Avg High
Sapporo in September
Avg Low
Rain
Daylight
13h
What to expect
In Sapporo, September sits in early autumn, a shoulder-season month where the feel can shift as the season turns. Most days land in a mild, easygoing zone, with evenings that ease back comfortably. Daylight is moderate, so steady pacing works well. Comfort is usually predictable, so a standard day plan works well.
September in context
How it compares to the rest of the year in Sapporo.
Hottest (avg)
#3 / 12
Wettest (avg)
#2 / 12
Daylight Hours
#6 / 12
Windiest (avg)
#9 / 12
Highest UV
#6 / 12
Most Humid
#4 / 12
Monthly climate breakdown
Temperature
- Daytime high
-
- Nighttime low
-
- Feels like (avg)
-
Sunshine
- Daylight hours
- 12.5 h
- UV index (max)
- 6
- Typical sun hours
- 05:13 - 17:44
Rain & Snow
- Total rain
-
- Rainy days
- 16 days
- Cloud cover (avg)
- 63%
Humidity & Wind
- Humidity (avg)
- 82%
- Wind (avg)
-
- Wind (max gusts)
-
Daily climate explorer
Day 15 selected for September. Typical high 20.7°C and low 14.5°C.
Typical disruptions in September
Based on 30 years of historical data, these are the disruption patterns most likely to affect plans in September.
Rain High impact
Rain disruption Measures: Likely rain disruption days. Observed about 24% of days (7.3 days/month) in September. Historical risk signal only, not a day-by-day forecast.
7.3 days / month
~24% of days
Why this matters
- Expected days 7.3 days / month
- Probability ~24% of days
- Intensity Up to ~46mm (P95)
Rain disruption risk appears on ~7 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Rain High impact
Washout risk Measures: Washout day risk. Observed about 23% of days (6.9 days/month) in September. Historical risk signal only, not a day-by-day forecast.
6.9 days / month
~23% of days
Why this matters
- Expected days 6.9 days / month
- Probability ~23% of days
- Intensity Up to ~47mm (P95)
Washout conditions are possible on ~7 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Rain High impact
Heavy rain days Measures: Heavy rain days (>=10mm). Observed about 15% of days (4.5 days/month) in September. Historical risk signal only, not a day-by-day forecast.
4.5 days / month
~15% of days
Why this matters
- Expected days 4.5 days / month
- Probability ~15% of days
- Intensity Up to ~51mm (P95)
Heavy rain is possible on ~4 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Wind High impact
Strong gusts Measures: Strong gust days (>=60 km/h). Observed about 6% of days (1.8 days/month) in September. Historical risk signal only, not a day-by-day forecast.
1.8 days / month
~6% of days
Why this matters
- Expected days 1.8 days / month
- Probability ~6% of days
- Intensity Up to ~90km/h (P95)
Strong gusts are possible on ~2 days. Exposed activities and transport links are more likely to be disrupted, so keep sheltered alternatives ready.
Wind High impact
Stormy conditions Measures: Storm-impact proxy days. Observed about 5% of days (1.5 days/month) in September. Historical risk signal only, not a day-by-day forecast.
1.5 days / month
~5% of days
Why this matters
- Expected days 1.5 days / month
- Probability ~5% of days
- Intensity Up to ~89km/h (P95)
Stormy conditions are possible on ~2 days. Exposed activities and transport links are more likely to be disrupted, so keep sheltered alternatives ready.
Humidity Moderate
Muggy days Measures: Muggy days (dew point >=20C). Observed about 6% of days (1.8 days/month) in September. Historical risk signal only, not a day-by-day forecast.
1.8 days / month
~6% of days
Why this matters
- Expected days 1.8 days / month
- Probability ~6% of days
- Intensity Up to ~22°C (P95)
Muggy conditions are possible on ~2 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Show all disruptions (20 more)
Rain High impact
Very heavy rain Measures: Very heavy rain days (>=25mm). Observed about 5% of days (1.5 days/month) in September. Historical risk signal only, not a day-by-day forecast.
1.5 days / month
~5% of days
Why this matters
- Expected days 1.5 days / month
- Probability ~5% of days
- Intensity Up to ~73mm (P95)
Very heavy rain is possible on ~2 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Rain High impact
Washout run Measures: Multi-day washout runs. Observed about 1.5 days/month in September. Historical risk signal only, not a day-by-day forecast.
1.5 days / month
Probability unavailable
Why this matters
- Expected days 1.5 days / month
- Probability —
- Intensity Up to ~52mm (P95)
Multi-day washout runs are possible on ~2 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Wind High impact
Severe gusts Measures: Severe gust days (>=80 km/h). Observed about 1% of days (0.3 days/month) in September. Historical risk signal only, not a day-by-day forecast.
0.3 days / month
~1% of days
Why this matters
- Expected days 0.3 days / month
- Probability ~1% of days
- Intensity Up to ~132km/h (P95)
Severe gusts are possible on ~0 days. Exposed activities and transport links are more likely to be disrupted, so keep sheltered alternatives ready.
Rain High impact
Extreme rain Measures: Extreme rain days (>=50mm). Observed about 1% of days (0.3 days/month) in September. Historical risk signal only, not a day-by-day forecast.
0.3 days / month
~1% of days
Why this matters
- Expected days 0.3 days / month
- Probability ~1% of days
- Intensity Up to ~106mm (P95)
Extreme rain is possible on ~0 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Visibility Moderate
Fog-likely signal Measures: Fog-likely visibility proxy. Observed about 5% of days (1.6 days/month) in September. Historical risk signal only, not a day-by-day forecast.
1.6 days / month
~5% of days
Why this matters
- Expected days 1.6 days / month
- Probability ~5% of days
- Intensity Up to ~95% (P95)
Fog-likely conditions are possible on ~2 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Cold Moderate
Cold feels-like nights Measures: Cold feels-like nights (min <=5C). Observed about 1% of days (0.2 days/month) in September. Historical risk signal only, not a day-by-day forecast.
0.2 days / month
~1% of days
Why this matters
- Expected days 0.2 days / month
- Probability ~1% of days
- Intensity Up to ~5°C (P95)
Cold feels-like nights are possible on ~0 days. Long outdoor blocks become harder to sustain, so layer up and keep a warm indoor fallback nearby.
Heat Moderate
Hot feels-like days Measures: Hot feels-like days (>=32C). Observed about 1% of days (0.2 days/month) in September. Historical risk signal only, not a day-by-day forecast.
0.2 days / month
~1% of days
Why this matters
- Expected days 0.2 days / month
- Probability ~1% of days
- Intensity Up to ~37°C (P95)
Feels-like heat >=32C is possible on ~0 days. Midday activity often needs adjustment around shade, hydration, and indoor fallback options.
Humidity Minor
High humidity Measures: High humidity days (RH >=80%). Observed about 65% of days (19.4 days/month) in September. Historical risk signal only, not a day-by-day forecast.
19.4 days / month
~65% of days
Why this matters
- Expected days 19.4 days / month
- Probability ~65% of days
- Intensity Up to ~93% (P95)
High humidity is possible on ~19 days. Comfort and pace can drop quickly, so plan shorter outdoor blocks with air-conditioned backup stops.
Rain Minor
Wet days Measures: Wet days (>=0.1mm). Observed about 64% of days (19.3 days/month) in September. Historical risk signal only, not a day-by-day forecast.
19.3 days / month
~64% of days
Why this matters
- Expected days 19.3 days / month
- Probability ~64% of days
- Intensity Up to ~34mm (P95)
Measurable rain is possible on ~19 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Cloud Minor
Cloudy days Measures: Cloudy days (cloud cover >=60%). Observed about 64% of days (19.2 days/month) in September. Historical risk signal only, not a day-by-day forecast.
19.2 days / month
~64% of days
Why this matters
- Expected days 19.2 days / month
- Probability ~64% of days
- Intensity Up to ~100% (P95)
Cloudy skies are possible on ~19 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Rain Minor
Rainy hours Measures: Rain-hours signal (>=3h rain). Observed about 53% of days (15.9 days/month) in September. Historical risk signal only, not a day-by-day forecast.
15.9 days / month
~53% of days
Why this matters
- Expected days 15.9 days / month
- Probability ~53% of days
- Intensity Up to ~21h (P95)
Several rainy hours are possible on ~16 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Cloud Minor
Mostly cloudy days Measures: Mostly cloudy days (cloud cover >=80%). Observed about 40% of days (12.0 days/month) in September. Historical risk signal only, not a day-by-day forecast.
12.0 days / month
~40% of days
Why this matters
- Expected days 12.0 days / month
- Probability ~40% of days
- Intensity Up to ~100% (P95)
Mostly cloudy skies are possible on ~12 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Rain Minor
Wet most of day Measures: Wet-most-of-day signal (>=6h rain). Observed about 38% of days (11.5 days/month) in September. Historical risk signal only, not a day-by-day forecast.
11.5 days / month
~38% of days
Why this matters
- Expected days 11.5 days / month
- Probability ~38% of days
- Intensity Up to ~23h (P95)
Wet-most-of-day conditions are possible on ~12 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Wind Minor
Gusty days Measures: Gusty days (>=40 km/h). Observed about 37% of days (11.2 days/month) in September. Historical risk signal only, not a day-by-day forecast.
11.2 days / month
~37% of days
Why this matters
- Expected days 11.2 days / month
- Probability ~37% of days
- Intensity Up to ~72km/h (P95)
Gusty conditions are possible on ~11 days. Exposed activities and transport links are more likely to be disrupted, so keep sheltered alternatives ready.
Cloud Minor
Overcast days Measures: Overcast days (cloud cover >=95%). Observed about 20% of days (5.9 days/month) in September. Historical risk signal only, not a day-by-day forecast.
5.9 days / month
~20% of days
Why this matters
- Expected days 5.9 days / month
- Probability ~20% of days
- Intensity Up to ~100% (P95)
Overcast skies are possible on ~6 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Humidity Minor
Humid days Measures: Humid days (dew point >=18C). Observed about 14% of days (4.1 days/month) in September. Historical risk signal only, not a day-by-day forecast.
4.1 days / month
~14% of days
Why this matters
- Expected days 4.1 days / month
- Probability ~14% of days
- Intensity Up to ~22°C (P95)
Humid conditions are possible on ~4 days. Comfort and pace can drop quickly, so plan shorter outdoor blocks with air-conditioned backup stops.
Humidity Minor
Convective risk Measures: Convective storm risk proxy. Observed about 6% of days (1.8 days/month) in September. Historical risk signal only, not a day-by-day forecast.
1.8 days / month
~6% of days
Why this matters
- Expected days 1.8 days / month
- Probability ~6% of days
- Intensity Up to ~22°C (P95)
Convective risk signal appears on ~2 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Other Minor
Low visibility proxy: same as fog-likely (RH ≥90% AND cloud ≥95%) — true visibility requires hourly visibility data Measures: Low visibility proxy: same as fog-likely (RH ≥90% AND cloud ≥95%) — true visibility requires hourly visibility data. Observed about 5% of days (1.6 days/month) in September. Historical risk signal only, not a day-by-day forecast.
1.6 days / month
~5% of days
Why this matters
- Expected days 1.6 days / month
- Probability ~5% of days
- Intensity Up to ~95 (P95)
Low visibility proxy: same as fog-likely (RH ≥90% AND cloud ≥95%) — true visibility requires hourly visibility data is possible on ~2 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Wind Minor
Breezy days Measures: Breezy days (mean wind >=25 km/h). Observed about 1% of days (0.3 days/month) in September. Historical risk signal only, not a day-by-day forecast.
0.3 days / month
~1% of days
Why this matters
- Expected days 0.3 days / month
- Probability ~1% of days
- Intensity Up to ~35km/h (P95)
Breezy conditions are possible on ~0 days. Exposed activities and transport links are more likely to be disrupted, so keep sheltered alternatives ready.
Heat Minor
Warm nights Measures: Warm nights (min >=22C). Observed about 1% of days (0.2 days/month) in September. Historical risk signal only, not a day-by-day forecast.
0.2 days / month
~1% of days
Why this matters
- Expected days 0.2 days / month
- Probability ~1% of days
- Intensity Up to ~23°C (P95)
Warm nights are possible on ~0 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Frequently asked questions
Is September a good time to visit Sapporo?
Typical September days in Sapporo reach highs of 21°C (70°F) with nights around 14°C (57°F). It usually feels mild by day and cool after dark. It is among the wetter months, so it is wise to have some indoor backup plans or flexible activities.
What are temperatures like in September?
Daytime temperatures in September typically peak near 21°C (70°F), while nights drop to around 14°C (57°F). Expect mild afternoons and cool evenings.
How much does it rain in September?
Rainfall in September averages 138 mm (5.4 in) across roughly 16 days. Overall it is a very wet time of year, so a light rain jacket and waterproof shoes are very handy.
How many hours of daylight are there in September?
You can expect about 13 hours of daylight in September. Sunrise is typically around 05:13 and sunset near 17:44. Daylight is fairly typical, with enough time for sightseeing.
How strong is the sun in September?
UV levels are often high (around 6). Regular sunscreen and a hat are recommended.
Is it windy in September?
In September, average wind speeds are around 12 km/h (7 mph), with gusts on the windiest days reaching about 54 km/h (34 mph). On the ground, it is it can feel quite windy at times, particularly when weather systems move through.