Saint Helens (OR) Temperature by Month

Saint Helens, Oregon, United States of America has an average annual maximum temperature of 17°C (63°F), ranging from 7°C (45°F) in December to 28°C (82°F) in August. Below you'll find a full monthly breakdown and a comparison with cities worldwide.

Depending on the time of the year, temperatures range from comfortable to cold in Saint Helens. At night, minimum temperatures range from 13°C (55°F) in August to 1°C (34°F) in December.

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

Daily lows are most common between 4 AM and 6 AM. By 3 PM temperatures reach their daily high, driven by peak solar heating. August, the warmest month of the year, receives 298 hours of sunshine.

The chart below shows the average temperature throughout the year:

Saint Helens's average annual maximum temperature is 17°C (63°F). To put that in context, here's how it compares to a few well-known destinations:

Seville, Spain averages 23°C (73°F) a year, one of the warmer cities in Western Europe, with long hot summers.

Interlaken, Switzerland averages 8°C (46°F) a year, with cold winters and cool summers thanks to its Alpine setting.

Boston, USA averages 16°C (61°F) annually, with four distinct seasons and cold winters that rival northern Europe.

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

Temperature alone doesn't tell the whole story, humidity plays a big role in how warm or cold it actually feels. High humidity in summer makes the heat feel more intense, particularly once temperatures climb above 25°C. In winter, the same humidity can make cold air feel sharper than the thermometer suggests.

In the cooler months, when temperatures drop below 10°C, high humidity makes the cold feel more cutting than it would in dry conditions.

In Saint Helens, December is the coolest month, with average highs of 7°C (45°F) and humidity around 83%, considered very high. In August, the warmest month, temperatures average 28°C (82°F) with 65% humidity, conditions that feel high. For a full picture, see our humidity page.

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.

Global average temperatures have risen by around 1.2°C since the pre-industrial era, and the effects are visible across many regions. Winters are milder on average, with fewer frost days and less snow in many parts of the world. Heatwaves are more frequent and more intense, and Europe's summers of 2018, 2019, and 2020 all set records.

Summers are also getting drier in some areas, while winter rainfall has increased in others. This contributies to higher river levels and more flooding. In many countries, spring arrives earlier and autumn lasts longer. It has knock-on effects for wildlife, agriculture, and local ecosystems.

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