September weather forecast
Duncan, OK

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Weather in September

September nudges towards fall but continues to hold on to the last tendrils of summer. The change in Duncan's weather is more noticeable, with temperatures cooling, and the daylight hours reducing to 12.4. Despite the transition, the maximum temperature averages still hit a high of 86.2°F (30.1°C) with the minimum settling around a comfortable 66.9°F (19.4°C). It is this moderate weather that marks the departure of the summer heat and the arrival of the cooler fall months.

Temperature

The transition to September in Duncan results in a modest reduction in average high-temperature, moving from a very hot 95°F (35°C) in August to a hot 86.2°F (30.1°C). During September nights, Duncan witnesses a consistent average temperature of 66.9°F (19.4°C).

Heat index

The heat index value during September is estimated at a hot 93.2°F (34°C). Extra safeguards are necessary to prevent heat exhaustion and heat cramps. Prolonged activity might cause heatstroke.
When referencing the heat index, its values are suitable for shady environments and light breezes. When under direct sunshine, the heat index may be elevated by 15 Fahrenheit (8 Celsius) degrees.
Note: The heat index, also known as 'feels like' or 'felt air temperature', melds the effects of warmth and moisture to generate a feeling of heat. This impact is subjective, influenced by the person's physical activity and individual heat perception, affected by factors including wind, attire, and metabolic differences. 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 primarily vital for children. In general, younger individuals are at greater risk than adults because they tend to sweat less. Also, having a larger skin surface to body size ratio and greater heat production due to their active behavior contribute to this danger.

Humidity

In Duncan, Oklahoma, the average relative humidity in September is 63%.

Rainfall

In Duncan, during September, the rain falls for 12.1 days and regularly aggregates up to 2.64" (67mm) of precipitation. In Duncan, during the entire year, the rain falls for 113.4 days and collects up to 24.61" (625mm) of precipitation.

Snowfall

May through October are months without snowfall.

Daylight

In September, the average length of the day is 12h and 23min.
On the first day of September in Duncan, sunrise is at 7:05 am and sunset at 7:57 pm. On the last day of the month, sunrise is at 7:26 am and sunset at 7:16 pm CDT.

Sunshine

The average sunshine in September in Duncan is 8.3h.

UV index

In September, the average daily maximum UV index in Duncan is 5. A UV Index value of 3 to 5 symbolizes a moderate threat to health from exposure to the Sun's UV radiation for the average person.
Note: A daily maximum UV index of 5 in September translates into the following instructions:
Act with care - The suggestion to avoid sunburn is emphasized. Limiting exposure to the direct Sun during midday hours can help prevent harmful UV radiation effects. Opt for tightly woven and loose clothing to enhance protection from the Sun.
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Frequently asked questions

Is it hot in Duncan during September?

The average high-temperature and low-temperature during September are 86.2°F (30.1°C) and 66.9°F (19.4°C) respectively. The average heat index (a.k.a. 'feels like', 'felt air temperature'), which combines air temperature and relative humidity, in September is estimated at 93.2°F (34°C).

What is the average humidity in September in Duncan?

In Duncan, the average relative humidity in September is 63%.

How many days does it rain in September in Duncan?

In Duncan, Oklahoma, in September, it is raining for 12.1 days, with typically 2.64" (67mm) of accumulated precipitation.

When it does not snow in Duncan?

May through October are months without snowfall in Duncan, Oklahoma.

What is the average length of the day in September in Duncan?

In Duncan, the average day length in September is 12h and 23min.

What time are sunrise and sunset in September in Duncan?

In September, on the first day of the month, sunrise is at 7:05 am and sunset at 7:57 pm. On the last day of the month, in Duncan, sunrise is at 7:26 am and sunset at 7:16 pm CDT.

How long on average sun shines in September in Duncan?

In September, the average sunshine duration is 8.3h.

What is the UV index intensity in September in Duncan?

In September, the average daily maximum UV index is 5. A UV Index estimate of 3 to 5 represents a moderate health threat from exposure to Sun's UV rays.
Average humidity
Average rainfall days
Average snowfall
Average snowfall days
Average daylight
Average sunshine
Average sunshine days
Average UV index
Average cloud cover
Average visibility

Average temperature in September
Duncan, OK

Average temperature in September - Duncan, OK
  • Average high temperature in September: 86.2°F

The warmest month (with the highest average high temperature) is August (95°F).
The months with the lowest average high temperature are January and December (51.3°F).

  • Average low temperature in September: 66.9°F

The month with the highest average low temperature is July (73.9°F).
The coldest month (with the lowest average low temperature) is January (33.6°F).

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Average pressure in September
Duncan, OK

Average pressure in September - Duncan, OK
  • Average pressure in September: 29.97"Hg

The month with the highest atmospheric pressure is January (30.16"Hg).
The month with the lowest atmospheric pressure is June (29.88"Hg).

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Average wind speed in September
Duncan, OK

Average wind speed in September - Duncan, OK
  • Average wind speed in September: 8.3mph

The windiest month (with the highest average wind speed) is April (11.6mph).
The calmest months (with the lowest average wind speed) are July, August and September (8.3mph).

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Average humidity in September
Duncan, OK

Average humidity in September - Duncan, OK
  • Average humidity in September: 63%

The month with the highest relative humidity is May (73%).
The month with the lowest relative humidity is August (55%).

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Average rainfall in September
Duncan, OK

Average rainfall in September - Duncan, OK
  • Average rainfall in September: 2.64"

The wettest month (with the highest rainfall) is May (4.37").
The driest month (with the least rainfall) is February (1.02").

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Average rainfall days in September
Duncan, OK

Average rainfall days in September - Duncan, OK
  • Average rainfall days in September: 12.1 days

The month with the highest number of rainy days is May (13.5 days).
The month with the least rainy days is January (5 days).

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Average snowfall in September
Duncan, OK

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

The month with the highest snowfall is February (1.3").
The months with the least snowfall are May, June, July, August, September and October (0").

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Average snowfall days in September
Duncan, OK

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

The month with the highest number of snowfall days is February (1.8 days).
The months with the least snowfall days are May, June, July, August, September and October (0 days).

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Average daylight in September /
Average sunshine in September
Duncan, OK

Average daylight in September / Average sunshine in September - Duncan, OK
  • Average daylight in September: 12h and 2min

The month with the longest days is June (Average daylight: 14h and 24min).
The month with the shortest days is December (Average daylight: 9h and 54min).

  • Average sunshine in September: 8h and 2min

The month with the most sunshine is July (Average sunshine: 11h and 6min).
The month with the least sunshine is December (Average sunshine: 6h and 0min).

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Average sunshine days in September
Duncan, OK

Average sunshine days in September - Duncan, OK
  • Average sunshine days in September: 16 days

The month with the most sunshine days is January (24.3 days).
The month with the least sunshine days is May (15.7 days).

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Average UV index in September
Duncan, OK

Average UV index in September - Duncan, OK
  • Average UV index in September: 5

The months with the highest UV index are June, July and August (UV index 7).
The month with the lowest UV index is December (UV index 2).

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Average cloud cover in September
Duncan, OK

Average cloud cover in September - Duncan, OK
  • Average cloud cover in September: 29

The month with the most cloud cover is March (Cloud cover 36).
The month with the least cloud cover is August (Cloud cover 20).

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Average visibility in September
Duncan, OK

Average visibility in September - Duncan, OK
  • 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).

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Duncan, Oklahoma, USA

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