Tosa weather in September

In September, Tosa sees average daytime highs of 27°C and overnight lows near 22°C, with 323 mm of rain across 17.1 wet days and about 12.2 hours of daylight. It is the 3rd-warmest and 3rd-wettest month of the year here.

Highs ease over the month, from about 28°C in the first days to 25°C by the end. The sky is clear or mostly clear about 30% of the time in September, and the air most often feels oppressive.

Daylight stretches from about 12 h 42 min at the start of September to 11 h 42 min by month's end. Set against the rest of the year, September is Tosa's 8th-clearest and 9th-windiest month. For the whole year in context, see Tosa's year-round climate.

Daytime high
27°
3rd warmest
Overnight low
22°
10th coldest
Rainfall
323 mm
17.1 wet days
Daylight
12 h 12 min
5:54 AM – 6:07 PM
Cloud cover
62%
8th clearest
Wind
8 km/h
9th windiest
Solar energy
4.38 kWh/m²
Travel score
5.4
out of 10

Temperature in September

Average highAverage lowShaded bands: 10–90% of days

Highs ease over the month, from about 28°C in the first days to 25°C by the end.

A typical September day in Tosa reaches about 27°C in the afternoon and slips back to 22°C overnight — a 5°C spread between the day's warmth and the night's chill. On most days the high lands between 24°C and 29°C. Set against its neighbours, September runs about 2°C cooler than August and about 4°C warmer than October.

15°20°25°30°35°151015202530
Avg high (°C)Avg low (°C)
12823
22823
32823
42823
52823
62823
72823
82823
92823
102822
112822
122722
132722
142722
152722
162722
172721
182721
192721
202621
212621
222621
232620
242620
252620
262620
272520
282520
292519
302519

How September really feels in Tosa

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.

Tosa 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
Jan10° / 726.30.3102.6
Feb11° / 987.90.510.82.9
Mar14° / 16411.6011.74.2
Apr19° / 11°20311.6012.85.7
May22° / 16°24213.2013.76.1
Jun25° / 20°35819.1014.25.0
Jul28° / 24°37421.60144.2
Aug29° / 24°29820.6013.24.1
Sep27° / 22°32317.1012.25.4
Oct23° / 16°23011.2011.26.7
Nov18° / 11°1188.4010.36.0
Dec13° / 906.309.83.8

Cloud cover in September

ClearMostly clearPartly cloudyMostly cloudyOvercast

The sky is clear or mostly clear about 30% 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 54%.

0%25%50%75%100%151015202530
Clearer (%)Cloudier (%)
14555
24456
34456
44456
54456
64456
74555
84456
94555
104555
114555
124555
134654
144555
154654
164555
174555
184654
194555
204654
214654
224654
234753
244753
254654
264654
274654
284654
294654
304654

Chance of precipitation in September

Any precipitation

Tosa gets around 323 mm of rain over 17.1 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 57% and peaks near 66% on the wettest days. The odds ease toward the end of the month.

0%20%40%60%80%151015202530
Rain chance (%)
166
266
365
464
564
663
762
862
961
1061
1160
1259
1358
1458
1557
1656
1756
1855
1954
2054
2153
2252
2352
2451
2551
2650
2750
2849
2948
3048

Humidity in September

DryComfortableHumidMuggyOppressiveMiserable

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

By dew point, September lands in the oppressive band about 38% of days. Sticky, muggy-or-worse air turns up on roughly 72% of them.

0%25%50%75%100%151015202530
Dry (%)Comfortable (%)Humid (%)Muggy (%)Oppressive (%)Miserable (%)
1004216114
2004226113
3004246012
4005255911
5015275710
601628569
701729558
802730547
902831527
1002932516
11131033485
12141233465
13141333444
14251433424
15261633403
16371832373
17381932362
18392032332
194102231312
204112331291
215122530271
225132630251
235142729241
246152828221
256163028201
266173127180
277183127170
287193226150
298203225140
308213324130

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 8 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
308calm

Sunrise & sunset in September

DaylightNight

Daylight runs from about 12 h 42 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 60 minutes over September. Sunrise moves from 5:44 AM to 6:04 AM, and sunset from 6:28 PM to 5:47 PM.

12 AM4 AM8 AM12 PM4 PM8 PM12 AM151015202530
Daylight (h)Sunrise (AM)Sunset (PM)
112.75:446:28
212.75:456:26
312.75:456:25
412.65:466:24
512.65:476:22
612.65:486:21
712.55:486:20
812.55:496:18
912.55:506:17
1012.45:506:15
1112.45:516:14
1212.35:526:12
1312.35:526:11
1412.35:536:10
1512.25:546:08
1612.25:546:07
1712.25:556:05
1812.15:566:04
1912.15:566:02
2012.15:576:01
2112.05:585:59
2212.05:595:58
2312.05:595:57
2411.96:005:55
2511.96:015:54
2611.86:015:52
2711.86:025:51
2811.86:035:50
2911.76:045:48
3011.76:045:47

Solar energy in September

Daily solar energy (kWh/m²)

Average shortwave solar energy reaching the ground each day in September, about 4.38 kWh/m².

For context, solar energy here swings from a low near 2.59 kWh/m² to a high of 5.6 kWh/m² in May across the year — September's 4.38 kWh/m² falls in the middle.

024151015202530
Solar energy (kWh/m²)Level
14.9Bright
24.8Bright
34.8Bright
44.8Bright
54.8Bright
64.7Bright
74.7Bright
84.7Bright
94.6Bright
104.6Bright
114.6Bright
124.5Bright
134.5Bright
144.5Bright
154.4Bright
164.4Bright
174.4Bright
184.3Bright
194.3Bright
204.3Bright
214.2Bright
224.2Bright
234.2Bright
244.2Bright
254.1Bright
264.1Bright
274.1Bright
284.0Bright
294.0Bright
304.0Moderate
Planning a trip in September

Hazard calendar for Tosa

In seasonPeak

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

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

Tosa's rainy season runs April–October, when most of the year's rain falls.

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

Is September a good time to visit Tosa?

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

5.4
Sightseeing
5th-best month of the year
5.5
Beach & pool
1st-best month of the year

September is a reasonable time to visit Tosa for sightseeing.

What to pack for Tosa in September

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

In September, Tosa sees daytime highs around 27°C and nights near 22°C. Pack rain gear. Worth having: light clothes. About 17 days see rain.

rain gearlight clothes

Sea temperature near Tosa in September

The nearest coast averages about 27°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 16 km away) is warmest in August at about 28°C and coldest in February near 17°C.

It's comfortable for a long swim from May 8 to Dec 15 — about 7.3 months when the water holds above 20°C.

15°20°25°30°JanFebMarAprMayJunJulAugSepOctNovDecbracingcoolrefreshingwarmtropicalcomfortable to swim
Sea temperature (°C)Comfort
Jan18Cool
Feb17Cool
Mar17Cool
Apr18Cool
May21Refreshing
Jun23Refreshing
Jul26Warm
Aug28Warm
Sep27Warm
Oct25Warm
Nov23Refreshing
Dec20Cool

UV index in Tosa in September

LowModerateHighVery highExtreme

Clear-sky midday UV in September peaks around 10 (very high — sun protection essential). The full-year curve, shaded by WHO exposure level, is below.

Under clear skies, the midday UV index in Tosa peaks around June 23 at about 10 (extreme) — sunscreen, a hat and midday shade are essential. It bottoms out near December 22 at about 3 (moderate).

The index reaches 3 or more — the level where the WHO recommends sun protection — in 11 months of the year.

025710JanFebMarAprMayJunJulAugSepOctNovDecModerateHighVery highExtremeVery highModerateJun 23UV 10Dec 22UV 3
UV index (midday)Level
Jan3Moderate
Feb4Moderate
Mar6High
Apr7Very high
May9Very high
Jun10Extreme
Jul10Extreme
Aug9Very high
Sep10Very high
Oct7High
Nov4Moderate
Dec3Moderate

Air quality in Tosa 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 Tosa is worst in April — around 22 µg/m³ PM2.5 (moderate), about 2.0× the cleanest month (October, 11 µg/m³).

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

0102030JanFebMarAprMayJunJulAugSepOctNovDecModerateGoodApr 1321 µg/m³Oct 1311 µg/m³
PM2.5 (µg/m³)Level
Jan13Moderate
Feb16Moderate
Mar20Moderate
Apr22Moderate
May19Moderate
Jun16Moderate
Jul13Moderate
Aug12Moderate
Sep11Good
Oct11Good
Nov12Good
Dec11Good
Location & terrain

Where is Tosa?

Tosa sits at 33.5°N, 133.4°E, 13 m above sea level, in Japan. The nearest listed city is Ino, 5.0 km away.

Topography around Tosa

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

Within 3 km, the terrain around Tosa has significant variations in elevation — a maximum elevation change of 253 m around an average of 39 m above sea level; within 16 km, large variations in elevation — a maximum elevation change of 931 m; within 80 km, very significant variations in elevation — a maximum elevation change of 1,939 m.

The land around Tosa is covered by trees (44%), artificial surfaces (25%) and cropland (20%) within 3 km, trees (56%) and water (28%) within 16 km, and trees (61%) and water (34%) within 80 km.

3 km
253 m
16 km
931 m
80 km
1,939 m
treesgrasslandcroplandartificial surfacesbare terrainwater
September weather nearby: Ino 5.0 km · Kochi 10 km · Susaki 19 km · Nankoku 20 km · Tosayamadachō-nakano 25 km · Yamashita 25 km · Aki 42 km · Shinagawa 43 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 Tosa (33.5048°, 133.4447°, elevation 13 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).