Hachimantai weather in September

In September, Hachimantai sees average daytime highs of 21°C and overnight lows near 14°C, with 138 mm of rain across 12.9 wet days and about 12.3 hours of daylight. It is the 3rd-warmest and 3rd-wettest month of the year here.

Highs ease over the month, from about 24°C in the first days to 19°C by the end. The sky is clear or mostly clear about 16% of the time in September, and the air most often feels dry.

Daylight stretches from about 12 h 54 min at the start of September to 11 h 36 min by month's end. Set against the rest of the year, September is Hachimantai's 8th-clearest and 9th-windiest month. For the whole year in context, see Hachimantai's year-round climate.

Daytime high
21°
3rd warmest
Overnight low
14°
10th coldest
Rainfall
138 mm
12.9 wet days
Daylight
12 h 18 min
5:22 AM – 5:38 PM
Cloud cover
71%
8th clearest
Wind
8 km/h
9th windiest
Solar energy
3.55 kWh/m²
Travel score
5.8
out of 10

Hachimantai is city in Iwate Prefecture, Japan.

Density
29/km²
people per km²
Founded
2005

Air quality: WHO Ambient Air Quality Database. Density & description: Wikidata (CC0), GeoNames.

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 24°C in the first days to 19°C by the end.

A typical September day in Hachimantai reaches about 21°C in the afternoon and slips back to 14°C overnight — a 8°C spread between the day's warmth and the night's chill. On most days the high lands between 17°C and 25°C. Set against its neighbours, September runs about 4°C cooler than August and about 6°C warmer than October.

10°15°20°25°30°151015202530
Avg high (°C)Avg low (°C)
12417
22417
32417
42416
52316
62316
72316
82316
92316
102315
112215
122215
132215
142214
152214
162114
172114
182113
192113
202013
212012
222012
232012
242012
251911
261911
271911
281911
291910
301810

How September really feels in Hachimantai

Once humidity and wind are folded in, September averages 0 days that feel above 32°C and 0 that feel at or below 0°C — the comfort signal a plain temperature reading hides.

Days feeling ≥ 32°C
0
heat index over the day's high
Days feeling ≤ C
0
wind chill below the day's low

September sits comfortably in between — no days that feel dangerously hot or drop to a hard freeze once humidity and wind are folded in.

Hachimantai weather by month

How September compares with the rest of the year at a glance. September is the 3rd-warmest and 3rd-wettest month here — the current month is highlighted below.

MonthHigh / Low (°C)Rainfall (mm)Wet daysSnow daysDaylight (hours)Travel score
Jan-1° / -9°6010.513.29.50.0
Feb / -8°5910.412.110.40.0
Mar / -4°9014.212.111.70.2
Apr11° / 9014.14132.6
May17° / 9312.70.314.25.1
Jun21° / 13°10512.8014.85.7
Jul24° / 17°14416.4014.55.6
Aug25° / 18°14114.9013.65.9
Sep21° / 14°13812.9012.35.8
Oct15° / 11111.20.110.94.5
Nov / 7612.849.81.4
Dec / -5°7412129.20.0

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 16% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 17% of September, with mostly cloudy or overcast conditions the remaining 67%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
12773
22773
32773
42872
52872
62872
73070
83070
93070
103070
113169
123268
133268
143268
153268
163367
173466
183466
193466
203664
213664
223664
233763
243763
253862
263862
273763
283763
293763
303862

Chance of precipitation in September

Any precipitation

Hachimantai gets around 138 mm of rain over 12.9 wet days in September. The line is the day-by-day chance of measurable precipitation.

Day to day, the chance of measurable rain averages around 44% and peaks near 50% on the wettest days. The odds ease toward the end of the month.

0%20%40%60%151015202530
Rain chance (%)
150
249
349
449
549
649
748
848
948
1047
1147
1247
1346
1446
1545
1645
1744
1843
1942
2042
2141
2241
2340
2440
2540
2640
2740
2840
2939
3039

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

Most of September feels dry — the stacked bands show each day's mix of comfort levels, read off the dew point.

By dew point, September lands in the dry band about 37% of days. Sticky, muggy-or-worse air turns up on roughly 14% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
192233314
292333304
3102434294
4112534273
5122633263
6132733243
7142832233
8162932213
9182931202
10203030192
11223029172
12253028161
13273027151
14303025131
15333023121
16373022111
17403020100
1843291890
1946291780
2049281570
2152281460
2256271250
2358271140
2461261030
256325930
266624820
276724720
287023610
297222510
307420510

Wind in September

Winds average 8 km/h in September.

Across September, daily wind ranges from about 7 km/h on the calmest days to 9 km/h at its breeziest. It stays fairly steady from day to day.

051015151015202530
Wind speed (km/h)Feels
17calm
27calm
37calm
47calm
57calm
67calm
78calm
88calm
98calm
108calm
118calm
128calm
138calm
148calm
158calm
168calm
178calm
188calm
198calm
208calm
218calm
228calm
238calm
248calm
258calm
268calm
278calm
288calm
298calm
309calm

Sunrise & sunset in September

DaylightNight

Daylight runs from about 12 h 54 min at the start of September to 11 h 36 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 78 minutes over September. Sunrise moves from 5:08 AM to 5:36 AM, and sunset from 6:03 PM to 5:14 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.95:086:03
212.95:086:01
312.85:096:00
412.85:105:58
512.75:115:56
612.75:125:55
712.75:135:53
812.65:145:51
912.65:155:50
1012.55:165:48
1112.55:175:46
1212.45:185:44
1312.45:195:43
1412.35:205:41
1512.35:215:39
1612.35:225:38
1712.25:235:36
1812.25:245:34
1912.15:255:32
2012.15:265:31
2112.05:275:29
2212.05:285:27
2311.95:295:26
2411.95:305:24
2511.95:315:22
2611.85:325:20
2711.85:335:19
2811.75:345:17
2911.75:355:15
3011.65:365:14

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 3.55 kWh/m².

For context, solar energy here swings from a low near 1.87 kWh/m² to a high of 5.27 kWh/m² in May across the year — September's 3.55 kWh/m² falls in the middle.

01234151015202530
Solar energy (kWh/m²)Level
13.8Moderate
23.8Moderate
33.8Moderate
43.7Moderate
53.7Moderate
63.7Moderate
73.7Moderate
83.6Moderate
93.6Moderate
103.6Moderate
113.6Moderate
123.6Moderate
133.5Moderate
143.5Moderate
153.5Moderate
163.5Moderate
173.5Moderate
183.5Moderate
193.5Moderate
203.5Moderate
213.4Moderate
223.4Moderate
233.4Moderate
243.4Moderate
253.4Moderate
263.4Moderate
273.3Moderate
283.3Moderate
293.3Moderate
303.3Moderate
Planning a trip in September

Is September a good time to visit Hachimantai?

Our two travel scores rate September for general sightseeing and for beach or pool weather — 0 (poor) to 10 (ideal).

5.8
Sightseeing
2nd-best month of the year
3.6
Beach & pool
3rd-best month of the year

September is a reasonable time to visit Hachimantai for sightseeing.

What to pack for Hachimantai in September

From September's temperature range, rain chance, sun and wind — what's worth putting in the bag.

In September, Hachimantai sees daytime highs around 21°C and nights near 14°C. Worth packing: rain gear. About 13 days see rain.

rain gear

Sea temperature near Hachimantai in September

The nearest coast averages about 21°C in September — the other half of the beach question. The full-year curve and swim-comfort zones are below.

The sea at the nearest coast (about 68 km away) is warmest in August at about 21°C and coldest in March near 6°C.

It's comfortable for a long swim from Aug 8 to Sep 25 — about 1.6 months when the water holds above 20°C.

5°10°15°20°25°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarm
Sea temperature (°C)Comfort
Jan10Bracing
Feb8Bracing
Mar6Bracing
Apr7Bracing
May10Bracing
Jun14Bracing
Jul18Cool
Aug21Refreshing
Sep21Refreshing
Oct18Cool
Nov15Cool
Dec12Bracing

UV index in Hachimantai in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 7 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Hachimantai peaks around August 18 at about 9 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near January 1 at about 2 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 8 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecLowModerateHighVery highHighVery highHighModerateLowAug 18UV 9Jan 1UV 2
UV index (midday)Level
Jan2Low
Feb3Moderate
Mar4Moderate
Apr6High
May8Very high
Jun8Very high
Jul6High
Aug9Very high
Sep7High
Oct5Moderate
Nov2Moderate
Dec2Low

Air quality in Hachimantai in September

GoodModeratePoorUnhealthyVery unhealthy

Average fine-particle pollution (PM2.5) through the year — so you can see where September falls, not just the annual average.

Air quality in Hachimantai is worst in April — around 20 µg/m³ PM2.5 (moderate), about 2.1× the cleanest month (December, 9 µg/m³).

Modeled monthly averages (CAMS reanalysis, 2015–2024).

0102030JanFebMarAprMayJunJulAugSepOctNovDecGoodModerateGoodApr 1420 µg/m³Dec 1610 µg/m³
PM2.5 (µg/m³)Level
Jan11Good
Feb14Moderate
Mar19Moderate
Apr20Moderate
May19Moderate
Jun14Moderate
Jul12Moderate
Aug11Good
Sep11Good
Oct12Good
Nov11Good
Dec9Good
Location & terrain

Where is Hachimantai?

Hachimantai sits at 39.9°N, 141.1°E, 228 m above sea level, in Japan. The nearest listed city is Takizawa, 11 km away.

Topography around Hachimantai

How much the land rises and falls, and what covers it, within 3, 16 and 80 km of Hachimantai.

Within 3 km, the terrain around Hachimantai has only modest variations in elevation — a maximum elevation change of 149 m around an average of 245 m above sea level; within 16 km, very significant variations in elevation — a maximum elevation change of 1,870 m; within 80 km, very significant variations in elevation — a maximum elevation change of 2,117 m.

The land around Hachimantai is covered by cropland (46%) and trees (38%) within 3 km, trees (75%) within 16 km, and trees (84%) within 80 km.

3 km
149 m
16 km
1,870 m
80 km
2,117 m
treesgrasslandcroplandartificial surfaceswater
September weather nearby: Takizawa 11 km · Morioka 22 km · Shizukuishi 26 km · Yahaba 32 km · Semboku 39 km · Hizume 39 km · Hanawa 43 km · Ninohe 46 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
Shintoism 49%Buddhism 46%other 4%Christianity 1%

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 Hachimantai (39.8998°, 141.1299°, elevation 228 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. Sea temperatures are the NOAA OISST v2.1 1991–2020 monthly climatology (public domain), sampled at the nearest ocean point. UV index is derived from CAMS (Copernicus Atmosphere Monitoring Service) clear-sky UV data — contains modified Copernicus Atmosphere Monitoring Service information. Monthly air-quality (PM2.5) seasonality is from the CAMS EAC4 reanalysis (Copernicus Atmosphere Monitoring Service), scaled to the WHO annual mean where available. Topography is sampled from the Copernicus DEM GLO-90 elevation model (© ESA/Airbus) and ESA WorldCover 2021 land cover (CC BY 4.0).