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Average Weather at Sibley Peak Wyoming, United States

At Sibley Peak, the summers are hot and mostly clear; the winters are very cold, windy, and partly cloudy; and it is dry year round. Over the course of the year, the temperature typically varies from 18°F to 90°F and is rarely below -0°F or above 98°F.

Climate Summary

very coldcoldcoolwarmhotwarmcoolcoldJanFebMarAprMayJunJulAugSepOctNovDec76%76%48%48%clearovercastprecipitation: 2.1 inprecipitation: 2.1 in0.2 in0.2 inmuggy: 0%muggy: 0%0%0%drydrytourism score: 7.1tourism score: 7.10.10.1
Click on each chart for more information.

Based on the tourism score, the best time of year to visit Sibley Peak for warm-weather activities is from late June to late August.

Temperature

The hot season lasts for 3.0 months, from June 13 to September 12, with an average daily high temperature above 80°F. The hottest day of the year is July 25, with an average high of 90°F and low of 61°F.

The cold season lasts for 3.6 months, from November 17 to March 6, with an average daily high temperature below 50°F. The coldest day of the year is January 1, with an average low of 18°F and high of 40°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 at Sibley PeakJanFebMarAprMayJunJulAugSepOctNovDec12 AM4 AM8 AM12 PM4 PM8 PM12 AMfreezingfreezingfreezingvery coldvery coldcoldcoldcoolwarmhotcomfortablecomfortablefreezing
The average hourly temperature, color coded into bands: 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 shaded overlays indicate night and civil twilight.

Balışeyh, Turkey (6,195 miles away) and Takāb, Iran (6,720 miles) are the far-away foreign places with temperatures most similar to Sibley Peak (view comparison).

Clouds

At Sibley Peak, 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 at Sibley Peak begins around June 6 and lasts for 4.2 months, ending around October 13. On July 4, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 76% of the time, and overcast or mostly cloudy 24% of the time.

The cloudier part of the year begins around October 13 and lasts for 7.8 months, ending around June 6. On March 28, the cloudiest day of the year, the sky is overcast or mostly cloudy 52% of the time, and clear, mostly clear, or partly cloudy 48% of the time.

Cloud Cover Categories

Cloud Cover Categories at Sibley PeakclearercloudiercloudierJanFebMarAprMayJunJulAugSepOctNovDec0%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%Jul 476%Jul 476%Mar 2848%Mar 2848%Jun 662%Jun 662%Oct 1363%Oct 1363%clearmostly clearovercastpartly cloudymostly cloudy
The percentage of time spent in each cloud cover band, categorized by the percentage of the sky covered by clouds: clear < 20% < mostly clear < 40% < partly cloudy < 60% < mostly cloudy < 80% < overcast.

Precipitation

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

The wetter season lasts 4.1 months, from April 11 to August 14, with a greater than 18% chance of a given day being a wet day. The chance of a wet day peaks at 32% on May 24.

The drier season lasts 7.9 months, from August 14 to April 11. The smallest chance of a wet day is 4% on January 14.

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 at Sibley Peak changes throughout the year.

Rain alone is the most common for 9.3 months, from February 19 to November 29. The highest chance of a day with rain alone is 31% on May 25.

Snow alone is the most common for 2.7 months, from November 29 to February 19. The highest chance of a day with snow alone is 3% on December 14.

Daily Chance of Precipitation

Daily Chance of Precipitation at Sibley PeaksnowrainsnowJanFebMarAprMayJunJulAugSepOctNovDec0%10%20%30%40%50%60%70%80%90%100%May 2432%May 2432%Jan 144%Jan 144%Feb 197%Feb 197%Nov 295%Nov 295%Apr 1118%Apr 1118%Aug 1418%Aug 1418%rainmixedsnow
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. Sibley Peak experiences significant seasonal variation in monthly rainfall.

The rainy period of the year lasts for 7.3 months, from March 25 to November 3, 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 2.1 inches.

The rainless period of the year lasts for 4.7 months, from November 3 to March 25. The least rain falls around January 2, 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

The sliding 31-day liquid-equivalent quantity of snowfall at Sibley Peak does not vary significantly over the course of the year, staying within 0.1 inches of 0.1 inches throughout.

Average Liquid-Equivalent Monthly Snowfall

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 at Sibley Peak varies significantly over the course of the year. In 2017, the shortest day is December 21, with 9 hours, 4 minutes of daylight; the longest day is June 20, with 15 hours, 18 minutes of daylight.

Hours of Daylight and Twilight

Hours of Daylight and Twilight at Sibley PeakJanFebMarAprMayJunJulAugSepOctNovDec0 hr24 hr4 hr20 hr8 hr16 hr12 hr12 hr16 hr8 hr20 hr4 hr24 hr0 hr12 hr, 7 minMar 2012 hr, 7 minMar 2015 hr, 18 minJun 2015 hr, 18 minJun 2012 hr, 9 minSep 2212 hr, 9 minSep 229 hr, 4 minDec 219 hr, 4 minDec 21nightnightday
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 5:22 AM on June 14, and the latest sunrise is 2 hours, 15 minutes later at 7:37 AM on November 4. The earliest sunset is at 4:27 PM on December 9, and the latest sunset is 4 hours, 14 minutes later at 8:41 PM on June 26.

Daylight saving time (DST) is observed at Sibley Peak during 2017, starting in the spring on March 12, lasting 7.8 months, and ending in the fall on November 5.

Sunrise & Sunset with Twilight and Daylight Saving Time

Sunrise & Sunset with Twilight and Daylight Saving Time at Sibley PeakJanFebMarAprMayJunJulAugSepOctNovDec12 AM2 AM4 AM6 AM8 AM10 AM12 PM2 PM4 PM6 PM8 PM10 PM12 AMJun 145:22 AMJun 145:22 AM8:41 PMJun 268:41 PMJun 26Dec 94:27 PMDec 94:27 PM7:37 AMNov 47:37 AMNov 4Mar 12DSTMar 12DSTDSTNov 5DSTNov 5daynightnightnightnightSolarMidnightSolarMidnightSolarNoonSunriseSunset
The solar day over the course of the year 2017. 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 at Sibley Peak, 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 at Sibley PeakJanFebMarAprMayJunJulAugSepOctNovDec0%10%20%30%40%50%60%70%80%90%100%Mar 250%Mar 250%Aug 20%Aug 20%drydryhumidhumid
The percentage of time spent at various humidity comfort levels, categorized by dew point: dry < 55°F < comfortable < 60°F < humid < 65°F < muggy < 70°F < oppressive < 75°F < miserable.

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 at Sibley Peak experiences significant seasonal variation over the course of the year.

The windier part of the year lasts for 5.5 months, from October 30 to April 14, with average wind speeds of more than 12.4 miles per hour. The windiest day of the year is January 17, with an average hourly wind speed of 16.0 miles per hour.

The calmer time of year lasts for 6.5 months, from April 14 to October 30. The calmest day of the year is July 26, with an average hourly wind speed of 8.8 miles per hour.

Average Wind Speed

Average Wind Speed at Sibley PeakwindywindyJanFebMarAprMayJunJulAugSepOctNovDec0 mph2 mph4 mph6 mph8 mph10 mph12 mph14 mph16 mph18 mph20 mph22 mph24 mphJan 1716.0 mphJan 1716.0 mphJul 268.8 mphJul 268.8 mphOct 3012.4 mphOct 3012.4 mphApr 1412.4 mphApr 1412.4 mph
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 at Sibley Peak is from the west throughout the year.

Wind Direction

Wind Direction at Sibley PeakJanFebMarAprMayJunJulAugSepOctNovDec0%100%20%80%40%60%60%40%80%20%100%0%westsouthnortheast
The percentage of hours in which the mean wind direction is from each of the four cardinal wind directions (north, east, south, and west), excluding hours in which the mean wind speed is less than 1 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 at Sibley Peak 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 Sibley Peak for general outdoor tourist activities is from late June to late August, with a peak score in the second week of July.

Tourism Score

Tourism Score at Sibley Peakbest timeJanFebMarAprMayJunJulAugSepOctNovDec02468107.17.10.10.1 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 Sibley Peak 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 at Sibley Peakbest timeJanFebMarAprMayJunJulAugSepOctNovDec02468105.05.00.00.0 precipitationprecipitationcloudscloudstemperaturetemperaturebeach/pool score
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 at Sibley Peak typically lasts for 5.1 months (155 days), from around May 5 to around October 7, rarely starting before April 14 or after May 22, and rarely ending before September 18 or after October 27.

Time Spent in Various Temperature Bands and the Growing Season

Time Spent in Various Temperature Bands and the Growing Season at Sibley Peakgrowing seasonJanFebMarAprMayJunJulAugSepOctNovDec0%100%10%90%20%80%30%70%40%60%50%50%60%40%70%30%80%20%90%10%100%0%May 550%May 550%Oct 750%Oct 750%May 2290%May 2290%Sep 1890%Sep 1890%Apr 1410%Apr 1410%Oct 2710%Oct 2710%0%Feb 100%Feb 10Jul 17100%Jul 17100%freezingvery coldcoldcoolcomfortablewarmhotfrigid
The percentage of time spent in various temperature bands: 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 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 at Sibley Peak should appear around April 10, only rarely appearing before March 25 or after April 28.

Growing Degree Days

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 12 to August 13, with an average daily incident shortwave energy per square meter above 6.8 kWh. The brightest day of the year is July 3, with an average of 7.9 kWh.

The darker period of the year lasts for 3.4 months, from October 30 to February 12, with an average daily incident shortwave energy per square meter below 3.2 kWh. The darkest day of the year is December 21, with an average of 2.0 kWh.

Average Daily Incident Shortwave Solar Energy

Average Daily Incident Shortwave Solar Energy at Sibley PeakbrightdarkdarkJanFebMarAprMayJunJulAugSepOctNovDec0 kWh1 kWh2 kWh3 kWh4 kWh5 kWh6 kWh7 kWh8 kWh9 kWh10 kWhJul 37.9 kWhJul 37.9 kWhDec 212.0 kWhDec 212.0 kWhMay 126.8 kWhMay 126.8 kWhAug 136.8 kWhAug 136.8 kWhOct 303.2 kWhOct 303.2 kWhFeb 123.2 kWhFeb 123.2 kWh
The average daily shortwave solar energy reaching the ground per square meter (orange line), with 25th to 75th and 10th to 90th percentile bands.

Data Sources

This report illustrates the typical weather at Sibley Peak, 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

Sibley Peak has a weather station that reported reliably enough during the analysis period that we have included it in our network. When available, historical temperature and dew point measurements are taken directly from this weather station. These records are obtained from NOAA's Integrated Surface Hourly data set, falling back on ICAO METAR records as required.

In the case of missing or erroneous measurements from this station, we fall back on records from nearby stations, adjusted according to typical seasonal and diurnal intra-station differences. For a given day of the year and hour of the day, the fallback station is selected to minimize the prediction error over the years for which there are measurements for both stations.

The stations on which we may fall back include but are not limited to Converse County Airport, Torrington Municipal Airport, Laramie Regional Airport, Cheyenne Airport, Casper–Natrona County International Airport, Western Nebraska Regional Airport, Kimball Municipal Airport-Robert E Arraj Field, and Custer County Airfield.

Other Data

All data relating to the Sun's position (e.g., sunrise and sunset) are computed using astronomical formulas from the book, Astronomical Tables of the Sun, Moon and Planets , 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.