Contents
- Weather in September
- Frequently asked questions
- Average temperature in September
- Average pressure in September
- Average wind speed in September
- Average humidity in September
- Average rainfall in September
- Average rainfall days in September
- Average snowfall in September
- Average snowfall days in September
- Average daylight in September
- Average sunshine in September
- Average sunshine days in September
- Average UV index in September
- Average cloud cover in September
- Average visibility in September
Weather in September
Temperature
The advent of September denotes an average high-temperature of a pleasant 72.1°F (22.3°C), subtly different from August's 77.4°F (25.2°C). Nighttime temperature experiences an average drop to a cool 53.6°F (12°C) in September.Humidity
In September, the average relative humidity is 77%.Rainfall
In Crystal Lake, in September, during 12.5 rainfall days, 2.44" (62mm) of precipitation is typically accumulated. In Crystal Lake, during the entire year, the rain falls for 136.2 days and collects up to 25.39" (645mm) of precipitation.Snowfall
June through September are months without snowfall.Daylight
In Crystal Lake, the average length of the day in September is 12h and 29min.On the first day of the month, sunrise is at 6:40 am and sunset at 7:49 pm. On the last day of September, sunrise is at 7:12 am and sunset at 6:57 pm CDT.
Sunshine
In September, the average sunshine is 9.1h.UV index
The average daily maximum UV index in September is 4. A UV Index value of 3 to 5 symbolizes a medium vulnerability from exposure to the Sun's UV radiation for average individuals.Note: An average UV index of 4 in September transforms into this advice:
Put precautions into practice - Ensuring skin and eye safety is a necessity. The Sun's radiation is especially intense around midday; try to stay in shade during this period. A hat with a generous brim can prevent nearly 50% of UV rays from reaching your eyes.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What are the temperatures in September?
What is the average humidity in September?
How much does it rain in September?
When it does not snow?
Does it snow in September?
How many hours of daylight does Crystal Lake have in September?
When is the sunrise / sunset in September?
How long on average sun shines in September?
What is the UV index intensity in September?
Average temperature in September
Crystal Lake, IA
- Average high temperature in September: 72.1°F
The warmest month (with the highest average high temperature) is July (79.3°F).
The month with the lowest average high temperature is January (22.1°F).
- Average low temperature in September: 53.6°F
The month with the highest average low temperature is July (62.6°F).
The coldest month (with the lowest average low temperature) is January (9.9°F).
Average pressure in September
Crystal Lake, IA
- Average pressure in September: 30.01"Hg
The month with the highest atmospheric pressure is January (30.15"Hg).
The month with the lowest atmospheric pressure is June (29.88"Hg).
Average wind speed in September
Crystal Lake, IA
- Average wind speed in September: 8.6mph
The windiest month (with the highest average wind speed) is April (10.9mph).
The calmest month (with the lowest average wind speed) is July (7.4mph).
Average humidity in September
Crystal Lake, IA
- Average humidity in September: 77%
The month with the highest relative humidity is January (89%).
The month with the lowest relative humidity is October (70%).
Average rainfall in September
Crystal Lake, IA
- Average rainfall in September: 2.44"
The wettest month (with the highest rainfall) is June (4.21").
The driest month (with the least rainfall) is January (0.98").
Average rainfall days in September
Crystal Lake, IA
- Average rainfall days in September: 12.5 days
The month with the highest number of rainy days is June (18.8 days).
The month with the least rainy days is February (3 days).
Average snowfall in September
Crystal Lake, IA
- Average snowfall in September: 0"
The month with the highest snowfall is February (5.79").
The months with the least snowfall are June, July, August and September (0").
Average snowfall days in September
Crystal Lake, IA
- Average snowfall days in September: 0 days
The month with the highest number of snowfall days is January (13.3 days).
The months with the least snowfall days are June, July, August and September (0 days).
Average daylight in September /
Average sunshine in September
Crystal Lake, IA
- Average daylight in September: 12h and 3min
The month with the longest days is June (Average daylight: 15h and 18min).
The month with the shortest days is December (Average daylight: 9h and 0min).
- Average sunshine in September: 9h and 1min
The month with the most sunshine is July (Average sunshine: 9h and 48min).
The month with the least sunshine is January (Average sunshine: 3h and 30min).
Average sunshine days in September
Crystal Lake, IA
- Average sunshine days in September: 15.1 days
The months with the most sunshine days are October and November (17.4 days).
The month with the least sunshine days is June (9.2 days).
Average UV index in September
Crystal Lake, IA
- Average UV index in September: 4
The months with the highest UV index are June and July (UV index 6).
The months with the lowest UV index are January and December (UV index 1).
Average cloud cover in September
Crystal Lake, IA
- Average cloud cover in September: 33
The month with the most cloud cover is January (Cloud cover 63).
The month with the least cloud cover is August (Cloud cover 32).
Average visibility in September
Crystal Lake, IA
- Average visibility in September: 6mi
The months with the highest visibility are March, April, May, June, September, October and November (6mi).
The months with the lowest visibility are January, February, July, August and December (5mi).
Crystal Lake, Iowa, USA
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