The top-line figure follows revenue increases of 7.6% and 6.7% in August and July, respectively.

On a trailing 12-month basis, annual sales growth through September was 3.7%.

“Temps have a diminishing impact on demand as we proceed through cooling season, but they certainly had an impact this year,” said Brian Loftus, Senior Market Analyst at HARDI. “Cooling degree days increased by more than 40% from September of 2025 with significant increases in five of our seven regions.”

HARDI’s monthly distributor sales survey also calculates Days Sales Outstanding or DSO which is a measure of how quickly customers pay their bills. The DSO for September 2026 was nearly 38 days, which the group said is comparable to the level for the month during 2024 and 2025.

“The DSO ticked-up from August but we believe that reflects the normal seasonal pattern, not any market deterioration,” Loftus added. “The recent monthly sales growth has been encouraging, but the annual pace remains within the 2.5% to 4.5% range of the past two years,” said Loftus. “A breakout to the upside looks unlikely with existing home sales and new construction trending flat to down, interest rates rising and dismal consumer confidence.”