Astronomical autumn came to Colorado Springs on Tuesday, September 22, with the autumnal equinox arriving at 6:04 p.m. The moment marked the official close of summer by scientific definition.
The equinox is a product of the 23.5-degree tilt of Earth's axis — an orientation that determines how solar energy is spread across the planet as it orbits the sun. With the season now turning, morning light will arrive progressively later while evening darkness will set in earlier.
The day prior, September 21, brought a rough balance of light and dark hours to all points on the globe. That equilibrium has now shifted in favor of darkness, and the gap will widen steadily over the coming months. By the time the winter solstice arrives on December 21 — the year's briefest day — the region will have shed roughly two hours and 45 minutes of total daylight compared to now.
Beyond the changing light, fall typically brings Colorado's first hard freezes within a matter of weeks. Residents across the Pikes Peak region should begin monitoring local forecasts for frost advisories and overnight temperature drops as the season takes hold.
How soon that first freeze materializes across the Colorado Springs area remains the key development to watch in the coming days.