October, October, October. Another fantastic month for weather in Colorado, with piles of beautiful fall days, and of course some infamous winter storms that have buried the state in feet of wet, heavy snow.
Average temperatures in October continue to fall as we head toward the winter months. The average high drops from a very comfortable 72° F to start the month, to a cool 59° to end the month. Overnight lows also dip by 11 degrees, from 42 to begin October, to below freezing (31°) by October 31st. Brr!
The record high for the month is 90°, occurring on October 1st, 1892. The record low for the month is an incredible 92° colder than the record high, with a temperature of -2° F being recorded in Denver on October 29th, 1917. The thermometer has dipped into the single digits many times during the month, with the earliest single digit recording occurring on October 13th 1969, with the low bottoming out at 3° F.
October 19th is the date of the average first snowfall in Denver. October is the city's seventh snowiest month, averaging 4.2" of snow between 1882 and 2015. That's not to say the month doesn't see its share of big-time snows. As those who have lived in eastern Colorado will attest, we often see our biggest snowfalls in the early and latter portions of the snowfall season (September - May).
The snowiest recorded October came in 1969, when 31.2" of snow fell in Denver. 1969 was an very wintry October for the state, with the year still laying claim to six record lows (including the earliest single degree reading, see above), and not only is the snowiest but also the wettest October on record. Below is a look at the precipitation anomalies (left) and precipitation anomalies (right) for October 1969. What a month!
The next snowiest October on record comes in nearly 10" below 1969, with 22.7" record in October 1906, followed by the great El Niño-year snow of 1997, tallying all of its 22.1" of snow in one storm on the 24th and 25th of the month. The snow of 1997 also set the 24 hour snowfall record for October, with 19.1" falling in a 24 hour span. Here's a look at the weather maps from October 25th, 1997:
Octobers aren't always snow producers, however, with 17 years between 1882 and 2015 recording no snowfall at all, and 18 years recording just a trace of snow.
The month, overall, is not typically a very wet month, though certainly can be. The longterm average for precipitation is 1.04", making it the 8th wettest month on average. A few years have seen plentiful moisture, however, with 1969 taking the cake with 4.17" of precipitation recorded for the month. The driest October on record occurred in 1934, when just a trace of precipitation was recorded.
Like any month in Colorado, October has the potential to be mean or nice, and very often will feature some of both in the same year. So far October 2015 has come in cooler than the record hot September the month prior, even with some rainfall for the Front Range. The average first snowfall is just a few short weeks away, but no snow is in the forecast yet!