Avg High
Reykjavik in September
Avg Low
Rain
Daylight
13h
What to expect
In Reykjavik, September sits in early autumn, a shoulder-season month where the feel can shift as the season turns. Most days sit on the cooler side, and relatively steady temperatures through the day. Comfort is usually predictable, so a standard day plan works well. You get long daylight windows for full-day exploring.
September in context
How it compares to the rest of the year in Reykjavik.
Hottest (avg)
#4 / 12
Wettest (avg)
#1 / 12
Daylight Hours
#6 / 12
Windiest (avg)
#7 / 12
Highest UV
#6 / 12
Most Humid
#2 / 12
Monthly climate breakdown
Temperature
- Daytime high
-
- Nighttime low
-
- Feels like (avg)
-
Sunshine
- Daylight hours
- 13 h
- UV index (max)
- 4
- Typical sun hours
- 06:52 - 19:52
Rain & Snow
- Total rain
-
- Rainy days
- 20 days
- Cloud cover (avg)
- 78%
- Snowfall
-
Humidity & Wind
- Humidity (avg)
- 84%
- Wind (avg)
-
- Wind (max gusts)
-
Daily climate explorer
Day 15 selected for September. Typical high 10.2°C and low 5.1°C.
Typical disruptions in September
Based on 30 years of historical data, these are the disruption patterns most likely to affect plans in September.
Cold High impact
Cold feels-like nights Measures: Cold feels-like nights (min <=5C). Observed about 78% of days (23.5 days/month) in September. Historical risk signal only, not a day-by-day forecast.
23.5 days / month
~78% of days
Why this matters
- Expected days 23.5 days / month
- Probability ~78% of days
- Intensity Up to ~5°C (P95)
Cold feels-like nights are possible on ~23 days. Long outdoor blocks become harder to sustain, so layer up and keep a warm indoor fallback nearby.
Rain High impact
Rain disruption Measures: Likely rain disruption days. Observed about 33% of days (9.8 days/month) in September. Historical risk signal only, not a day-by-day forecast.
9.8 days / month
~33% of days
Why this matters
- Expected days 9.8 days / month
- Probability ~33% of days
- Intensity Up to ~26mm (P95)
Rain disruption risk appears on ~10 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 33% of days (9.8 days/month) in September. Historical risk signal only, not a day-by-day forecast.
9.8 days / month
~33% of days
Why this matters
- Expected days 9.8 days / month
- Probability ~33% of days
- Intensity Up to ~26mm (P95)
Washout conditions are possible on ~10 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 26% of days (7.7 days/month) in September. Historical risk signal only, not a day-by-day forecast.
7.7 days / month
~26% of days
Why this matters
- Expected days 7.7 days / month
- Probability ~26% of days
- Intensity Up to ~96km/h (P95)
Strong gusts are possible on ~8 days. Exposed activities and transport links are more likely to be disrupted, so keep sheltered alternatives ready.
Rain High impact
Heavy rain days Measures: Heavy rain days (>=10mm). Observed about 15% of days (4.4 days/month) in September. Historical risk signal only, not a day-by-day forecast.
4.4 days / month
~15% of days
Why this matters
- Expected days 4.4 days / month
- Probability ~15% of days
- Intensity Up to ~31mm (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
Stormy conditions Measures: Storm-impact proxy days. Observed about 12% of days (3.5 days/month) in September. Historical risk signal only, not a day-by-day forecast.
3.5 days / month
~12% of days
Why this matters
- Expected days 3.5 days / month
- Probability ~12% of days
- Intensity Up to ~98km/h (P95)
Stormy conditions are possible on ~4 days. Exposed activities and transport links are more likely to be disrupted, so keep sheltered alternatives ready.
Show all disruptions (20 more)
Rain High impact
Washout run Measures: Multi-day washout runs. Observed about 2.5 days/month in September. Historical risk signal only, not a day-by-day forecast.
2.5 days / month
Probability unavailable
Why this matters
- Expected days 2.5 days / month
- Probability —
- Intensity Up to ~24mm (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 6% of days (1.9 days/month) in September. Historical risk signal only, not a day-by-day forecast.
1.9 days / month
~6% of days
Why this matters
- Expected days 1.9 days / month
- Probability ~6% of days
- Intensity Up to ~107km/h (P95)
Severe gusts are possible on ~2 days. Exposed activities and transport links are more likely to be disrupted, so keep sheltered alternatives ready.
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.
0.6 days / month
~2% of days
Why this matters
- Expected days 0.6 days / month
- Probability ~2% of days
- Intensity Up to ~39mm (P95)
Very heavy rain is possible on ~1 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 16% of days (4.8 days/month) in September. Historical risk signal only, not a day-by-day forecast.
4.8 days / month
~16% of days
Why this matters
- Expected days 4.8 days / month
- Probability ~16% of days
- Intensity Up to ~98% (P95)
Fog-likely conditions are possible on ~5 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Cold Moderate
Cold snap run Measures: Cold snap runs (>=3 cold days). Observed about 1.6 days/month in September. Historical risk signal only, not a day-by-day forecast.
1.6 days / month
Probability unavailable
Why this matters
- Expected days 1.6 days / month
- Probability —
- Intensity Up to ~10°C (P95)
Cold snap runs are possible on ~2 days. Long outdoor blocks become harder to sustain, so layer up and keep a warm indoor fallback nearby.
Cold Moderate
Wind chill risk Measures: Wind chill risk days. Observed about 4% of days (1.2 days/month) in September. Historical risk signal only, not a day-by-day forecast.
1.2 days / month
~4% of days
Why this matters
- Expected days 1.2 days / month
- Probability ~4% of days
- Intensity Up to ~-0°C (P95)
Wind chill risk is possible on ~1 days. Exposed activities and transport links are more likely to be disrupted, so keep sheltered alternatives ready.
Cloud Minor
Cloudy days Measures: Cloudy days (cloud cover >=60%). Observed about 81% of days (24.2 days/month) in September. Historical risk signal only, not a day-by-day forecast.
24.2 days / month
~81% of days
Why this matters
- Expected days 24.2 days / month
- Probability ~81% of days
- Intensity Up to ~100% (P95)
Cloudy skies are possible on ~24 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Rain Minor
Wet days Measures: Wet days (>=0.1mm). Observed about 74% of days (22.2 days/month) in September. Historical risk signal only, not a day-by-day forecast.
22.2 days / month
~74% of days
Why this matters
- Expected days 22.2 days / month
- Probability ~74% of days
- Intensity Up to ~21mm (P95)
Measurable rain is possible on ~22 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 72% of days (21.7 days/month) in September. Historical risk signal only, not a day-by-day forecast.
21.7 days / month
~72% of days
Why this matters
- Expected days 21.7 days / month
- Probability ~72% of days
- Intensity Up to ~96% (P95)
High humidity is possible on ~22 days. Comfort and pace can drop quickly, so plan shorter outdoor blocks with air-conditioned backup stops.
Rain Minor
Rainy hours Measures: Rain-hours signal (>=3h rain). Observed about 66% of days (19.8 days/month) in September. Historical risk signal only, not a day-by-day forecast.
19.8 days / month
~66% of days
Why this matters
- Expected days 19.8 days / month
- Probability ~66% of days
- Intensity Up to ~23h (P95)
Several rainy hours are possible on ~20 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 61% of days (18.3 days/month) in September. Historical risk signal only, not a day-by-day forecast.
18.3 days / month
~61% of days
Why this matters
- Expected days 18.3 days / month
- Probability ~61% of days
- Intensity Up to ~89km/h (P95)
Gusty conditions are possible on ~18 days. Exposed activities and transport links are more likely to be disrupted, so keep sheltered alternatives ready.
Cloud Minor
Mostly cloudy days Measures: Mostly cloudy days (cloud cover >=80%). Observed about 59% of days (17.7 days/month) in September. Historical risk signal only, not a day-by-day forecast.
17.7 days / month
~59% of days
Why this matters
- Expected days 17.7 days / month
- Probability ~59% of days
- Intensity Up to ~100% (P95)
Mostly cloudy skies are possible on ~18 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 57% of days (17.2 days/month) in September. Historical risk signal only, not a day-by-day forecast.
17.2 days / month
~57% of days
Why this matters
- Expected days 17.2 days / month
- Probability ~57% of days
- Intensity Up to ~23h (P95)
Wet-most-of-day conditions are possible on ~17 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Cold Minor
Cold days Measures: Cold days (max <=10C). Observed about 43% of days (12.9 days/month) in September. Historical risk signal only, not a day-by-day forecast.
12.9 days / month
~43% of days
Why this matters
- Expected days 12.9 days / month
- Probability ~43% of days
- Intensity Up to ~10°C (P95)
Cold daytime conditions are possible on ~13 days. Long outdoor blocks become harder to sustain, so layer up and keep a warm indoor fallback nearby.
Cold Minor
Cold nights Measures: Cold nights (min <=5C). Observed about 36% of days (10.9 days/month) in September. Historical risk signal only, not a day-by-day forecast.
10.9 days / month
~36% of days
Why this matters
- Expected days 10.9 days / month
- Probability ~36% of days
- Intensity Up to ~5°C (P95)
Cold nights are possible on ~11 days. Long outdoor blocks become harder to sustain, so layer up and keep a warm indoor fallback nearby.
Cloud Minor
Overcast days Measures: Overcast days (cloud cover >=95%). Observed about 29% of days (8.8 days/month) in September. Historical risk signal only, not a day-by-day forecast.
8.8 days / month
~29% of days
Why this matters
- Expected days 8.8 days / month
- Probability ~29% of days
- Intensity Up to ~100% (P95)
Overcast skies are possible on ~9 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 16% of days (4.8 days/month) in September. Historical risk signal only, not a day-by-day forecast.
4.8 days / month
~16% of days
Why this matters
- Expected days 4.8 days / month
- Probability ~16% of days
- Intensity Up to ~98 (P95)
Low visibility proxy: same as fog-likely (RH ≥90% AND cloud ≥95%) — true visibility requires hourly visibility data is possible on ~5 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 11% of days (3.4 days/month) in September. Historical risk signal only, not a day-by-day forecast.
3.4 days / month
~11% of days
Why this matters
- Expected days 3.4 days / month
- Probability ~11% of days
- Intensity Up to ~34km/h (P95)
Breezy conditions are possible on ~3 days. Exposed activities and transport links are more likely to be disrupted, so keep sheltered alternatives ready.
Cold Minor
Freezing nights Measures: Freezing nights (min <=0C). Observed about 2% of days (0.7 days/month) in September. Historical risk signal only, not a day-by-day forecast.
0.7 days / month
~2% of days
Why this matters
- Expected days 0.7 days / month
- Probability ~2% of days
- Intensity Up to ~-0°C (P95)
Freezing nights are possible on ~1 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Snow Minor
Snow days Measures: Snow days (>=0.1mm snowfall). Observed about 2% of days (0.6 days/month) in September. Historical risk signal only, not a day-by-day forecast.
0.6 days / month
~2% of days
Why this matters
- Expected days 0.6 days / month
- Probability ~2% of days
- Intensity Up to ~2.4mm (P95)
Snowfall is possible on ~1 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Frequently asked questions
Is September a good time to visit Reykjavik?
Typical September days in Reykjavik reach highs of 10°C (50°F) with nights around 6°C (43°F). It usually feels cool by day and cold 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 10°C (50°F), while nights drop to around 6°C (43°F). Expect cool afternoons and cold evenings.
How much does it rain in September?
Rainfall in September averages 138 mm (5.4 in) across roughly 20 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 06:52 and sunset near 19:52. You get long days with comfortable amounts of daylight.
How strong is the sun in September?
UV levels are moderate (around 4); sunscreen and sunglasses are still a good idea.
Is it windy in September?
In September, average wind speeds are around 15 km/h (9 mph), with gusts on the windiest days reaching about 73 km/h (45 mph). On the ground, it is it is a notably windy place, and strong gusts are fairly common.