Category Archives: Climatology

Climatology, Thornton Weather

Thornton’s December weather preview: Winter arrives in earnest

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Thornton, Colorado's December Weather Preview

Recent months have, overall, been warmer and drier than normal.  Last month continued that trend.  What will December hold for us?

The month of December brings with it the official start of winter and oftentimes, colder and snowier weather conditions.

It however can also offer unseasonably warm temperatures and bone dry conditions.  Given our recent mild and dry weather, we are certainly hoping for a change in the coming month.

Overall December’s monthly mean temperature of 30.0 degrees (1981 – 2010 averages) makes it our coldest month.  Snow is always on everyone’s mind this time of year but December is only our 3rd snowiest month behind March and November with an average of 8.5 inches of the white stuff.

Get all the details on Thornton’s December weather including a look back at historical events and a look at the long range forecast in our December weather preview here.

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Climatology, Thornton Weather

Thornton’s November weather preview: Transition to winter weather begins in earnest

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Thornton's November weather previewThe weather during the month of November in Denver metro area can offer just about anything.  While it is normally a quiet month, it can be prone to extremes.

November has historically been one of Denver’s snowiest months and major snowstorms are not entirely uncommon.  However conditions can also be quite dry.

Temperatures during the month continue to cool as we get closer to winter and by the end of the month the low temperatures routinely dip to 20 degrees or below.  At times it can in fact bring conditions more like what we see in January.

Get all the details on November’s weather and what we can expect in our complete preview here.

Climatology, Thornton Weather

Denver sets record low temperature for October 27

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Record Cold Temperatures

Brrr! Following our snowstorm, the cold has lingered and this morning plunged into record-setting territory.

Denver’s official low temperature this morning, as measured at DIA, dropped to 8 degrees. This easily bests the previous record low for October 27 of 11 degrees set in 1925.

Thornton actually came out on the colder end of things this morning with a low of 5 degrees recorded at 5:37am.

Today’s cold weather record comes on the tail of a record low maximum set yesterday that also was the coldest high temperature ever recorded in October.

Climatology, Thornton Weather

Denver sets record low maximum temperature for October 26

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Record Cold Temperatures

Oh, yes, it was a surprisingly cold one today with temperature readings more like what we would expect in January, not the end of October.

As measured at Denver International Airport, the Mile High City’s official high temperature today topped out at 16 degrees. That shatters the record for the coldest maximum temperature ever recorded on October 26 of 31 degrees set in 1923.

Perhaps more notable, that 16 degree high temperature is the coldest October high temperature EVER recorded in Denver.

Here in Thornton we managed to be just a little bit warmer with a high of 17 degrees.

Given the cold today and clear skies tonight, it is likely Denver will be setting a record low temperature tomorrow morning.

Climatology, Thornton Weather

Denver ties one cold weather temperature record for September 9, breaks another

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As our first taste of wintry weather for the season comes to an end, we close it out with two more weather records in the books.

This morning, as measured at Denver International Airport, the temperature dropped to 31 degrees. This ties the Mile High City’s record low for September 9 set in 1962.

The daytime didn’t bring much relief as the high at the airport only reached 42 degrees. This shatters the old record low maximum for the date of 53 degrees set in 1989.

Here in Thornton, we matched both of those marks with a low of 31 degrees and a high of 42 degrees.

The past few days have seen an extraordinary bout of weather as we went from record heat to record cold. The graphic below shows just some of what has occurred.

Some of the weather records tied or broken in the first part of September 2020. Click for a larger view. (National Weather Service)
Some of the weather records tied or broken in the first part of September 2020. Click for a larger view. (National Weather Service)
Climatology, Thornton Weather

Denver ties two cold weather records for September 8, sees second earliest snow on record

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Record Cold Temperatures

From record heat to record cold. You must live in Colorado. 😉  Today, Denver tied two cold weather records and saw its second earliest snow on record.

As measured at Denver International Airport, the low temperature in the Mile High City dropped to 31 degrees at 7:33pm. This ties the record low temperature for September 8 last set in 1962. Going hand-in-hand with that record, it tied the record for the earliest freeze in Denver history last set on the same date.

Here in Thornton, we managed to stay just a hair warmer with a low of 32 degrees.

Notable as well is that the Mile High City’s official 1.0 inch of snow is the second earliest snowfall on record. The snow was also the first September snowfall seen in 20 years. The number one spot for earliest snow on record, September 3, 1962, remains secure.

Climatology, Thornton Weather

Denver sets record high minimum and ties record high for September 6

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Record High Temperature

Our recent warm weather not only impacts daily high temperatures, it also impacts overnight lows as seen by the record set tonight.

As measured at Denver International Airport, the Mile High City saw a low of 67 degrees. This set a record high minimum for the date, beating the old mark of 66 degrees set in 1933.

Here in Thornton, we were quite a bit cooler seeing a low of 56 degrees.

Additionally, Denver’s official high temperature came in at 97 degrees. This tied the record high for September 6, last set in 2013. Thornton was actually hotter with a high of 99 degrees.

Climatology, Thornton Weather

Multiple high temperature records broken on September 5

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Record High Temperature

While snow and cold are on the horizon, that will wait and until then, we continue to experience extraordinarily warm weather. Today, September 5, Denver actually broke three records.

As measured at Denver International Airport, the high temperature topped out at 101 degrees. This easily bested the record high temperature for the date of 98 degrees set just last year.

Additionally, the 101 degree reading is the warmest temperature ever recorded in Denver during the month of September. Only one other time has it been 100 degrees or warmer in the month, that coming on September 2, 2019 with a 100 degree reading.

Lastly, this is the latest in the year a 100 degree or higher reading has been recorded.

Here in Thornton, we managed to stay just a bit cooler with a high of 99 degrees.

Climatology, Thornton Weather

September snow in Denver is not entirely uncommon

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Denver September Snow History. (ThorntonWeather.com)
Denver September Snow History. Click for larger view. (ThorntonWeather.com)

There is lots of talk (and hype!) about next week’s storm and the potential for our first snowfall of the season. While it is somewhat unusual to get snow so early in the season, it is far from unprecedented and not near as rare as you might think.

Whipping out the weather history books, we see that snow has fallen in 28 Septembers in the 139 years since the National Weather Service began recording snow in the Mile High City. That equates to about 20% of the years.

It has, however, been quite a while since we have seen one, the most recent occurring in 2000. That was the last in a stretch in which six out of eight years saw September snow.

Our earliest snowfall on record came on September 3, 1961 when 4.2 inches of the white stuff fell. The average date of Denver’s first snow is October 18th.

Most concerning about these early season snows is the potential for tree damage and power outages. Like spring storms, early season snows are usually quite wet and heavy and have the potential to wreak havoc, even if there isn’t much to them.