The National Weather Service started tracking temperatures in Denver in 1872, and since then, temperatures have only reached 100 degrees in September twice.
While Denver did set records for the hottest temperatures multiple times this year, Pinpoint Weather Chief Meteorologist Dave Fraser said he doubts temperatures can reach 100 degrees at this point.
“We’re too far past summer heating, the sun angle is low, the days are getting shorter, so it’s probably virtually impossible that we would see a 100-degree day,” Fraser said.
When was the last 100-degree day in Denver?
Over 150 years, the NWS has only recorded triple-digit temperatures in Denver 105 times.
The last time Denver got to triple-digit heat was about 13 months ago on Aug. 5, 2022, at 101 degrees.
When was the latest 100-degree day in Denver history?
The latest day of the summer to hit triple digits in Denver was recorded on Sept. 5, 2020, at 101 degrees. The only other time Denver temperatures have reached 100 in September was on Sept. 2, 2019, according to the NWS.
Typically, September starts with temperatures around 85 degrees, and the normal highs toward the end of the month are in the low 70s, according to NWS climate records.
When was the last year without a 100-degree day?
A summer in Denver hasn’t been without at least one 100-degree day since 2015. Fraser said it’s not uncommon for temperatures never to reach 100, but it is a significant difference compared to recent years.
Denver hit 100 degrees or hotter five times in 2021 and 2022, according to the NWS. The last two summers are tied for third for the greatest number of 100-degree days recorded in history. The only years with more 100-degree days were 2005 and 2012.
The last two summers were part of a grand total of 15 years since 1872 with two or more consecutive days hitting 100 degrees.
Why hasn’t it been as hot this year?
“The difference this year was that we just had more of a monsoon flow and we just had a wet pattern, so that wet pattern leads to higher humidity that leads to cooler temperatures,” Fraser said.
Heat tends to build on itself, Fraser said, so in a summer like this year where the hot days are separated by cool, wet days, it makes it harder to build up heat.
While temperatures are getting lower, it’s important to remember that the inside of a car gets significantly hotter than the temperature outside in a matter of minutes, so be sure you don’t leave children or pets in hot cars.