Last updated: June 24, 2025
In Happy Valley, United States, the average temperature in September hovers around 11°C (51°F). Expect a minimum of 3°C (37°F) and a comfortable maximum of 16°C (62°F). This month also brings about 139 mm (5.5 in) of precipitation spread over 16 days, contributing to an average humidity of a high 90%. Be prepared for a cool and damp experience!
In September in Happy Valley, the average temperature is 11°C (51°F), with maximums reaching 16°C (62°F) and minimums dropping as low as 3°C (37°F). Travelers should pack layers to stay comfortable while exploring the varied temperatures.
In Happy Valley in September, the total precipitation amount is 139 mm (5.5 in) spread over 16 days.
In Happy Valley in September, humidity is 90%. With an average temperature of 11°C (51°F), this humidity feels like a damp blanket wrapping around you, making traveling uncomfortable and sticky, as every step leaves you feeling sluggish and clinging to the air.
In Happy Valley in September, the maximum UV index reaches 4, which corresponds to a moderate Exposure Category. With a time to burn of 30 minutes, it’s important to take precautions to protect your skin. You can find more details in the Hourly UV Index in Happy Valley for better planning.
UV Risk Categories
Weather in Happy Valley varies notably across the year, with each month offering distinct climate conditions. This page compares September’s weather to other months in Happy Valley, focusing on differences in temperature, rainfall, humidity, and UV levels.
| Temperature | Precipitation | Humidity | UV | |
|---|---|---|---|---|
| January Weather | -3°C (26°F) | 78 mm (3.1 inches) | 92% | low |
| February Weather | -2°C (28°F) | 70 mm (2.8 inches) | 92% | low |
| March Weather | -1°C (30°F) | 54 mm (2.1 inches) | 86% | moderate |
| April Weather | 3°C (37°F) | 51 mm (2.0 inches) | 79% | moderate |
| May Weather | 7°C (45°F) | 96 mm (3.8 inches) | 87% | high |
| June Weather | 10°C (51°F) | 64 mm (2.5 inches) | 91% | high |
| July Weather | 13°C (55°F) | 85 mm (3.3 inches) | 92% | high |
| August Weather | 13°C (56°F) | 99 mm (3.9 inches) | 92% | high |
| September Weather | 11°C (51°F) | 139 mm (5.5 inches) | 90% | moderate |
| October Weather | 6°C (44°F) | 164 mm (6.5 inches) | 87% | low |
| November Weather | 0°C (33°F) | 124 mm (4.9 inches) | 91% | low |
| December Weather | -1°C (31°F) | 155 mm (6.1 inches) | 92% | low |