Last updated: February 24, 2025
In September, Lake Arrowhead experiences a remarkable range in temperatures, with highs soaring to 42°C (108°F) and lows dipping to a refreshing 9°C (48°F). The average temperature hovers around a comfortable 23°C (74°F), making it an inviting time for outdoor activities. This month is relatively dry, with only 9 mm (0.4 in) of precipitation over just two days, and a humidity level of 41% that balances the warmth. Whether you're hiking, fishing, or simply enjoying the scenic views, September provides a perfect blend of sunshine and mild evenings.
September in Lake Arrowhead reveals a transition from the sweltering summer toward the cooler embrace of autumn. With minimum temperatures averaging around 9°C (48°F), the days retain warmth, peaking at an impressive 42°C (108°F), showcasing a lingering summer heat that can surprise visitors. The month boasts an average temperature of 23°C (74°F), which is inviting for outdoor activities and scenic explorations. As the landscape shifts from vibrant greens to shades of autumn, September serves as a beautiful bridge, blending the warmth of summer with the refreshing coolness that autumn promises. This trend highlights a remarkable ability of the area to captivate all who visit, with an enviable climate that balances warmth and comfort.
In September, Lake Arrowhead experiences a noticeable drop in precipitation, with only 9 mm (0.4 in) of rainfall recorded over just 2 days. This marks a continuation of the declining trend from the wetter spring months, where peaks in January and February brought significant moisture. The summer months were relatively drier, and as September ushers in the fall season, the landscape transitions toward a drier, more sun-soaked period. It's interesting to note that this month's modest precipitation further emphasizes a stark contrast to the earlier months of the year, highlighting Lake Arrowhead's seasonal variability and hinting at a gradual shift toward the drier conditions often associated with October and November.
In September, Lake Arrowhead experiences a noticeable increase in humidity, rising to 41% after several months of dry conditions—where levels dipped to a low of 28% in August. This upward trend signals the onset of autumn, as humidity gradually builds from the summer's arid spells. The change in September marks a shift from the dry warmth of mid-summer, hinting at the refreshing breezes to come. As the year progresses, the humidity continues to rise again, peaking in late fall and winter months, with December reaching 75%. Thus, September serves as a transitional month, reflecting both the tail end of summer's dryness and the upcoming cooler, more humid autumn days.
As summer wanes in Lake Arrowhead, the UV Index begins to drop but remains significant through September, reaching a level of 10 classified as very high. This indicates that while the intense sun of July and August has passed, sun safety remains crucial, with a burn time of merely 15 minutes for unprotected skin. This trend reflects a gradual decline from the extreme levels earlier in the summer, but the sun's rays can still deliver strong exposure. Visitors should be mindful of these conditions to enjoy the beautiful surroundings while protecting themselves effectively. For more in-depth information on UV trends, please explore Lake Arrowhead UV Index.
UV Risk Categories
September in Lake Arrowhead is a beautiful transition month, embracing the lingering warmth of summer with an impressive 322 hours of sunshine. As summer reaches its end, the sunshine hours slightly taper off from the peak of 383 hours in July, yet this month still basks in more sunlight than October's 299 hours. The trend reveals a gradual decrease in daylight as the year progresses, with summer months boasting the most sunshine hours, peaking in July and August. However, September still offers a generous dose of sunshine, making it a perfect time for outdoor activities amid the stunning fall foliage that begins to emerge. This blend of warmth and light signals the end of summer while inviting the crispness of autumn, ensuring that Lake Arrowhead remains a picturesque getaway for nature lovers.
In Lake Arrowhead, September marks a peak in the likelihood of sunny weather, boasting an impressive 87% chance of sunshine. This month stands out as one of the sunniest times of the year, following a summer characterized by warm and bright days, such as August's 82% chance. As the seasons transition, September not only offers a delightful continuation of summer's warmth but also hints at the cooler, cloudier days of fall to come. Compared to the more variable months earlier in the year, like January and July with their chances around 61% and 63%, respectively, September's abundant sunshine sets the stage for outdoor activities, making it a prime time for enjoying the beauty of Lake Arrowhead under clear skies.
As summer fades and September unfolds in Lake Arrowhead, the length of daylight gradually begins its descent, offering 12 hours of sunlight—a subtle shift from the peak brightness of 14 hours experienced in July and June. This month serves as a bridge, where the warm, lingering days gradually give way to the softer glow of autumn. While the daylight duration remains robust compared to the winter months ahead, the reduction signals a transition, inviting both locals and visitors to savor the changing scenery and the early signs of fall. With this adjustment in light, September becomes a time of reflection and preparation, as nature prepares for the cozy embrace of the cooler season.
As summer transitions to fall in Lake Arrowhead, September brings a gentle lull in the winds, averaging 2.0 m/s (5 mph)—the calmest gusts of the year. This slight decrease in wind speed, following a series of relatively stable rates from January through August, signals a shift in the seasonal atmosphere. While the breezes remain mild, they offer a serene backdrop for outdoor activities, allowing visitors to fully enjoy the serene beauty of the landscape. As the months progress towards winter, with only a slight rise back to 2.1 m/s in October, the tranquil winds of September set the stage for a peaceful autumn experience in this picturesque mountain locale.
The weather in Lake Arrowhead 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 Lake Arrowhead and find detailed weather information for every month.
In September, the weather is typically warm and dry, with average temperatures around 23°C (74°F) and a maximum that can reach up to 42°C (108°F). With only 9 mm (0.4 in) of precipitation spread over just 2 days, humidity remains relatively low at 41%. In contrast, January brings much cooler temperatures, with averages dropping to around 9°C (49°F) and minimums plunging to -5°C (24°F). January also experiences significantly more precipitation, totaling 51 mm (2.0 in) over 6 days, coupled with higher humidity levels at 76%. For a more detailed look at winter conditions, check out Lake Arrowhead weather in January.
In September, temperatures can soar significantly, with a minimum of 9°C (48°F) and an average of 23°C (74°F), peaking at a scorching 42°C (108°F). The month typically experiences low precipitation, averaging only 9 mm (0.4 in) over just 2 days, and a humidity level around 41%. In contrast, February brings much cooler weather, characterized by a minimum of -4°C (24°F) and an average temperature of 9°C (49°F), with a maximum reaching 25°C (77°F). This winter month sees much higher precipitation at 56 mm (2.2 in) spread over 6 days, alongside a notably increased humidity of 80%. For more details, see Lake Arrowhead weather in February.
September and March present strikingly different weather conditions. In September, temperatures are much warmer, ranging from a minimum of 9°C (48°F) to a scorching maximum of 42°C (108°F), with an average of 23°C (74°F). The month experiences very little precipitation, only 9 mm (0.4 in) over just two days, and the humidity is relatively low at 41%. In contrast, March is significantly cooler, with temperatures dipping as low as -2°C (29°F) and averaging 11°C (52°F). The maximum reaches 29°C (84°F), but the month is also wetter, with 52 mm (2.1 in) of rain spread over nine days and a higher humidity of 69%. For more detailed insights on the weather during this time, you can check out Lake Arrowhead weather in March.
September and April offer distinct contrasts in weather. September boasts warmer temperatures, with an average of 23°C (74°F) and a maximum reaching up to 42°C (108°F), while April is cooler, averaging 15°C (60°F) and peaking at 32°C (89°F). Precipitation is scarce in September, with only 9 mm (0.4 in) over 2 days, compared to April's 24 mm (0.9 in). Additionally, humidity levels are generally lower in September at 41%, while April experiences higher humidity at 57%. For more specific details on April weather, you can visit Lake Arrowhead weather in April.
When comparing the weather in September and May, it's clear that September tends to be warmer overall. In September, temperatures range from a minimum of 9°C (48°F) to a maximum of 42°C (108°F), with an average of 23°C (74°F). In contrast, May features a cooler temperature range, with a minimum of 3°C (37°F) and a maximum of 34°C (94°F), averaging at 17°C (64°F). Additionally, May experiences slightly higher rainfall, with about 13 mm (0.5 in) over three days, compared to September's 9 mm (0.4 in) over just two days. Humidity levels are also marginally higher in May at 45%, compared to 41% in September. For more specific insights, you can check Lake Arrowhead weather in May.
In comparing the weather of September and June, both months exhibit similar minimum temperatures, starting at 9°C (48°F), but September reaches higher maximum temperatures, peaking at 42°C (108°F), compared to June's max of 39°C (103°F). The average temperature remains relatively consistent, with September averaging 23°C (74°F) and June slightly cooler at 23°C (73°F). Precipitation is minimal in both months, with September receiving 9 mm (0.4 in) over 2 days and June only 4 mm (0.1 in) spread over 1 day. Additionally, humidity levels are slightly higher in September at 41%, while June stands at a more comfortable 34%. For more detailed information, you can check out the Lake Arrowhead weather in June.
In comparing the weather between September and July, September presents a wider temperature range, with minimums dropping to 9°C (48°F) and maximums peaking at 42°C (108°F), while July stays slightly warmer overall, with minimums of 13°C (55°F) and maximums of 41°C (106°F). The average temperature in September is 23°C (74°F), compared to July's 26°C (79°F). Precipitation is slightly lower in September at 9 mm (0.4 in) compared to July's 12 mm (0.5 in), both receiving rainfall on two days. Interestingly, September features a higher humidity level at 41%, while July remains drier at 29%. For a more detailed look at July weather conditions, check out Lake Arrowhead weather in July.
September's weather presents a noticeable shift from August, characterized by slightly cooler temperatures with a minimum of 9°C (48°F) compared to August's 14°C (57°F). While the average high in September reaches 42°C (108°F), it still surpasses August's maximum of 39°C (103°F), indicating some lingering summer heat. Precipitation remains low in both months, with September receiving 9 mm (0.4 in) and August slightly more at 11 mm (0.4 in), both over two days. Interestingly, September has higher humidity at 41%, contrasting with the drier conditions of August, which boasts a humidity of 28%. For a closer look at August weather specifics, check out Lake Arrowhead weather in August.
In September, the weather is characterized by warm temperatures ranging from a minimum of 9°C (48°F) to a scorching maximum of 42°C (108°F), with an average of 23°C (74°F). The month sees light precipitation of 9 mm (0.4 in) over just 2 days and boasts a humidity level of 41%. In contrast, October brings cooler temperatures, with a minimum of 3°C (38°F) and a maximum of 36°C (97°F), averaging 18°C (65°F). Precipitation decreases slightly to 8 mm (0.3 in) but occurs over only 1 day, while humidity rises to 54%. For more detailed insights into what to expect in October, visit Lake Arrowhead weather in October.
In September, temperatures in Lake Arrowhead can soar with a minimum of 9°C (48°F) and an average high of 23°C (74°F), reaching a maximum of 42°C (108°F). The month experiences minimal rainfall, with only 9 mm (0.4 in) over two days and relatively low humidity at 41%. In contrast, November brings a significant drop in temperature, with a minimum of -1°C (31°F) and an average high of 14°C (57°F), peaking at 28°C (83°F). This month sees a higher level of precipitation at 19 mm (0.8 in) over the same two days, accompanied by increased humidity at 68%. For a detailed look at November weather, you can visit Lake Arrowhead weather in November.
September and December present stark contrasts in weather. In September, temperatures range from a mild minimum of 9°C (48°F) to a sweltering maximum of 42°C (108°F), with an average of 23°C (74°F). The month sees minimal precipitation, at only 9 mm (0.4 in) over 2 days, and a relatively low humidity of 41%. In contrast, December usher in a chillier climate, with temperatures dropping significantly, ranging from a minimum of -4°C (25°F) to a maximum of 24°C (76°F) and an average of 9°C (49°F). This month experiences much higher precipitation of 56 mm (2.2 in) over 5 days, along with increased humidity at 75%. For more specific weather details, check out Lake Arrowhead weather in December.
September in Lake Arrowhead marks a transition into the cooler embrace of autumn, contrasting sharply with the sweltering summer months. As temperatures average around a comfortable 23°C (74°F), you’ll enjoy a pleasant reprieve from the peak summer heat, where highs can soar to 42°C (108°F). With only 9 mm of precipitation distributed over just a couple of days, September remains relatively dry, allowing for ample sunshine and outdoor activities. The humidity level sits at a refreshing 41%, providing a crispness in the air that hints at the upcoming change of seasons. For more insights on the year-round climatic nuances, explore Lake Arrowhead Climate.