Weathermondo.com
United StatesThe weather in September in Cornwall
It's warm in September in Cornwall with an average temperature of 24°C. Temperatures this month range from a low of 19°C to a high of 28°C. At night, you can expect temperatures between 11°C and 17°C.
Looking for sun? September isn’t a good month to be in Cornwall. The temperature is nice, but there’s too much chance of rain.
Average temperatures and precipitation
This chart shows the average daily maximum and minimum temperatures (in degrees Celsius) and precipitation (in millimeters) in September for Cornwall, Connecticut. A low precipitation value usually indicates little to no rainfall on that day in recent years, while a higher value suggests more frequent rainfall.
Temperature records
With 35°C in 2015, Cornwall reached the highest temperature in September over the past 10 years. The lowest daytime temperature in this month was 13°C in 2017. The extreme nighttime temperatures ranged from a lowest recorded value of 2°C to a highest value of 23°C.
Rainfall amount
In September, there is an average of 128 mm of precipitation, spread over 15 days. The wind speed is around 3 Bft, mostly coming from the South.
Daily weather in September for Cornwall
Click on any day in September to get detailed info about the usual weather on that day in Cornwall. Check out the historical temperatures and precipitation over the past 10 years on this day.
September weather comparison
| Cornwall | New York | |
|---|---|---|
| Average temperature | 24°C | 27°C |
| Max. temperature | 28°C | 31°C |
| Min. temperature | 11°C | -5°C |
| Total precipitation | 128 mm | 57 mm |
| Rainy days | 15 days | 9 days |
Start of September
The month of September starts in Cornwall with hot temps, averaging around 27°C during the day and nights around 17°C.
Mid September
By mid-September, daytime temps drop to around 24°C, with nights around 14°C. There’s a chance of some showers during this time, but plenty of dry and sunny days too.
End of September
By the end of September, the average daytime temperature in Cornwall is around 23°C, while nighttime temps are about 12°C. Expect regular precipitation, but if you’re lucky, you’ll also get some dry and sunny days.
UV index
The UV index is a maximum of 7 this month. That's a moderate to high value on the intensity scale of 1 to 11. Unprotected skin can burn within 15-25 minutes.
Check out the climate of Cornwall for all months and discover the best travel time
Temperature charts
These charts show the average temperatures in September in Cornwall, Connecticut. The temperatures are shown in degrees Celsius and are calculated based on data from the past 10 years.
Daily Temperature in September in Cornwall
Temperature in September in Cornwall over the years
Precipitation charts
These charts show the average amount of precipitation in September in Cornwall, Connecticut. Precipitation is always measured as water, even when it falls as snow or hail The amount of precipitation is displayed in millimeters, while snowfall is shown in centimeters.
Daily Precipitation in September in Cornwall
Total precipitation in September in Cornwall over the years
Daily UV index in September in Cornwall
This chart shows the average daily UV index in September in Cornwall, with the UV index ranging from 0 to a maximum of 11. The bottom of the chart shows the days of the month. Based on historical data, this chart provides an idea of the daily UV radiation levels you can expect.
Weather experiences in September in Cornwall
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Average weather in Cornwall by month
Click on a month below to see detailed weather info for Cornwall. Based on historical weather data, you can see the average temperature, precipitation, wind, and UV index for each day of the month.