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Average Weather in Ketchum Idaho, United States

In Ketchum, the summers are warm, dry, and mostly clear and the winters are freezing, snowy, and partly cloudy. Over the course of the year, the temperature typically varies from 10°F to 81°F and is rarely below -5°F or above 88°F.

Based on the tourism score, the best time of year to visit Ketchum for warm-weather activities is from early July to mid August.

Climate Summary

freezingvery coldcoldcoolwarmcoolcoldJanFebMarAprMayJunJulAugSepOctNovDecNowNow82%82%45%45%clearovercastprecipitation: 1.5 inprecipitation: 1.5 in0.4 in0.4 inmuggy: 0%muggy: 0%drydrytourism score: 5.4tourism score: 5.40.00.0
Click on each chart for more information.

Temperature

The warm season lasts for 3.0 months, from June 13 to September 12, with an average daily high temperature above 70°F. The hottest day of the year is July 26, with an average high of 81°F and low of 48°F.

The cold season lasts for 3.4 months, from November 18 to February 28, with an average daily high temperature below 37°F. The coldest day of the year is January 1, with an average low of 10°F and high of 26°F.

Average High and Low Temperature

The daily average high (red line) and low (blue line) temperature, with 25th to 75th and 10th to 90th percentile bands. The thin dotted lines are the corresponding average perceived temperatures.

The figure below shows you a compact characterization of the entire year of hourly average temperatures. The horizontal axis is the day of the year, the vertical axis is the hour of the day, and the color is the average temperature for that hour and day.

Average Hourly Temperature

Average Hourly Temperature in KetchumJanFebMarAprMayJunJulAugSepOctNovDec12 AM4 AM8 AM12 PM4 PM8 PM12 AMNowNowfrigidfreezingfreezingvery coldvery coldcoldcoolwarmfrigidcoolcomfortable
frigid 15°F freezing 32°F very cold 45°F cold 55°F cool 65°F comfortable 75°F warm 85°F hot 95°F sweltering
The average hourly temperature, color coded into bands. The shaded overlays indicate night and civil twilight.

Anton, Bulgaria (5,947 miles away); Kale, Turkey (6,474 miles); and Gogaran, Armenia (6,450 miles) are the far-away foreign places with temperatures most similar to Ketchum (view comparison).

Clouds

In Ketchum, the average percentage of the sky covered by clouds experiences significant seasonal variation over the course of the year.

The clearer part of the year in Ketchum begins around June 14 and lasts for 3.9 months, ending around October 10. On July 27, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 82% of the time, and overcast or mostly cloudy 18% of the time.

The cloudier part of the year begins around October 10 and lasts for 8.1 months, ending around June 14. On February 27, the cloudiest day of the year, the sky is overcast or mostly cloudy 55% of the time, and clear, mostly clear, or partly cloudy 45% of the time.

Cloud Cover Categories

Cloud Cover Categories in KetchumclearercloudiercloudierJanFebMarAprMayJunJulAugSepOctNovDec0%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%Jul 2782%Jul 2782%Feb 2745%Feb 2745%Jun 1463%Jun 1463%Oct 1063%Oct 1063%NowNowclearmostly clearovercastmostly cloudypartly cloudy
0% clear 20% mostly clear 40% partly cloudy 60% mostly cloudy 80% overcast 100%
The percentage of time spent in each cloud cover band, categorized by the percentage of the sky covered by clouds.

Precipitation

A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days in Ketchum varies throughout the year.

The wetter season lasts 7.5 months, from November 2 to June 16, with a greater than 15% chance of a given day being a wet day. The chance of a wet day peaks at 22% on May 23.

The drier season lasts 4.5 months, from June 16 to November 2. The smallest chance of a wet day is 7% on July 6.

Among wet days, we distinguish between those that experience rain alone, snow alone, or a mixture of the two. Based on this categorization, the most common form of precipitation in Ketchum changes throughout the year.

Rain alone is the most common for 8.2 months, from March 9 to November 15. The highest chance of a day with rain alone is 21% on May 23.

Snow alone is the most common for 3.4 months, from November 15 to February 28. The highest chance of a day with snow alone is 15% on December 22.

Mixed snow and rain is the most common for 1.4 weeks, from February 28 to March 9. The highest chance of a day with mixed snow and rain is 7% on February 27.

Daily Chance of Precipitation

Daily Chance of Precipitation in KetchumsnowrainsnowJanFebMarAprMayJunJulAugSepOctNovDec0%10%20%30%40%50%60%70%80%90%100%May 2322%May 2322%Jul 67%Jul 67%Feb 2818%Feb 2818%Nov 1518%Nov 1518%NowNowsnowrainmixed
The percentage of days in which various types of precipitation are observed, excluding trace quantities: rain alone, snow alone, and mixed (both rain and snow fell in the same day).

Rainfall

To show variation within the months and not just the monthly totals, we show the rainfall accumulated over a sliding 31-day period centered around each day of the year. Ketchum experiences some seasonal variation in monthly rainfall.

The rainy period of the year lasts for 8.7 months, from March 3 to November 25, with a sliding 31-day rainfall of at least 0.5 inches. The most rain falls during the 31 days centered around May 23, with an average total accumulation of 1.1 inches.

The rainless period of the year lasts for 3.3 months, from November 25 to March 3. The least rain falls around January 20, with an average total accumulation of 0.1 inches.

Average Monthly Rainfall

The average rainfall (solid line) accumulated over the course of a sliding 31-day period centered on the day in question, with 25th to 75th and 10th to 90th percentile bands. The thin dotted line is the corresponding average liquid-equivalent snowfall.

Snowfall

We report snowfall in liquid-equivalent terms. The actual depth of new snowfall is typically between 5 and 10 times the liquid-equivalent amount, assuming the ground is frozen. Colder, drier snow tends to be on the higher end of that range and warmer, wetter snow on the lower end.

As with rainfall, we consider the snowfall accumulated over a sliding 31-day period centered around each day of the year. Ketchum experiences significant seasonal variation in monthly liquid-equivalent snowfall.

The snowy period of the year lasts for 6.1 months, from October 19 to April 22, with a sliding 31-day liquid-equivalent snowfall of at least 0.1 inches. The most snow falls during the 31 days centered around December 25, with an average total liquid-equivalent accumulation of 1.2 inches.

The snowless period of the year lasts for 5.9 months, from April 22 to October 19. The least snow falls around July 29, with an average total liquid-equivalent accumulation of 0.0 inches.

Average Liquid-Equivalent Monthly Snowfall

Average Liquid-Equivalent Monthly Snowfall in KetchumsnowsnowJanFebMarAprMayJunJulAugSepOctNovDec0.0 in0.5 in1.0 in1.5 in2.0 in2.5 in3.0 inDec 251.2 inDec 251.2 inJul 290.0 inJul 290.0 inOct 190.1 inOct 190.1 inApr 220.1 inApr 220.1 inNowNow
The average liquid-equivalent snowfall (solid line) accumulated over the course of a sliding 31-day period centered on the day in question, with 25th to 75th and 10th to 90th percentile bands. The thin dotted line is the corresponding average rainfall.

Sun

The length of the day in Ketchum varies significantly over the course of the year. In 2020, the shortest day is December 21, with 8 hours, 55 minutes of daylight; the longest day is June 20, with 15 hours, 27 minutes of daylight.

Hours of Daylight and Twilight

Hours of Daylight and Twilight in KetchumJanFebMarAprMayJunJulAugSepOctNovDec0 hr24 hr4 hr20 hr8 hr16 hr12 hr12 hr16 hr8 hr20 hr4 hr24 hr0 hr12 hr, 8 minMar 1912 hr, 8 minMar 1915 hr, 27 minJun 2015 hr, 27 minJun 2012 hr, 11 minSep 2212 hr, 11 minSep 228 hr, 56 minDec 218 hr, 56 minDec 21nightnightdayNowNow
The number of hours during which the Sun is visible (black line). From bottom (most yellow) to top (most gray), the color bands indicate: full daylight, twilight (civil, nautical, and astronomical), and full night.

The earliest sunrise is at 5:55 AM on June 14, and the latest sunrise is 2 hours, 18 minutes later at 8:12 AM on October 31. The earliest sunset is at 5:00 PM on December 8, and the latest sunset is 4 hours, 23 minutes later at 9:23 PM on June 26.

Daylight saving time (DST) is observed in Ketchum during 2020, starting in the spring on March 8, lasting 7.8 months, and ending in the fall on November 1.

Sunrise & Sunset with Twilight and Daylight Saving Time

Sunrise & Sunset with Twilight and Daylight Saving Time in KetchumJanFebMarAprMayJunJulAugSepOctNovDec2 AM4 AM6 AM8 AM10 AM12 PM2 PM4 PM6 PM8 PM10 PM12 AMJun 145:55 AMJun 145:55 AM9:23 PMJun 269:23 PMJun 26Dec 85:00 PMDec 85:00 PM8:12 AMOct 318:12 AMOct 31Mar 8DSTMar 8DSTDSTNov 1DSTNov 1daynightnightnightnightSolarMidnightSolarMidnightSolarNoonSunriseSunset
The solar day over the course of the year 2020. From bottom to top, the black lines are the previous solar midnight, sunrise, solar noon, sunset, and the next solar midnight. The day, twilights (civil, nautical, and astronomical), and night are indicated by the color bands from yellow to gray. The transitions to and from daylight saving time are indicated by the 'DST' labels.

Humidity

We base the humidity comfort level on the dew point, as it determines whether perspiration will evaporate from the skin, thereby cooling the body. Lower dew points feel drier and higher dew points feel more humid. Unlike temperature, which typically varies significantly between night and day, dew point tends to change more slowly, so while the temperature may drop at night, a muggy day is typically followed by a muggy night.

The perceived humidity level in Ketchum, as measured by the percentage of time in which the humidity comfort level is muggy, oppressive, or miserable, does not vary significantly over the course of the year, remaining a virtually constant 0% throughout.

Humidity Comfort Levels

Humidity Comfort Levels in KetchumJanFebMarAprMayJunJulAugSepOctNovDec0%10%20%30%40%50%60%70%80%90%100%Jul 20%Jul 20%NowNowdrydry
dry 55°F comfortable 60°F humid 65°F muggy 70°F oppressive 75°F miserable
The percentage of time spent at various humidity comfort levels, categorized by dew point.

Wind

This section discusses the wide-area hourly average wind vector (speed and direction) at 10 meters above the ground. The wind experienced at any given location is highly dependent on local topography and other factors, and instantaneous wind speed and direction vary more widely than hourly averages.

The average hourly wind speed in Ketchum experiences mild seasonal variation over the course of the year.

The windier part of the year lasts for 6.1 months, from March 2 to September 6, with average wind speeds of more than 6.2 miles per hour. The windiest day of the year is April 10, with an average hourly wind speed of 7.1 miles per hour.

The calmer time of year lasts for 5.9 months, from September 6 to March 2. The calmest day of the year is December 25, with an average hourly wind speed of 5.4 miles per hour.

Average Wind Speed

Average Wind Speed in KetchumwindyJanFebMarAprMayJunJulAugSepOctNovDec0 mph2 mph4 mph6 mph8 mph10 mph12 mphApr 107.1 mphApr 107.1 mphDec 255.4 mphDec 255.4 mphSep 66.2 mphSep 66.2 mphNowNow
The average of mean hourly wind speeds (dark gray line), with 25th to 75th and 10th to 90th percentile bands.

The predominant average hourly wind direction in Ketchum varies throughout the year.

The wind is most often from the north for 1.3 weeks, from January 23 to February 1, with a peak percentage of 35% on January 26. The wind is most often from the west for 12 months, from February 1 to January 23, with a peak percentage of 35% on January 1.

Wind Direction

Wind Direction in KetchumWWJanFebMarAprMayJunJulAugSepOctNovDec0%100%20%80%40%60%60%40%80%20%100%0%NowNowwestnorthsoutheast
northeastsouthwest
The percentage of hours in which the mean wind direction is from each of the four cardinal wind directions, excluding hours in which the mean wind speed is less than 1.0 mph. The lightly tinted areas at the boundaries are the percentage of hours spent in the implied intermediate directions (northeast, southeast, southwest, and northwest).

Best Time of Year to Visit

To characterize how pleasant the weather is in Ketchum throughout the year, we compute two travel scores.

The tourism score favors clear, rainless days with perceived temperatures between 65°F and 80°F. Based on this score, the best time of year to visit Ketchum for general outdoor tourist activities is from early July to mid August, with a peak score in the last week of July.

Tourism Score

Tourism Score in KetchumJanFebMarAprMayJunJulAugSepOctNovDec02468105.45.40.00.0NowNow precipitationprecipitationcloudscloudstemperaturetemperaturetourism score
The tourism score (filled area), and its constituents: the temperature score (red line), the cloud cover score (blue line), and the precipitation score (green line).

The beach/pool score favors clear, rainless days with perceived temperatures between 75°F and 90°F. Based on this score, the best time of year to visit Ketchum for hot-weather activities is from early July to mid August, with a peak score in the last week of July.

Beach/Pool Score

Beach/Pool Score in KetchumJanFebMarAprMayJunJulAugSepOctNovDec02468102.72.70.00.0NowNow precipitationprecipitationcloudscloudstemperaturetemperature
The beach/pool score (filled area), and its constituents: the temperature score (red line), the cloud cover score (blue line), and the precipitation score (green line).

Methodology

For each hour between 8:00 AM and 9:00 PM of each day in the analysis period (1980 to 2016), independent scores are computed for perceived temperature, cloud cover, and total precipitation. Those scores are combined into a single hourly composite score, which is then aggregated into days, averaged over all the years in the analysis period, and smoothed.

Our cloud cover score is 10 for fully clear skies, falling linearly to 9 for mostly clear skies, and to 1 for fully overcast skies.

Our precipitation score, which is based on the three-hour precipitation centered on the hour in question, is 10 for no precipitation, falling linearly to 9 for trace precipitation, and to 0 for 0.04 inches of precipitation or more.

Our tourism temperature score is 0 for perceived temperatures below 50°F, rising linearly to 9 for 65°F, to 10 for 75°F, falling linearly to 9 for 80°F, and to 1 for 90°F or hotter.

Our beach/pool temperature score is 0 for perceived temperatures below 65°F, rising linearly to 9 for 75°F, to 10 for 82°F, falling linearly to 9 for 90°F, and to 1 for 100°F or hotter.

Growing Season

Definitions of the growing season vary throughout the world, but for the purposes of this report, we define it as the longest continuous period of non-freezing temperatures (≥ 32°F) in the year (the calendar year in the Northern Hemisphere, or from July 1 until June 30 in the Southern Hemisphere).

The growing season in Ketchum typically lasts for 3.1 months (94 days), from around June 11 to around September 13, rarely starting before May 20 or after July 4, and rarely ending before August 26 or after September 30.

Time Spent in Various Temperature Bands and the Growing Season

Time Spent in Various Temperature Bands and the Growing Season in KetchumJanFebMarAprMayJunJulAugSepOctNovDec0%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%Jun 1150%Jun 1150%Sep 1350%Sep 1350%Jul 490%Jul 490%Aug 2690%Aug 2690%May 2010%May 2010%Sep 3010%Sep 3010%0%Nov 260%Nov 26Aug 1100%Aug 1100%NowNowfrigidfreezingcoldcoolcomfortablevery coldwarm
frigid 15°F freezing 32°F very cold 45°F cold 55°F cool 65°F comfortable 75°F warm 85°F hot 95°F sweltering
The percentage of time spent in various temperature bands. The black line is the percentage chance that a given day is within the growing season.

Growing degree days are a measure of yearly heat accumulation used to predict plant and animal development, and defined as the integral of warmth above a base temperature, discarding any excess above a maximum temperature. In this report, we use a base of 50°F and a cap of 86°F.

Based on growing degree days alone, the first spring blooms in Ketchum should appear around May 16, only rarely appearing before May 2 or after June 5.

Growing Degree Days

Growing Degree Days in KetchumJanFebMarAprMayJunJulAugSepOctNovDec0°F200°F400°F600°F800°F1,000°F1,200°F1,400°F1,600°FMay 1690°FMay 1690°FAug 5900°FAug 5900°FDec 311,468°FDec 311,468°FNowNow
The average growing degree days accumulated over the course of the year, with 25th to 75th and 10th to 90th percentile bands.

Solar Energy

This section discusses the total daily incident shortwave solar energy reaching the surface of the ground over a wide area, taking full account of seasonal variations in the length of the day, the elevation of the Sun above the horizon, and absorption by clouds and other atmospheric constituents. Shortwave radiation includes visible light and ultraviolet radiation.

The average daily incident shortwave solar energy experiences extreme seasonal variation over the course of the year.

The brighter period of the year lasts for 3.0 months, from May 19 to August 17, with an average daily incident shortwave energy per square meter above 7.0 kWh. The brightest day of the year is July 1, with an average of 8.3 kWh.

The darker period of the year lasts for 3.4 months, from October 28 to February 11, with an average daily incident shortwave energy per square meter below 3.2 kWh. The darkest day of the year is December 18, with an average of 1.9 kWh.

Average Daily Incident Shortwave Solar Energy

Average Daily Incident Shortwave Solar Energy in KetchumbrightdarkdarkJanFebMarAprMayJunJulAugSepOctNovDec0 kWh1 kWh2 kWh3 kWh4 kWh5 kWh6 kWh7 kWh8 kWh9 kWh10 kWhJul 18.3 kWhJul 18.3 kWhDec 181.9 kWhDec 181.9 kWhMay 197.0 kWhMay 197.0 kWhAug 177.0 kWhAug 177.0 kWhOct 283.2 kWhOct 283.2 kWhFeb 113.2 kWhFeb 113.2 kWhNowNow
The average daily shortwave solar energy reaching the ground per square meter (orange line), with 25th to 75th and 10th to 90th percentile bands.

Topography

For the purposes of this report, the geographical coordinates of Ketchum are 43.681 deg latitude, -114.364 deg longitude, and 6,257 ft elevation.

The topography within 2 miles of Ketchum contains large variations in elevation, with a maximum elevation change of 2,415 feet and an average elevation above sea level of 6,213 feet. Within 10 miles contains large variations in elevation (5,039 feet). Within 50 miles also contains extreme variations in elevation (8,950 feet).

The area within 2 miles of Ketchum is covered by shrubs (79%), within 10 miles by shrubs (55%) and sparse vegetation (26%), and within 50 miles by shrubs (65%).

Data Sources

This report illustrates the typical weather in Ketchum, based on a statistical analysis of historical hourly weather reports and model reconstructions from January 1, 1980 to December 31, 2016.

Temperature and Dew Point

There are 3 weather stations near enough to contribute to our estimation of the temperature and dew point in Ketchum.

For each station, the records are corrected for the elevation difference between that station and Ketchum according to the International Standard Atmosphere , and by the relative change present in the MERRA-2 satellite-era reanalysis between the two locations.

The estimated value at Ketchum is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Ketchum and a given station.

The stations contributing to this reconstruction are: Friedman Memorial Airport (64%, 21 kilometers, south); Stanley, Stanley Ranger Station (23%, 71 kilometers, northwest); and Challis Airport (13%, 95 kilometers, north).

Other Data

All data relating to the Sun's position (e.g., sunrise and sunset) are computed using astronomical formulas from the book, Astronomical Algorithms 2nd Edition , by Jean Meeus.

All other weather data, including cloud cover, precipitation, wind speed and direction, and solar flux, come from NASA's MERRA-2 Modern-Era Retrospective Analysis . This reanalysis combines a variety of wide-area measurements in a state-of-the-art global meteorological model to reconstruct the hourly history of weather throughout the world on a 50-kilometer grid.

Land Use data comes from the Global Land Cover SHARE database , published by the Food and Agriculture Organization of the United Nations.

Elevation data comes from the Shuttle Radar Topography Mission (SRTM) , published by NASA's Jet Propulsion Laboratory.

Names, locations, and time zones of places and some airports come from the GeoNames Geographical Database .

Time zones for aiports and weather stations are provided by AskGeo.com .

Maps are © Esri, with data from National Geographic, Esri, DeLorme, NAVTEQ, UNEP-WCMC, USGS, NASA, ESA, METI, NRCAN, GEBCO, NOAA, and iPC.

Disclaimer

The information on this site is provided as is, without any assurances as to its accuracy or suitability for any purpose. Weather data is prone to errors, outages, and other defects. We assume no responsibility for any decisions made on the basis of the content presented on this site.

We draw particular cautious attention to our reliance on the MERRA-2 model-based reconstructions for a number of important data series. While having the tremendous advantages of temporal and spatial completeness, these reconstructions: (1) are based on computer models that may have model-based errors, (2) are coarsely sampled on a 50 km grid and are therefore unable to reconstruct the local variations of many microclimates, and (3) have particular difficulty with the weather in some coastal areas, especially small islands.

We further caution that our travel scores are only as good as the data that underpin them, that weather conditions at any given location and time are unpredictable and variable, and that the definition of the scores reflects a particular set of preferences that may not agree with those of any particular reader.