Last updated: June 24, 2025
In Mountain View, United States, the average temperature in September hovers around 24°C (75°F). While you might enjoy a pleasant day, be prepared for fluctuations as temperatures can dip to a cool 8°C (46°F) or soar to a sweltering 38°C (100°F). During this month, expect 78 mm (3.1 in) of rain over approximately 7 days, contributing to an average humidity of 64%. Stay hydrated and enjoy the blend of sunshine and occasional showers!
In September in Mountain View, the average temperature is 24°C (75°F). Maximums can reach 38°C (100°F), and minimums can be as low as 8°C (46°F). Be sure to pack for both warm and cool weather to fully enjoy your travels.
In Mountain View in September, the total precipitation amount is 78 mm (3.1 in) over a duration of 7 days.
In Mountain View in September humidity is 64%. With average temperature 24°C (75°F), this humidity feels like a warm blanket enveloping you, making outdoor exploration both refreshing and a little sticky, perfect for leisurely strolls and shaded cafes but with a need for frequent water breaks.
In Mountain View in September, the maximum UV index is 9, which corresponds to a very high Exposure Category. The time to burn is just 15 minutes, so it's essential to take precautions. For detailed information, you can check the Hourly UV Index in Mountain View.
UV Risk Categories
Weather in Mountain View varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Mountain View, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | 4°C (40°F) | 39 mm (1.5 inches) | 76% | moderate |
| February Weather | 5°C (41°F) | 31 mm (1.2 inches) | 76% | high |
| March Weather | 12°C (54°F) | 65 mm (2.6 inches) | 70% | very high |
| April Weather | 16°C (60°F) | 94 mm (3.7 inches) | 72% | very high |
| May Weather | 21°C (70°F) | 141 mm (5.6 inches) | 82% | extreme |
| June Weather | 26°C (80°F) | 63 mm (2.5 inches) | 82% | extreme |
| July Weather | 29°C (84°F) | 37 mm (1.5 inches) | 80% | extreme |
| August Weather | 28°C (82°F) | 44 mm (1.7 inches) | 72% | extreme |
| September Weather | 24°C (75°F) | 78 mm (3.1 inches) | 64% | very high |
| October Weather | 17°C (62°F) | 81 mm (3.2 inches) | 71% | high |
| November Weather | 10°C (50°F) | 21 mm (0.8 inches) | 81% | moderate |
| December Weather | 7°C (44°F) | 29 mm (1.1 inches) | 84% | moderate |