DENVER -- Before Sunday, it had never reached 98 degrees in September during Denver's recorded temperature history.
On Thursday, the temperature reached that mark or higher for the third time in five days.
The temperature hit 98 degrees at 2:05 p.m. at Denver International Airport, breaking the previous record high for the date of 97 degrees set in 2013 and 1899, the National Weather Service said.
On Monday, it reached 100 degrees at the airport, the official recording station for the city.
That broke the all-time hottest temperature in September in the city of 98 degrees that was set the day before.
Before Sunday, it had never reached 98 degrees in Denver in September in nearly 150 years of record keeping.
It had reached 97 degrees in September in Denver five previous times before Sunday.
Monday's reading was also latest date in the year that Denver has recorded a 100-degree temperature. The previous latest 100-degree reading was Aug. 16, 2002.
But relief is coming. A cold front moves in Thursday night, dropping temperatures on Friday by 15 degrees with highs about 80 degrees.
It will start dry, then there will be a 50% chance of afternoon rain and thunderstorms.