Historical weather data, all-time temperature records, and monthly climate averages for Castle Rock, CO. Explore typical weather conditions by week for trip planning, and see how today compares to the historical record.
April 5 in Castle Rock sits right on the edge of winter's last gasp — the average high of 59° feels promising, but that record low of 6° set just two years ago in 2023 is a reminder that the Rockies play by their own rules. Snow is still in the picture about 11% of the time on this date, so don't pack the scraper away just yet.
Castle Rock's weather history is a story of extremes: 139° of separation between its all-time high of 102° in July 2022 and its all-time low of -37° in January 1913. October can hit like a freight train — 36 inches of snow fell in a single day back in 1906, a record that still stands.
Castle Rock peaks in summer, with average highs in the mid-80s during the second week of July and a wet season that arrives right alongside the heat — late July is the rainiest stretch of the year, averaging nearly 0.7 inches in a single week. Winter is mild by Colorado standards, with January highs still reaching the mid-40s, making spring and fall the sweet spots for visitors who want comfortable temperatures without the afternoon storm gamble.