Idaho Annual Rainfall and Climate Data, see below for individual cities 

 Idaho Average Annual Precipitation

Idaho city precipitation totals

City

Avg Annual Precip

Avg Annual Snow

 Avg. days of Precip Avg # snow days Avg # thunderstorm days Avg # hail days

Avg # severe thunderstorm watches per year

Avg # tornado watches per year

 # of tornadoes reported in county, 1960-2010
Boise 12.19 20.4 90 55 10 2 0 1 0
Lewiston 12.74 15.7 103 44 27 0 0 1 3
Pocatello 12.58 42.0 96 81 24 1 0 2 6
  • Idaho Annual Precipitation Average - 18.96 inches, 42nd wettest state in the U.S.
  • Idaho Tornado Average - 2.6 per year - 36th most in the U.S.
  • Largest reported Tornado in Idaho from 1950-2011, 6/4/2006 - 1,760 yards / 1 mile wide
  • Date with highest number of reported Tornadoes in Idaho from 1950-2011, June 15th - 6 tornadoes
  • Average time of occurrence of reported Tornadoes in Idaho from 1950-2011 - 3:22 pm
  • Idaho Annual Lightning Density - 1.0 flashes per square mile - 45th highest in U.S. 
  • Record Driest year in Idaho from 1895-2012 - 1935, avg precipitation 12.42 inches 
  • Record Wettest year in Idaho from 1895-2012 - 1927, avg precipitation 25.47 inches 

Idaho Precipitation Records

  • Driest location ranked by lowest annual average precipitation: Grand View, southwestern Idaho, 7.11"
  • Wettest location ranked by highest annual average precipitation: Burke, northern Idaho, 48.87"
  • Snowiest location ranked by highest annual average snowfall: Mullan Pass, northern Idaho, 283.5"
  • State precipitation record for 24 hours - Rattlesnake Pass, northern Idaho, 11/23/1909, 7.17"
  • State precipitation record for 1 year - Roland, northern Idaho, 1933, 81.05"
  • State snowfall record for 24 hours - Sun Valley, central Idaho, 2/11/1959, 38.00"
  • State snow record for 1 season - Roland, northern Idaho, 1949-1950, 441.8"
  • On 1/03/1961, a three day long ice storm hit northern Idaho, producing an accumulation of ice eight
    inches thick, a U.S. record
  • Floods in Idaho occur most often during the period of seasonal snowmelt in spring, particularly  in April
    and May. A few areas in the State are actually flooded or threatened by floodwaters nearly every
    year. These areas include the Kootenai River valley and in the vicinity of Bonners Ferry. Another area is
    the Snake River upstream from Idaho Falls in the areas of Roberts and Menan
  • Idaho temperature averages and extremes, precipitation and temperature data for all U.S. states and 
    interesting Top 10 U.S. climate extremes
Data sources: National Climatic Data Center, Severe thunderstorm / tornado watch data
period is 1999 - 2008, NOAA Storm Prediction Center, Tornado climate data - NOAA Storm Prediction Center  State lightning flash density average - 1997-2011, Vaisala
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