Weather

People like to joke that the only seasons in Yellowstone are July, August, and Winter.  And while it isn’t uncommon at all for it to snow even in July or August, there’s a lot more variety within the seasons than that statement might suggest.  Historical data is provided below, along with information about weather monitoring systems in the park.

Summer: Daytime temperatures are often in the 70s (25C) and occasionally in the 80s (30C) in lower elevations. It’s not unheard of for daytime temps to reach into the 90s during some of the warmer summers.  Nights are usually cool (in the 30s and 40s F) and temperatures may drop below freezing at higher elevations. Thunderstorms are common in the afternoons, and it isn’t terribly uncommon for it to snow lightly at some of the higher elevations.

Winter: Temperatures often range from zero to 20F (-20 to -5C) throughout the day. Overnight temperatures well below zero are common. The record low temperature is -66F (-54C). Snowfall is highly variable, with the southern portions of the park getting more snow than the northern portions. While the average is 150 inches per year, it is not uncommon for higher elevations to get twice that amount. See the Winter Daily Reports for specific conditions.

Spring & Fall: Daytime temperatures range from the 30s to the 60s (0 to 20C) with overnight lows in the teens to single digits (-5 to -20C). Snow is common in the Spring and Fall with regular accumulations of 12″ in a 24 hour period. At any time of year, be prepared for sudden changes.

Unpredictability, more than anything else, characterizes Yellowstone’s weather. Always be equipped with a wide range of clothing options. Be sure to bring a warm jacket and rain gear even in the summer, and dress in layers at all times of the year.  It tends to stay pretty windy in certain areas of the park as well, particularly at the higher elevations.

Yellowstone’s Current Weather Information & Forecasts

Yellowstone’s Historical Weather Information

The following tables provide information on historical averages at various locations throughout the park.  The data are based on readings taken from 1948 through 2005.  You can see the tremendous variation in temperatures and precipitation totals among the different areas of the park. 1

Mammoth
J F M A M J J A S O N D
Avg Max 29.5 34.0 40.1 49.6 60.4 69.5 80.2 78.7 68.0 55.5 38.8 30.6
Avg Min 10.2 12.9 17.8 26.0 34.2 41.2 47.0 45.4 37.4 29.4 19.4 12.2
Avg T Prec 1.05 0.70 1.05 1.18 1.94 2.07 1.43 1.34 1.23 1.00 1.02 0.96
Avg T Snow 14.6 9.7 12.6 6.0 1.5 0.2 0 0 0.5 3.3 9.5 13.0
Avg S Dpth 8 8 5 1 0 0 0 0 0 0 2 4
Lamar Ranger Station
J F M A M J J A S O N D
Avg Max 24.6 30.7 37.5 48.7 60.6 68.4 78.2 76.6 68.0 55.8 37.4 26.8
Avg Min 0.8 4.2 9.1 20.0 27.2 33.3 36.3 34.2 27.1 20.7 11.1 1.9
Avg T Prec 0.97 0.63 0.67 0.90 1.45 2.05 1.40 1.36 1.45 0.94 0.79 0.89
Avg T Snow 20.7 15.0 13.4 8.5 1.9 0.3 0 0 1.9 4.0 10.9 17.6
Avg S Dpth 12 15 13 4 0 0 0 0 0 0 2 6
Tower Falls
J F M A M J J A S O N D
Avg Max 26.9 33.3 41.6 50.4 61.3 69.7 79.4 78.9 68.9 55.8 37.6 27.6
Avg Min 0.1 3.4 10.5 20.0 28.1 33.8 37.7 35.8 28.3 20.7 10.8 1.8
Avg T Prec 1.33 0.88 1.04 1.20 1.93 2.17 1.64 1.45 1.39 1.13 1.13 1.30
Avg T Snow 21.6 13.5 13.5 8.2 1.9 0.3 0 0 0.8 3.6 12.4 20.1
Avg S Dpth 17 20 19 6 0 0 0 0 0 0 3 10
Lake Ranger Station
J F M A M J J A S O N D
Avg Max 23.0 28.0 34.6 42.8 52.3 61.2 71.5 71.0 61.4 49.2 33.9 25.3
Avg Min -1.7 -1.0 3.6 14.5 24.9 32.8 38.4 37.3 29.4 21.8 11.3 2.6
Avg T Prec 2.00 1.48 1.64 1.57 1.94 2.21 1.53 1.67 1.61 1.33 1.64 1.74
Avg T Snow 35.1 25.2 26.0 15.5 5.90 0.80 0 0.10 1.40 7.70 22.9 30.2
Avg S Dpth 30 37 41 33 9 0 0 0 0 1 7 18
South Entrance/Snake River
J F M A M J J A S O N D
Avg Max 26.0 31.0 37.6 46.9 56.9 67.3 77.3 76.4 66.6 52.8 35.9 26.5
Avg Min 0.3 0.6 8.1 18.5 27.1 33.4 37.5 35.3 27.1 19.9 9.8 0.5
Avg T Prec 4.22 3.12 2.77 2.31 2.62 2.41 1.58 1.61 1.69 2.08 3.21 4.29
Avg T Snow 55.7 45.3 35.8 18.9 6.4 0.9 0 0 0.7 9.5 37.0 58.5
Avg S Dpth 43 55 57 42 10 0 0 0 0 1 9 28
Old Faithful Ranger Station
J F M A M J J A S O N D
Avg Max 28.2 32.0 39.1 46.6 55.3 64.7 74.4 73.6 64.1 50.8 34.8 27.1
Avg Min 0.2 0.7 9.3 18.4 27.8 34.4 39.0 36.5 28.8 20.8 8.4 -0.6
Avg T Prec 2.34 1.84 2.20 2.06 2.66 2.31 1.67 1.53 1.52 1.61 2.26 2.43
Avg T Snow 38.6 32.2 30.1 20.2 8.1 1.4 0 0 1.7 8.2 30.5 41.3
Avg S Dpth 29 36 37 23 4 0 0 0 0 1 7 20

Weather Monitoring Systems in Yellowstone

You can find out more about the devices and systems used to monitor various aspects of the weather on the Weather/Seismic Monitoring Systems page.

  1. Temperatures are expressed in degrees F, precipitation figures are expressed in inches.  Avg T Prec = Average Total Precipitation.  Avg T Snow = Average total snowfall.  Avg S Dpth = Average snow depth. []