Record envelope, standing records and threshold days for South Weymouth NAS (USW00014790), Massachusetts, United States, with 52 years of record.
Key Facts for South Weymouth NAS
South Weymouth NAS (USW00014790) is a weather station in Massachusetts, United States at 42.15 latitude and -70.93 longitude, 48 m (157 ft) above sea level.
The station reports from 1945 to 1996, 52 years of record.
1,464 records set at South Weymouth NAS still stand.
Records are tracked for tmax, tmin, prcp, snow, snwd: an element needs 30 years of data to be eligible.
South Weymouth NAS set a monthly record daily precipitation of 111.5 mm (4.4 in) on 18 September 1996.
About the Station
Location: Massachusetts, United States, 42.15 latitude, -70.93 longitude.
Elevation: 48 m (157 ft).
Period of record: 1945 to 1996, 52 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 South Weymouth NAS. 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 South Weymouth NAS, with 2026 drawn through them
Month
Highest record high
Lowest record low
2026 highest maximum
2026 lowest minimum
Jan
21.1 C (70.0 F)
-26.1 C (-15.0 F)
n/a
n/a
Feb
20.0 C (68.0 F)
-23.3 C (-9.9 F)
n/a
n/a
Mar
27.2 C (81.0 F)
-16.7 C (1.9 F)
n/a
n/a
Apr
33.9 C (93.0 F)
-9.4 C (15.1 F)
n/a
n/a
May
35.6 C (96.1 F)
-2.2 C (28.0 F)
n/a
n/a
Jun
37.8 C (100.0 F)
3.3 C (37.9 F)
n/a
n/a
Jul
38.3 C (100.9 F)
7.2 C (45.0 F)
n/a
n/a
Aug
38.9 C (102.0 F)
2.8 C (37.0 F)
n/a
n/a
Sep
35.6 C (96.1 F)
-0.6 C (30.9 F)
n/a
n/a
Oct
31.1 C (88.0 F)
-7.8 C (18.0 F)
n/a
n/a
Nov
27.2 C (81.0 F)
-14.4 C (6.1 F)
n/a
n/a
Dec
23.3 C (73.9 F)
-23.3 C (-9.9 F)
n/a
n/a
Which Years Hold Standing Records
1,464 standing records
Year with most
1,464 records at South Weymouth NAS still stand. 1965 holds the most, with 49.
Standing records at South Weymouth NAS by the year they were set
Year set
Standing records
1945
34
1954
29
1955
28
1956
41
1957
31
1958
27
1959
31
1960
22
1961
44
1962
46
1963
47
1964
47
1965
49
1966
34
1967
46
1968
42
1969
34
1970
24
1971
31
1972
28
1973
23
1974
28
1975
22
1976
45
1977
25
1978
25
1979
43
1980
26
1981
30
1982
24
1983
20
1984
36
1985
22
1986
28
1987
32
1988
48
1989
37
1990
45
1991
40
1992
46
1993
29
1994
24
1995
30
1996
21
All-Time Record Progression
1 new records
1 all-time records were set at South Weymouth NAS between 11 January 1996 and 11 January 1996. Each dot is a new record.
When South Weymouth NAS set new all-time records
Date
Kind
Detail
1996-01-11
Record snow depth
Record snow depth 101.6 cm (40.0 in)
Wettest Day of Each Month
Aug: 158.2 mm (6.2 in)
The wettest day on record for each calendar month at South Weymouth NAS. The most was 158.2 mm (6.2 in) on 18 August 1955.
Record daily precipitation for each month at South Weymouth NAS
Month
Record daily precipitation (mm)
Date
Jan
67.3 mm (2.6 in)
15 January 1958
Feb
78.7 mm (3.1 in)
13 February 1985
Mar
98.6 mm (3.9 in)
18 March 1968
Apr
71.9 mm (2.8 in)
17 April 1954
May
74.2 mm (2.9 in)
25 May 1967
Jun
61.2 mm (2.4 in)
6 June 1982
Jul
69.1 mm (2.7 in)
24 July 1988
Aug
158.2 mm (6.2 in)
18 August 1955
Sep
111.5 mm (4.4 in)
18 September 1996
Oct
71.6 mm (2.8 in)
31 October 1991
Nov
78.7 mm (3.1 in)
25 November 1983
Dec
69.3 mm (2.7 in)
5 December 1993
Period of Record Coverage
1945 to 1996
Complete yearUnder 90 percent of days
45 years of record at South Weymouth NAS, 1945 to 1996. 4 years have data for under 90 percent of days and are left out of rankings: 1945, 1949, 1954, 1996.
Cooler than the station meanWarmer than the station mean
One stripe for each of 39 complete years at South Weymouth NAS, 1955 to 1995. Blue stripes are years cooler than the station's own mean of 10.0 C (50.1 F); red stripes are warmer. The coolest year was 1962, at 8.6 C (47.5 F), and the warmest was 1995, at 11.1 C (51.9 F). The strongest colour marks a difference of 1.5 C (2.7 F).
Annual mean temperature at South Weymouth NAS as warming stripes, 1955 to 1995
Year
Annual mean temperature
Difference from the station mean
1955
9.9 C
-0.11 C
1956
9.4 C
-0.61 C
1957
10.5 C
+0.41 C
1958
9.3 C
-0.79 C
1959
10.3 C
+0.28 C
1960
10.0 C
-0.06 C
1961
9.4 C
-0.63 C
1962
8.6 C
-1.44 C
1963
9.0 C
-1.07 C
1965
9.2 C
-0.86 C
1966
9.4 C
-0.62 C
1967
9.7 C
-0.32 C
1968
9.5 C
-0.50 C
1969
9.8 C
-0.23 C
1970
9.9 C
-0.15 C
1971
10.4 C
+0.38 C
1972
9.5 C
-0.50 C
1973
10.9 C
+0.88 C
1974
10.1 C
+0.01 C
1975
10.8 C
+0.78 C
1976
10.2 C
+0.13 C
1977
10.8 C
+0.73 C
1978
9.0 C
-1.05 C
1979
10.4 C
+0.34 C
1980
9.9 C
-0.13 C
1981
10.0 C
+0.00 C
1982
10.0 C
-0.09 C
1983
10.7 C
+0.63 C
1984
10.9 C
+0.83 C
1985
10.4 C
+0.37 C
1986
9.7 C
-0.38 C
1987
10.3 C
+0.22 C
1988
10.7 C
+0.69 C
1989
10.1 C
+0.04 C
1990
10.8 C
+0.72 C
1991
10.7 C
+0.65 C
1992
9.4 C
-0.61 C
1994
10.9 C
+0.90 C
1995
11.1 C
+1.01 C
The annual mean temperature here has risen by 0.3 C (0.1 to 0.4) per decade over 1955 to 1995. In Fahrenheit: 0.5 F (0.2 to 0.8) per decade. The slope is a straight line fitted to 39 complete years; the brackets give its 95 percent interval.
Fitted temperature trends per decade at South Weymouth NAS
Measure
Per decade (C)
Per decade (F)
Period
Complete years
Reading
Annual mean temperature
0.3 C (0.1 to 0.4) per decade
0.5 F (0.2 to 0.8) per decade
1955 to 1995
39
Rise
Mean daily maximum
0.4 C (0.2 to 0.5) per decade
0.7 F (0.4 to 0.9) per decade
1955 to 1995
39
Rise
Mean daily minimum
0.18 C (-0.04 to 0.39) per decade
0.3 F (-0.1 to 0.7) per decade
1955 to 1995
39
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
1945 to 1996
Yearly extremes at South Weymouth NAS: the record and the median year
Measure
Record
Year of the record
Median year
Years with a value
Hottest day (TXx)
38.9 C (102.0 F)
1975
35.0 C (95.0 F)
45
Coldest night (TNn)
-26.1 C (-15.0 F)
1981
-18.9 C (-2.0 F)
45
Wettest day (Rx1day)
158.2 mm (6.2 in)
1955
67.3 mm (2.6 in)
44
Wettest five days (Rx5day)
315.2 mm (12.4 in)
1955
107.7 mm (4.2 in)
44
Longest dry spell (CDD)
27 days
1959
17 days
44
Hottest day (TXx)
The hottest day of the year at South Weymouth NAS, 1945 to 1996. The record is 38.9 C (102.0 F) in 1975, marked on the chart; the median year is 35.0 C (95.0 F).
Hottest day (TXx) at South Weymouth NAS by year
Year
Hottest day (TXx)
1945
33.9 C (93.0 F)
1949
17.2 C (63.0 F)
1954
35.0 C (95.0 F)
1955
37.8 C (100.0 F)
1956
35.0 C (95.0 F)
1957
35.0 C (95.0 F)
1958
33.3 C (91.9 F)
1959
34.4 C (93.9 F)
1960
32.2 C (90.0 F)
1961
33.3 C (91.9 F)
1962
33.3 C (91.9 F)
1963
36.1 C (97.0 F)
1964
36.1 C (97.0 F)
1965
34.4 C (93.9 F)
1966
36.7 C (98.1 F)
1967
35.6 C (96.1 F)
1968
36.1 C (97.0 F)
1969
35.0 C (95.0 F)
1970
34.4 C (93.9 F)
1971
34.4 C (93.9 F)
1972
33.3 C (91.9 F)
1973
34.4 C (93.9 F)
1974
33.9 C (93.0 F)
1975
38.9 C (102.0 F)
1976
33.3 C (91.9 F)
1977
37.2 C (99.0 F)
1978
35.6 C (96.1 F)
1979
33.9 C (93.0 F)
1980
36.7 C (98.1 F)
1981
35.6 C (96.1 F)
1982
36.7 C (98.1 F)
1983
35.6 C (96.1 F)
1984
36.1 C (97.0 F)
1985
34.4 C (93.9 F)
1986
34.4 C (93.9 F)
1987
36.1 C (97.0 F)
1988
38.3 C (100.9 F)
1989
35.6 C (96.1 F)
1990
33.9 C (93.0 F)
1991
37.8 C (100.0 F)
1992
34.4 C (93.9 F)
1993
37.8 C (100.0 F)
1994
36.7 C (98.1 F)
1995
36.7 C (98.1 F)
1996
35.6 C (96.1 F)
Coldest night (TNn)
The coldest night of the year at South Weymouth NAS, 1945 to 1996. The record is -26.1 C (-15.0 F) in 1981, marked on the chart; the median year is -18.9 C (-2.0 F).
Coldest night (TNn) at South Weymouth NAS by year
Year
Coldest night (TNn)
1945
-13.3 C (8.1 F)
1949
3.9 C (39.0 F)
1954
-13.9 C (7.0 F)
1955
-19.4 C (-2.9 F)
1956
-15.0 C (5.0 F)
1957
-24.4 C (-11.9 F)
1958
-20.0 C (-4.0 F)
1959
-18.9 C (-2.0 F)
1960
-17.2 C (1.0 F)
1961
-23.3 C (-9.9 F)
1962
-22.2 C (-8.0 F)
1963
-21.7 C (-7.1 F)
1964
-23.3 C (-9.9 F)
1965
-20.6 C (-5.1 F)
1966
-18.9 C (-2.0 F)
1967
-20.0 C (-4.0 F)
1968
-21.7 C (-7.1 F)
1969
-13.9 C (7.0 F)
1970
-24.4 C (-11.9 F)
1971
-22.8 C (-9.0 F)
1972
-18.9 C (-2.0 F)
1973
-16.1 C (3.0 F)
1974
-17.8 C (0.0 F)
1975
-17.8 C (0.0 F)
1976
-18.9 C (-2.0 F)
1977
-18.3 C (-0.9 F)
1978
-16.7 C (1.9 F)
1979
-20.0 C (-4.0 F)
1980
-23.3 C (-9.9 F)
1981
-26.1 C (-15.0 F)
1982
-21.1 C (-6.0 F)
1983
-18.9 C (-2.0 F)
1984
-22.2 C (-8.0 F)
1985
-16.7 C (1.9 F)
1986
-18.3 C (-0.9 F)
1987
-20.6 C (-5.1 F)
1988
-22.8 C (-9.0 F)
1989
-19.4 C (-2.9 F)
1990
-17.8 C (0.0 F)
1991
-18.9 C (-2.0 F)
1992
-16.7 C (1.9 F)
1993
-16.1 C (3.0 F)
1994
-20.0 C (-4.0 F)
1995
-17.2 C (1.0 F)
1996
-17.8 C (0.0 F)
Wettest day (Rx1day)
The wettest day of the year at South Weymouth NAS, 1945 to 1996. The record is 158.2 mm (6.2 in) in 1955, marked on the chart; the median year is 67.3 mm (2.6 in).
Wettest day (Rx1day) at South Weymouth NAS by year
Year
Wettest day (Rx1day)
1945
67.6 mm (2.7 in)
1949
n/a
1954
71.9 mm (2.8 in)
1955
158.2 mm (6.2 in)
1956
53.3 mm (2.1 in)
1957
46.2 mm (1.8 in)
1958
67.3 mm (2.6 in)
1959
41.7 mm (1.6 in)
1960
83.1 mm (3.3 in)
1961
99.8 mm (3.9 in)
1962
71.1 mm (2.8 in)
1963
43.7 mm (1.7 in)
1964
38.4 mm (1.5 in)
1965
48.5 mm (1.9 in)
1966
90.2 mm (3.6 in)
1967
74.2 mm (2.9 in)
1968
98.6 mm (3.9 in)
1969
67.1 mm (2.6 in)
1970
67.8 mm (2.7 in)
1971
57.2 mm (2.3 in)
1972
95.5 mm (3.8 in)
1973
71.9 mm (2.8 in)
1974
62.5 mm (2.5 in)
1975
51.1 mm (2.0 in)
1976
80.0 mm (3.1 in)
1977
51.6 mm (2.0 in)
1978
72.9 mm (2.9 in)
1979
60.5 mm (2.4 in)
1980
56.4 mm (2.2 in)
1981
59.2 mm (2.3 in)
1982
61.2 mm (2.4 in)
1983
78.7 mm (3.1 in)
1984
73.2 mm (2.9 in)
1985
78.7 mm (3.1 in)
1986
58.7 mm (2.3 in)
1987
59.7 mm (2.4 in)
1988
69.6 mm (2.7 in)
1989
63.0 mm (2.5 in)
1990
66.0 mm (2.6 in)
1991
71.6 mm (2.8 in)
1992
62.7 mm (2.5 in)
1993
69.3 mm (2.7 in)
1994
64.5 mm (2.5 in)
1995
67.3 mm (2.6 in)
1996
111.5 mm (4.4 in)
Wettest five days (Rx5day)
The wettest five days of the year at South Weymouth NAS, 1945 to 1996. The record is 315.2 mm (12.4 in) in 1955, marked on the chart; the median year is 107.7 mm (4.2 in).
Wettest five days (Rx5day) at South Weymouth NAS by year
Year
Wettest five days (Rx5day)
1945
135.9 mm (5.4 in)
1949
n/a
1954
94.0 mm (3.7 in)
1955
315.2 mm (12.4 in)
1956
113.1 mm (4.5 in)
1957
124.7 mm (4.9 in)
1958
77.0 mm (3.0 in)
1959
67.9 mm (2.7 in)
1960
97.6 mm (3.8 in)
1961
178.3 mm (7.0 in)
1962
175.2 mm (6.9 in)
1963
89.2 mm (3.5 in)
1964
64.7 mm (2.5 in)
1965
55.9 mm (2.2 in)
1966
92.7 mm (3.6 in)
1967
94.8 mm (3.7 in)
1968
147.6 mm (5.8 in)
1969
117.7 mm (4.6 in)
1970
92.3 mm (3.6 in)
1971
89.1 mm (3.5 in)
1972
95.5 mm (3.8 in)
1973
103.1 mm (4.1 in)
1974
67.3 mm (2.6 in)
1975
105.9 mm (4.2 in)
1976
139.4 mm (5.5 in)
1977
82.1 mm (3.2 in)
1978
114.1 mm (4.5 in)
1979
114.9 mm (4.5 in)
1980
74.1 mm (2.9 in)
1981
109.5 mm (4.3 in)
1982
166.8 mm (6.6 in)
1983
103.6 mm (4.1 in)
1984
153.2 mm (6.0 in)
1985
147.5 mm (5.8 in)
1986
95.0 mm (3.7 in)
1987
128.1 mm (5.0 in)
1988
133.9 mm (5.3 in)
1989
122.0 mm (4.8 in)
1990
86.8 mm (3.4 in)
1991
140.5 mm (5.5 in)
1992
114.5 mm (4.5 in)
1993
84.5 mm (3.3 in)
1994
122.2 mm (4.8 in)
1995
85.3 mm (3.4 in)
1996
140.2 mm (5.5 in)
Longest dry spell (CDD)
The longest dry spell of the year at South Weymouth NAS, 1945 to 1996. The record is 27 days in 1959, marked on the chart; the median year is 17 days.
Longest dry spell (CDD) at South Weymouth NAS by year
Year
Longest dry spell (CDD)
1945
10 days
1949
n/a
1954
16 days
1955
18 days
1956
15 days
1957
14 days
1958
21 days
1959
27 days
1960
18 days
1961
17 days
1962
16 days
1963
16 days
1964
20 days
1965
22 days
1966
14 days
1967
21 days
1968
22 days
1969
16 days
1970
17 days
1971
14 days
1972
10 days
1973
15 days
1974
15 days
1975
22 days
1976
23 days
1977
22 days
1978
22 days
1979
12 days
1980
26 days
1981
14 days
1982
19 days
1983
11 days
1984
19 days
1985
16 days
1986
18 days
1987
22 days
1988
15 days
1989
17 days
1990
20 days
1991
12 days
1992
15 days
1993
13 days
1994
16 days
1995
20 days
1996
12 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
39 years with a frost
Across 39 years with a frost, the median last spring frost at South Weymouth NAS falls on 23 April and the median first autumn frost on 16 October, which leaves a median of 178 days between them.
Fitted over all years, the growing season changes by -0.4 days per decade at this station.
Frost dates and growing season at South Weymouth NAS
Measure
Median, all years
Earliest period
Recent period (1965 to 1995)
Recent against earliest
Fitted trend
Last spring frost
23 April
n/a
23 April
n/a
-0.1 days per decade
First autumn frost
16 October
n/a
16 October
n/a
-0.5 days per decade
Growing days
178 days
n/a
176 days
n/a
-0.4 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
41 years, 1955 to 1995
A day with at least 64.8 mm (2.6 in) of rain is expected about once in 2 years. A day with at least 133.2 mm (5.2 in) of rain is expected about once in 100 years.
Rainfall return levels at South Weymouth NAS: the daily rain expected about once in a given number of years
Expected about once in
A day with at least
Note
2 years
64.8 mm (2.6 in)
5 years
81.2 mm (3.2 in)
10 years
92.8 mm (3.7 in)
25 years
108.3 mm (4.3 in)
50 years
120.5 mm (4.7 in)
Longer than the 41 years of record
100 years
133.2 mm (5.2 in)
Longer than the 41 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, 41 years of values from 1955 to 1995.
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: 158.2 mm (6.2 in) in 1955; 99.8 mm (3.9 in) in 1961; 98.6 mm (3.9 in) in 1968.
Download the Data
Data for South Weymouth NAS standing records by year: CSV or JSON. Field meanings are on the data page.
Data for South Weymouth NAS 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.