Normal weather for Keystone in September
It's cool in September in Keystone with an average temperature of 14°C. Temperatures this month range from a low of 11°C to a high of 17°C. At night, you can expect temperatures between 1°C and 8°C.
In September, there is an average of 18 mm of precipitation, spread over 5 days. Of the total precipitation, about 1,3 cm falls as snow in September. The wind speed is around 5 Bft, mostly coming from the West.
Keystone in September |
London | ||
|---|---|---|---|
 Average Temperature |
14°C | 20°C | |
 High Temp |
17°C | 22°C | |
| Low Temp |
11°C | 17°C | |
 Total Precipitation |
18 mm | 44 mm | |
| Rainy Days |
5 days | 8 days | |
 Total Snowfall |
1,3 cm | 0 cm | |
| Snowy Days |
1 day | 0 days | |
Start of September
The month of September starts in Keystone with cool temperatures, averaging around 16°C during the day and nights close to 6°C. A few showers might pop up in the first days of the month, but the weather remains mostly sunny and dry.
Since temperatures can differ between day and night, it’s a good idea to dress in layers. During the day, go for a light coat, jumper or cardigan, and long trousers. For the evening and morning, we recommend a thick coat, jumper, and long trousers.
Mid-September
By mid-September, the average daytime temperature drops to around 14°C, with nights close to 5°C. Not much precipitation expected during this period. It’s mostly dry with sunshine.
Temperatures vary between day and night, so it’s smart to wear layers. During the day, go for a light coat, jumper or cardigan, and long trousers. For the evening and morning, we recommend a thick coat, jumper, and long trousers.
End of September
By the end of September, the average daytime temperature in Keystone will be around 13°C, with nights close to 4°C. Barely any chance of precipitation. The weather will mostly be dry with lots of sunshine.
As it gets cooler in the evening, it’s best to wear layers. During the day, opt for a warm coat, jumper or cardigan, and long trousers. For the evening and morning, we recommend a thick coat, jumper, and long trousers.
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UV index
The UV index is a maximum of 9 this month. That's a very high value on the intensity scale of 1 to 11. Unprotected skin can burn within 10-15 minutes.
Temperature records for Keystone in September
With 23°C, Keystone hit the highest temperature in the last 10 years in September 2018. The lowest daytime temperature in this month was 1°C in 2014. The extreme night temperatures ranged from a low of -9°C to a high of 14°C.
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Daily Temperature in September in Keystone
This chart shows the average daily temperatures, both day and night, for each day in September in Keystone, measured in degrees Celsius. The red line represents the maximum temperatures, while the blue line shows the minimums. The days of the month are displayed at the bottom of the chart. The data, based on historical observations, gives an overview of the average daily temperatures during this month.
Daily Precipitation in September in Keystone
The chart below shows the average daily precipitation in September for Keystone, measured in millimetres over the past years. Precipitation is always measured as water, even if it’s snow or hail. The days of the month are shown at the bottom of the chart.
A low average precipitation means that the chance of rain on that day is usually small, while a higher average suggests that rain is more likely. But it’s still an average, so each day can be different. Based on historical weather data for September, you can expect around 5 days of rain in Keystone.
Daily Snowfall in September in Keystone
This chart shows the average daily snowfall in September in Keystone, measured in centimetres. The bottom of the chart shows the days of the month. The data is based on historical measurements and gives an idea of the average snowfall in September.
Daily UV Index in September in Keystone
This chart shows the average daily UV index in September in Keystone, 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.
Temperature in September in Keystone Over the Years
This chart shows the average temperature in September in Keystone, measured in degrees Celsius, over the past years.
Total Precipitation in September in Keystone Over the Years
This chart shows the average precipitation in September in Keystone, measured in millimetres over the past years. Precipitation is always measured as water, even if it’s snow or hail.
Snowfall in September in Keystone per year
This chart shows the average snowfall in September in Keystone, measured in centimetres, over the past years.
Daily climate in September for Keystone
Click on a specific day in September for detailed info on the typical weather on that day in Keystone. Check out the historical temperatures and precipitation over the past 10 years on this day.
Weather experiences in September in Keystone
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Average Weather in Keystone by Month
Click on a month below to see detailed weather info for Keystone. Based on historical weather data, you can see the average temperature, precipitation, wind, and UV index for each day of the month.
