October weather forecast
Boulder, CO

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The old building of the University of Colorado in Boulder, Colorado
The old building of the University of Colorado in Boulder, Colorado

Weather in October

October brings with it cooler temperatures and the full onset of autumn in Boulder. The month is fitting for outdoor activities, with clear skies, optimal visibility, and less intense sunshine. The city's rainfall drops to approximately 0.91" (23mm), just as winter starts making its presence felt with a slight surge in snowfall. November will experience a further plunge in temperature and an escalation in snowfall. Therefore, October stands as a serene phase before the onset of winter, offering a balanced weather medley.

Temperature

The shift from September to October in Boulder, Colorado, is characterized by a clear decrease in the average high-temperature, reducing from an agreeable 72.3°F (22.4°C) to a mild 57.2°F (14°C). Despite the stark contrast with daytime temperatures, Boulder's October nights average at an icy 35.2°F (1.8°C).

Humidity

In Boulder, the average relative humidity in October is 51%.

Rainfall

In Boulder, in October, during 7 rainfall days, 0.91" (23mm) of precipitation is typically accumulated. In Boulder, during the entire year, the rain falls for 117.3 days and collects up to 14.17" (360mm) of precipitation.

Snowfall

Months with snowfall are January through May, October through December. October is the first month it typically snows. Throughout October, in the average 2.6 snowfall days, it receives 4.09" (104mm) of snow. In Boulder, during the entire year, snow falls for 44.8 days and aggregates up to 37.01" (940mm) of snow.

Daylight

The average length of the day in October in Boulder is 11h and 8min.
On the first day of October in Boulder, sunrise is at 6:58 am and sunset at 6:42 pm. On the last day of the month, sunrise is at 7:29 am and sunset at 5:59 pm MDT.

Sunshine

In October, the average sunshine is 7.3h.

UV index

The average daily maximum UV index in October in Boulder is 3. A UV Index of 3 to 5 symbolizes a moderate health risk from unsafe exposure to UV radiation for the ordinary person.
Note: In October, the maximum UV index of 3 suggests this advice:
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. Wearing sunglasses with both UVA and UVB protection effectively reduces sun-induced eye damage. Be vigilant! The reflective nature of snow can increase the Sun's UV radiation nearly twofold.
Updated: Feb 10, 2024
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate

Frequently asked questions

What are the temperatures in Boulder in October?

October temperatures in Boulder vary between a high-temperature of 57.2°F (14°C) and a low-temperature of 35.2°F (1.8°C).

What is the average humidity in October in Boulder?

In Boulder, the average relative humidity in October is 51%.

How many days does it rain in October in Boulder?

In October, in Boulder, the rain falls for 7 days. Throughout October, 0.91" (23mm) of precipitation is accumulated.

When does it start to snow in Boulder?

October is the first month it typically snows in Boulder. Throughout October, in the average 2.6 snowfall days, it receives 4.09" (104mm) of snow.

How many hours of daylight does Boulder have in October?

In October, the average day length is 11h and 8min.

When is the sunrise / sunset in October in Boulder?

In October, on the first day of the month, sunrise is at 6:58 am and sunset at 6:42 pm. On the last day of the month, in Boulder, sunrise is at 7:29 am and sunset at 5:59 pm MDT.

How many hours of sunshine does Boulder have in October?

The average sunshine duration in October is 7.3h.

How high is the UV index in October in Boulder?

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

Average temperature in October
Boulder, CO

Average temperature in October - Boulder, CO
  • Average high temperature in October: 57.2°F

The warmest month (with the highest average high temperature) is July (80.4°F).
The month with the lowest average high temperature is December (35.2°F).

  • Average low temperature in October: 35.2°F

The month with the highest average low temperature is July (55.2°F).
The coldest month (with the lowest average low temperature) is February (18°F).

Average pressure in October
Boulder, CO

Average pressure in October - Boulder, CO
  • Average pressure in October: 30.03"Hg

The month with the highest atmospheric pressure is January (30.15"Hg).
The months with the lowest atmospheric pressure are April, May and June (29.92"Hg).

Average wind speed in October
Boulder, CO

Average wind speed in October - Boulder, CO
  • Average wind speed in October: 6.2mph

The windiest month (with the highest average wind speed) is January (7.3mph).
The calmest months (with the lowest average wind speed) are May, July, August and September (5.7mph).

Average humidity in October
Boulder, CO

Average humidity in October - Boulder, CO
  • Average humidity in October: 51%

The month with the highest relative humidity is February (70%).
The months with the lowest relative humidity are June, August and September (45%).

Average rainfall in October
Boulder, CO

Average rainfall in October - Boulder, CO
  • Average rainfall in October: 0.91"

The wettest month (with the highest rainfall) is May (2.48").
The driest month (with the least rainfall) is January (0.39").

Average rainfall days in October
Boulder, CO

Average rainfall days in October - Boulder, CO
  • Average rainfall days in October: 7 days

The month with the highest number of rainy days is July (17.8 days).
The month with the least rainy days is November (3.3 days).

Average snowfall in October
Boulder, CO

Average snowfall in October - Boulder, CO
  • Average snowfall in October: 4.09"

The month with the highest snowfall is April (7.76").
The months with the least snowfall are June, July, August and September (0").

Average snowfall days in October
Boulder, CO

Average snowfall days in October - Boulder, CO
  • Average snowfall days in October: 2.6 days

The month with the highest number of snowfall days is February (10.3 days).
The months with the least snowfall days are June, July and August (0 days).

Average daylight in October /
Average sunshine in October
Boulder, CO

Average daylight in October / Average sunshine in October - Boulder, CO
  • Average daylight in October: 11h and 1min

The month with the longest days is June (Average daylight: 15h and 0min).
The month with the shortest days is December (Average daylight: 9h and 24min).

  • Average sunshine in October: 7h and 2min

The months with the most sunshine are June and July (Average sunshine: 11h and 42min).
The month with the least sunshine is February (Average sunshine: 6h and 36min).

Average sunshine days in October
Boulder, CO

Average sunshine days in October - Boulder, CO
  • Average sunshine days in October: 20.2 days

The month with the most sunshine days is January (22.2 days).
The month with the least sunshine days is July (9.9 days).

Average UV index in October
Boulder, CO

Average UV index in October - Boulder, CO
  • Average UV index in October: 3

The months with the highest UV index are June, July and August (UV index 5).
The months with the lowest UV index are January, February, November and December (UV index 2).

Average cloud cover in October
Boulder, CO

Average cloud cover in October - Boulder, CO
  • Average cloud cover in October: 19

The months with the most cloud cover are April and May (Cloud cover 28).
The month with the least cloud cover is September (Cloud cover 16).

Average visibility in October
Boulder, CO

Average visibility in October - Boulder, CO
  • Average visibility in October: 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).

Boulder, Colorado, USA

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