Duncan
Oklahoma, USA
Long-term weather forecast
Long-term weather forecast

September weather forecast and climate
Duncan, OK

September, the first month of the autumn, in Duncan, is still a hot month, with temperature in the range of an average high of 89.1°F (31.7°C) and an average low of 64°F (17.8°C).

Temperature

In Duncan, the average high-temperature marginally drops, from a sweltering 96.1°F (35.6°C) in August, to a tropical 89.1°F (31.7°C). The average low-temperature, in September, is 64°F (17.8°C).

Heat index

In September, the average heat index is appraised at a sweltering 96.4°F (35.8°C). Take special precautions - heat exhaustion and heat cramps are expected. Heatstroke may occur with lengthy activity.
Take into consideration that the heat index values are calculated for shade and light wind conditions. Exposure to direct sunshine can increase heat index values by up to 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'felt air temperature', 'apparent temperature', 'feels like', or 'real feel', is a measure that combines both air temperature and relative humidity into a single value that indicates how hot the weather feels. This effect is individual, with diverse people perceiving weather differently for numerous reasons (metabolic differences, wind, differences in body mass, height, and shape), and activity. Be aware that direct exposure to sunlight increases heat impact, and may raise the heat index additionally, by up to 15 Fahrenheit (8 Celsius) degrees. Heat index values are particularly important for children. Children are often less aware of the need to rest and re-hydrate. Thirst is a late sign of dehydration - it is vital to remain hydrated, particularly during prolonged physical activities.
To prevent overheating and help regulate its internal temperature, the human body sweat and rely on the evaporation to cool down. With a lot of moisture in the air, the evaporation process is not as effective, and the body does not cool down as efficiently, creating a perception of overheating. If the body can not disperse the excessive heat and body temperature reaches conditions of hyperthermia, above 99.5°F (37.5°C) to 100.9°F (38.3°C), thermal conditions are potentially life-threatening.

Humidity

August and September, with an average relative humidity of 58%, are the least humid months in Duncan.

Rainfall

In Duncan, in September, it is raining for 4.3 days, with typically 2.5" (63.5mm) of accumulated precipitation. In Duncan, during the entire year, the rain falls for 60.1 days and collects up to 33.1" (840.9mm) of precipitation.

Snowfall

May through November are months without snowfall.

Daylight

In Duncan, Oklahoma, the average length of the day in September is 12.4h.

What is the temperature in September in Duncan?

The average high-temperature, in September, in Duncan, Oklahoma, is 89.1°F (31.7°C), while the average low-temperature is 64°F (17.8°C). In September, the average heat index (a.k.a. 'real feel', 'feels like'), that combines air temperature and relative humidity, is calculated to 96.4°F (35.8°C).

What are the least humid months in Duncan?

August and September, with an average relative humidity of 58%, are the least humid months.

What is the average humidity in September in Duncan?

In Duncan, the average relative humidity in September is 58%.

How many days does it rain in September in Duncan?

In September, the rain falls for 4.3 days. Throughout September, 2.5" (63.5mm) of precipitation is accumulated.

When it does not snow in Duncan?

May through November are months without snowfall.

How many hours of daylight does Duncan have in September?

In September, the average length of the day is 12.4h.
Average temperature in September - Duncan, OK
  • Average high temperature in September: 89°F

The warmest month (with the highest average high temperature) is August (96°F).
The month with the lowest average high temperature is January (52°F).

  • Average low temperature in September: 64°F

Months with the highest average low temperature are July and August (71°F).
The coldest month (with the lowest average low temperature) is January (29°F).

Average humidity in September - Duncan, OK
  • Average humidity in September: 58%

The month with the highest relative humidity is January (70%).
Months with the lowest relative humidity are August and September (58%).

Average rainfall in September - Duncan, OK
  • Average rainfall in September: 2.5"

The wettest month (with the highest rainfall) is May (6.4").
The driest month (with the lowest rainfall) is January (1.4").

Average rainfall days in September - Duncan, OK
  • Average rainfall days in September: 4.3 days

The month with the highest number of rainy days is May (7.6 days).
The month with the lowest number of rainy days is November (2.9 days).

Average snowfall in September - Duncan, OK
  • Average snowfall in September: 0"

The month with the highest snowfall is February (2.2").
Months with the lowest snowfall are May, June, July, August, September, October and November (0").

Average daylight in September - Duncan, OK
  • Average daylight in September: 12.4h

The month with the longest days is June (Average daylight: 14.4h).
The month with shortest days is December (Average daylight: 9.9h).