Bristol · September
Run in the morning.
Cool month: average high 65°F, low 52°F. Humidity averages 81% — the limiting factor on most runs. Expect 16 rain days — plan around the radar. Cool, runnable conditions throughout — morning still has the steadiest air and lightest wind.
Avg high / low
65° / 52°F
Humidity
81%
Rain days
16/mo
Wind
12 mph
What September feels like in Bristol
Sunrise
06:46
Mid-month average
Sunset
19:24
Mid-month average
Time-of-day breakdown
Morning
Coolest, driest air of the day. The window before sunrise is the most reliable comfortable hour.
Midday
Mild but UV and traffic peak. Workable if you don't mind shifting your pace.
Evening
Warm and runnable. Crowded routes but the air's typically calm.
What to wear running in Bristol in September
The kit for September in Bristol: shorts and a short-sleeve are the standard kit, a water-resistant cap or jacket on standby.
September vs the surrounding months
vs August
-3° avg high
-3 rain days
Bristol in August →
September
65°F avg high
16 rain days
Best: morning
vs October
+7° avg high
-1 rain days
Bristol in October →
Frequently Asked Questions
What is the best time of day to run in Bristol in September?+
Morning. Cool, runnable conditions throughout — morning still has the steadiest air and lightest wind.
What's the average temperature in Bristol in September?+
Average high 65°F, average low 52°F.
How does September compare to surrounding months in Bristol?+
Compared to August (avg high 68°F), September is cooler. Compared to October (avg high 58°F), September is warmer.
Does it rain often in Bristol in September?+
Expect about 16 measurable rain days in September, on average.