Pick the day you arrive in Denver and what applies to you. The planner lists the dates that matter over your first twelve months: paperwork deadlines, seasonal rules, park reservation windows and the average dates of the first and last freeze and snow.
Your first year
Averages and the 2026 dates, not forecasts or legal advice. Check the official source for the current year. Nothing you enter leaves your browser.
Where the dates come from
Vehicle registration follows Colorado’s rule, as summarized by the Adams County clerk, that new residents have 90 days from the date residency is established, with late fees of $25 a month up to $100. The planner counts 90 days from your arrival as the earliest likely date; residency can begin later, so confirm with your own county clerk.
The traction law season (September 1 to May 31 on I-70 between Morrison and Dotsero) is from CDOT, the summer watering window (May 1 to October 1) from Denver Water, the ozone forecast season (May 31 to August 31) from the Colorado Department of Public Health and Environment, and the fishing license year (March 1 to March 31 of the next year) from Colorado Parks and Wildlife.
Rocky Mountain National Park’s timed entry dates are the 2026 season’s; the park sets new dates each year. Freeze and snow dates are the National Weather Service’s averages for Denver, not forecasts. More in Denver in October: First Freeze, First Snow and Closing Up Summer and Denver in May: Last Frost, Watering Rules and Booking the Mountains.