Hottest (avg)
#4 / 12
Sits around the middle of the year.
September in context
How it compares to the rest of the year in Phoenix.
Wettest (avg)
#6 / 12
Typical rainfall for the year.
Daylight Hours
#6 / 12
Around the yearly average.
Windiest (avg)
#6 / 12
Close to the yearly wind average.
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
12.4 h
Average daylight
- UV index (max)
- 8
- Typical sun hours
- 06:11 - 18:33
Wet-day pattern
Rain & Snow
Typical rainfall
- Rainy days
- 4 days
- Cloud cover (avg)
- 21%
Air feel
Humidity & Wind
33%
Average humidity
- Wind (avg)
-
- Wind (max gusts)
-
Historical daily baseline
Daily climate explorer
Pick a day to inspect the usual conditions through September in Phoenix. 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 36.9°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.
Heat High impact
Hot days Measures: Hot days (>=30C). Observed about 96% of days (28.7 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
28.7 days / month
- Share of days
- ~96% of days
- Upper edge
- Up to ~42°C (P95)
Why this matters
Hot days are possible on ~29 days. Midday activity often needs adjustment around shade, hydration, and indoor fallback options.
Heat High impact
Hot feels-like days Measures: Hot feels-like days (>=32C). Observed about 91% of days (27.4 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
27.4 days / month
- Share of days
- ~91% of days
- Upper edge
- Up to ~42°C (P95)
Why this matters
Feels-like heat >=32C is possible on ~27 days. Midday activity often needs adjustment around shade, hydration, and indoor fallback options.
Heat High impact
Very hot days Measures: Very hot days (>=35C). Observed about 77% of days (23.1 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
23.1 days / month
- Share of days
- ~77% of days
- Upper edge
- Up to ~42°C (P95)
Why this matters
Very hot days are possible on ~23 days. Midday activity often needs adjustment around shade, hydration, and indoor fallback options.
Heat High impact
Very hot feels-like Measures: Very hot feels-like days (>=35C). Observed about 75% of days (22.5 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
22.5 days / month
- Share of days
- ~75% of days
- Upper edge
- Up to ~42°C (P95)
Why this matters
Very hot feels-like conditions are possible on ~23 days. Midday activity often needs adjustment around shade, hydration, and indoor fallback options.
Heat High impact
Extreme heat days Measures: Extreme heat days (>=40C). Observed about 22% of days (6.7 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
6.7 days / month
- Share of days
- ~22% of days
- Upper edge
- Up to ~43°C (P95)
Why this matters
Extreme heat is possible on ~7 days. Midday activity often needs adjustment around shade, hydration, and indoor fallback options.
Heat High impact
Feels-like heatwave Measures: Feels-like heatwave runs (>=3 days). Observed about 1.6 days/month in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
1.6 days / month
- Share of days
- —
- Upper edge
- Up to ~42°C (P95)
Why this matters
Feels-like heatwave runs are possible on ~2 days. Midday activity often needs adjustment around shade, hydration, and indoor fallback options.
Show all disruptions (20 more)
Heat High impact
Heatwave run Measures: Heatwave runs (>=3 hot days). Observed about 1.5 days/month in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
1.5 days / month
- Share of days
- —
- Upper edge
- Up to ~43°C (P95)
Why this matters
Heatwave runs are possible on ~1 days. Midday activity often needs adjustment around shade, hydration, and indoor fallback options.
Rain High impact
Rain disruption Measures: Likely rain disruption days. Observed about 4% of days (1.3 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
1.3 days / month
- Share of days
- ~4% of days
- Upper edge
- Up to ~39mm (P95)
Why this matters
Rain disruption risk appears on ~1 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 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 ~44mm (P95)
Why this matters
Washout conditions are possible on ~1 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 2% of days (0.7 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
0.7 days / month
- Share of days
- ~2% of days
- Upper edge
- Up to ~50mm (P95)
Why this matters
Heavy rain is 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 1% of days (0.2 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
0.2 days / month
- Share of days
- ~1% of days
- Upper edge
- Up to ~53mm (P95)
Why this matters
Very heavy rain is possible on ~0 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 1% of days (0.2 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
0.2 days / month
- Share of days
- ~1% of days
- Upper edge
- Up to ~72km/h (P95)
Why this matters
Strong 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
Washout run Measures: Multi-day washout runs. Observed about 0.2 days/month in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
0.2 days / month
- Share of days
- —
- Upper edge
- Up to ~15mm (P95)
Why this matters
Multi-day washout runs are possible on ~0 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Heat Moderate
Heat stress risk Measures: High heat stress days. Observed about 8% of days (2.4 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
2.4 days / month
- Share of days
- ~8% of days
- Upper edge
- Up to ~41°C (P95)
Why this matters
Heat stress is possible on ~2 days. Midday activity often needs adjustment around shade, hydration, and indoor fallback options.
Humidity Moderate
Muggy days Measures: Muggy days (dew point >=20C). Observed about 5% of days (1.4 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
1.4 days / month
- Share of days
- ~5% of days
- Upper edge
- Up to ~22°C (P95)
Why this matters
Muggy conditions are possible on ~1 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Heat Minor
Warm nights Measures: Warm nights (min >=22C). Observed about 72% of days (21.7 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
21.7 days / month
- Share of days
- ~72% of days
- Upper edge
- Up to ~29°C (P95)
Why this matters
Warm nights are possible on ~22 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Heat Minor
Hot nights Measures: Hot nights (min >=25C). Observed about 39% of days (11.7 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
11.7 days / month
- Share of days
- ~39% of days
- Upper edge
- Up to ~30°C (P95)
Why this matters
Hot nights are possible on ~12 days. Midday activity often needs adjustment around shade, hydration, and indoor fallback options.
Rain Minor
Wet days Measures: Wet days (>=0.1mm). Observed about 18% of days (5.5 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
5.5 days / month
- Share of days
- ~18% of days
- Upper edge
- Up to ~22mm (P95)
Why this matters
Measurable rain is possible on ~6 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Wind Minor
Gusty days Measures: Gusty days (>=40 km/h). 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 ~58km/h (P95)
Why this matters
Gusty conditions are possible on ~4 days. Exposed activities and transport links are more likely to be disrupted, so keep sheltered alternatives ready.
Humidity Minor
Humid days Measures: Humid days (dew point >=18C). Observed about 12% of days (3.7 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
3.7 days / month
- Share of days
- ~12% of days
- Upper edge
- Up to ~22°C (P95)
Why this matters
Humid conditions are possible on ~4 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 11% of days (3.2 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
3.2 days / month
- Share of days
- ~11% of days
- Upper edge
- Up to ~15h (P95)
Why this matters
Several rainy hours are possible on ~3 days. Outdoor plans can become unreliable, so keep an indoor backup and flexibility around start times.
Cloud Minor
Cloudy days Measures: Cloudy days (cloud cover >=60%). Observed about 9% of days (2.7 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
2.7 days / month
- Share of days
- ~9% of days
- Upper edge
- Up to ~98% (P95)
Why this matters
Cloudy skies are possible on ~3 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 4% of days (1.3 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
1.3 days / month
- Share of days
- ~4% of days
- Upper edge
- Up to ~20h (P95)
Why this matters
Wet-most-of-day conditions are possible on ~1 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 4% of days (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
- ~4% of days
- Upper edge
- Up to ~100% (P95)
Why this matters
Mostly cloudy skies are possible on ~1 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Humidity Minor
Convective risk Measures: Convective storm risk proxy. 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 ~22°C (P95)
Why this matters
Convective risk signal appears on ~1 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Cloud Minor
Overcast days Measures: Overcast days (cloud cover >=95%). Observed about 2% of days (0.5 days/month) in September. Historical risk signal only, not a day-by-day forecast.
Likely frequency
0.5 days / month
- Share of days
- ~2% of days
- Upper edge
- Up to ~100% (P95)
Why this matters
Overcast skies are possible on ~1 days. Fixed-time outdoor plans are safer with a backup option and flexible timing.
Travel planning FAQ
Frequently asked questions
Quick answers to the weather questions you ask the most.
Is September a good time to visit Phoenix?
Typical September days in Phoenix reach highs of 37°C (99°F) with nights around 24°C (75°F). It usually feels very hot by day and warm after dark. Overall, September sits in the middle of the Phoenix climate range.
What are temperatures like in September?
Daytime temperatures in September typically peak near 37°C (99°F), while nights drop to around 24°C (75°F). Expect very hot afternoons and warm evenings.
How much does it rain in September?
Rainfall in September averages 25 mm (0.98 in) across roughly 4 days. Overall it is a mostly dry time of year, so showers are usually brief rather than all-day downpours.
How many hours of daylight are there in September?
You can expect about 12 hours of daylight in September. Sunrise is typically around 06:11 and sunset near 18:33. Daylight is fairly typical, with enough time for sightseeing.
How strong is the sun in September?
UV levels are often high (around 8). Regular sunscreen and a hat are recommended.
Is it windy in September?
In September, average wind speeds are around 8 km/h (5 mph), with gusts on the windiest days reaching about 42 km/h (26 mph). On the ground, it is it often feels breezy, especially in more exposed spots or along the coast.