Shiroishi weather in September

In September, Shiroishi sees average daytime highs of 23°C and overnight lows near 16°C, with 153 mm of rain across 14 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 25°C in the first days to 21°C by the end. The sky is clear or mostly clear about 15% of the time in September, and the air most often feels humid.

Daylight stretches from about 12 h 54 min at the start of September to 11 h 42 min by month's end. Set against the rest of the year, September is Shiroishi's 9th-clearest and 9th-windiest month. For the whole year in context, see Shiroishi's year-round climate.

Daytime high
23°
3rd warmest
Overnight low
16°
10th coldest
Rainfall
153 mm
14 wet days
Daylight
12 h 12 min
5:25 AM – 5:39 PM
Cloud cover
72%
9th clearest
Wind
6 km/h
9th windiest
Solar energy
3.49 kWh/m²
Travel score
5.8
out of 10

Shiroishi is city in Miyagi Prefecture, Japan.

Density
116/km²
people per km²
Founded
1954

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 25°C in the first days to 21°C by the end.

A typical September day in Shiroishi reaches about 23°C in the afternoon and slips back to 16°C overnight — a 7°C spread between the day's warmth and the night's chill. On most days the high lands between 19°C and 28°C. Set against its neighbours, September runs about 4°C cooler than August and about 6°C warmer than October.

10°20°30°151015202530
Avg high (°C)Avg low (°C)
12619
22619
32519
42519
52519
62518
72518
82518
92518
102418
112417
122417
132417
142417
152417
162316
172316
182316
192316
202215
212215
222215
232215
242214
252114
262114
272114
282114
292113
302013

How September really feels in Shiroishi

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.

Shiroishi 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 / -4°7814.5159.70.0
Feb / -4°5811.911.710.50.0
Mar / -1°9213.48.211.71.0
Apr14° / 9512.51.8133.8
May19° / 10°9812.40145.7
Jun22° / 15°12613.6014.65.8
Jul26° / 19°18818.2014.45.2
Aug27° / 20°16015.8013.55.5
Sep23° / 16°15314012.35.8
Oct18° / 10°13511.50115.4
Nov12° / 7111.629.92.9
Dec / -1°6914.510.19.40.3

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 15% of the time in September.

Beyond those clear spells, partly cloudy skies cover about 16% of September, with mostly cloudy or overcast conditions the remaining 69%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
13169
23169
33268
43169
53268
63268
73268
83169
93268
103268
113268
123268
133169
143268
153169
163169
173169
183169
193169
203070
213070
223169
233169
243268
253268
263268
273268
283367
293367
303367

Chance of precipitation in September

Any precipitation

Shiroishi gets around 153 mm of rain over 14 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 48% and peaks near 51% on the wettest days. The odds ease toward the end of the month.

0%20%40%60%151015202530
Rain chance (%)
151
251
351
451
551
651
751
851
950
1050
1150
1250
1350
1449
1549
1649
1748
1848
1947
2046
2145
2245
2344
2444
2543
2643
2743
2842
2942
3042

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, September lands in the humid band about 29% of days. Sticky, muggy-or-worse air turns up on roughly 29% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)
119313820
2110323819
3110343817
4211343716
5212353615
6313353614
7314353512
8415353411
9517353310
1061835329
1171935318
1282034307
13102234286
14122333266
15132532255
16152632234
17172731213
18192930193
19223029182
20243128162
21263127141
22293226121
23313324111
2433342391
2535342281
2637352171
2739361961
2841361850
2943371740
3045371530

Wind in September

Winds average 6 km/h in September.

Across September, daily wind ranges from about 6 km/h on the calmest days to 7 km/h at its breeziest. It stays fairly steady from day to day.

0246810151015202530
Wind speed (km/h)Feels
16calm
26calm
36calm
46calm
56calm
66calm
76calm
86calm
96calm
106calm
116calm
126calm
136calm
146calm
156calm
166calm
176calm
186calm
196calm
206calm
216calm
226calm
236calm
247calm
257calm
267calm
277calm
287calm
297calm
307calm

Sunrise & sunset in September

DaylightNight

Daylight runs from about 12 h 54 min at the start of September to 11 h 42 min by month's end. The lit band spans sunrise to sunset each day.

Days shrink by about 72 minutes over September. Sunrise moves from 5:11 AM to 5:37 AM, and sunset from 6:03 PM to 5:16 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.95:116:03
212.85:126:02
312.85:136:00
412.75:145:58
512.75:155:57
612.75:165:55
712.65:175:54
812.65:185:52
912.55:185:50
1012.55:195:49
1112.55:205:47
1212.45:215:46
1312.45:225:44
1412.35:235:42
1512.35:245:41
1612.25:255:39
1712.25:255:37
1812.25:265:36
1912.15:275:34
2012.15:285:33
2112.05:295:31
2212.05:305:29
2311.95:315:28
2411.95:325:26
2511.95:335:24
2611.85:345:23
2711.85:345:21
2811.75:355:20
2911.75:365:18
3011.75:375:16

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 3.49 kWh/m².

For context, solar energy here swings from a low near 2.03 kWh/m² to a high of 5.33 kWh/m² in May across the year — September's 3.49 kWh/m² falls in the middle.

01234151015202530
Solar energy (kWh/m²)Level
13.8Moderate
23.8Moderate
33.8Moderate
43.7Moderate
53.7Moderate
63.7Moderate
73.6Moderate
83.6Moderate
93.6Moderate
103.6Moderate
113.5Moderate
123.5Moderate
133.5Moderate
143.5Moderate
153.5Moderate
163.4Moderate
173.4Moderate
183.4Moderate
193.4Moderate
203.4Moderate
213.4Moderate
223.3Moderate
233.3Moderate
243.3Moderate
253.3Moderate
263.3Moderate
273.2Moderate
283.2Moderate
293.2Moderate
303.2Moderate
Planning a trip in September

Hazard calendar for Shiroishi

In seasonPeak

In September, Shiroishi sits inside its pacific typhoon season. The full year is below, with each hazard's peak months called out.

Shiroishi sits in the Pacific typhoon belt; the season peaks July–October.

Pacific typhoon
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec

Is September a good time to visit Shiroishi?

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

5.8
Sightseeing
1st-best month of the year
4.5
Beach & pool
3rd-best month of the year

September is a reasonable time to visit Shiroishi for sightseeing.

What to pack for Shiroishi in September

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

In September, Shiroishi sees daytime highs around 23°C and nights near 16°C. Pack rain gear. Worth having: light clothes. About 14 days see rain.

rain gearlight clothes

Sea temperature near Shiroishi in September

The nearest coast averages about 23°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 46 km away) is warmest in August at about 24°C and coldest in March near 9°C.

It's comfortable for a long swim from Jul 7 to Oct 10 — about 3.2 months when the water holds above 20°C.

5°10°15°20°25°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarmcomfortable to swim
Sea temperature (°C)Comfort
Jan11Bracing
Feb9Bracing
Mar9Bracing
Apr10Bracing
May14Bracing
Jun18Cool
Jul21Refreshing
Aug24Refreshing
Sep23Refreshing
Oct19Cool
Nov17Cool
Dec14Bracing

UV index in Shiroishi in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 8 — enough to warrant sun protection. The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Shiroishi peaks around August 13 at about 9 (very high) — sunscreen, a hat and midday shade are essential. It bottoms out near January 10 at about 2 (low).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 9 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highModerateAug 13UV 9Jan 10UV 2
UV index (midday)Level
Jan2Low
Feb3Moderate
Mar4Moderate
Apr6High
May8Very high
Jun8Very high
Jul9Very high
Aug9Very high
Sep8Very high
Oct5High
Nov3Moderate
Dec2Low

Air quality in Shiroishi 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 Shiroishi is worst in April — around 22 µg/m³ PM2.5 (moderate), about 2.2× the cleanest month (December, 10 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecModerateGoodApr 1622 µg/m³Dec 1710 µg/m³
PM2.5 (µg/m³)Level
Jan11Good
Feb14Moderate
Mar21Moderate
Apr22Moderate
May21Moderate
Jun16Moderate
Jul14Moderate
Aug12Moderate
Sep12Good
Oct12Good
Nov11Good
Dec10Good
Location & terrain

Where is Shiroishi?

Shiroishi sits at 38.0°N, 140.6°E, 57 m above sea level, in Japan. The nearest listed city is Ōkawara, 11 km away.

Topography around Shiroishi

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

Within 3 km, the terrain around Shiroishi has significant variations in elevation — a maximum elevation change of 493 m around an average of 100 m above sea level; within 16 km, very significant variations in elevation — a maximum elevation change of 1,805 m; within 80 km, very significant variations in elevation — a maximum elevation change of 2,031 m.

The land around Shiroishi is covered by trees (50%), cropland (23%) and artificial surfaces (23%) within 3 km, trees (80%) within 16 km, and trees (63%) and water (20%) within 80 km.

3 km
493 m
16 km
1,805 m
80 km
2,031 m
treesgrasslandcroplandartificial surfacesbare terrainwater
September weather nearby: Ōkawara 11 km · Kakuda 14 km · Murata 16 km · Yanagawamachi-saiwaichō 17 km · Watari 21 km · Hobaramachi 22 km · Date 23 km · Iwanuma 24 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 Shiroishi (38.0033°, 140.6183°, elevation 57 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. Tropical-cyclone seasons are the published climatological basin seasons (NOAA National Hurricane Center / regional warning centres). 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).