Climate Insights for Hermiston

The climate in Hermiston is temperate. The average annual temperature is 14°C and approximately 309mm of precipitation falls per year. October is the wettest month, receiving around 73mm of rainfall. Hermiston is in the Northern Hemisphere. Summer begins at the end of June and lasts through September. The summer months are: August, July, June. The coldest months are December, January, February, when temperatures can drop to -3°C. Light snow can occur between January and December.

Hermiston has a wide annual temperature range, spanning 37°C from the coldest to warmest months. The warmest month is August, when average highs reach 34°C and the mean temperature sits around 25°C. The coldest month is December, when overnight lows fall to -3°C and the daily average is 0°C. On average, daily temperatures fluctuate by about 12°C between overnight lows and afternoon highs. The sharpest temperature change occurs between November and December, with a 10°C shift in average temperatures.

Hermiston is a quite dry location, receiving approximately 309mm of precipitation annually, which averages out to around 26mm per month. The wettest month is October, averaging 73mm of rainfall. December and January also tend to see above-average precipitation. The driest month is August, with just 0mm. That's 73mm less than October, the wettest month. Rainfall is heavily concentrated in certain months, creating a distinct wet and dry season. Visitors should plan around these patterns, as the difference between peak and low months is dramatic. Light snowfall can occur between January and December, totalling around 35cm annually. December is the snowiest month with approximately 32cm.

Hermiston is relatively calm, with an average annual wind speed of 3km/h. For context, sustained winds below 12km/h are generally light, while anything above 25km/h is considered strong. The windiest month is June, averaging 4km/h, though still comfortable for most outdoor activities. The calmest conditions occur in January, with average winds dropping to 2km/h, making it an ideal period for wind-sensitive activities. There is moderate seasonal variation in wind speed, with a 2km/h gap between the calmest and windiest months.

It is currently summer in Hermiston, which began on June 21, 2026. Hermiston is in the Northern Hemisphere, where spring begins in March, summer in June, autumn in September, and winter in December. The warmest period peaks in August at around 34°C, while the coldest stretch bottoms out in December near -3°C. Autumn is next, beginning on September 23, 2026 — 52 days from now.

The best time to visit Hermiston is during April, May, June and September, when the weather is most comfortable for travellers. During these months, average temperatures hover around 19°C with modest rainfall averaging 15mm per month. By contrast, August can be uncomfortably hot with highs reaching 34°C, while December is the coldest period with lows dropping to -3°C. With minimal rainfall expected, you can pack light and plan outdoor activities with confidence.

The table below shows monthly climate averages for Hermiston based on historical weather data. Min and max temperatures represent typical overnight lows and afternoon highs for each month, shown in degrees Celsius (°C). Precipitation is measured in millimetres (mm) and indicates the average total rainfall per month. Snow is measured in centimetres (cm) and reflects average monthly snowfall accumulation. Wind speed is the average sustained speed in kilometres per hour (km/h). All values are based on averages from over 10 years of historical weather data. The current month is highlighted for quick reference.