Last updated: June 24, 2025
In September, the average temperature in Mountain View, United States is a pleasant 22°C (72°F). Expect lows dipping to 7°C (45°F) and highs soaring up to 35°C (95°F). With an average humidity of 68%, the air can feel quite comfortable. Just keep in mind that you might encounter 53 mm (2.1 in) of precipitation over 6 days, so a light umbrella may come in handy!
In September in Mountain View, the average temperature is 22°C (72°F). The maximum can reach 35°C (95°F), while the minimum can drop to as low as 7°C (45°F). This diverse temperature range makes it a perfect time for travelers to enjoy both warm days and cooler evenings while exploring the sights.
In Mountain View in September, the precipitation amount is 53 mm (2.1 in) over a span of 6 days.
In Mountain View in September humidity is 68%. With an average temperature of 22°C (72°F), this humidity feels like a warm embrace, slightly stifling but still manageable for traveling, creating an atmosphere that encourages leisurely outdoor activities while prompting occasional breaks for refreshment.
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 | 2°C (35°F) | 79 mm (3.1 inches) | 83% | moderate |
| February Weather | 3°C (39°F) | 107 mm (4.2 inches) | 81% | high |
| March Weather | 9°C (49°F) | 148 mm (5.8 inches) | 80% | high |
| April Weather | 13°C (55°F) | 164 mm (6.5 inches) | 80% | very high |
| May Weather | 19°C (66°F) | 189 mm (7.4 inches) | 83% | extreme |
| June Weather | 24°C (75°F) | 77 mm (3.0 inches) | 83% | extreme |
| July Weather | 26°C (79°F) | 80 mm (3.2 inches) | 76% | extreme |
| August Weather | 24°C (76°F) | 108 mm (4.2 inches) | 69% | very high |
| September Weather | 22°C (72°F) | 53 mm (2.1 inches) | 68% | very high |
| October Weather | 15°C (59°F) | 122 mm (4.8 inches) | 72% | high |
| November Weather | 8°C (46°F) | 73 mm (2.9 inches) | 83% | moderate |
| December Weather | 5°C (41°F) | 71 mm (2.8 inches) | 86% | moderate |