Record envelope, standing records and threshold days for Chatham (USC00191386), Massachusetts, United States, with 50 years of record.
Key Facts for Chatham
Chatham (USC00191386) is a weather station in Massachusetts, United States at 41.66 latitude and -69.96 longitude, 12 m (40 ft) above sea level.
The station reports from 1972 to 2021, 50 years of record.
1,464 records set at Chatham still stand.
Records are tracked for tmax, tmin, prcp, snow, snwd: an element needs 30 years of data to be eligible.
Chatham set a daily record high minimum temperature of 7.2 C (45.0 F) on 27 March 2021.
About the Station
Location: Massachusetts, United States, 41.66 latitude, -69.96 longitude.
Elevation: 12 m (40 ft).
Period of record: 1972 to 2021, 50 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 Chatham. 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 Chatham, with 2026 drawn through them
Month
Highest record high
Lowest record low
2026 highest maximum
2026 lowest minimum
Jan
14.4 C (57.9 F)
-21.1 C (-6.0 F)
n/a
n/a
Feb
14.4 C (57.9 F)
-20.0 C (-4.0 F)
n/a
n/a
Mar
21.1 C (70.0 F)
-13.9 C (7.0 F)
n/a
n/a
Apr
27.2 C (81.0 F)
-7.2 C (19.0 F)
n/a
n/a
May
31.1 C (88.0 F)
0.6 C (33.1 F)
n/a
n/a
Jun
32.2 C (90.0 F)
6.7 C (44.1 F)
n/a
n/a
Jul
35.0 C (95.0 F)
10.6 C (51.1 F)
n/a
n/a
Aug
33.9 C (93.0 F)
8.3 C (46.9 F)
n/a
n/a
Sep
29.4 C (84.9 F)
4.4 C (39.9 F)
n/a
n/a
Oct
27.8 C (82.0 F)
-0.6 C (30.9 F)
n/a
n/a
Nov
20.0 C (68.0 F)
-7.8 C (18.0 F)
n/a
n/a
Dec
16.7 C (62.1 F)
-17.8 C (0.0 F)
n/a
n/a
Which Years Hold Standing Records
1,464 standing records
Year with most
1,464 records at Chatham still stand. 1976 holds the most, with 61.
Standing records at Chatham by the year they were set
Year set
Standing records
1972
18
1973
29
1974
47
1975
37
1976
61
1977
44
1978
38
1979
57
1980
31
1981
34
1982
39
1983
25
1984
31
1985
28
1986
12
1987
22
1988
28
1989
36
1990
40
1991
29
1992
31
1993
26
1994
21
1995
12
1996
23
1997
23
1998
16
1999
26
2000
26
2001
26
2002
39
2003
28
2004
25
2005
25
2006
23
2007
34
2008
24
2009
23
2010
29
2011
19
2012
31
2013
16
2014
24
2015
44
2016
45
2017
36
2018
31
2019
24
2020
23
2021
5
All-Time Record Progression
4 new records
4 all-time records were set at Chatham between 16 January 2004 and 2 August 2006. Each dot is a new record.
When Chatham set new all-time records
Date
Kind
Detail
2004-01-16
Record low minimum temperature
Record low minimum temperature -21.1 C (-6.0 F)
2005-08-14
Record high minimum temperature
Record high minimum temperature 23.3 C (73.9 F)
2006-07-30
Record high minimum temperature
Record high minimum temperature 23.9 C (75.0 F)
2006-08-02
Record high minimum temperature
Record high minimum temperature 24.4 C (75.9 F)
Wettest Day of Each Month
Sep: 155.4 mm (6.1 in)
The wettest day on record for each calendar month at Chatham. The most was 155.4 mm (6.1 in) on 3 September 1972.
Record daily precipitation for each month at Chatham
Month
Record daily precipitation (mm)
Date
Jan
79.5 mm (3.1 in)
15 January 1980
Feb
88.9 mm (3.5 in)
21 February 1982
Mar
65.5 mm (2.6 in)
31 March 2001
Apr
67.3 mm (2.6 in)
16 April 2007
May
74.9 mm (2.9 in)
25 May 1999
Jun
91.4 mm (3.6 in)
10 June 1977
Jul
96.8 mm (3.8 in)
17 July 1989
Aug
94.2 mm (3.7 in)
19 August 2017
Sep
155.4 mm (6.1 in)
3 September 1972
Oct
90.9 mm (3.6 in)
9 October 1982
Nov
100.1 mm (3.9 in)
4 November 2007
Dec
77.5 mm (3.1 in)
22 December 1975
Period of Record Coverage
1972 to 2021
Complete yearUnder 90 percent of days
50 years of record at Chatham, 1972 to 2021. 10 years have data for under 90 percent of days and are left out of rankings: 1972, 1986, 1987, 1991, 1992, 1995, 2000, 2001 and others.
Cooler than the station meanWarmer than the station mean
One stripe for each of 33 complete years at Chatham, 1973 to 2020. Blue stripes are years cooler than the station's own mean of 10.1 C (50.1 F); red stripes are warmer. The coolest year was 1978, at 8.9 C (48.1 F), and the warmest was 2016, at 11.2 C (52.2 F). The strongest colour marks a difference of 1.2 C (2.2 F).
Annual mean temperature at Chatham as warming stripes, 1973 to 2020
Year
Annual mean temperature
Difference from the station mean
1973
10.1 C
-0.01 C
1974
9.7 C
-0.40 C
1975
10.1 C
0.00 C
1976
9.5 C
-0.58 C
1977
9.5 C
-0.59 C
1978
8.9 C
-1.13 C
1979
9.6 C
-0.50 C
1980
9.3 C
-0.76 C
1981
9.5 C
-0.59 C
1982
9.4 C
-0.66 C
1983
10.4 C
+0.37 C
1984
10.1 C
+0.06 C
1988
9.6 C
-0.48 C
1990
10.5 C
+0.43 C
1993
9.7 C
-0.34 C
1994
10.1 C
+0.02 C
1996
9.7 C
-0.35 C
1997
10.0 C
-0.10 C
1998
10.7 C
+0.67 C
2005
10.0 C
-0.09 C
2006
11.0 C
+0.96 C
2007
10.2 C
+0.09 C
2008
10.6 C
+0.49 C
2010
10.4 C
+0.35 C
2011
10.5 C
+0.39 C
2013
9.8 C
-0.23 C
2014
9.6 C
-0.46 C
2015
10.5 C
+0.45 C
2016
11.2 C
+1.18 C
2017
10.6 C
+0.56 C
2018
10.4 C
+0.33 C
2019
10.0 C
-0.06 C
2020
11.1 C
+0.99 C
The annual mean temperature here has risen by 0.2 C (0.1 to 0.3) per decade over 1973 to 2020. In Fahrenheit: 0.4 F (0.2 to 0.6) per decade. The slope is a straight line fitted to 33 complete years; the brackets give its 95 percent interval.
Fitted temperature trends per decade at Chatham
Measure
Per decade (C)
Per decade (F)
Period
Complete years
Reading
Annual mean temperature
0.2 C (0.1 to 0.3) per decade
0.4 F (0.2 to 0.6) per decade
1973 to 2020
33
Rise
Mean daily maximum
0.2 C (0.1 to 0.3) per decade
0.3 F (0.2 to 0.5) per decade
1973 to 2020
33
Rise
Mean daily minimum
0.3 C (0.1 to 0.4) per decade
0.5 F (0.3 to 0.7) per decade
1973 to 2020
33
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
1972 to 2021
Yearly extremes at Chatham: the record and the median year
Measure
Record
Year of the record
Median year
Years with a value
Hottest day (TXx)
35.0 C (95.0 F)
1999
30.0 C (86.0 F)
50
Coldest night (TNn)
-21.1 C (-6.0 F)
2004
-13.9 C (7.0 F)
50
Wettest day (Rx1day)
155.4 mm (6.1 in)
1972
65.9 mm (2.6 in)
50
Wettest five days (Rx5day)
224.2 mm (8.8 in)
1982
99.2 mm (3.9 in)
50
Longest dry spell (CDD)
37 days
1995
17 days
50
Hottest day (TXx)
The hottest day of the year at Chatham, 1972 to 2021. The record is 35.0 C (95.0 F) in 1999, marked on the chart; the median year is 30.0 C (86.0 F).
Hottest day (TXx) at Chatham by year
Year
Hottest day (TXx)
1972
27.8 C (82.0 F)
1973
31.7 C (89.1 F)
1974
30.0 C (86.0 F)
1975
33.9 C (93.0 F)
1976
28.9 C (84.0 F)
1977
31.1 C (88.0 F)
1978
30.0 C (86.0 F)
1979
30.0 C (86.0 F)
1980
30.6 C (87.1 F)
1981
31.1 C (88.0 F)
1982
28.9 C (84.0 F)
1983
30.6 C (87.1 F)
1984
30.0 C (86.0 F)
1985
28.3 C (82.9 F)
1986
31.7 C (89.1 F)
1987
27.8 C (82.0 F)
1988
28.3 C (82.9 F)
1989
27.8 C (82.0 F)
1990
30.0 C (86.0 F)
1991
31.7 C (89.1 F)
1992
29.4 C (84.9 F)
1993
30.6 C (87.1 F)
1994
31.7 C (89.1 F)
1995
31.7 C (89.1 F)
1996
27.2 C (81.0 F)
1997
31.1 C (88.0 F)
1998
28.9 C (84.0 F)
1999
35.0 C (95.0 F)
2000
27.8 C (82.0 F)
2001
29.4 C (84.9 F)
2002
31.1 C (88.0 F)
2003
30.6 C (87.1 F)
2004
27.2 C (81.0 F)
2005
31.7 C (89.1 F)
2006
30.6 C (87.1 F)
2007
31.1 C (88.0 F)
2008
30.0 C (86.0 F)
2009
27.8 C (82.0 F)
2010
31.7 C (89.1 F)
2011
28.3 C (82.9 F)
2012
32.2 C (90.0 F)
2013
29.4 C (84.9 F)
2014
28.3 C (82.9 F)
2015
29.4 C (84.9 F)
2016
31.1 C (88.0 F)
2017
28.9 C (84.0 F)
2018
30.6 C (87.1 F)
2019
31.7 C (89.1 F)
2020
30.0 C (86.0 F)
2021
13.9 C (57.0 F)
Coldest night (TNn)
The coldest night of the year at Chatham, 1972 to 2021. The record is -21.1 C (-6.0 F) in 2004, marked on the chart; the median year is -13.9 C (7.0 F).
Coldest night (TNn) at Chatham by year
Year
Coldest night (TNn)
1972
-9.4 C (15.1 F)
1973
-12.2 C (10.0 F)
1974
-10.6 C (12.9 F)
1975
-12.8 C (9.0 F)
1976
-19.4 C (-2.9 F)
1977
-16.7 C (1.9 F)
1978
-12.2 C (10.0 F)
1979
-17.2 C (1.0 F)
1980
-17.8 C (0.0 F)
1981
-18.9 C (-2.0 F)
1982
-18.9 C (-2.0 F)
1983
-15.6 C (3.9 F)
1984
-12.8 C (9.0 F)
1985
-13.9 C (7.0 F)
1986
-14.4 C (6.1 F)
1987
-14.4 C (6.1 F)
1988
-15.6 C (3.9 F)
1989
-14.4 C (6.1 F)
1990
-11.1 C (12.0 F)
1991
-11.7 C (10.9 F)
1992
-12.2 C (10.0 F)
1993
-13.3 C (8.1 F)
1994
-18.3 C (-0.9 F)
1995
-16.1 C (3.0 F)
1996
-13.9 C (7.0 F)
1997
-13.9 C (7.0 F)
1998
-10.6 C (12.9 F)
1999
-14.4 C (6.1 F)
2000
-16.7 C (1.9 F)
2001
-7.2 C (19.0 F)
2002
-8.3 C (17.1 F)
2003
-14.4 C (6.1 F)
2004
-21.1 C (-6.0 F)
2005
-12.8 C (9.0 F)
2006
-11.7 C (10.9 F)
2007
-13.9 C (7.0 F)
2008
-11.1 C (12.0 F)
2009
-13.9 C (7.0 F)
2010
-13.3 C (8.1 F)
2011
-15.0 C (5.0 F)
2012
-11.1 C (12.0 F)
2013
-13.9 C (7.0 F)
2014
-13.3 C (8.1 F)
2015
-17.8 C (0.0 F)
2016
-20.0 C (-4.0 F)
2017
-13.9 C (7.0 F)
2018
-15.6 C (3.9 F)
2019
-15.0 C (5.0 F)
2020
-12.2 C (10.0 F)
2021
-11.1 C (12.0 F)
Wettest day (Rx1day)
The wettest day of the year at Chatham, 1972 to 2021. The record is 155.4 mm (6.1 in) in 1972, marked on the chart; the median year is 65.9 mm (2.6 in).
Wettest day (Rx1day) at Chatham by year
Year
Wettest day (Rx1day)
1972
155.4 mm (6.1 in)
1973
86.1 mm (3.4 in)
1974
50.8 mm (2.0 in)
1975
77.5 mm (3.1 in)
1976
51.8 mm (2.0 in)
1977
91.4 mm (3.6 in)
1978
71.1 mm (2.8 in)
1979
61.0 mm (2.4 in)
1980
79.5 mm (3.1 in)
1981
81.5 mm (3.2 in)
1982
114.8 mm (4.5 in)
1983
67.3 mm (2.6 in)
1984
80.8 mm (3.2 in)
1985
80.5 mm (3.2 in)
1986
76.5 mm (3.0 in)
1987
61.7 mm (2.4 in)
1988
70.6 mm (2.8 in)
1989
96.8 mm (3.8 in)
1990
57.2 mm (2.3 in)
1991
49.0 mm (1.9 in)
1992
65.5 mm (2.6 in)
1993
70.4 mm (2.8 in)
1994
54.6 mm (2.1 in)
1995
52.1 mm (2.1 in)
1996
64.0 mm (2.5 in)
1997
52.1 mm (2.1 in)
1998
51.8 mm (2.0 in)
1999
74.9 mm (2.9 in)
2000
61.2 mm (2.4 in)
2001
66.3 mm (2.6 in)
2002
64.5 mm (2.5 in)
2003
79.2 mm (3.1 in)
2004
47.5 mm (1.9 in)
2005
47.5 mm (1.9 in)
2006
72.6 mm (2.9 in)
2007
100.1 mm (3.9 in)
2008
62.5 mm (2.5 in)
2009
75.7 mm (3.0 in)
2010
85.1 mm (3.4 in)
2011
94.5 mm (3.7 in)
2012
48.8 mm (1.9 in)
2013
62.2 mm (2.4 in)
2014
70.9 mm (2.8 in)
2015
62.0 mm (2.4 in)
2016
62.2 mm (2.4 in)
2017
94.2 mm (3.7 in)
2018
61.0 mm (2.4 in)
2019
54.1 mm (2.1 in)
2020
55.4 mm (2.2 in)
2021
44.2 mm (1.7 in)
Wettest five days (Rx5day)
The wettest five days of the year at Chatham, 1972 to 2021. The record is 224.2 mm (8.8 in) in 1982, marked on the chart; the median year is 99.2 mm (3.9 in).
Wettest five days (Rx5day) at Chatham by year
Year
Wettest five days (Rx5day)
1972
155.4 mm (6.1 in)
1973
95.0 mm (3.7 in)
1974
58.7 mm (2.3 in)
1975
126.6 mm (5.0 in)
1976
68.6 mm (2.7 in)
1977
130.5 mm (5.1 in)
1978
77.4 mm (3.0 in)
1979
129.6 mm (5.1 in)
1980
95.0 mm (3.7 in)
1981
91.4 mm (3.6 in)
1982
224.2 mm (8.8 in)
1983
137.5 mm (5.4 in)
1984
99.1 mm (3.9 in)
1985
119.9 mm (4.7 in)
1986
156.6 mm (6.2 in)
1987
122.5 mm (4.8 in)
1988
88.1 mm (3.5 in)
1989
98.6 mm (3.9 in)
1990
77.3 mm (3.0 in)
1991
88.9 mm (3.5 in)
1992
87.9 mm (3.5 in)
1993
77.3 mm (3.0 in)
1994
99.3 mm (3.9 in)
1995
76.9 mm (3.0 in)
1996
119.4 mm (4.7 in)
1997
101.7 mm (4.0 in)
1998
86.6 mm (3.4 in)
1999
104.7 mm (4.1 in)
2000
83.6 mm (3.3 in)
2001
84.9 mm (3.3 in)
2002
115.6 mm (4.6 in)
2003
104.9 mm (4.1 in)
2004
80.3 mm (3.2 in)
2005
83.1 mm (3.3 in)
2006
150.9 mm (5.9 in)
2007
107.8 mm (4.2 in)
2008
135.7 mm (5.3 in)
2009
109.0 mm (4.3 in)
2010
110.7 mm (4.4 in)
2011
97.8 mm (3.9 in)
2012
78.0 mm (3.1 in)
2013
85.1 mm (3.4 in)
2014
121.0 mm (4.8 in)
2015
124.7 mm (4.9 in)
2016
120.7 mm (4.8 in)
2017
103.9 mm (4.1 in)
2018
113.3 mm (4.5 in)
2019
88.9 mm (3.5 in)
2020
78.5 mm (3.1 in)
2021
51.1 mm (2.0 in)
Longest dry spell (CDD)
The longest dry spell of the year at Chatham, 1972 to 2021. The record is 37 days in 1995, marked on the chart; the median year is 17 days.
Longest dry spell (CDD) at Chatham by year
Year
Longest dry spell (CDD)
1972
11 days
1973
17 days
1974
14 days
1975
22 days
1976
12 days
1977
16 days
1978
23 days
1979
22 days
1980
19 days
1981
12 days
1982
21 days
1983
20 days
1984
17 days
1985
13 days
1986
13 days
1987
16 days
1988
12 days
1989
17 days
1990
15 days
1991
14 days
1992
13 days
1993
27 days
1994
18 days
1995
37 days
1996
16 days
1997
17 days
1998
19 days
1999
19 days
2000
14 days
2001
28 days
2002
22 days
2003
16 days
2004
19 days
2005
31 days
2006
19 days
2007
20 days
2008
11 days
2009
14 days
2010
13 days
2011
16 days
2012
20 days
2013
17 days
2014
19 days
2015
25 days
2016
10 days
2017
19 days
2018
18 days
2019
14 days
2020
15 days
2021
16 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
33 years with a frost
Across 33 years with a frost, the median last spring frost at Chatham falls on 9 April and the median first autumn frost on 19 November, which leaves a median of 221 days between them.
Fitted over all years, the growing season changes by +3.3 days per decade at this station.
Frost dates and growing season at Chatham
Measure
Median, all years
Earliest period
Recent period (1976 to 2020)
Recent against earliest
Fitted trend
Last spring frost
9 April
n/a
8 April
n/a
-1.9 days per decade
First autumn frost
19 November
n/a
19 November
n/a
+1.4 days per decade
Growing days
221 days
n/a
222 days
n/a
+3.3 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
43 years, 1973 to 2020
A day with at least 67.5 mm (2.7 in) of rain is expected about once in 2 years. A day with at least 119.5 mm (4.7 in) of rain is expected about once in 100 years.
Rainfall return levels at Chatham: the daily rain expected about once in a given number of years
Expected about once in
A day with at least
Note
2 years
67.5 mm (2.7 in)
5 years
82.5 mm (3.2 in)
10 years
92.0 mm (3.6 in)
25 years
103.5 mm (4.1 in)
50 years
111.6 mm (4.4 in)
Longer than the 43 years of record
100 years
119.5 mm (4.7 in)
Longer than the 43 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, 43 years of values from 1973 to 2020.
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: 114.8 mm (4.5 in) in 1982; 100.1 mm (3.9 in) in 2007; 96.8 mm (3.8 in) in 1989.
Download the Data
Data for Chatham standing records by year: CSV or JSON. Field meanings are on the data page.
Data for Chatham 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.