Iwaki climate

Name: Iwaki
Address: JP

Iwaki is warmest in August, with average highs of 28 °C, and coldest in February, when nights average 1.1 °C. September is the wettest month (194 mm) and February the driest (61 mm). Figures are 1991–2020 climate normals.

Across a full year Iwaki averages 1,522 mm of rain, 65 days above 25 °C and 23 days below freezing.

Japan · population 357,309 · 1991–2020 normals

Temperature below 0 °C to above 30 °C Rain band height is that month’s share of the wettest month

Warmest month August 28 °C
Coldest month February 1.1 °C
Driest month February 61 mm
Wettest month September 194 mm
Least cloud December 41 % cloud
Hottest on record July 34 °C
Coldest on record February -7.7 °C
Warmest sea August 24 °C

What to expectIwaki through the year

Iwaki has a clear annual cycle: average daily highs run from 7.3 °C in February to 28 °C in August, a swing of 21 °C in mean temperature across the year.

Counted across a normal year, 65 days a year reach 25 °C, 10 of them reach 30 °C, 23 nights drop below freezing. The warmest reading in the 1991–2020 record is 34 °C, in July.

Rain is strongly seasonal. September averages 194 mm against 61 mm in February — 3.2 times as much. Planning around the dry months matters more here than planning around temperature.

The sea off Iwaki is warmest in August at 24 °C and coldest in March at 12 °C. Sea temperature lags the air by a month or two, which is why late summer swims warmer than early summer at the same air temperature.

Month by month

Month	Avg high	Rainfall	Cloud
January	6.8 °C	64 mm	42 %
February	7.3 °C	61 mm	49 %
March	10.6 °C	112 mm	56 %
April	15.5 °C	124 mm	60 %
May	19.9 °C	138 mm	67 %
June	22.7 °C	146 mm	79 %
July	26.1 °C	191 mm	79 %
August	27.5 °C	152 mm	72 %
September	24.5 °C	194 mm	71 %
October	19.5 °C	187 mm	62 %
November	14.6 °C	93 mm	50 %
December	9.4 °C	61 mm	41 %

Temperature month by month

Month	Avg high	Avg low	Mean	Record high	Record low	Days above 25 °C	Days above 30 °C	Days below 0 °C
January	6.8 °C	1.1 °C	3.5 °C	16.3 °C	-7.1 °C	0	0	9
February	7.3 °C	1.1 °C	3.7 °C	18.7 °C	-7.7 °C	0	0	9
March	10.6 °C	3.5 °C	6.6 °C	21.5 °C	-6.4 °C	0	0	3
April	15.5 °C	8.1 °C	11.5 °C	25.8 °C	-0.5 °C	0	0	0
May	19.9 °C	13.0 °C	16.1 °C	28.4 °C	5.4 °C	1	0	0
June	22.7 °C	17.0 °C	19.6 °C	31.6 °C	10.0 °C	6	0	0
July	26.1 °C	20.9 °C	23.2 °C	34.2 °C	13.8 °C	20	4	0
August	27.5 °C	22.4 °C	24.6 °C	33.9 °C	15.0 °C	25	6	0
September	24.5 °C	19.4 °C	21.6 °C	32.4 °C	10.8 °C	13	1	0
October	19.5 °C	14.1 °C	16.5 °C	28.0 °C	6.1 °C	1	0	0
November	14.6 °C	8.5 °C	11.1 °C	22.4 °C	-0.7 °C	0	0	0
December	9.4 °C	3.6 °C	6.0 °C	20.1 °C	-4.4 °C	0	0	2

Rain, sun and wind month by month

Month	Rainfall	Wet days	Daylight	Cloud cover	Humidity	Wind	Sea temp
January	64 mm	7	9.9 h/day	42 %	65 %	22 km/h	13.9 °C
February	61 mm	8	11 h/day	49 %	66 %	22 km/h	12.4 °C
March	112 mm	12	12 h/day	56 %	68 %	21 km/h	12.3 °C
April	124 mm	12	13 h/day	60 %	73 %	20 km/h	13.8 °C
May	138 mm	13	14 h/day	67 %	78 %	17 km/h	16.1 °C
June	146 mm	16	15 h/day	79 %	85 %	14 km/h	18.8 °C
July	191 mm	17	14 h/day	79 %	88 %	13 km/h	21.3 °C
August	152 mm	16	14 h/day	72 %	87 %	13 km/h	23.7 °C
September	194 mm	15	12 h/day	71 %	84 %	16 km/h	23.0 °C
October	187 mm	12	11 h/day	62 %	79 %	17 km/h	20.4 °C
November	93 mm	9	10 h/day	50 %	74 %	18 km/h	18.4 °C
December	61 mm	8	9.6 h/day	41 %	69 %	21 km/h	16.1 °C

How Iwaki compares

The same four figures for nearby destinations, so the numbers above have something to be read against. Summer high is the warmest month's average high; winter low is the coldest month's average low.

Destination	Summer high	Winter low	Rain per year	Days above 25 °C
Iwaki	28 °C	1.1 °C	1,522 mm	65
Hitachi · Japan	27 °C	1.6 °C	1,531 mm	59
Kōriyama · Japan	28 °C	-3.4 °C	1,232 mm	70
Hitachi-Naka · Japan	27 °C	1.3 °C	1,512 mm	63
Fukushima · Japan	28 °C	-3.6 °C	1,358 mm	74
Mito · Japan	28 °C	1.1 °C	1,541 mm	67
Utsunomiya · Japan	28 °C	-2.5 °C	1,399 mm	80

Where Iwaki ranks

Ranking	Position	Value
The coolest places in Asia in June	41st of 50	23 °C

Planning a trip? See the best time to visit Iwaki.

QuestionsCommon questions about Iwaki’s climate

When is the best time to visit Iwaki?

That depends on what you want, so the honest answer is a comparison rather than a single month. June, July, September sit closest to 20 °C on average, August is the warmest month and February the driest. The month-by-month table above has the full picture.

How hot does Iwaki get?

In August, the warmest month, daily highs average 28 °C. About 10 days a year pass 30 °C. The highest value in the 1991–2020 record is 34 °C.

How cold does it get in winter?

Nights average 1.1 °C in February, the coldest month. A normal year has 23 nights below freezing.

Which month is wettest in Iwaki?

September, averaging 194 mm over 15 days with rain. The driest month is February with 61 mm. The year as a whole averages 1,522 mm.

Are these figures a forecast?

No. They are 1991–2020 climate normals: the average of thirty years, which describes what a month is usually like in Iwaki rather than what any particular week will bring. Individual years can differ substantially from the normal.

Data sources and method

ERA5 / ERA5-Land reanalysis — Copernicus Climate Change Service (C3S), ECMWF. Copernicus Licence
Open-Meteo — Open-Meteo.com. CC BY 4.0
NOAA OISST v2.1 — NOAA Physical Sciences Laboratory. Public domain
GeoNames — GeoNames.org. CC BY 4.0

Normal period: 1991–2020
Data point: 37.050°, 140.883° (the coordinates the reanalysis values are taken for)
Dataset version: era5-1991-2020-scores1.1
Last processed: 1 August 2026

Measured values come from ERA5 reanalysis and are reproduced unchanged. Calculated by us: monthly rankings, daylight hours, beach and comfort scores. Full formulas are on the methodology page.

Contains modified Copernicus Climate Change Service information 2026. Neither the European Commission nor ECMWF is responsible for any use that may be made of the Copernicus information or data it contains.