Iwamizawa in Winter
In winter (December, January and February), Iwamizawa sees average daytime highs around -1°C and overnight lows near -9°C, with 160 mm of precipitation over about 39 wet days across the season. It is the coldest season of the year and the driest season of the year.
Over the season highs ease from about 2°C in early December to -0°C by late February. The sky is clear or mostly clear about 11% of the time across winter, and the air most often feels dry.
Winter is Iwamizawa's weakest season of the year to visit on our travel score. For the whole year in context, see Iwamizawa's year-round climate.
- Avg daytime high
- -1°C
- coldest season of the year
- Avg overnight low
- -9°C
- Precipitation
- 160 mm
- 39 wet days
- Avg wind
- 10 km/h
- Travel score
- 0.0
- weakest season of the year
- Months
- Dec · Jan · Feb
Temperature in Iwamizawa in Winter
Over the season highs ease from about 2°C in early December to -0°C by late February.
A typical winter day in Iwamizawa reaches about -1°C and drops to -9°C overnight. The warmest of the three months is December, the coolest January.
How winter really feels in Iwamizawa
Once humidity and wind are folded in, winter brings about 0 days that feel above 32°C and 90 that feel at or below 0°C.
The story in winter is cold — wind chill drags the overnight "feels like" below the raw low.
Iwamizawa weather by month
How the three winter months (December, January and February) compare with the rest of the year — the season's months are highlighted.
| Month | High / Low (°C) | Rainfall (mm) | Wet days | Snow days | Daylight (hours) | Travel score |
|---|---|---|---|---|---|---|
| Jan | -3° / -10° | 49 | 12.7 | 18.1 | 9.2 | 0.0 |
| Feb | -2° / -9° | 42 | 10.7 | 14.9 | 10.2 | 0.0 |
| Mar | 3° / -5° | 57 | 11.6 | 10.5 | 11.6 | 0.1 |
| Apr | 11° / 2° | 67 | 11.8 | 3.3 | 13.1 | 2.5 |
| May | 16° / 8° | 84 | 11.4 | 0.1 | 14.4 | 4.9 |
| Jun | 20° / 12° | 64 | 9.6 | 0 | 15.1 | 6.1 |
| Jul | 23° / 17° | 113 | 11.6 | 0 | 14.9 | 6.4 |
| Aug | 24° / 18° | 161 | 12.5 | 0 | 13.8 | 6.3 |
| Sep | 21° / 13° | 126 | 13.2 | 0 | 12.3 | 5.9 |
| Oct | 15° / 6° | 92 | 13.6 | 0.3 | 10.8 | 4.1 |
| Nov | 7° / 0° | 87 | 16.1 | 8.4 | 9.5 | 0.9 |
| Dec | 0° / -7° | 69 | 15.3 | 18.1 | 8.9 | 0.0 |
Cloud cover in Winter
The sky is clear or mostly clear about 11% of the time across winter.
Chance of precipitation in Winter
Iwamizawa gets around 160 mm of rain and snow over 39 wet days across winter. The line is the day-by-day chance of measurable precipitation.
Humidity in Winter
Most of winter feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.
Wind in Winter
Winds average 10 km/h across winter.
Sunrise & sunset in Winter
Daylight runs from about 9 hours in early December to 10 h 48 min by late February. The lit band spans sunrise to sunset each day.
Solar energy in Winter
Average shortwave solar energy reaching the ground each day across winter, about 2.3 kWh/m².
Hazard calendar for Iwamizawa
In winter, Iwamizawa overlaps its pacific typhoon season. The full year is below, with each hazard's peak months called out.
Iwamizawa sits in the Pacific typhoon belt; the season peaks July–October.
Is winter a good time to visit Iwamizawa?
Our two travel scores rate winter for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal), averaged across the three months.
winter is a weaker month for outdoor sightseeing in Iwamizawa.
What to pack for Iwamizawa in Winter
From winter's temperature range, rain chance, sun and wind — what's worth putting in the bag.
In winter, Iwamizawa sees daytime highs around -1°C and nights near -9°C. Pack a warm layer, a heavy coat and rain gear. About 39 days see rain.
Sea temperature near Iwamizawa in Winter
The nearest coast averages about 7°C across winter — the other half of the beach question. The full-year curve and swim-comfort zones are below.
The sea at the nearest coast (about 37 km away) is warmest in August at about 22°C and coldest in February near 5°C.
It's comfortable for a long swim from Jul 31 to Sep 22 — about 1.8 months when the water holds above 20°C.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sea temperature (°C) | 7 | 5 | 5 | 7 | 10 | 14 | 19 | 22 | 21 | 17 | 13 | 9 |
| Comfort | Bracing | Bracing | Bracing | Bracing | Bracing | Bracing | Cool | Refreshing | Refreshing | Cool | Bracing | Bracing |
| Sea temperature (°C) | Comfort | |
|---|---|---|
| Jan | 7 | Bracing |
| Feb | 5 | Bracing |
| Mar | 5 | Bracing |
| Apr | 7 | Bracing |
| May | 10 | Bracing |
| Jun | 14 | Bracing |
| Jul | 19 | Cool |
| Aug | 22 | Refreshing |
| Sep | 21 | Refreshing |
| Oct | 17 | Cool |
| Nov | 13 | Bracing |
| Dec | 9 | Bracing |
UV index in Iwamizawa in Winter
Clear-sky midday UV across winter averages around 2. The full-year curve, shaded by WHO exposure level, is below.
Under clear skies, the midday UV index in Iwamizawa peaks around August 18 at about 8 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near December 19 at about 1 (low).
The index reaches 3 or more — the level where the WHO recommends sun protection — in 8 months of the year.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| UV index (midday) | 1 | 3 | 3 | 6 | 7 | 7 | 5 | 8 | 6 | 4 | 2 | 1 |
| Level | Low | Moderate | Moderate | High | Very high | High | Moderate | Very high | High | Moderate | Low | Low |
| UV index (midday) | Level | |
|---|---|---|
| Jan | 1 | Low |
| Feb | 3 | Moderate |
| Mar | 3 | Moderate |
| Apr | 6 | High |
| May | 7 | Very high |
| Jun | 7 | High |
| Jul | 5 | Moderate |
| Aug | 8 | Very high |
| Sep | 6 | High |
| Oct | 4 | Moderate |
| Nov | 2 | Low |
| Dec | 1 | Low |
Air quality in Iwamizawa in Winter
Average fine-particle pollution (PM2.5) through the year — so you can see where winter falls, not just the annual average.
Air quality in Iwamizawa is worst in April — around 21 µg/m³ PM2.5 (moderate), about 2.3× the cleanest month (December, 9 µg/m³).
Modeled monthly averages (CAMS reanalysis, 2015–2024).
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| PM2.5 (µg/m³) | 11 | 15 | 20 | 21 | 19 | 14 | 13 | 11 | 11 | 12 | 10 | 9 |
| Level | Good | Moderate | Moderate | Moderate | Moderate | Moderate | Moderate | Good | Good | Good | Good | Good |
| PM2.5 (µg/m³) | Level | |
|---|---|---|
| Jan | 11 | Good |
| Feb | 15 | Moderate |
| Mar | 20 | Moderate |
| Apr | 21 | Moderate |
| May | 19 | Moderate |
| Jun | 14 | Moderate |
| Jul | 13 | Moderate |
| Aug | 11 | Good |
| Sep | 11 | Good |
| Oct | 12 | Good |
| Nov | 10 | Good |
| Dec | 9 | Good |
Where is Iwamizawa?
Iwamizawa sits at 43.2°N, 141.8°E, 17 m above sea level, in Japan. The nearest listed city is Bibai, 16 km away.
Topography around Iwamizawa
How much the land rises and falls, and what covers it, within 3, 16 and 80 km of Iwamizawa.
Within 3 km, the terrain around Iwamizawa has only modest variations in elevation — a maximum elevation change of 101 m around an average of 24 m above sea level; within 16 km, significant variations in elevation — a maximum elevation change of 559 m; within 80 km, very significant variations in elevation — a maximum elevation change of 2,032 m.
The land around Iwamizawa is covered by artificial surfaces (43%) and cropland (35%) within 3 km, cropland (54%) and trees (33%) within 16 km, and trees (64%) within 80 km.
Japan travel facts
- Travel advisory
- Level 1
- Exercise Normal Precautions
- Power plugs
- Type A / B
- 100 V · 50 / 60 Hz
- Prices
- ≈ 65% of US
- price level, 2025
- GDP per capita
- $35,951
- 2025
- Happiness
- 6.1 / 10
- World Happiness, 2025
- Safe drinking water
- 99%
- of population, 2024
- Homicide rate
- 0.2
- per 100k, 2023
- Road deaths
- 3.6
- per 100k/yr, 2019
- Income group
- High
- World Bank
- English
- Very low
- EF EPI 446
- Religion
Sources: World Bank, US State Department, World Happiness Report, WHO/UNICEF, EF EPI, CIA World Factbook.
Data sources
Temperature, precipitation, cloud, humidity, wind and solar figures are a 1991–2020 climatology for Iwamizawa (43.2003°, 141.7597°, elevation 17 m), computed from hourly ERA5 reanalysis — contains modified Copernicus Climate Change Service information. Sun figures are astronomical calculations, not observations. City data © GeoNames, CC BY 4.0. Map outlines from Natural Earth (public domain); interactive map © Google.