Last updated: February 24, 2025
In September, Castle Rock experiences a notable range in temperatures, with a maximum reaching 33°C (92°F) and a minimum dipping to -4°C (26°F), resulting in an average of 17°C (62°F). The month is marked by a relatively moderate precipitation level of 34 mm (1.3 in) spread over approximately 6 days, contributing to an overall humidity of 79%. This blend of warm days and cooler nights, coupled with occasional rain, creates a unique and pleasant climate, making September an inviting time to explore the natural beauty of Castle Rock.
In September, Castle Rock experiences a notable transition as summer gradually yields to the briskness of autumn. With minimum temperatures dipping to a cool -4°C (26°F), the average temperature settles at a comfortable 17°C (62°F), while highs can still reach a warm 33°C (92°F). This month marks a significant shift from the heat of August, yet it retains enough warmth to enjoy outdoor activities. As the days shorten and the air grows crisper, September serves as a bridge between the fiery summer days and the chill of the impending winter, inviting residents and visitors alike to embrace the changing seasons with open arms.
In September, Castle Rock experiences a moderate precipitation amount of 34 mm (1.3 in), typically spread over 6 days of the month. This represents a slight decrease from the showers of the preceding summer, with August receiving 42 mm of rain. As the region transitions into autumn, the rainfall begins to taper off, mirroring the trend observed in the early fall months. The drop in both precipitation and rainy days indicates a shift towards drier conditions, setting the stage for the crisp and cooler climates of October. With September serving as a bridge between the wetter summer months and the dry autumn period, residents can enjoy a refreshing balance as they prepare for the changing seasons.
As summer transitions into fall, September in Castle Rock sees a noticeable dip in humidity compared to the peak levels of August, settling at a comfortable 79%. This month represents a slight decrease, aligning with the trend of diminishing moisture as the year progresses. From January's high of 74% through to June, where humidity peaks at 76%, Castle Rock experiences its most humid months during the mid-summer. Interestingly, the levels begin to fluctuate more significantly as autumn approaches, with October following closely behind at 77%. Overall, September's humidity indicates a gradual shift in the atmospheric feel, making it a key month for both comfort and the onset of crisp fall air.
As September rolls into Castle Rock, the UV Index reflects a transition from the extreme heights of summer. With an index of 10, categorized as very high, it signifies a notable decrease from the peak summer values, yet still calls for caution when enjoying outdoor activities. The 15-minute burn time serves as a reminder to protect your skin, as the sun's rays remain potent. This month typically leads into the cooler fall days, with October dropping to a 7, but residents should stay aware that sunny September weather can still pack a punch. For more detailed insights, visit Castle Rock UV Index to stay updated on sun safety all year round.
UV Risk Categories
As September rolls into Castle Rock, the lingering warmth of summer begins to wane, yet the city still basks in a generous 307 hours of sunshine. This month gracefully transitions from the sun-soaked heights of July and August, where residents enjoyed 372 and 352 hours, respectively. Although September marks a slight decline compared to those peak summer months, it remains a vibrant tapestry of sunny days. The gradual descent from June's pinnacle of 365 hours hints at the approaching autumn, while still offering ample opportunities for outdoor adventures. As the days shorten, the golden hues of fall start to emerge, creating a beautiful backdrop for the pleasant sunlight that continues to greet the community.
As September rolls in, Castle Rock begins to enjoy a notable increase in sunny days, reaching a 69% chance of sunshine. This trend marks an uplifting shift from the summer months, where sun exposure peaked in August at 66%. While the sunshine probability begins to drop slightly in the fall, it remains higher than several previous months, including May and June. October follows closely with a 70% likelihood of sunny weather, suggesting that early fall is a splendid time for outdoor activities. Overall, the Transition into fall in Castle Rock continues to offer ample opportunities to soak up the sun before the chill of winter sets in.
As summer fades into autumn, September in Castle Rock brings a gentle decline in daylight duration, offering 12 hours of sunshine each day. This marks a transition from the peak brightness of July and August, which bask in 14 hours of daylight. The month sets the stage for shorter days ahead, as daylight further decreases to 11 hours in October, resembling the shorter periods seen at the beginning of the year. With each passing month, Castle Rock gracefully shifts from long, vibrant summer days to the cozy, reflective moments of fall, reminding us of nature's cycles and the richness each season carries.
In September, the winds in Castle Rock, United States, settle into a gentle rhythm, with an average speed of 2.3 m/s (5 mph), mirroring the calm of previous months like January and August. This trend of light breezes continues to reflect a transition from the warmth of summer into the crispness of fall. Overall, wind speeds remain fairly consistent throughout the year, fluctuating between 2.3 and 2.9 m/s. As the year progresses toward October, there is a slight uptick to 2.6 m/s (6 mph), hinting at the invigorating gusts that often accompany the changing seasons. This creates a serene yet dynamic atmosphere, encouraging residents and visitors alike to savor the beauty of early autumn in Castle Rock.
The weather in Castle Rock changes throughout the year, offering a unique experience in each season. Below is a month-by-month comparison of September's weather with other months, highlighting differences in temperature, precipitation, and other key factors. Click on each section to discover seasonal trends in Castle Rock and find detailed weather information for every month.
September and January present striking contrasts in weather. In September, temperatures range from a refreshing minimum of -4°C (26°F) to a warm average of 17°C (62°F), peaking at a sizzling 33°C (92°F). The month is characterized by moderate precipitation, with about 34 mm (1.3 in) over 6 days and relatively high humidity at 79%. In stark contrast, January is much colder, with minimum temperatures dropping to a frigid -26°C (-15°F) and an average of -3°C (27°F). The maximum temperature is a mild 17°C (62°F), but only 17 mm (0.7 in) of precipitation falls over just 3 days, and humidity levels decrease slightly to 74%. For a closer look at January weather, you can refer to Castle Rock weather in January.
September and February present stark contrasts in weather patterns. In September, temperatures can range from a chilly -4°C (26°F) at night to a warm average of 17°C (62°F) during the day, with highs reaching as much as 33°C (92°F). The month experiences moderate precipitation of 34 mm (1.3 in) over about six days, paired with a humidity level of 79%. In contrast, February is much colder, with temperatures plunging to a minimum of -30°C (-22°F) and averaging around -3°C (26°F). Despite the continued chill, February features a high of 22°C (72°F) but sees less precipitation overall, totaling 22 mm (0.9 in) across seven days, with a slightly lower humidity of 75%. For more detailed weather insights, you can check out Castle Rock weather in February.
The weather in September contrasts significantly with that of March. September boasts milder temperatures, ranging from a minimum of -4°C (26°F) to a comfortable average of 17°C (62°F) and a high of 33°C (92°F). With only 34 mm (1.3 in) of precipitation over about six days, it maintains a relatively high humidity level of 79%. In stark contrast, March experiences much colder conditions, with temperatures dropping as low as -24°C (-10°F), an average of just 2°C (36°F), and a maximum of 24°C (76°F). This month also sees increased precipitation, totaling 59 mm (2.3 in) across seven days, but with a lower humidity of 66%. For more details on the specifics of March weather, check out Castle Rock weather in March.
In comparing the weather patterns of September and April, a few notable differences emerge. September tends to be milder, with average temperatures around 17°C (62°F) and a maximum of 33°C (92°F), whereas April is cooler, with an average temperature of just 6°C (43°F) and a maximum of 27°C (82°F). Additionally, September experiences less precipitation, averaging 34 mm (1.3 in) over 6 days, compared to April's 42 mm (1.7 in) over 9 days. Humidity levels are also higher in September at 79%, while April's humidity sits at 62%. For more detailed insights into April's weather, you can visit Castle Rock weather in April.
When comparing the weather in September and May, several differences emerge. September typically enjoys a broader temperature range, with minimums around -4°C (26°F) and maximums reaching 33°C (92°F), resulting in an average temperature of 17°C (62°F). In contrast, May experiences cooler temperatures, with minimums around -8°C (17°F) and an average of 11°C (53°F), although it can still peak at 31°C (88°F). Precipitation is notably higher in May, with 87 mm (3.4 in) spread over 14 days, compared to September’s 34 mm (1.3 in) over just 6 days. Humidity levels are also slightly higher in September at 79%, compared to 74% in May. For a more detailed look at May weather, check this link: Castle Rock weather in May.
In September, temperatures typically range from a chilly minimum of -4°C (26°F) to a warm maximum of 33°C (92°F), with an average temperature of 17°C (62°F). The month sees an average of 34 mm (1.3 inches) of rainfall over about 6 days, coupled with a relatively high humidity level of 79%. In contrast, June experiences slightly higher temperatures, with a minimum of 2°C (35°F), an average of 18°C (65°F), and a maximum reaching up to 35°C (96°F). However, June also tends to be wetter, averaging 45 mm (1.8 inches) of precipitation over approximately 8 days, while maintaining a slightly lower humidity of 76%. For more details on the weather in June, check out Castle Rock weather in June.
In comparing the weather between September and July, September tends to be cooler with a minimum temperature dropping to -4°C (26°F) and an average of 17°C (62°F), while July showcases milder temperatures with a minimum of 8°C (47°F) and an average of 21°C (70°F). July also experiences slightly higher maximum temperatures, reaching up to 35°C (95°F), whereas September peaks at 33°C (92°F). Additionally, September sees less precipitation with 34 mm (1.3 in) over 6 days compared to July’s 59 mm (2.3 in) over 11 days. Humidity levels are relatively similar, with September at 79% and July at 75%. For more detailed insights, you can check out Castle Rock weather in July.
In comparing the weather of September to August, September experiences a wider range of temperatures, with a minimum of -4°C (26°F) and an average of 17°C (62°F), while August has milder minimum temperatures of 7°C (45°F) and an average of 20°C (68°F). Both months share the same maximum temperature of 33°C (92°F), but September averages slightly less precipitation at 34 mm (1.3 in) over 6 days, compared to August's 42 mm (1.6 in) over 9 days. Additionally, humidity levels are quite similar, with September at 79% and August at 80%, making both months relatively humid. For more detailed information, you can check Castle Rock weather in August.
September and October exhibit notable shifts in weather patterns. September boasts a more temperate climate, with average temperatures around 17°C (62°F) and maximums reaching a warm 33°C (92°F), while October experiences a marked decrease in temperature, averaging just 8°C (46°F) and dipping to a minimum of -23°C (-9°F). Both months see similar precipitation levels, with about 34 mm (1.3 in) falling over six days, but October's cooler temperatures and slightly lower humidity at 77% create a distinctly autumnal feel. For more specific details about October weather, you can explore Castle Rock weather in October.
September and November present a striking contrast in weather conditions. September typically enjoys a mild climate with average temperatures around 17°C (62°F), reaching a maximum of 33°C (92°F) on warmer days, while dipping to a chilly minimum of -4°C (26°F). The month sees around 34 mm (1.3 in) of precipitation over approximately 6 days and maintains a relatively high humidity of 79%. In contrast, November brings significantly colder temperatures, with averages around 2°C (37°F) and a maximum of 24°C (75°F), while the minimum can plunge to -23°C (-9°F). Precipitation is lower at 20 mm (0.8 in) spread across only 4 days, and humidity levels decrease slightly to 74%. For a closer look at the weather specifics in November, you can visit Castle Rock weather in November.
September weather in Castle Rock presents a warmer and more varied climate, with temperatures ranging from a chilly -4°C (26°F) to a scorching 33°C (92°F). With an average temperature of 17°C (62°F), this month also experiences a moderate amount of precipitation, totaling 34 mm (1.3 in) spread over six days, and maintaining a humidity level of 79%.
In contrast, December brings a significant drop in temperature, with a minimum of -21°C (-5°F) and a maximum of 21°C (70°F), averaging around -1°C (30°F). The month is much drier, receiving only 9 mm (0.4 in) of precipitation over just three days, while humidity remains consistent at 80%. For a closer look at weather conditions and specifics, you can visit Castle Rock weather in December.
As September unfolds in Castle Rock, the warmth of late summer begins to wane, offering a refreshing transition into autumn. With pleasant average temperatures around 17°C, the days bring a delightful mix of sunshine and mild conditions, contrasting sharply with both the heat of July and the chill of October. However, this month also sees an uptick in humidity, reaching 79%—a notable change as the area prepares for the coming season. While some rain is expected, with about 6 days of precipitation, the overall atmosphere is generally mild and inviting. This unique blend of warmth and moisture sets September apart, making it a charming time to enjoy the beauty of Castle Rock. For more insights on the year-round weather patterns, visit Castle Rock Climate.