Severe Weather

Throughout Wasco County, communities are vulnerable to a variety of severe storm hazards, such as ice and snowstorms, violent windstorms such as tornadoes, and even summer heatwaves. Severe weather seldom causes death and serious property damage, but they can cause major utility and transportation disruptions.



General Education


Snow Storm or Blizzard

Moderate snowfall can occur in Wasco County. Wasco County has had accumulations that vary depending on geographic location. For example, accumulations average between 4 – 5 inches in the City of the Dalles each year. However, during December of 1884, almost 30 inches of snow fell over a 3 day period, and again in 1909, more than 14 inches fell over 5 days. Accumulations of snow usually increase with distance and elevation as the terrain rises to the South of the Columbia River. January is usually the month with the greatest snowfall.

Moisture and cold air are required for snow to fall. While moisture is common in the winter months, the Cascades act as a barrier to moist air coming from the west. On occasion, cold air can slip through low points in the Cascades, bringing snow to the lower elevations; however, it melts quickly when the warm air moves in. It is common for cold air to come into the County from Washington and Oregon's central basins.

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Heat Wave

Wasco County is on the east side of the Cascade Mountains and the northern Oregon high desert region. The rain shadow effect of these mountains causes the area to have almost 300 days of sun a year. In the height of summer, temperatures regularly hover around 90 and occasionally cross above the 100-degree threshold. When this excessively hot weather remains in the area for an extended period of time, it is called a heatwave. Multiple heat waves hit Wasco County in the summer of 2018, exposing vulnerable populations to increased risk and creating hazardous conditions for wildfire or drought potential.



Every so often, the Northwest is severely impacted by strong windstorms. In the past, peak wind gusts have gone above 100 miles per hour. The strongest winds that impact Wasco County come from either east or west. Frequent and widespread strong winds come from the west and are associated with strong storms moving onto the Pacific Ocean coast. Strong east winds may also originate from Eastern Washington and Oregon when high atmospheric pressure is over the upper Columbia River Basin, and low pressure is over the Pacific Ocean. The Columbia River Gorge acts as a funnel, concentrating the wind's intensity as they flow to the West. This generates strong winds throughout the Gorge.

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Tornadoes can be an extremely violent weather phenomenon. They are characterized by funnel clouds of varying sizes that generate winds as fast as 500 miles per hour. They can affect an area of ¼ to ¾ of a mile, though seldom more than 16 miles long. Tornadoes normally descend from the large cumulonimbus clouds that characterize severe thunderstorms. They form when a strong crosswind intersects with strong warm updrafts in these clouds, causing a slowly spinning vortex to form within a cloud. No recorded instance of a tornado causing damage in Wasco County is available.