Record highRecord low2026 daily maximum2026 daily minimum
The band shows the record high and record low for each calendar day at Iwakuni. 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 Iwakuni, with 2026 drawn through them
Month
Highest record high
Lowest record low
2026 highest maximum
2026 lowest minimum
Jan
19.4 C (66.9 F)
-6.7 C (19.9 F)
n/a
n/a
Feb
21.1 C (70.0 F)
-7.2 C (19.0 F)
n/a
n/a
Mar
23.3 C (73.9 F)
-4.4 C (24.1 F)
n/a
n/a
Apr
29.4 C (84.9 F)
0.6 C (33.1 F)
n/a
n/a
May
30.6 C (87.1 F)
5.0 C (41.0 F)
n/a
n/a
Jun
32.8 C (91.0 F)
11.1 C (52.0 F)
n/a
n/a
Jul
36.1 C (97.0 F)
13.3 C (55.9 F)
n/a
n/a
Aug
37.8 C (100.0 F)
16.7 C (62.1 F)
n/a
n/a
Sep
35.0 C (95.0 F)
10.0 C (50.0 F)
n/a
n/a
Oct
30.6 C (87.1 F)
2.8 C (37.0 F)
n/a
n/a
Nov
27.2 C (81.0 F)
0.0 C (32.0 F)
n/a
n/a
Dec
21.1 C (70.0 F)
-3.9 C (25.0 F)
n/a
n/a
Which Years Hold Standing Records
1,464 standing records
Year with most
1,464 records at Iwakuni still stand. 1966 holds the most, with 55.
Standing records at Iwakuni by the year they were set
Year set
Standing records
1954
12
1955
26
1956
52
1957
40
1958
37
1959
44
1960
44
1961
52
1962
32
1963
34
1964
35
1965
35
1966
55
1967
33
1968
27
1969
42
1970
24
1971
19
1972
30
1973
40
1974
21
1975
29
1976
46
1977
47
1978
17
1979
20
1980
41
1981
34
1982
26
1983
35
1984
37
1985
28
1986
15
1987
28
1988
14
1989
20
1990
29
1991
22
1992
13
1993
28
1994
27
1995
15
1996
20
1997
22
1998
26
2001
11
2002
28
2003
15
2004
21
2005
16
Wettest Day of Each Month
Jun: 219.2 mm (8.6 in)
The wettest day on record for each calendar month at Iwakuni. The most was 219.2 mm (8.6 in) on 26 June 1981.
Record daily precipitation for each month at Iwakuni
Month
Record daily precipitation (mm)
Date
Jan
59.7 mm (2.4 in)
24 January 1973
Feb
74.2 mm (2.9 in)
19 February 1990
Mar
74.9 mm (2.9 in)
11 March 1988
Apr
98.6 mm (3.9 in)
11 April 1985
May
158.2 mm (6.2 in)
26 May 1965
Jun
219.2 mm (8.6 in)
26 June 1981
Jul
183.6 mm (7.2 in)
27 July 1993
Aug
167.9 mm (6.6 in)
8 August 1992
Sep
199.9 mm (7.9 in)
6 September 2005
Oct
167.6 mm (6.6 in)
4 October 1955
Nov
95.5 mm (3.8 in)
29 November 1982
Dec
64.0 mm (2.5 in)
19 December 1979
Period of Record Coverage
1954 to 2005
Complete yearUnder 90 percent of days
50 years of record at Iwakuni, 1954 to 2005. 1 years have data for under 90 percent of days and are left out of rankings: 1954.
Cooler than the station meanWarmer than the station mean
One stripe for each of 47 complete years at Iwakuni, 1955 to 2005. Blue stripes are years cooler than the station's own mean of 15.7 C (60.3 F); red stripes are warmer. The coolest year was 1965, at 14.9 C (58.8 F), and the warmest was 1998, at 16.9 C (62.3 F). The strongest colour marks a difference of 1.2 C (2.2 F).
Annual mean temperature at Iwakuni as warming stripes, 1955 to 2005
Year
Annual mean temperature
Difference from the station mean
1955
15.9 C
+0.20 C
1956
15.1 C
-0.68 C
1957
15.3 C
-0.44 C
1958
15.9 C
+0.12 C
1959
16.4 C
+0.68 C
1960
16.1 C
+0.40 C
1961
16.4 C
+0.66 C
1962
15.4 C
-0.31 C
1963
15.1 C
-0.67 C
1964
16.3 C
+0.55 C
1965
14.9 C
-0.84 C
1966
15.2 C
-0.49 C
1967
15.7 C
-0.08 C
1968
15.2 C
-0.50 C
1969
15.4 C
-0.33 C
1970
15.3 C
-0.42 C
1972
15.6 C
-0.17 C
1973
16.0 C
+0.22 C
1974
15.5 C
-0.28 C
1975
16.4 C
+0.70 C
1976
15.4 C
-0.31 C
1977
15.7 C
-0.05 C
1978
15.9 C
+0.20 C
1979
16.0 C
+0.26 C
1980
14.9 C
-0.81 C
1981
15.0 C
-0.73 C
1982
15.5 C
-0.25 C
1983
16.2 C
+0.50 C
1984
15.5 C
-0.25 C
1985
16.6 C
+0.91 C
1986
15.2 C
-0.52 C
1987
15.6 C
-0.10 C
1988
15.4 C
-0.38 C
1989
15.7 C
-0.07 C
1990
16.2 C
+0.48 C
1991
15.7 C
+0.01 C
1992
15.9 C
+0.21 C
1993
15.4 C
-0.33 C
1994
16.6 C
+0.91 C
1995
15.6 C
-0.15 C
1996
15.6 C
-0.18 C
1997
16.1 C
+0.38 C
1998
16.9 C
+1.13 C
2001
15.9 C
+0.20 C
2002
16.1 C
+0.40 C
2003
15.8 C
+0.05 C
2005
16.0 C
+0.24 C
The fitted trend in annual mean temperature here over 1955 to 2005 is 0.08 C (-0.01 to 0.18) per decade. The interval includes zero, so the trend is not clearly different from zero. In Fahrenheit: 0.15 F (-0.03 to 0.32) per decade. The slope is a straight line fitted to 47 complete years; the brackets give its 95 percent interval.
Fitted temperature trends per decade at Iwakuni
Measure
Per decade (C)
Per decade (F)
Period
Complete years
Reading
Annual mean temperature
0.08 C (-0.01 to 0.18) per decade
0.15 F (-0.03 to 0.32) per decade
1955 to 2005
47
Not clearly different from zero
Mean daily maximum
0.10 C (-0.01 to 0.21) per decade
0.18 F (-0.01 to 0.37) per decade
1955 to 2005
47
Not clearly different from zero
Mean daily minimum
0.07 C (-0.03 to 0.17) per decade
0.1 F (-0.1 to 0.3) per decade
1955 to 2005
47
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
1954 to 2005
Yearly extremes at Iwakuni: the record and the median year
Measure
Record
Year of the record
Median year
Years with a value
Hottest day (TXx)
37.8 C (100.0 F)
1974
35.0 C (95.0 F)
50
Coldest night (TNn)
-7.2 C (19.0 F)
1977
-3.9 C (25.0 F)
50
Wettest day (Rx1day)
219.2 mm (8.6 in)
1981
113.8 mm (4.5 in)
50
Wettest five days (Rx5day)
330.2 mm (13.0 in)
1979
198.5 mm (7.8 in)
50
Longest dry spell (CDD)
41 days
1973
20 days
50
Hottest day (TXx)
The hottest day of the year at Iwakuni, 1954 to 2005. The record is 37.8 C (100.0 F) in 1974, marked on the chart; the median year is 35.0 C (95.0 F).
Hottest day (TXx) at Iwakuni by year
Year
Hottest day (TXx)
1954
28.9 C (84.0 F)
1955
35.6 C (96.1 F)
1956
35.6 C (96.1 F)
1957
35.0 C (95.0 F)
1958
33.3 C (91.9 F)
1959
35.0 C (95.0 F)
1960
36.7 C (98.1 F)
1961
35.0 C (95.0 F)
1962
35.6 C (96.1 F)
1963
34.4 C (93.9 F)
1964
34.4 C (93.9 F)
1965
33.9 C (93.0 F)
1966
33.3 C (91.9 F)
1967
37.2 C (99.0 F)
1968
33.3 C (91.9 F)
1969
36.1 C (97.0 F)
1970
35.0 C (95.0 F)
1971
35.0 C (95.0 F)
1972
34.4 C (93.9 F)
1973
35.6 C (96.1 F)
1974
37.8 C (100.0 F)
1975
34.4 C (93.9 F)
1976
35.6 C (96.1 F)
1977
35.0 C (95.0 F)
1978
35.6 C (96.1 F)
1979
33.9 C (93.0 F)
1980
33.9 C (93.0 F)
1981
33.9 C (93.0 F)
1982
32.2 C (90.0 F)
1983
37.2 C (99.0 F)
1984
36.1 C (97.0 F)
1985
35.0 C (95.0 F)
1986
35.0 C (95.0 F)
1987
33.9 C (93.0 F)
1988
35.0 C (95.0 F)
1989
32.2 C (90.0 F)
1990
35.0 C (95.0 F)
1991
35.0 C (95.0 F)
1992
35.0 C (95.0 F)
1993
32.8 C (91.0 F)
1994
36.1 C (97.0 F)
1995
36.1 C (97.0 F)
1996
35.0 C (95.0 F)
1997
33.3 C (91.9 F)
1998
34.4 C (93.9 F)
2001
33.9 C (93.0 F)
2002
35.6 C (96.1 F)
2003
32.8 C (91.0 F)
2004
35.0 C (95.0 F)
2005
35.6 C (96.1 F)
Coldest night (TNn)
The coldest night of the year at Iwakuni, 1954 to 2005. The record is -7.2 C (19.0 F) in 1977, marked on the chart; the median year is -3.9 C (25.0 F).
Coldest night (TNn) at Iwakuni by year
Year
Coldest night (TNn)
1954
0.0 C (32.0 F)
1955
-3.9 C (25.0 F)
1956
-3.3 C (26.1 F)
1957
-3.9 C (25.0 F)
1958
-3.9 C (25.0 F)
1959
-3.9 C (25.0 F)
1960
-3.9 C (25.0 F)
1961
-3.9 C (25.0 F)
1962
-2.2 C (28.0 F)
1963
-5.0 C (23.0 F)
1964
-2.2 C (28.0 F)
1965
-3.9 C (25.0 F)
1966
-3.3 C (26.1 F)
1967
-6.7 C (19.9 F)
1968
-2.8 C (27.0 F)
1969
-3.3 C (26.1 F)
1970
-3.9 C (25.0 F)
1971
-2.8 C (27.0 F)
1972
-1.1 C (30.0 F)
1973
-3.3 C (26.1 F)
1974
-3.9 C (25.0 F)
1975
-3.3 C (26.1 F)
1976
-3.9 C (25.0 F)
1977
-7.2 C (19.0 F)
1978
-3.3 C (26.1 F)
1979
-1.7 C (28.9 F)
1980
-3.9 C (25.0 F)
1981
-7.2 C (19.0 F)
1982
-2.2 C (28.0 F)
1983
-2.8 C (27.0 F)
1984
-5.0 C (23.0 F)
1985
-3.9 C (25.0 F)
1986
-3.9 C (25.0 F)
1987
-2.2 C (28.0 F)
1988
-3.9 C (25.0 F)
1989
-1.1 C (30.0 F)
1990
-5.0 C (23.0 F)
1991
-3.9 C (25.0 F)
1992
-2.2 C (28.0 F)
1993
-2.2 C (28.0 F)
1994
-2.2 C (28.0 F)
1995
-2.8 C (27.0 F)
1996
-5.0 C (23.0 F)
1997
-3.9 C (25.0 F)
1998
-3.9 C (25.0 F)
2001
-4.4 C (24.1 F)
2002
-2.2 C (28.0 F)
2003
-4.4 C (24.1 F)
2004
-5.0 C (23.0 F)
2005
-3.9 C (25.0 F)
Wettest day (Rx1day)
The wettest day of the year at Iwakuni, 1954 to 2005. The record is 219.2 mm (8.6 in) in 1981, marked on the chart; the median year is 113.8 mm (4.5 in).
Wettest day (Rx1day) at Iwakuni by year
Year
Wettest day (Rx1day)
1954
82.8 mm (3.3 in)
1955
167.6 mm (6.6 in)
1956
122.9 mm (4.8 in)
1957
138.4 mm (5.4 in)
1958
115.8 mm (4.6 in)
1959
94.5 mm (3.7 in)
1960
163.3 mm (6.4 in)
1961
94.7 mm (3.7 in)
1962
97.5 mm (3.8 in)
1963
137.2 mm (5.4 in)
1964
112.3 mm (4.4 in)
1965
198.6 mm (7.8 in)
1966
86.1 mm (3.4 in)
1967
137.4 mm (5.4 in)
1968
101.1 mm (4.0 in)
1969
126.5 mm (5.0 in)
1970
134.6 mm (5.3 in)
1971
93.5 mm (3.7 in)
1972
154.2 mm (6.1 in)
1973
139.2 mm (5.5 in)
1974
89.4 mm (3.5 in)
1975
98.3 mm (3.9 in)
1976
68.1 mm (2.7 in)
1977
91.7 mm (3.6 in)
1978
99.8 mm (3.9 in)
1979
119.4 mm (4.7 in)
1980
152.4 mm (6.0 in)
1981
219.2 mm (8.6 in)
1982
112.5 mm (4.4 in)
1983
151.4 mm (6.0 in)
1984
76.2 mm (3.0 in)
1985
115.1 mm (4.5 in)
1986
101.6 mm (4.0 in)
1987
108.2 mm (4.3 in)
1988
119.9 mm (4.7 in)
1989
94.0 mm (3.7 in)
1990
158.5 mm (6.2 in)
1991
109.7 mm (4.3 in)
1992
167.9 mm (6.6 in)
1993
183.6 mm (7.2 in)
1994
85.9 mm (3.4 in)
1995
108.2 mm (4.3 in)
1996
91.7 mm (3.6 in)
1997
199.4 mm (7.9 in)
1998
148.1 mm (5.8 in)
2001
93.5 mm (3.7 in)
2002
112.5 mm (4.4 in)
2003
80.8 mm (3.2 in)
2004
126.0 mm (5.0 in)
2005
199.9 mm (7.9 in)
Wettest five days (Rx5day)
The wettest five days of the year at Iwakuni, 1954 to 2005. The record is 330.2 mm (13.0 in) in 1979, marked on the chart; the median year is 198.5 mm (7.8 in).
Wettest five days (Rx5day) at Iwakuni by year
Year
Wettest five days (Rx5day)
1954
155.0 mm (6.1 in)
1955
259.0 mm (10.2 in)
1956
217.7 mm (8.6 in)
1957
199.1 mm (7.8 in)
1958
146.1 mm (5.8 in)
1959
138.9 mm (5.5 in)
1960
203.4 mm (8.0 in)
1961
177.9 mm (7.0 in)
1962
233.4 mm (9.2 in)
1963
198.3 mm (7.8 in)
1964
201.5 mm (7.9 in)
1965
318.4 mm (12.5 in)
1966
199.9 mm (7.9 in)
1967
245.8 mm (9.7 in)
1968
143.7 mm (5.7 in)
1969
254.0 mm (10.0 in)
1970
250.6 mm (9.9 in)
1971
181.9 mm (7.2 in)
1972
227.6 mm (9.0 in)
1973
160.9 mm (6.3 in)
1974
152.9 mm (6.0 in)
1975
232.7 mm (9.2 in)
1976
164.9 mm (6.5 in)
1977
175.5 mm (6.9 in)
1978
122.2 mm (4.8 in)
1979
330.2 mm (13.0 in)
1980
304.3 mm (12.0 in)
1981
321.1 mm (12.6 in)
1982
198.6 mm (7.8 in)
1983
278.1 mm (10.9 in)
1984
159.3 mm (6.3 in)
1985
311.4 mm (12.3 in)
1986
162.3 mm (6.4 in)
1987
164.9 mm (6.5 in)
1988
155.0 mm (6.1 in)
1989
145.3 mm (5.7 in)
1990
166.4 mm (6.6 in)
1991
240.8 mm (9.5 in)
1992
229.9 mm (9.1 in)
1993
327.6 mm (12.9 in)
1994
135.2 mm (5.3 in)
1995
290.9 mm (11.5 in)
1996
156.2 mm (6.1 in)
1997
252.8 mm (10.0 in)
1998
169.7 mm (6.7 in)
2001
177.5 mm (7.0 in)
2002
119.2 mm (4.7 in)
2003
138.3 mm (5.4 in)
2004
194.8 mm (7.7 in)
2005
238.8 mm (9.4 in)
Longest dry spell (CDD)
The longest dry spell of the year at Iwakuni, 1954 to 2005. The record is 41 days in 1973, marked on the chart; the median year is 20 days.
Longest dry spell (CDD) at Iwakuni by year
Year
Longest dry spell (CDD)
1954
23 days
1955
28 days
1956
24 days
1957
17 days
1958
15 days
1959
20 days
1960
16 days
1961
18 days
1962
19 days
1963
18 days
1964
34 days
1965
19 days
1966
15 days
1967
30 days
1968
15 days
1969
20 days
1970
15 days
1971
30 days
1972
16 days
1973
41 days
1974
20 days
1975
23 days
1976
18 days
1977
25 days
1978
28 days
1979
19 days
1980
18 days
1981
22 days
1982
14 days
1983
17 days
1984
23 days
1985
32 days
1986
40 days
1987
22 days
1988
22 days
1989
30 days
1990
24 days
1991
16 days
1992
15 days
1993
21 days
1994
24 days
1995
34 days
1996
17 days
1997
20 days
1998
31 days
2001
23 days
2002
21 days
2003
18 days
2004
20 days
2005
19 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
40 years with a frost
Across 40 years with a frost, the median last spring frost at Iwakuni falls on 11 March and the median first autumn frost on 17 December, which leaves a median of 282 days between them.
Fitted over all years, the growing season changes by +0.1 days per decade at this station.
Frost dates and growing season at Iwakuni
Measure
Median, all years
Earliest period
Recent period (1968 to 2005)
Recent against earliest
Fitted trend
Last spring frost
11 March
n/a
11 March
n/a
-0.1 days per decade
First autumn frost
17 December
n/a
18 December
n/a
0.0 days per decade
Growing days
282 days
n/a
282 days
n/a
+0.1 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
49 years, 1955 to 2005
A day with at least 117.2 mm (4.6 in) of rain is expected about once in 2 years. A day with at least 250.9 mm (9.9 in) of rain is expected about once in 100 years.
Rainfall return levels at Iwakuni: the daily rain expected about once in a given number of years
Expected about once in
A day with at least
Note
2 years
117.2 mm (4.6 in)
5 years
150.0 mm (5.9 in)
10 years
172.8 mm (6.8 in)
25 years
203.1 mm (8.0 in)
50 years
226.6 mm (8.9 in)
Longer than the 49 years of record
100 years
250.9 mm (9.9 in)
Longer than the 49 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, 49 years of values from 1955 to 2005.
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: 219.2 mm (8.6 in) in 1981; 199.9 mm (7.9 in) in 2005; 199.4 mm (7.9 in) in 1997.
Station Changes
No change in the annual mean temperature of this station was found against its neighbours.
Download the Data
Data for Iwakuni standing records by year: CSV or JSON. Field meanings are on the data page.
Data for Iwakuni 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.