September 2020 turned out to be the 13th coolest September on record for DFW with an average monthly temperature of 75°F. We were 3.3°F below normal for the month. The coolest temperature of 50°F was recorded on September 29th, only 10°F above the all-time coldest monthly low of 40°F. Pretty impressive considering that only last year, September 2019, was the all-time hottest September on record for DFW. Weather records date back 122 years to September 1898 for the DFW area.