Yellowstone Weather & Climate Guide: Year-Round Expectations

Yellowstone’s climate is defined by its high-altitude continental geography. With approximately 80% of the park sitting above 7,500 feet, the atmosphere is thin, crisp, and extremely responsive to solar radiation and mountain weather systems. This results in a climate where unpredictability is the only constant.

Seasonal Trends

Summer (July – August)

This is the park's most "dependable" window, characterized by warm, sunny days and cool, refreshing nights. Highs typically reach into the 70s and low 80s°F (21-28°C) at lower elevations like Mammoth Hot Springs, while staying in the 60s at higher plateaus. July and August are the driest months, though the "monsoonal" influence often brings brief, intense afternoon thunderstorms.

Fall (September – October)

Autumn is a season of rapid transition. September often starts with "Indian Summer" days—clear, dry, and cool—but by October, the first major snowstorms typically arrive. Temperatures fluctuate wildly; a 60°F afternoon can plummet into the teens by dawn. The air becomes noticeably drier, and the golden light of the low sun provides exceptional clarity for photography.

Winter (November – March)

Winter in Yellowstone is a world of "fire and ice." Temperatures regularly hover between 0°F and 20°F (-18°C to -7°C) during the day, with sub-zero nights being the norm. The park receives an average of 150 inches of snow annually, though higher elevations can see over 400 inches. This season features the "Chinook" winds—warm, dry gusts that can cause sudden, massive snowmelts in a matter of hours.

Spring (April – June)

Spring is often the wettest and most volatile period. May is historically the rainiest month, and heavy snow remains common through June. Transitioning from winter to summer means you might experience all four seasons in a single 24-hour cycle. Yellowstone Lake remains frozen often until early July, keeping the surrounding air significantly cooler than the northern valleys.

Diurnal Temperature Variation

One of the most striking aspects of Yellowstone’s climate is the "diurnal swing." Because the high-altitude air does not hold heat well, the temperature can drop 40 to 50 degrees Fahrenheit as soon as the sun sets. Even in the height of summer, morning frost is possible in the central plateaus.

Microclimates and Geothermal Effects

Yellowstone’s topographical diversity creates distinct microclimates:

• The Northern Range: Locations like Gardiner and Mammoth are at lower elevations and reside in a "rain shadow," making them significantly warmer and drier than the rest of the park.
• Geothermal Microclimates: Areas near the Geyser Basins (like Old Faithful or Norris) experience localized humidity and slightly warmer ground temperatures. In winter, steam from these features can create "diamond dust" (ice crystals suspended in the air) and ghostly "ghost trees" coated in thick rime ice.
• Cold Air Drainage: Deep valleys and basins often trap cold, heavy air at night, leading to temperatures that are much lower than the surrounding ridges.

Historical Context & Unique Phenomena

Yellowstone holds some of the most extreme weather records in the United States, including a record low of -66°F (-54°C) near the West Entrance in 1933.

Common Weather Phenomena:

• Graupel: Often mistaken for hail, these "soft" snow pellets are common during spring and summer afternoon storms.
• Rime Ice: Built up by freezing fog, this covers trees near geyser basins in a thick, white crust during winter.
• Flash Flooding: Rapid snowmelt in June, occasionally combined with heavy rain, can cause dramatic flooding in the park’s river systems.

What the Weather "Feels Like"

The high elevation means the sun's UV rays are much more intense than at sea level; even on a cool day, the sun can feel piercing and warm on the skin. Conversely, the "dry cold" of winter feels different than a coastal damp cold—it is biting and immediate, requiring local knowledge of wind chill and layering to navigate safely.