
1962
35.0 C (95.0 F)
1963
36.7 C (98.1 F)
1964
36.7 C (98.1 F)
1965
35.0 C (95.0 F)
1966
39.4 C (102.9 F)
1967
35.0 C (95.0 F)
1968
36.1 C (97.0 F)
1969
36.7 C (98.1 F)
1970
35.0 C (95.0 F)
1971
35.0 C (95.0 F)
1972
35.0 C (95.0 F)
1973
37.2 C (99.0 F)
1974
35.6 C (96.1 F)
1975
36.7 C (98.1 F)
1976
33.9 C (93.0 F)
1977
37.2 C (99.0 F)
1978
37.2 C (99.0 F)
1979
35.0 C (95.0 F)
1980
36.7 C (98.1 F)
1981
35.6 C (96.1 F)
1982
35.6 C (96.1 F)
1983
37.8 C (100.0 F)
1984
36.1 C (97.0 F)
1985
37.2 C (99.0 F)
1986
40.0 C (104.0 F)
1987
37.2 C (99.0 F)
1988
42.8 C (109.0 F)
1989
36.7 C (98.1 F)
1990
40.6 C (105.1 F)
1991
40.6 C (105.1 F)
1992
18.9 C (66.0 F)
1993
40.0 C (104.0 F)
1994
41.1 C (106.0 F)
1995
40.6 C (105.1 F)
1996
37.2 C (99.0 F)
1997
39.4 C (102.9 F)
1998
37.8 C (100.0 F)
1999
38.3 C (100.9 F)
2000
37.8 C (100.0 F)
2001
38.3 C (100.9 F)
2002
40.0 C (104.0 F)
2003
31.7 C (89.1 F)
2004
34.4 C (93.9 F)
2005
37.8 C (100.0 F)
2006
37.8 C (100.0 F)
2007
37.8 C (100.0 F)
2008
40.0 C (104.0 F)
2009
35.6 C (96.1 F)
2010
40.0 C (104.0 F)
2011
40.0 C (104.0 F)
2012
36.7 C (98.1 F)
2013
34.4 C (93.9 F)
2014
33.3 C (91.9 F)
2015
32.2 C (90.0 F)
2016
35.0 C (95.0 F)
2017
33.3 C (91.9 F)
2018
35.6 C (96.1 F)
2019
35.0 C (95.0 F)
2020
36.1 C (97.0 F)
2021
35.0 C (95.0 F)
2022
35.6 C (96.1 F)
2023
35.0 C (95.0 F)
2024
37.2 C (99.0 F)
2025
36.7 C (98.1 F)
2026
37.8 C (100.0 F)
Coldest night (TNn)
The coldest night of the year at Conowingo Dam, 1936 to 2026. The record is -23.3 C (-9.9 F) in 1979, marked on the chart; the median year is -15.6 C (3.9 F).
Coldest night (TNn) at Conowingo Dam by year
Year
Coldest night (TNn)
1936
-21.7 C (-7.1 F)
1937
-11.7 C (10.9 F)
1938
-12.8 C (9.0 F)
1939
-15.0 C (5.0 F)
1940
-17.8 C (0.0 F)
1941
-11.7 C (10.9 F)
1942
-20.0 C (-4.0 F)
1943
-16.7 C (1.9 F)
1944
-16.1 C (3.0 F)
1945
-15.6 C (3.9 F)
1946
-14.4 C (6.1 F)
1947
-15.6 C (3.9 F)
1948
-20.0 C (-4.0 F)
1949
-11.7 C (10.9 F)
1950
-15.6 C (3.9 F)
1951
-15.6 C (3.9 F)
1952
-12.2 C (10.0 F)
1953
-11.1 C (12.0 F)
1954
-17.8 C (0.0 F)
1955
-15.6 C (3.9 F)
1956
-13.3 C (8.1 F)
1957
-20.6 C (-5.1 F)
1958
-15.0 C (5.0 F)
1959
-16.1 C (3.0 F)
1960
-17.8 C (0.0 F)
1961
-22.8 C (-9.0 F)
1962
-15.6 C (3.9 F)
1963
-20.0 C (-4.0 F)
1964
-18.3 C (-0.9 F)
1965
-17.8 C (0.0 F)
1966
-18.3 C (-0.9 F)
1967
-18.3 C (-0.9 F)
1968
-17.8 C (0.0 F)
1969
-12.8 C (9.0 F)
1970
-18.9 C (-2.0 F)
1971
-16.7 C (1.9 F)
1972
-12.8 C (9.0 F)
1973
-13.3 C (8.1 F)
1974
-15.0 C (5.0 F)
1975
-12.2 C (10.0 F)
1976
-15.0 C (5.0 F)
1977
-21.7 C (-7.1 F)
1978
-16.7 C (1.9 F)
1979
-23.3 C (-9.9 F)
1980
-12.8 C (9.0 F)
1981
-21.1 C (-6.0 F)
1982
-22.2 C (-8.0 F)
1983
-16.7 C (1.9 F)
1984
-22.8 C (-9.0 F)
1985
-21.7 C (-7.1 F)
1986
-13.3 C (8.1 F)
1987
-21.1 C (-6.0 F)
1988
-20.6 C (-5.1 F)
1989
-18.3 C (-0.9 F)
1990
-13.3 C (8.1 F)
1991
-13.9 C (7.0 F)
1992
-13.9 C (7.0 F)
1993
-10.0 C (14.0 F)
1994
-20.0 C (-4.0 F)
1995
-16.1 C (3.0 F)
1996
-18.9 C (-2.0 F)
1997
-15.0 C (5.0 F)
1998
-8.9 C (16.0 F)
1999
-12.2 C (10.0 F)
2000
-12.8 C (9.0 F)
2001
-11.1 C (12.0 F)
2002
-12.2 C (10.0 F)
2003
-20.6 C (-5.1 F)
2004
-6.7 C (19.9 F)
2005
-9.4 C (15.1 F)
2006
-10.0 C (14.0 F)
2007
-15.0 C (5.0 F)
2008
-13.3 C (8.1 F)
2009
-17.8 C (0.0 F)
2010
-10.6 C (12.9 F)
2011
-15.0 C (5.0 F)
2012
-11.7 C (10.9 F)
2013
-12.8 C (9.0 F)
2014
-17.2 C (1.0 F)
2015
-17.8 C (0.0 F)
2016
-13.9 C (7.0 F)
2017
-12.8 C (9.0 F)
2018
-16.7 C (1.9 F)
2019
-18.9 C (-2.0 F)
2020
-7.8 C (18.0 F)
2021
-7.2 C (19.0 F)
2022
-15.6 C (3.9 F)
2023
-11.7 C (10.9 F)
2024
-15.0 C (5.0 F)
2025
-16.7 C (1.9 F)
2026
-17.2 C (1.0 F)
Wettest day (Rx1day)
The wettest day of the year at Conowingo Dam, 1936 to 2026. The record is 209.6 mm (8.3 in) in 1999, marked on the chart; the median year is 71.6 mm (2.8 in).
Wettest day (Rx1day) at Conowingo Dam by year
Year
Wettest day (Rx1day)
1936
72.4 mm (2.9 in)
1937
61.2 mm (2.4 in)
1938
85.1 mm (3.4 in)
1939
75.2 mm (3.0 in)
1940
65.0 mm (2.6 in)
1941
50.3 mm (2.0 in)
1942
34.5 mm (1.4 in)
1943
52.1 mm (2.1 in)
1944
53.1 mm (2.1 in)
1945
45.5 mm (1.8 in)
1946
35.8 mm (1.4 in)
1947
69.3 mm (2.7 in)
1948
60.5 mm (2.4 in)
1949
83.1 mm (3.3 in)
1950
84.6 mm (3.3 in)
1951
97.8 mm (3.9 in)
1952
141.0 mm (5.6 in)
1953
63.0 mm (2.5 in)
1954
34.8 mm (1.4 in)
1955
69.9 mm (2.8 in)
1956
61.5 mm (2.4 in)
1957
67.3 mm (2.6 in)
1958
93.0 mm (3.7 in)
1959
70.1 mm (2.8 in)
1960
92.2 mm (3.6 in)
1961
39.6 mm (1.6 in)
1962
44.5 mm (1.8 in)
1963
58.4 mm (2.3 in)
1964
44.7 mm (1.8 in)
1965
47.2 mm (1.9 in)
1966
69.6 mm (2.7 in)
1967
75.9 mm (3.0 in)
1968
81.5 mm (3.2 in)
1969
60.7 mm (2.4 in)
1970
71.1 mm (2.8 in)
1971
127.8 mm (5.0 in)
1972
109.7 mm (4.3 in)
1973
71.6 mm (2.8 in)
1974
58.2 mm (2.3 in)
1975
93.0 mm (3.7 in)
1976
56.6 mm (2.2 in)
1977
71.4 mm (2.8 in)
1978
86.4 mm (3.4 in)
1979
100.6 mm (4.0 in)
1980
60.2 mm (2.4 in)
1981
38.9 mm (1.5 in)
1982
55.9 mm (2.2 in)
1983
78.0 mm (3.1 in)
1984
81.0 mm (3.2 in)
1985
134.4 mm (5.3 in)
1986
51.1 mm (2.0 in)
1987
144.0 mm (5.7 in)
1988
50.3 mm (2.0 in)
1989
77.0 mm (3.0 in)
1990
53.6 mm (2.1 in)
1991
40.1 mm (1.6 in)
1992
15.5 mm (0.6 in)
1993
83.3 mm (3.3 in)
1994
43.9 mm (1.7 in)
1995
58.2 mm (2.3 in)
1996
80.3 mm (3.2 in)
1997
45.7 mm (1.8 in)
1998
82.6 mm (3.3 in)
1999
209.6 mm (8.3 in)
2000
85.1 mm (3.4 in)
2001
89.9 mm (3.5 in)
2002
53.3 mm (2.1 in)
2003
91.7 mm (3.6 in)
2004
89.2 mm (3.5 in)
2005
116.1 mm (4.6 in)
2006
92.7 mm (3.6 in)
2007
116.8 mm (4.6 in)
2008
82.6 mm (3.3 in)
2009
102.1 mm (4.0 in)
2010
149.9 mm (5.9 in)
2011
121.9 mm (4.8 in)
2012
119.4 mm (4.7 in)
2013
86.4 mm (3.4 in)
2014
144.8 mm (5.7 in)
2015
88.9 mm (3.5 in)
2016
50.8 mm (2.0 in)
2017
88.4 mm (3.5 in)
2018
60.5 mm (2.4 in)
2019
78.7 mm (3.1 in)
2020
113.5 mm (4.5 in)
2021
119.4 mm (4.7 in)
2022
63.5 mm (2.5 in)
2023
55.4 mm (2.2 in)
2024
97.8 mm (3.9 in)
2025
64.5 mm (2.5 in)
2026
43.2 mm (1.7 in)
Wettest five days (Rx5day)
The wettest five days of the year at Conowingo Dam, 1936 to 2026. The record is 248.4 mm (9.8 in) in 2006, marked on the chart; the median year is 99.3 mm (3.9 in).
Wettest five days (Rx5day) at Conowingo Dam by year
Year
Wettest five days (Rx5day)
1936
71.2 mm (2.8 in)
1937
120.1 mm (4.7 in)
1938
165.6 mm (6.5 in)
1939
114.1 mm (4.5 in)
1940
86.5 mm (3.4 in)
1941
60.5 mm (2.4 in)
1942
69.4 mm (2.7 in)
1943
66.3 mm (2.6 in)
1944
80.3 mm (3.2 in)
1945
51.6 mm (2.0 in)
1946
41.9 mm (1.6 in)
1947
83.0 mm (3.3 in)
1948
65.6 mm (2.6 in)
1949
94.5 mm (3.7 in)
1950
87.7 mm (3.5 in)
1951
115.1 mm (4.5 in)
1952
198.2 mm (7.8 in)
1953
88.4 mm (3.5 in)
1954
57.5 mm (2.3 in)
1955
175.3 mm (6.9 in)
1956
71.9 mm (2.8 in)
1957
111.2 mm (4.4 in)
1958
144.8 mm (5.7 in)
1959
118.3 mm (4.7 in)
1960
175.0 mm (6.9 in)
1961
84.5 mm (3.3 in)
1962
77.5 mm (3.1 in)
1963
77.0 mm (3.0 in)
1964
73.2 mm (2.9 in)
1965
51.1 mm (2.0 in)
1966
72.2 mm (2.8 in)
1967
122.4 mm (4.8 in)
1968
93.7 mm (3.7 in)
1969
91.9 mm (3.6 in)
1970
101.8 mm (4.0 in)
1971
160.3 mm (6.3 in)
1972
158.7 mm (6.2 in)
1973
78.7 mm (3.1 in)
1974
80.3 mm (3.2 in)
1975
205.6 mm (8.1 in)
1976
105.6 mm (4.2 in)
1977
83.8 mm (3.3 in)
1978
99.3 mm (3.9 in)
1979
122.4 mm (4.8 in)
1980
105.9 mm (4.2 in)
1981
57.7 mm (2.3 in)
1982
84.1 mm (3.3 in)
1983
124.8 mm (4.9 in)
1984
84.8 mm (3.3 in)
1985
165.1 mm (6.5 in)
1986
85.8 mm (3.4 in)
1987
176.0 mm (6.9 in)
1988
98.0 mm (3.9 in)
1989
117.9 mm (4.6 in)
1990
137.5 mm (5.4 in)
1991
73.7 mm (2.9 in)
1992
23.1 mm (0.9 in)
1993
104.6 mm (4.1 in)
1994
75.6 mm (3.0 in)
1995
80.0 mm (3.1 in)
1996
96.4 mm (3.8 in)
1997
65.8 mm (2.6 in)
1998
103.9 mm (4.1 in)
1999
212.2 mm (8.4 in)
2000
101.1 mm (4.0 in)
2001
91.2 mm (3.6 in)
2002
74.9 mm (2.9 in)
2003
143.3 mm (5.6 in)
2004
101.4 mm (4.0 in)
2005
191.0 mm (7.5 in)
2006
248.4 mm (9.8 in)
2007
137.2 mm (5.4 in)
2008
105.5 mm (4.2 in)
2009
138.4 mm (5.4 in)
2010
234.3 mm (9.2 in)
2011
173.2 mm (6.8 in)
2012
156.3 mm (6.2 in)
2013
128.3 mm (5.1 in)
2014
223.6 mm (8.8 in)
2015
94.8 mm (3.7 in)
2016
76.2 mm (3.0 in)
2017
104.9 mm (4.1 in)
2018
146.6 mm (5.8 in)
2019
100.6 mm (4.0 in)
2020
141.0 mm (5.6 in)
2021
150.1 mm (5.9 in)
2022
86.4 mm (3.4 in)
2023
97.3 mm (3.8 in)
2024
130.9 mm (5.2 in)
2025
82.5 mm (3.2 in)
2026
84.4 mm (3.3 in)
Longest dry spell (CDD)
The longest dry spell of the year at Conowingo Dam, 1936 to 2026. The record is 38 days in 2024, marked on the chart; the median year is 17 days.
Longest dry spell (CDD) at Conowingo Dam by year
Year
Longest dry spell (CDD)
1936
20 days
1937
14 days
1938
16 days
1939
25 days
1940
18 days
1941
15 days
1942
13 days
1943
19 days
1944
13 days
1945
20 days
1946
14 days
1947
16 days
1948
19 days
1949
19 days
1950
15 days
1951
28 days
1952
16 days
1953
18 days
1954
18 days
1955
23 days
1956
15 days
1957
14 days
1958
23 days
1959
17 days
1960
12 days
1961
16 days
1962
15 days
1963
28 days
1964
29 days
1965
16 days
1966
20 days
1967
24 days
1968
26 days
1969
17 days
1970
15 days
1971
20 days
1972
13 days
1973
26 days
1974
16 days
1975
12 days
1976
23 days
1977
30 days
1978
16 days
1979
12 days
1980
11 days
1981
14 days
1982
15 days
1983
20 days
1984
12 days
1985
19 days
1986
22 days
1987
21 days
1988
22 days
1989
17 days
1990
14 days
1991
23 days
1992
8 days
1993
9 days
1994
22 days
1995
29 days
1996
12 days
1997
16 days
1998
27 days
1999
19 days
2000
21 days
2001
18 days
2002
16 days
2003
10 days
2004
8 days
2005
20 days
2006
32 days
2007
18 days
2008
15 days
2009
13 days
2010
19 days
2011
14 days
2012
14 days
2013
20 days
2014
17 days
2015
21 days
2016
16 days
2017
20 days
2018
11 days
2019
20 days
2020
14 days
2021
22 days
2022
12 days
2023
23 days
2024
38 days
2025
17 days
2026
20 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
56 years with a frost
Across 56 years with a frost, the median last spring frost at Conowingo Dam falls on 13 April and the median first autumn frost on 30 October, which leaves a median of 199 days between them.
Fitted over all years, the growing season changes by +4.6 days per decade at this station.
Frost dates and growing season at Conowingo Dam
Measure
Median, all years
Earliest period
Recent period (1971 to 2025)
Recent against earliest
Fitted trend
Last spring frost
13 April
n/a
11 April
n/a
-1.8 days per decade
First autumn frost
30 October
n/a
4 November
n/a
+2.8 days per decade
Growing days
199 days
n/a
206 days
n/a
+4.6 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
71 years, 1936 to 2025
A day with at least 73.0 mm (2.9 in) of rain is expected about once in 2 years. A day with at least 162.0 mm (6.4 in) of rain is expected about once in 100 years.
Rainfall return levels at Conowingo Dam: the daily rain expected about once in a given number of years
Expected about once in
A day with at least
Note
2 years
73.0 mm (2.9 in)
5 years
97.0 mm (3.8 in)
10 years
112.8 mm (4.4 in)
25 years
132.7 mm (5.2 in)
50 years
147.4 mm (5.8 in)
100 years
162.0 mm (6.4 in)
Longer than the 71 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, 71 years of values from 1936 to 2025.
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: 144.8 mm (5.7 in) in 2014; 144.0 mm (5.7 in) in 1987; 141.0 mm (5.6 in) in 1952.
Station Changes
No change in the annual mean temperature of this station was found against its neighbours.
Climate Twins
2002 to 2025 against 1961 to 1990
Over 2002 to 2025, Conowingo Dam had a mean temperature of 13.0 C (55.3 F) and 1,223.9 mm (48.2 in) of rain a year. The 3 stations whose 1961 to 1990 climate was closest to that are Ny City Cntrl Park (United States, 225 km away), Jackson (United States, 668 km away) and Ny Ave V Brooklyn (United States, 214 km away).
Climate twins of Conowingo Dam: stations whose 1961 to 1990 climate is closest to its 2002 to 2025 climate
Twins are stations, not cities. A twin is one of the three stations at least 100 km away whose earlier climate is closest to this station's recent one, so a close match does not mean the two places look alike in other ways. A station move or a gap in a record can change that station's averages. The list describes past climate; it is not a forecast and does not say what caused any change. How twins are found, and a search for any station.
Download the Data
Data for Conowingo Dam standing records by year: CSV or JSON. Field meanings are on the data page.
Data for Conowingo Dam 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 2026-10-16 (16 October 2026). Records are computed by this site and are not official.