September weather forecastJohnstown, CA
September
Weather in September
September, the first month of the autumn in Johnstown, is also a moderately hot month, with an average temperature varying between 63.5°F (17.5°C) and 83.3°F (28.5°C).Temperature
Johnstown's September reports an average high-temperature of a still warm 83.3°F (28.5°C), exhibiting a minor difference from August. Throughout the nights in September, Johnstown experiences an average low-temperature of 63.5°F (17.5°C).Heat index
The heat index value during September is computed to be a tropical 86°F (30°C). Exhaustion is likely with prolonged exposure and activity. Sustaining activity may result in heat cramps.From a standpoint of the heat index, values pertain to shaded conditions and mild breezes. Direct exposure to sunlight could raise the heat index by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'apparent temperature' or 'real feel', stands as a testimony to how temperature and humidity combine to impact our sense of warmth. An individual's perception of weather can be affected by a variety of elements including metabolic differences, being pregnant, and their level of physical exertion. Always consider that direct sunlight exposure might heighten the heat's effects, pushing the heat index up by 15 Fahrenheit (8 Celsius) degrees. Heat index values are essentially critical for children. Children usually face more risks than adults as their ability to sweat is less. Additionally, their larger skin surface in relation to their petite bodies and higher heat output due to their activities increases their vulnerability.
Humidity
The average relative humidity in September is 57%.Rainfall
In September, the rain falls for 3.9 days. Throughout September, 0.31" (8mm) of precipitation is accumulated. Throughout the year, there are 49.6 rainfall days, and 5.16" (131mm) of precipitation is accumulated.Daylight
In Johnstown, the average length of the day in September is 12h and 22min.On the first day of September, sunrise is at 6:22 am and sunset at 7:11 pm. On the last day of the month, sunrise is at 6:41 am and sunset at 6:33 pm PDT.
Sunshine
In Johnstown, the average sunshine in September is 10.4h.UV index
June through September, with an average maximum UV index of 6, are months with the highest UV index. A UV Index of 6 to 7 symbolizes a high health vulnerability from unsafe exposure to UV radiation for the ordinary person.Note: The daily high UV index of 6 during September translates into the following recommendations:
Persist with precautions and heed sun safety advice. Prevention of sunburn is compulsory. Between 10 a.m. and 4 p.m., the Sun emits the most powerful UV radiation. Limit direct exposure to the Sun during these hours. Sun protection is enhanced with clothing that boasts a tight weave yet offers a loose fit.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
Average temperature in September
Johnstown, CA
- Average high temperature in September: 83.3°F
The warmest month (with the highest average high temperature) is August (85.5°F).
The month with the lowest average high temperature is December (63.7°F).
- Average low temperature in September: 63.5°F
The month with the highest average low temperature is August (64.9°F).
The coldest month (with the lowest average low temperature) is February (46°F).
Average pressure in September
Johnstown, CA
- Average pressure in September: 29.87"Hg
The month with the highest atmospheric pressure is January (30.09"Hg).
The month with the lowest atmospheric pressure is June (29.86"Hg).
Average wind speed in September
Johnstown, CA
- Average wind speed in September: 4.2mph
The windiest months (with the highest average wind speed) are April and May (5.3mph).
The calmest months (with the lowest average wind speed) are August, September and October (4.2mph).
Average humidity in September
Johnstown, CA
- Average humidity in September: 57%
The month with the highest relative humidity is May (65%).
The month with the lowest relative humidity is November (52%).
Average rainfall in September
Johnstown, CA
- Average rainfall in September: 0.31"
The wettest month (with the highest rainfall) is February (1.06").
The driest month (with the least rainfall) is June (0.04").
Average rainfall days in September
Johnstown, CA
- Average rainfall days in September: 3.9 days
The month with the highest number of rainy days is March (6.8 days).
The month with the least rainy days is June (1.4 days).
Average daylight in September /
Average sunshine in September
Johnstown, CA
- Average daylight in September: 12h and 24min
The month with the longest days is June (Average daylight: 14h and 18min).
The month with the shortest days is December (Average daylight: 10h and 0min).
- Average sunshine in September: 10h and 24min
The months with the most sunshine are June and July (Average sunshine: 12h and 6min).
The month with the least sunshine is December (Average sunshine: 6h and 42min).
Average sunshine days in September
Johnstown, CA
- Average sunshine days in September: 23.1 days
The month with the most sunshine days is June (28 days).
The month with the least sunshine days is July (20.7 days).
Average UV index in September
Johnstown, CA
- Average UV index in September: 6
The months with the highest UV index are June, July, August and September (UV index 6).
The month with the lowest UV index is December (UV index 3).
Average cloud cover in September
Johnstown, CA
- Average cloud cover in September: 9
The months with the most cloud cover are March and December (Cloud cover 23).
The month with the least cloud cover is August (Cloud cover 6).
Average visibility in September
Johnstown, CA
- Average visibility in September: 6mi
The months with the highest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
The months with the lowest visibility are January, February, March, April, May, June, July, August, September, October, November and December (6mi).
