Sunnyside (WA) Temperature by Month

Sunnyside in Washington State, United States of America sees significant seasonal temperature differences, with daytime highs between 3°C (37°F) in December and 33°C (91°F) in July, averaging 18°C (64°F) annually. Explore the full monthly breakdown below.

Visitors to Sunnyside will encounter a climate influenced by big temperature differences across the year. Nighttime temperatures range from 14°C (57°F) in July to -5°C (23°F) in December.

The chart below illustrates the average maximum day and minimum night temperatures in Sunnyside by month:

Low temperatures are most often recorded between 4 AM and 6 AM, while highs typically occur around 3 PM.

The chart below shows the average temperature throughout the year:

Sunnyside's average annual maximum temperature is 18°C (64°F). To put that in context, here's how it compares to a few well-known destinations:

Lisbon, Portugal averages 21°C (70°F) annually, warm summers, mild winters, and rain mainly in the cooler months.

Reykjavík, Iceland averages 9°C (48°F) a year, mild summers by Icelandic standards, but cold winters and frequent wind.

Beijing, China averages 20°C (68°F) annually, but with big seasonal swings, very cold winters and hot summers.

Adelaide, Australia averages 21°C (70°F) a year, with warm summers, mild winters, and relatively low rainfall year-round.

Climate temperature data is typically calculated as a 30-year average. This smooths out year-to-year variability and gives a more reliable picture of what a place is actually like, rather than what happened in any single unusual year.

The readings come from a range of sources, land-based weather stations, ocean buoys, ships, and satellites. That data is collected by weather services around the world, then pooled, quality-checked, and averaged to produce the climate records you see here.

For cities and regions with significant elevation, altitude is one of the biggest factors shaping local temperatures. As a rule of thumb, temperatures fall by around 6°C for every 1,000 metres gained, so a city at 2,000 metres will typically be around 12°C cooler than a city at sea level in the same region. Higher ground also tends to see more dramatic day-to-night temperature swings, since thinner air loses heat faster after sunset.

For more on Sunnyside's weather, including monthly rainfall, sunshine hours, and humidity, visit our Sunnyside climate page.