In the middle of September, the mountains of Summit County, Colorado come alive with the quiet beauty of early fall. The air turns crisp and cool, especially in the mornings and evenings, while daytime still offers plenty of sunshine and mild temperatures. Aspen trees begin their transformation, with golden leaves lighting up hillsides and mountain passes—especially around Breckenridge, Dillon, and Frisco. Trails are quieter than in summer, offering peaceful hikes through changing forests and alpine meadows where the last wildflowers fade. The high-elevation light feels softer, casting long shadows across the peaks, and the first hints of frost may dust the mornings. It’s a perfect time to explore the outdoors, enjoy scenic drives, and soak in the calm before the arrival of late September’s peak fall color and the early snows of October.