Flash Flood Watch issued September 21 at 10:24AM MDT expiring September 22 at 9:00AM MDT in effect for: Archuleta, Dolores, Hinsdale, La Plata, Montezuma, San Juan, San Miguel
October is the first full month of the fall season, and across Colorado, it typically delivers quiet weather. By day it's usually sunny and mild but the nights do start to get chilly...so this would be a good time to search for those light jackets or sweaters and maybe even an extra blanket! Lower elevations usually see their first freeze of the season in October, including Denver. Our average date of first freeze is the 7th.Temperature extremes sometimes make headlines during the month, thanks to the "battle of the airmasses" we see each autumn. Afternoons can reach into the 80s on the plains and western slope, especially during the first half of October. Denver's highest October temperature was 90° set back on October 1, 1892.An occasional strong cold front can follow these warm days with colder and even snowy weather. An example would be October 2, 1969, when the afternoon high in Denver was 85°. Over the next two days, 15" of snow fell after the passage of a strong cold front.Toward the end of the month it is even possible to see our first subzero overnight lows, though not too common. Interestingly enough, many of Colorado's major reporting stations all recorded their lowest October temperature with a single blast of arctic air on October 29, 1917. These include Denver at -2°, Colorado Springs at -6°, Pueblo at -4°, and Grand Junction at +16°!The long-range temperature outlook for October 2005 calls for equal chances of having either above, below, or normal temperatures. Thus we look toward climatology (the 30 year recorded average) for a guide as to what we might expect.In the lower elevations of our state that would mean afternoon highs in the 70s on the first, falling to the upper 50s by Halloween. Overnight lows will fall from the mid 40s to lower 30s throughout the month. In the high country daytime highs will cool from the 60s to the mid 40s as the month progresses, with overnight lows falling from the 30s to the teens as we approach November.Precipitation trends show we could be in for below normal precipitation across much of the state. October is usually one of the drier months east of the Continental Divide and one of the wettest months out west. In fact, October is tied with March for the wettest month in the Grand Valley. Statewide, most locations will see about an inch of precipitation during October, with some of that falling as snow.
Looking back at 2004 the month was wet at the beginning with a dry and mild pattern during the middle of the month. A taste of winter moved into the state on Halloween night bringing below freezing weather and the season's first snowfall to places like Grand Junction (0.5") and Denver (1.4"). The month ended with average temperatures at most locations, and just at or slightly below normal on precipitation. An interesting fact about October 2004 was that no 80° temperatures were recorded at Grand Junction, Denver, Alamosa, or Colorado Springs.And finally, an October Outlook isn't complete without taking a look at some famous snowstorms! The "Bronco Blizzard" of 1984 was witnessed by the world on Monday Night Football. Before the game ended some 3 to 5" had accumulated in downtown Denver, and before the storm was over, much of the Metro Area had over a foot of the white stuff. Up to three feet fell in the foothills. It was a windy storm with tropical storm force gusts making for some huge drifts. The storm closed airports, schools, and both I-25 and I-70.The one most fresh in your mind is probably the 1997 blizzard that came on the 24th-25th. A record setting 19.1" of snow fell in Denver in just a 24-hour period, with a storm total of 21.9" at the old Stapleton Airport. Needless to say, October 1997 went down in the record books as third snowiest on record.So can we see severe weather in October? You betcha! Although rare, we can get afternoon thunderstorms with hail and even tornadoes. Just last year several tornadoes touched down near Brighton and Barr Lake on the 4th, causing some isolated but significant damage in the area.On October 15, 1980, a severe thunderstorm brought hail and even a tornado to Boulder causing damage to a few buildings and cars.By the first of October we still have two full months of hurricane season ahead of us, and sometimes they can affect Colorado. In 1984, the remnants of Hurricane Polo moved across the state and dropped very heavy rains. Over 2" of rain was recorded in some locations, including in and around the Denver Area.The following table shows the average date of first freeze for selected Colorado locations, along with the earliest and latest recorded for each community. Data is courtesy of the Colorado Climate Center.
- Denver -- Average 0.99" liquid, 4.1" of snow Grand Junction -- Average 1.00" liquid, 0.4" of snow Alamosa -- Average 0.70" liquid, 3.6" of snow Colorado Springs -- Average 0.86" liquid, 2.8" of snow Pueblo -- Average 0.57" liquid, 1.1" of snow