An unexpected spell of cold weather is sweeping across parts of the western United States. Areas in Idaho, Montana, Oregon, California, and Nevada are experiencing snow, frost, and freezing temperatures, leading to alerts from the National Weather Service (NWS). These conditions, typical of early spring or winter, contrast sharply with the summer season.

Areas Affected

In Montana, a Winter Weather Advisory is active through Thursday morning for the Absaroka and Beartooth Mountains. Light snow and gusty winds, reaching up to 35 mph, are affecting the Beartooth Highway.

Further south and west, freezing temperatures and frost are a major concern:

• Idaho: Eastern Magic Valley and Snake River Plain are under frost advisories and freeze warnings, with temperatures between 28°F and 32°F.
• Oregon and Northern California: The Klamath Basin and Modoc County are under frost advisories until Thursday morning, with lows forecast at 33°F, and potential freezing in colder areas.
• Nevada: Northern and south-central Elko County are experiencing frost advisories, with expected lows between 33°F and 37°F.
• Western Montana (Lemhi County): Temperatures may drop to 30°F, posing a frost risk.

Most advisories will expire by mid-morning Thursday as temperatures rise after sunrise.

Conditions and Impacts

Frost formation is likely throughout the region, with some areas experiencing below-freezing temperatures for several hours overnight. These conditions may:

• Damage or kill sensitive crops and outdoor vegetation.
• Harm unprotected plants during the early growing season.
• Pose risks to outdoor plumbing in colder areas.

In higher elevations, snow is adding to the hazards. Travel along mountain passes like the Beartooth Highway could face slippery conditions and reduced visibility, despite the mid-June timeframe.

Why This Is Unusual

The timing of this cold blast is remarkable. June usually brings milder temperatures overnight across the interior west, especially in lower-elevation deserts and valleys. Typically, overnight lows in places like southern Idaho, northern Nevada, and eastern Oregon stay well above freezing, supporting plant and crop growth.

The Beartooth Highway, elevated above 10,000 feet, occasionally experiences summer snow. However, snow events in June are significant due to their potential impact on travel during the tourist season.

Broadly, frost advisories in multiple western states during June emphasize what meteorologists call cold air outbreaks. These occur when cool air masses linger or move unusually far south.

Recommended Actions for Residents

The NWS advises residents to take immediate precautions:

• Cover or bring in sensitive plants.
• Protect outdoor irrigation or plumbing systems.
• Exercise caution when traveling through mountainous areas susceptible to snow.

Essentially, despite June’s typical warmth, parts of the West are experiencing winter-like conditions overnight. This highlights the region’s unpredictable weather during transitional seasons.