Hottest (avg)
#4 / 12
Sits around the middle of the year.
September in context
How it compares to the rest of the year in Lyon.
Wettest (avg)
#4 / 12
Typical rainfall for the year.
Daylight Hours
#6 / 12
Around the yearly average.
Windiest (avg)
#10 / 12
Usually calmer than most months.
Highest UV
#6 / 12
Near the middle of the yearly UV range.
Most Humid
#7 / 12
Humidity stays close to the yearly norm.
Monthly climate breakdown
A detailed look at the typical climate conditions for September.
Thermal profile
Temperature
Typical daytime high
- Nighttime low
-
- Feels like (avg)
-
Light window
Sunshine
12.5 h
Average daylight
- UV index (max)
- 6
- Typical sun hours
- 06:19 - 18:51
Wet-day pattern
Rain & Snow
Typical rainfall
- Rainy days
- 11 days
- Cloud cover (avg)
- 52%
Air feel
Humidity & Wind
71%
Average humidity
- Wind (avg)
-
- Wind (max gusts)
-
Historical daily baseline
Daily climate explorer
Pick a day to inspect the usual conditions through September in Lyon. Based on a 30-year historical climate baseline, not a forecast.
Primary control
Select a day
Scroll to compare daily conditions. The summary updates with your selection.
Secondary context
Monthly trend
Median daytime highs across the month, with a softer low line.
Median temperatureMedian lowTypical range
Day 15 selected for September. Temperature 20.1°C.
Historical disruption baseline
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 15% of days (4.6 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
4.6 days / month
- Share of days
- ~15% of days
- Upper edge
- Up to ~40mm (P95)
Why this matters
Rain disruption risk appears on ~5 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 15% of days (4.4 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
4.4 days / month
- Share of days
- ~15% of days
- Upper edge
- Up to ~39mm (P95)
Why this matters
Washout conditions are 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 3% of days (1.0 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
1.0 days / month
- Share of days
- ~3% of days
- Upper edge
- Up to ~82km/h (P95)
Why this matters
Strong gusts are possible on ~1 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 2% of days (0.6 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
0.6 days / month
- Share of days
- ~2% of days
- Upper edge
- Up to ~79km/h (P95)
Why this matters
Stormy conditions are possible on ~1 days. Exposed activities and transport links are more likely to be disrupted, so keep sheltered alternatives ready.
Heat Moderate
Hot days Measures: Hot days (>=30C). Observed about 4% of days (1.2 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
1.2 days / month
- Share of days
- ~4% of days
- Upper edge
- Up to ~33°C (P95)
Why this matters
Hot days are possible on ~1 days. Midday activity often needs adjustment around shade, hydration, and indoor fallback options.
Cold Moderate
Cold feels-like nights Measures: Cold feels-like nights (min <=5C). Observed about 3% of days (1.0 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
1.0 days / month
- Share of days
- ~3% of days
- Upper edge
- Up to ~5°C (P95)
Why this matters
Cold feels-like nights are possible on ~1 days. Long outdoor blocks become harder to sustain, so layer up and keep a warm indoor fallback nearby.
Show all disruptions (16 more)
Rain High impact
Heavy rain days Measures: Heavy rain days (>=10mm). Observed about 9% of days (2.8 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
2.8 days / month
- Share of days
- ~9% of days
- Upper edge
- Up to ~43mm (P95)
Why this matters
Heavy rain is possible on ~3 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 1.1 days/month in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
1.1 days / month
- Share of days
- —
- Upper edge
- Up to ~36mm (P95)
Why this matters
Multi-day washout runs are possible on ~1 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Rain High impact
Very heavy rain Measures: Very heavy rain days (>=25mm). Observed about 2% of days (0.6 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
0.6 days / month
- Share of days
- ~2% of days
- Upper edge
- Up to ~68mm (P95)
Why this matters
Very heavy rain is possible on ~1 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Heat Moderate
Hot feels-like days Measures: Hot feels-like days (>=32C). Observed about 1% of days (0.4 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
0.4 days / month
- Share of days
- ~1% of days
- Upper edge
- Up to ~33°C (P95)
Why this matters
Feels-like heat >=32C is possible on ~0 days. Midday activity often needs adjustment around shade, hydration, and indoor fallback options.
Rain Minor
Wet days Measures: Wet days (>=0.1mm). Observed about 47% of days (14.1 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
14.1 days / month
- Share of days
- ~47% of days
- Upper edge
- Up to ~23mm (P95)
Why this matters
Measurable rain is possible on ~14 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 45% of days (13.5 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
13.5 days / month
- Share of days
- ~45% of days
- Upper edge
- Up to ~98% (P95)
Why this matters
Cloudy skies are possible on ~14 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 35% of days (10.4 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
10.4 days / month
- Share of days
- ~35% of days
- Upper edge
- Up to ~19h (P95)
Why this matters
Several rainy hours are possible on ~10 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 27% of days (8.0 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
8.0 days / month
- Share of days
- ~27% of days
- Upper edge
- Up to ~64km/h (P95)
Why this matters
Gusty conditions are possible on ~8 days. Exposed activities and transport links are more likely to be disrupted, so keep sheltered alternatives ready.
Rain Minor
Wet most of day Measures: Wet-most-of-day signal (>=6h rain). Observed about 25% of days (7.5 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
7.5 days / month
- Share of days
- ~25% of days
- Upper edge
- Up to ~20h (P95)
Why this matters
Wet-most-of-day conditions are possible on ~7 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 22% of days (6.6 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
6.6 days / month
- Share of days
- ~22% of days
- Upper edge
- Up to ~99% (P95)
Why this matters
Mostly cloudy skies are possible on ~7 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Humidity Minor
High humidity Measures: High humidity days (RH >=80%). Observed about 20% of days (5.9 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
5.9 days / month
- Share of days
- ~20% of days
- Upper edge
- Up to ~91% (P95)
Why this matters
High humidity is possible on ~6 days. Comfort and pace can drop quickly, so plan shorter outdoor blocks with air-conditioned backup stops.
Cloud Minor
Overcast days Measures: Overcast days (cloud cover >=95%). Observed about 6% of days (1.7 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
1.7 days / month
- Share of days
- ~6% of days
- Upper edge
- Up to ~100% (P95)
Why this matters
Overcast skies are possible on ~2 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Visibility Minor
Fog-likely signal Measures: Fog-likely visibility proxy. Observed about 1% of days (0.3 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
0.3 days / month
- Share of days
- ~1% of days
- Upper edge
- Up to ~96% (P95)
Why this matters
Fog-likely conditions are possible on ~0 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 1% of days (0.3 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
0.3 days / month
- Share of days
- ~1% of days
- Upper edge
- Up to ~96 (P95)
Why this matters
Low visibility proxy: same as fog-likely (RH ≥90% AND cloud ≥95%) — true visibility requires hourly visibility data is possible on ~0 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 1% of days (0.3 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
0.3 days / month
- Share of days
- ~1% of days
- Upper edge
- Up to ~19°C (P95)
Why this matters
Humid conditions are possible on ~0 days. Comfort and pace can drop quickly, so plan shorter outdoor blocks with air-conditioned backup stops.
Heat Minor
Heatwave run Measures: Heatwave runs (>=3 hot days). Observed about 0.1 days/month in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
0.1 days / month
- Share of days
- —
- Upper edge
- Up to ~33°C (P95)
Why this matters
Heatwave runs are possible on ~0 days. Midday activity often needs adjustment around shade, hydration, and indoor fallback options.
Travel planning FAQ
Frequently asked questions
Quick answers to the weather questions you ask the most.
Is September a good time to visit Lyon?
Typical September days in Lyon reach highs of 22°C (72°F) with nights around 13°C (55°F). It usually feels warm by day and cool after dark. Overall, September sits in the middle of the Lyon climate range.
What are temperatures like in September?
In September, you can usually expect highs of 22°C (72°F) and lows near 13°C (55°F). That means warm days and cool nights, so pack layers you can add or remove.
How much does it rain in September?
Rainfall in September averages 84 mm (3.3 in) across roughly 11 days. Overall it is a quite rainy 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 06:19 and sunset near 18:51. 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 9 km/h (6 mph), with gusts on the windiest days reaching about 50 km/h (31 mph). On the ground, it is it often feels breezy, especially in more exposed spots or along the coast.