Record envelope, standing records and threshold days for Derry 4 SW (USC00362108), Pennsylvania, United States, with 113 years of record.
Key Facts for Derry 4 SW
Derry 4 SW (USC00362108) is a weather station in Pennsylvania, United States at 40.30 latitude and -79.33 longitude, 323 m (1,060 ft) above sea level.
The station reports from 1896 to 2008, 113 years of record.
1,464 records set at Derry 4 SW still stand.
Records are tracked for tmax, tmin, prcp, snow, snwd: an element needs 30 years of data to be eligible.
Derry 4 SW tied a daily record low maximum temperature of 21.7 C (71.1 F) on 11 August 2008.
About the Station
Location: Pennsylvania, United States, 40.30 latitude, -79.33 longitude.
Elevation: 323 m (1,060 ft).
Period of record: 1896 to 2008, 113 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 Derry 4 SW. 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 Derry 4 SW, with 2026 drawn through them
Month
Highest record high
Lowest record low
2026 highest maximum
2026 lowest minimum
Jan
28.3 C (82.9 F)
-33.9 C (-29.0 F)
n/a
n/a
Feb
26.1 C (79.0 F)
-29.4 C (-20.9 F)
n/a
n/a
Mar
30.0 C (86.0 F)
-23.3 C (-9.9 F)
n/a
n/a
Apr
33.3 C (91.9 F)
-15.6 C (3.9 F)
n/a
n/a
May
37.8 C (100.0 F)
-6.1 C (21.0 F)
n/a
n/a
Jun
36.7 C (98.1 F)
-2.2 C (28.0 F)
n/a
n/a
Jul
40.6 C (105.1 F)
2.2 C (36.0 F)
n/a
n/a
Aug
38.9 C (102.0 F)
0.0 C (32.0 F)
n/a
n/a
Sep
37.8 C (100.0 F)
-4.4 C (24.1 F)
n/a
n/a
Oct
34.4 C (93.9 F)
-10.0 C (14.0 F)
n/a
n/a
Nov
32.2 C (90.0 F)
-18.3 C (-0.9 F)
n/a
n/a
Dec
24.4 C (75.9 F)
-27.2 C (-17.0 F)
n/a
n/a
Which Years Hold Standing Records
1,464 standing records
Year with most
1,464 records at Derry 4 SW still stand. 1900 holds the most, with 47.
Standing records at Derry 4 SW by the year they were set
Year set
Standing records
1896
4
1897
17
1898
24
1899
33
1900
47
1901
21
1902
12
1903
15
1904
17
1905
12
1906
14
1907
12
1908
34
1909
14
1910
11
1911
26
1912
10
1913
13
1914
29
1915
10
1916
13
1917
16
1918
21
1919
19
1920
10
1921
9
1922
12
1923
14
1924
11
1925
17
1926
12
1927
25
1928
16
1929
22
1930
35
1931
12
1932
20
1933
15
1934
12
1935
9
1936
23
1937
8
1938
11
1939
13
1940
14
1941
11
1942
14
1943
20
1944
10
1945
20
1946
6
1947
16
1948
11
1949
18
1950
20
1951
16
1952
15
1953
7
1954
19
1955
9
1956
14
1957
11
1958
12
1959
4
1963
1
1964
15
1965
12
1966
11
1967
12
1968
9
1969
2
1970
11
1971
6
1972
13
1973
4
1974
4
1975
2
1977
18
1979
23
1980
16
1981
23
1982
17
1983
12
1984
21
1985
28
1986
12
1987
4
1988
20
1989
15
1990
10
1991
9
1992
8
1993
7
1994
13
1995
5
1996
9
1997
7
1998
8
1999
4
2000
10
2001
8
2002
7
2003
6
2004
3
2005
3
2006
7
2007
5
2008
7
All-Time Record Progression
4 new records
4 all-time records were set at Derry 4 SW between 19 January 1936 and 23 June 1972. Each dot is a new record.
When Derry 4 SW set new all-time records
Date
Kind
Detail
1936-01-19
Record daily snowfall
Record daily snowfall 40.6 cm (16.0 in)
1942-03-03
Record daily snowfall
Record daily snowfall 61.0 cm (24.0 in)
1954-10-15
Record daily precipitation
Record daily precipitation 127.0 mm (5.0 in)
1972-06-23
Record daily precipitation
Record daily precipitation 148.6 mm (5.9 in)
Wettest Day of Each Month
Jun: 148.6 mm (5.9 in)
The wettest day on record for each calendar month at Derry 4 SW. The most was 148.6 mm (5.9 in) on 23 June 1972.
Record daily precipitation for each month at Derry 4 SW
Month
Record daily precipitation (mm)
Date
Jan
94.7 mm (3.7 in)
22 January 1927
Feb
54.1 mm (2.1 in)
14 February 1971
Mar
81.5 mm (3.2 in)
17 March 1936
Apr
61.2 mm (2.4 in)
2 April 1901
May
69.1 mm (2.7 in)
6 May 1971
Jun
148.6 mm (5.9 in)
23 June 1972
Jul
124.0 mm (4.9 in)
21 July 1916
Aug
104.6 mm (4.1 in)
3 August 1935
Sep
140.0 mm (5.5 in)
18 September 2004
Oct
127.0 mm (5.0 in)
15 October 1954
Nov
55.9 mm (2.2 in)
28 November 1921
Dec
53.3 mm (2.1 in)
3 December 1991
Period of Record Coverage
1896 to 2008
Complete yearUnder 90 percent of days
109 years of record at Derry 4 SW, 1896 to 2008. 20 years have data for under 90 percent of days and are left out of rankings: 1896, 1897, 1901, 1931, 1956, 1959, 1963, 1964 and others.
Cooler than the station meanWarmer than the station mean
One stripe for each of 62 complete years at Derry 4 SW, 1898 to 2005. Blue stripes are years cooler than the station's own mean of 10.8 C (51.4 F); red stripes are warmer. The coolest year was 1980, at 8.7 C (47.6 F), and the warmest was 1938, at 12.1 C (53.9 F). The strongest colour marks a difference of 2.2 C (4.0 F).
Annual mean temperature at Derry 4 SW as warming stripes, 1898 to 2005
Year
Annual mean temperature
Difference from the station mean
1898
11.6 C
+0.77 C
1899
11.1 C
+0.34 C
1900
11.8 C
+0.96 C
1903
10.5 C
-0.30 C
1904
9.8 C
-1.01 C
1905
10.3 C
-0.51 C
1906
11.7 C
+0.88 C
1907
10.3 C
-0.54 C
1908
11.5 C
+0.67 C
1909
10.9 C
+0.12 C
1912
10.2 C
-0.64 C
1913
11.5 C
+0.71 C
1914
10.4 C
-0.37 C
1915
10.8 C
+0.03 C
1916
10.8 C
+0.01 C
1918
10.8 C
-0.01 C
1919
11.1 C
+0.26 C
1920
9.6 C
-1.16 C
1921
11.9 C
+1.10 C
1923
10.6 C
-0.15 C
1924
9.8 C
-1.04 C
1925
10.9 C
+0.09 C
1926
10.2 C
-0.63 C
1927
11.2 C
+0.36 C
1928
10.2 C
-0.64 C
1929
10.2 C
-0.61 C
1930
10.9 C
+0.05 C
1932
10.8 C
+0.04 C
1933
11.1 C
+0.30 C
1934
11.1 C
+0.30 C
1935
11.0 C
+0.18 C
1936
10.9 C
+0.10 C
1937
11.0 C
+0.17 C
1938
12.1 C
+1.35 C
1939
12.1 C
+1.27 C
1940
10.1 C
-0.73 C
1941
11.4 C
+0.63 C
1942
11.3 C
+0.53 C
1943
10.7 C
-0.08 C
1944
11.3 C
+0.47 C
1945
11.1 C
+0.34 C
1947
10.9 C
+0.13 C
1948
11.3 C
+0.48 C
1949
12.0 C
+1.22 C
1951
11.3 C
+0.48 C
1952
11.5 C
+0.71 C
1953
12.0 C
+1.23 C
1954
11.3 C
+0.54 C
1958
9.8 C
-1.02 C
1965
10.9 C
+0.10 C
1966
10.2 C
-0.60 C
1967
10.5 C
-0.33 C
1970
11.1 C
+0.30 C
1971
11.0 C
+0.21 C
1972
10.6 C
-0.16 C
1980
8.7 C
-2.13 C
1984
8.7 C
-2.10 C
1985
9.2 C
-1.62 C
2002
11.2 C
+0.37 C
2003
9.8 C
-0.95 C
2004
10.4 C
-0.39 C
2005
10.8 C
-0.04 C
The fitted trend in annual mean temperature here over 1898 to 2005 is -0.07 C (-0.13 to 0.00) per decade. The interval includes zero, so the trend is not clearly different from zero. In Fahrenheit: -0.12 F (-0.24 to 0.00) per decade. The slope is a straight line fitted to 62 complete years; the brackets give its 95 percent interval.
Fitted temperature trends per decade at Derry 4 SW
Measure
Per decade (C)
Per decade (F)
Period
Complete years
Reading
Annual mean temperature
-0.07 C (-0.13 to 0.00) per decade
-0.12 F (-0.24 to 0.00) per decade
1898 to 2005
62
Not clearly different from zero
Mean daily maximum
-0.1 C (-0.2 to -0.1) per decade
-0.2 F (-0.4 to -0.1) per decade
1898 to 2005
62
Fall
Mean daily minimum
-0.01 C (-0.10 to 0.09) per decade
-0.01 F (-0.18 to 0.15) per decade
1898 to 2005
62
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
1896 to 2008
Yearly extremes at Derry 4 SW: the record and the median year
Measure
Record
Year of the record
Median year
Years with a value
Hottest day (TXx)
40.6 C (105.1 F)
1911
34.4 C (93.9 F)
109
Coldest night (TNn)
-33.9 C (-29.0 F)
1912
-21.1 C (-6.0 F)
109
Wettest day (Rx1day)
148.6 mm (5.9 in)
1972
53.8 mm (2.1 in)
109
Wettest five days (Rx5day)
270.8 mm (10.7 in)
1972
88.9 mm (3.5 in)
109
Longest dry spell (CDD)
29 days
1932
13 days
109
Hottest day (TXx)
The hottest day of the year at Derry 4 SW, 1896 to 2008. The record is 40.6 C (105.1 F) in 1911, marked on the chart; the median year is 34.4 C (93.9 F).
Hottest day (TXx) at Derry 4 SW by year
Year
Hottest day (TXx)
1896
26.1 C (79.0 F)
1897
39.4 C (102.9 F)
1898
37.8 C (100.0 F)
1899
37.8 C (100.0 F)
1900
38.9 C (102.0 F)
1901
36.7 C (98.1 F)
1902
33.3 C (91.9 F)
1903
33.9 C (93.0 F)
1904
34.4 C (93.9 F)
1905
33.9 C (93.0 F)
1906
33.9 C (93.0 F)
1907
35.0 C (95.0 F)
1908
36.7 C (98.1 F)
1909
36.1 C (97.0 F)
1910
33.9 C (93.0 F)
1911
40.6 C (105.1 F)
1912
34.4 C (93.9 F)
1913
35.6 C (96.1 F)
1914
35.0 C (95.0 F)
1915
33.9 C (93.0 F)
1916
36.7 C (98.1 F)
1917
35.6 C (96.1 F)
1918
38.9 C (102.0 F)
1919
37.2 C (99.0 F)
1920
32.8 C (91.0 F)
1921
36.1 C (97.0 F)
1922
36.7 C (98.1 F)
1923
35.0 C (95.0 F)
1924
35.6 C (96.1 F)
1925
34.4 C (93.9 F)
1926
36.7 C (98.1 F)
1927
33.3 C (91.9 F)
1928
33.3 C (91.9 F)
1929
31.7 C (89.1 F)
1930
37.8 C (100.0 F)
1931
31.7 C (89.1 F)
1932
31.7 C (89.1 F)
1933
36.7 C (98.1 F)
1934
35.6 C (96.1 F)
1935
33.3 C (91.9 F)
1936
38.3 C (100.9 F)
1937
34.4 C (93.9 F)
1938
34.4 C (93.9 F)
1939
35.0 C (95.0 F)
1940
33.9 C (93.0 F)
1941
34.4 C (93.9 F)
1942
35.0 C (95.0 F)
1943
33.9 C (93.0 F)
1944
35.0 C (95.0 F)
1945
34.4 C (93.9 F)
1946
34.4 C (93.9 F)
1947
33.9 C (93.0 F)
1948
36.1 C (97.0 F)
1949
36.1 C (97.0 F)
1950
33.3 C (91.9 F)
1951
33.9 C (93.0 F)
1952
35.0 C (95.0 F)
1953
36.7 C (98.1 F)
1954
36.7 C (98.1 F)
1955
34.4 C (93.9 F)
1956
33.3 C (91.9 F)
1957
34.4 C (93.9 F)
1958
32.2 C (90.0 F)
1959
33.3 C (91.9 F)
1963
12.2 C (54.0 F)
1964
33.9 C (93.0 F)
1965
35.0 C (95.0 F)
1966
35.6 C (96.1 F)
1967
33.3 C (91.9 F)
1968
34.4 C (93.9 F)
1969
31.7 C (89.1 F)
1970
32.8 C (91.0 F)
1971
33.3 C (91.9 F)
1972
32.2 C (90.0 F)
1973
27.8 C (82.0 F)
1974
24.4 C (75.9 F)
1975
35.0 C (95.0 F)
1977
33.9 C (93.0 F)
1978
22.8 C (73.0 F)
1979
33.9 C (93.0 F)
1980
35.0 C (95.0 F)
1981
32.8 C (91.0 F)
1982
33.3 C (91.9 F)
1983
36.1 C (97.0 F)
1984
33.3 C (91.9 F)
1985
33.9 C (93.0 F)
1986
35.0 C (95.0 F)
1987
35.6 C (96.1 F)
1988
38.9 C (102.0 F)
1989
34.4 C (93.9 F)
1990
32.2 C (90.0 F)
1991
36.1 C (97.0 F)
1992
32.2 C (90.0 F)
1993
33.9 C (93.0 F)
1994
33.9 C (93.0 F)
1995
36.1 C (97.0 F)
1996
32.8 C (91.0 F)
1997
34.4 C (93.9 F)
1998
32.8 C (91.0 F)
1999
35.6 C (96.1 F)
2000
32.2 C (90.0 F)
2001
34.4 C (93.9 F)
2002
35.0 C (95.0 F)
2003
31.1 C (88.0 F)
2004
31.1 C (88.0 F)
2005
33.9 C (93.0 F)
2006
33.9 C (93.0 F)
2007
33.9 C (93.0 F)
2008
33.9 C (93.0 F)
Coldest night (TNn)
The coldest night of the year at Derry 4 SW, 1896 to 2008. The record is -33.9 C (-29.0 F) in 1912, marked on the chart; the median year is -21.1 C (-6.0 F).
Coldest night (TNn) at Derry 4 SW by year
Year
Coldest night (TNn)
1896
-13.9 C (7.0 F)
1897
-17.8 C (0.0 F)
1898
-21.7 C (-7.1 F)
1899
-29.4 C (-20.9 F)
1900
-22.2 C (-8.0 F)
1901
-19.4 C (-2.9 F)
1902
-17.8 C (0.0 F)
1903
-21.1 C (-6.0 F)
1904
-28.9 C (-20.0 F)
1905
-26.1 C (-15.0 F)
1906
-23.9 C (-11.0 F)
1907
-27.8 C (-18.0 F)
1908
-21.7 C (-7.1 F)
1909
-19.4 C (-2.9 F)
1910
-18.3 C (-0.9 F)
1911
-15.6 C (3.9 F)
1912
-33.9 C (-29.0 F)
1913
-16.7 C (1.9 F)
1914
-26.7 C (-16.1 F)
1915
-18.9 C (-2.0 F)
1916
-25.0 C (-13.0 F)
1917
-27.2 C (-17.0 F)
1918
-25.6 C (-14.1 F)
1919
-21.7 C (-7.1 F)
1920
-19.4 C (-2.9 F)
1921
-21.1 C (-6.0 F)
1922
-22.8 C (-9.0 F)
1923
-20.6 C (-5.1 F)
1924
-22.2 C (-8.0 F)
1925
-26.1 C (-15.0 F)
1926
-21.7 C (-7.1 F)
1927
-18.3 C (-0.9 F)
1928
-19.4 C (-2.9 F)
1929
-21.1 C (-6.0 F)
1930
-21.1 C (-6.0 F)
1931
-15.0 C (5.0 F)
1932
-19.4 C (-2.9 F)
1933
-21.1 C (-6.0 F)
1934
-28.3 C (-18.9 F)
1935
-20.6 C (-5.1 F)
1936
-25.6 C (-14.1 F)
1937
-18.3 C (-0.9 F)
1938
-16.7 C (1.9 F)
1939
-17.2 C (1.0 F)
1940
-22.2 C (-8.0 F)
1941
-17.2 C (1.0 F)
1942
-23.9 C (-11.0 F)
1943
-23.9 C (-11.0 F)
1944
-23.9 C (-11.0 F)
1945
-25.6 C (-14.1 F)
1946
-17.8 C (0.0 F)
1947
-18.9 C (-2.0 F)
1948
-23.3 C (-9.9 F)
1949
-15.0 C (5.0 F)
1950
-22.8 C (-9.0 F)
1951
-19.4 C (-2.9 F)
1952
-15.0 C (5.0 F)
1953
-12.8 C (9.0 F)
1954
-18.9 C (-2.0 F)
1955
-24.4 C (-11.9 F)
1956
-15.0 C (5.0 F)
1957
-21.1 C (-6.0 F)
1958
-22.8 C (-9.0 F)
1959
-18.3 C (-0.9 F)
1963
-21.1 C (-6.0 F)
1964
-17.8 C (0.0 F)
1965
-23.9 C (-11.0 F)
1966
-25.6 C (-14.1 F)
1967
-17.8 C (0.0 F)
1968
-22.2 C (-8.0 F)
1969
-17.2 C (1.0 F)
1970
-20.6 C (-5.1 F)
1971
-20.6 C (-5.1 F)
1972
-22.2 C (-8.0 F)
1973
-21.1 C (-6.0 F)
1974
-10.0 C (14.0 F)
1975
-19.4 C (-2.9 F)
1977
-26.1 C (-15.0 F)
1978
-2.8 C (27.0 F)
1979
-28.9 C (-20.0 F)
1980
-25.6 C (-14.1 F)
1981
-27.2 C (-17.0 F)
1982
-26.7 C (-16.1 F)
1983
-24.4 C (-11.9 F)
1984
-29.4 C (-20.9 F)
1985
-33.9 C (-29.0 F)
1986
-23.3 C (-9.9 F)
1987
-20.0 C (-4.0 F)
1988
-20.6 C (-5.1 F)
1989
-23.9 C (-11.0 F)
1990
-19.4 C (-2.9 F)
1991
-16.1 C (3.0 F)
1992
-18.9 C (-2.0 F)
1993
-19.4 C (-2.9 F)
1994
-30.6 C (-23.1 F)
1995
-19.4 C (-2.9 F)
1996
-23.3 C (-9.9 F)
1997
-20.0 C (-4.0 F)
1998
-18.9 C (-2.0 F)
1999
-18.3 C (-0.9 F)
2000
-19.4 C (-2.9 F)
2001
-13.3 C (8.1 F)
2002
-13.9 C (7.0 F)
2003
-22.2 C (-8.0 F)
2004
-22.2 C (-8.0 F)
2005
-18.3 C (-0.9 F)
2006
-10.0 C (14.0 F)
2007
-20.6 C (-5.1 F)
2008
-16.7 C (1.9 F)
Wettest day (Rx1day)
The wettest day of the year at Derry 4 SW, 1896 to 2008. The record is 148.6 mm (5.9 in) in 1972, marked on the chart; the median year is 53.8 mm (2.1 in).
Wettest day (Rx1day) at Derry 4 SW by year
Year
Wettest day (Rx1day)
1896
49.0 mm (1.9 in)
1897
44.7 mm (1.8 in)
1898
44.7 mm (1.8 in)
1899
58.2 mm (2.3 in)
1900
49.8 mm (2.0 in)
1901
61.2 mm (2.4 in)
1902
41.9 mm (1.6 in)
1903
52.3 mm (2.1 in)
1904
51.3 mm (2.0 in)
1905
57.2 mm (2.3 in)
1906
65.5 mm (2.6 in)
1907
54.1 mm (2.1 in)
1908
56.4 mm (2.2 in)
1909
43.7 mm (1.7 in)
1910
27.9 mm (1.1 in)
1911
74.9 mm (2.9 in)
1912
98.0 mm (3.9 in)
1913
52.6 mm (2.1 in)
1914
43.2 mm (1.7 in)
1915
48.8 mm (1.9 in)
1916
124.0 mm (4.9 in)
1917
57.7 mm (2.3 in)
1918
62.0 mm (2.4 in)
1919
54.6 mm (2.1 in)
1920
53.8 mm (2.1 in)
1921
91.4 mm (3.6 in)
1922
38.1 mm (1.5 in)
1923
36.6 mm (1.4 in)
1924
97.0 mm (3.8 in)
1925
48.5 mm (1.9 in)
1926
88.1 mm (3.5 in)
1927
94.7 mm (3.7 in)
1928
46.0 mm (1.8 in)
1929
73.4 mm (2.9 in)
1930
95.3 mm (3.8 in)
1931
39.4 mm (1.6 in)
1932
34.8 mm (1.4 in)
1933
41.9 mm (1.6 in)
1934
64.8 mm (2.6 in)
1935
104.6 mm (4.1 in)
1936
81.5 mm (3.2 in)
1937
66.0 mm (2.6 in)
1938
49.0 mm (1.9 in)
1939
43.2 mm (1.7 in)
1940
37.8 mm (1.5 in)
1941
59.7 mm (2.4 in)
1942
62.0 mm (2.4 in)
1943
50.3 mm (2.0 in)
1944
51.3 mm (2.0 in)
1945
63.5 mm (2.5 in)
1946
47.5 mm (1.9 in)
1947
61.2 mm (2.4 in)
1948
56.4 mm (2.2 in)
1949
45.2 mm (1.8 in)
1950
61.0 mm (2.4 in)
1951
66.8 mm (2.6 in)
1952
66.0 mm (2.6 in)
1953
53.3 mm (2.1 in)
1954
127.0 mm (5.0 in)
1955
65.0 mm (2.6 in)
1956
85.1 mm (3.4 in)
1957
37.1 mm (1.5 in)
1958
47.8 mm (1.9 in)
1959
30.0 mm (1.2 in)
1963
14.0 mm (0.6 in)
1964
62.5 mm (2.5 in)
1965
30.7 mm (1.2 in)
1966
47.0 mm (1.9 in)
1967
73.9 mm (2.9 in)
1968
67.3 mm (2.6 in)
1969
57.2 mm (2.3 in)
1970
95.5 mm (3.8 in)
1971
71.1 mm (2.8 in)
1972
148.6 mm (5.9 in)
1973
26.7 mm (1.1 in)
1974
30.0 mm (1.2 in)
1975
44.5 mm (1.8 in)
1977
51.3 mm (2.0 in)
1978
38.1 mm (1.5 in)
1979
46.5 mm (1.8 in)
1980
65.3 mm (2.6 in)
1981
53.3 mm (2.1 in)
1982
61.0 mm (2.4 in)
1983
52.6 mm (2.1 in)
1984
45.5 mm (1.8 in)
1985
105.4 mm (4.1 in)
1986
63.5 mm (2.5 in)
1987
54.6 mm (2.1 in)
1988
66.0 mm (2.6 in)
1989
53.3 mm (2.1 in)
1990
43.4 mm (1.7 in)
1991
53.3 mm (2.1 in)
1992
50.8 mm (2.0 in)
1993
58.4 mm (2.3 in)
1994
54.1 mm (2.1 in)
1995
36.6 mm (1.4 in)
1996
53.8 mm (2.1 in)
1997
51.8 mm (2.0 in)
1998
51.8 mm (2.0 in)
1999
52.1 mm (2.1 in)
2000
79.5 mm (3.1 in)
2001
33.5 mm (1.3 in)
2002
52.8 mm (2.1 in)
2003
50.8 mm (2.0 in)
2004
140.0 mm (5.5 in)
2005
59.4 mm (2.3 in)
2006
90.9 mm (3.6 in)
2007
61.5 mm (2.4 in)
2008
48.3 mm (1.9 in)
Wettest five days (Rx5day)
The wettest five days of the year at Derry 4 SW, 1896 to 2008. The record is 270.8 mm (10.7 in) in 1972, marked on the chart; the median year is 88.9 mm (3.5 in).
Wettest five days (Rx5day) at Derry 4 SW by year
Year
Wettest five days (Rx5day)
1896
69.6 mm (2.7 in)
1897
82.0 mm (3.2 in)
1898
92.5 mm (3.6 in)
1899
74.4 mm (2.9 in)
1900
86.3 mm (3.4 in)
1901
109.3 mm (4.3 in)
1902
81.3 mm (3.2 in)
1903
99.6 mm (3.9 in)
1904
82.1 mm (3.2 in)
1905
89.7 mm (3.5 in)
1906
85.1 mm (3.4 in)
1907
88.0 mm (3.5 in)
1908
85.7 mm (3.4 in)
1909
58.0 mm (2.3 in)
1910
64.0 mm (2.5 in)
1911
65.8 mm (2.6 in)
1912
118.8 mm (4.7 in)
1913
74.8 mm (2.9 in)
1914
75.5 mm (3.0 in)
1915
73.7 mm (2.9 in)
1916
127.3 mm (5.0 in)
1917
68.1 mm (2.7 in)
1918
131.6 mm (5.2 in)
1919
90.7 mm (3.6 in)
1920
80.7 mm (3.2 in)
1921
132.8 mm (5.2 in)
1922
63.3 mm (2.5 in)
1923
75.7 mm (3.0 in)
1924
109.7 mm (4.3 in)
1925
63.7 mm (2.5 in)
1926
184.1 mm (7.2 in)
1927
145.0 mm (5.7 in)
1928
89.9 mm (3.5 in)
1929
88.9 mm (3.5 in)
1930
104.7 mm (4.1 in)
1931
68.9 mm (2.7 in)
1932
82.4 mm (3.2 in)
1933
77.2 mm (3.0 in)
1934
116.1 mm (4.6 in)
1935
201.6 mm (7.9 in)
1936
146.5 mm (5.8 in)
1937
105.8 mm (4.2 in)
1938
93.4 mm (3.7 in)
1939
87.1 mm (3.4 in)
1940
89.9 mm (3.5 in)
1941
102.5 mm (4.0 in)
1942
77.0 mm (3.0 in)
1943
87.4 mm (3.4 in)
1944
81.7 mm (3.2 in)
1945
104.7 mm (4.1 in)
1946
65.8 mm (2.6 in)
1947
94.5 mm (3.7 in)
1948
112.5 mm (4.4 in)
1949
67.8 mm (2.7 in)
1950
111.2 mm (4.4 in)
1951
129.6 mm (5.1 in)
1952
93.0 mm (3.7 in)
1953
93.0 mm (3.7 in)
1954
167.6 mm (6.6 in)
1955
97.0 mm (3.8 in)
1956
130.3 mm (5.1 in)
1957
74.7 mm (2.9 in)
1958
106.5 mm (4.2 in)
1959
50.4 mm (2.0 in)
1963
26.1 mm (1.0 in)
1964
91.7 mm (3.6 in)
1965
51.1 mm (2.0 in)
1966
86.1 mm (3.4 in)
1967
134.7 mm (5.3 in)
1968
80.8 mm (3.2 in)
1969
65.9 mm (2.6 in)
1970
169.7 mm (6.7 in)
1971
110.8 mm (4.4 in)
1972
270.8 mm (10.7 in)
1973
60.5 mm (2.4 in)
1974
56.6 mm (2.2 in)
1975
85.6 mm (3.4 in)
1977
64.2 mm (2.5 in)
1978
54.6 mm (2.1 in)
1979
79.3 mm (3.1 in)
1980
96.0 mm (3.8 in)
1981
106.1 mm (4.2 in)
1982
87.9 mm (3.5 in)
1983
87.2 mm (3.4 in)
1984
67.1 mm (2.6 in)
1985
127.1 mm (5.0 in)
1986
99.6 mm (3.9 in)
1987
99.0 mm (3.9 in)
1988
92.4 mm (3.6 in)
1989
116.3 mm (4.6 in)
1990
82.6 mm (3.3 in)
1991
73.1 mm (2.9 in)
1992
123.2 mm (4.9 in)
1993
88.1 mm (3.5 in)
1994
87.3 mm (3.4 in)
1995
60.5 mm (2.4 in)
1996
85.3 mm (3.4 in)
1997
114.0 mm (4.5 in)
1998
109.7 mm (4.3 in)
1999
77.4 mm (3.0 in)
2000
93.7 mm (3.7 in)
2001
61.5 mm (2.4 in)
2002
57.9 mm (2.3 in)
2003
117.3 mm (4.6 in)
2004
141.5 mm (5.6 in)
2005
138.8 mm (5.5 in)
2006
116.3 mm (4.6 in)
2007
142.8 mm (5.6 in)
2008
113.8 mm (4.5 in)
Longest dry spell (CDD)
The longest dry spell of the year at Derry 4 SW, 1896 to 2008. The record is 29 days in 1932, marked on the chart; the median year is 13 days.
Longest dry spell (CDD) at Derry 4 SW by year
Year
Longest dry spell (CDD)
1896
18 days
1897
13 days
1898
14 days
1899
19 days
1900
17 days
1901
11 days
1902
12 days
1903
18 days
1904
15 days
1905
15 days
1906
11 days
1907
11 days
1908
21 days
1909
13 days
1910
13 days
1911
12 days
1912
13 days
1913
13 days
1914
14 days
1915
12 days
1916
10 days
1917
21 days
1918
19 days
1919
10 days
1920
11 days
1921
12 days
1922
24 days
1923
20 days
1924
25 days
1925
19 days
1926
14 days
1927
14 days
1928
10 days
1929
14 days
1930
22 days
1931
10 days
1932
29 days
1933
12 days
1934
16 days
1935
14 days
1936
16 days
1937
14 days
1938
13 days
1939
14 days
1940
13 days
1941
19 days
1942
21 days
1943
15 days
1944
17 days
1945
11 days
1946
11 days
1947
19 days
1948
16 days
1949
13 days
1950
16 days
1951
16 days
1952
21 days
1953
18 days
1954
13 days
1955
12 days
1956
13 days
1957
20 days
1958
12 days
1959
9 days
1963
4 days
1964
26 days
1965
13 days
1966
12 days
1967
13 days
1968
13 days
1969
13 days
1970
15 days
1971
12 days
1972
10 days
1973
10 days
1974
10 days
1975
15 days
1977
15 days
1978
7 days
1979
11 days
1980
11 days
1981
12 days
1982
12 days
1983
15 days
1984
9 days
1985
18 days
1986
9 days
1987
10 days
1988
10 days
1989
9 days
1990
12 days
1991
16 days
1992
9 days
1993
12 days
1994
15 days
1995
18 days
1996
10 days
1997
12 days
1998
10 days
1999
14 days
2000
15 days
2001
13 days
2002
16 days
2003
13 days
2004
12 days
2005
15 days
2006
14 days
2007
17 days
2008
13 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
62 years with a frost
Across 62 years with a frost, the median last spring frost at Derry 4 SW falls on 10 May and the median first autumn frost on 6 October, which leaves a median of 154 days between them.
In 1937 to 2005 the median growing season was 156 days. That is 3 days more than in 1898 to 1934.
Fitted over all years, the growing season changes by +1.2 days per decade at this station.
Frost dates and growing season at Derry 4 SW
Measure
Median, all years
Earliest period (1898 to 1934)
Recent period (1937 to 2005)
Recent against earliest
Fitted trend
Last spring frost
10 May
11 May
6 May
5 days earlier
-0.1 days per decade
First autumn frost
6 October
7 October
6 October
1 day earlier
+1.1 days per decade
Growing days
154 days
153 days
156 days
3 days more
+1.2 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
97 years, 1897 to 2007
A day with at least 55.8 mm (2.2 in) of rain is expected about once in 2 years. A day with at least 151.0 mm (5.9 in) of rain is expected about once in 100 years.
Rainfall return levels at Derry 4 SW: the daily rain expected about once in a given number of years
Expected about once in
A day with at least
Note
2 years
55.8 mm (2.2 in)
5 years
74.0 mm (2.9 in)
10 years
88.6 mm (3.5 in)
25 years
110.3 mm (4.3 in)
50 years
129.3 mm (5.1 in)
100 years
151.0 mm (5.9 in)
Longer than the 97 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, 97 years of values from 1897 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: 148.6 mm (5.9 in) in 1972; 140.0 mm (5.5 in) in 2004; 127.0 mm (5.0 in) in 1954.
Station Changes
1 suspected
One change was suspected in the annual mean temperature of Derry 4 SW, at 1934. Each is measured against neighbouring stations.
Relative to 5 neighbouring stations, the station's annual mean temperature from 1934 ran 0.3 C (0.5 F) higher than in the years before (likely change).
Suspected changes in the annual mean temperature at Derry 4 SW, against neighbouring stations
Year
Shift (C)
Shift (F)
Strength
Neighbours
1934
+0.3
+0.5
likely
5
Possible change at the station (a move, a new instrument or a new site); the record is kept as measured. A "likely" change has a larger test statistic than a "possible" one. Neither says why the station differs from its neighbours. How changes are found, and the largest ones.
Download the Data
Data for Derry 4 SW standing records by year: CSV or JSON. Field meanings are on the data page.
Data for Derry 4 SW 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.