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Average Weather in Sisters Oregon, United States

In Sisters, the summers are short, warm, dry, and mostly clear and the winters are chilly, wet, and partly cloudy. Over the course of the year, the temperature typically varies from 25°F to 83°F and is rarely below 13°F or above 92°F.

The warm season lasts for 2.7 months, from June 24 to September 14, with an average daily high temperature above 74°F. The hottest day of the year is August 4, with an average high of 83°F and low of 51°F.

The cold season lasts for 3.6 months, from November 12 to March 1, with an average daily high temperature below 49°F. The coldest day of the year is December 23, with an average low of 25°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 in Sisters12 AM4 AM8 AM12 PM4 PM8 PM12 AMJanFebMarAprMayJunJulAugSepOctNovDecfreezingchillycoldcoolcomfortablewarm
The average hourly temperature, color coded into bands: frigid < 15°F < freezing < 32°F < chilly < 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.

Clouds

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

The clearer part of the year in Sisters begins around June 15 and lasts for 3.7 months, ending around October 5. On July 28, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 84% of the time, and overcast or mostly cloudy 16% of the time.

The cloudier part of the year begins around October 5 and lasts for 8.3 months, ending around June 15. On January 16, the cloudiest day of the year, the sky is overcast or mostly cloudy 67% of the time, and clear, mostly clear, or partly cloudy 34% of the time.

Cloud Cover

Cloud Cover in Sistersclearercloudiercloudier0%10%20%30%40%50%60%70%80%90%100%JanFebMarAprMayJunJulAugSepOctNovDecJan 1667%Jan 1667%Jul 2816%Jul 2816%Jun 1541%Jun 1541%Oct 542%Oct 542%overcastmostly cloudypartly cloudymostly clearclear
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 in Sisters varies significantly throughout the year.

The wetter season lasts 6.6 months, from October 19 to May 8, with a greater than 27% chance of a given day being a wet day. The chance of a wet day peaks at 49% on November 30.

The drier season lasts 5.4 months, from May 8 to October 19. The smallest chance of a wet day is 5% on August 5.

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 throughout the year is rain alone, with a peak probability of 38% on November 10.

Daily Chance of Precipitation

Daily Chance of Precipitation in Sisterswetwetdry0%10%20%30%40%50%60%70%80%90%100%JanFebMarAprMayJunJulAugSepOctNovDecNov 3049%Nov 3049%Aug 55%Aug 55%Oct 1927%Oct 1927%May 827%May 827%snowmixedrain
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. Sisters experiences extreme seasonal variation in monthly rainfall.

The rainy period of the year lasts for 10 months, from August 31 to July 8, with a sliding 31-day rainfall of at least 0.5 inches. The most rain falls during the 31 days centered around November 25, with an average total accumulation of 4.3 inches.

The rainless period of the year lasts for 1.7 months, from July 8 to August 31. The least rain falls around August 3, with an average total accumulation of 0.3 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. Sisters experiences some seasonal variation in monthly liquid-equivalent snowfall.

The snowy period of the year lasts for 5.2 months, from October 26 to April 2, 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 24, with an average total liquid-equivalent accumulation of 0.8 inches.

The snowless period of the year lasts for 6.8 months, from April 2 to October 26. The least snow falls around July 24, with an average total liquid-equivalent accumulation of 0.0 inches.

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 in Sisters varies significantly over the course of the year. In 2017, the shortest day is December 21, with 8 hours, 51 minutes of daylight; the longest day is June 21, with 15 hours, 32 minutes of daylight.

Hours of Daylight and Twilight

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 5:21 AM on June 14, and the latest sunrise is 2 hours, 26 minutes later at 7:47 AM on November 4. The earliest sunset is at 4:27 PM on December 9, and the latest sunset is 4 hours, 27 minutes later at 8:54 PM on June 26.

Daylight saving time (DST) is observed in Sisters 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 in Sisters12 AM2 AM4 AM6 AM8 AM10 AM12 PM2 PM4 PM6 PM8 PM10 PM12 AMJanFebMarAprMayJunJulAugSepOctNovDecJun 145:21 AMJun 145:21 AM8:54 PMJun 268:54 PMJun 26Dec 94:27 PMDec 94:27 PM7:47 AMNov 47:47 AMNov 4Mar 12DSTMar 12DSTDSTNov 5DSTNov 5daynightnightnightnight
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 in Sisters, 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 Sisters0%10%20%30%40%50%60%70%80%90%100%JanFebMarAprMayJunJulAugSepOctNovDecFeb 270%Feb 270%Aug 290%Aug 290%drydrycomfortablecomfortable
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 in Sisters experiences mild seasonal variation over the course of the year.

The windier part of the year lasts for 6.8 months, from October 23 to May 17, with average wind speeds of more than 3.0 miles per hour. The windiest day of the year is December 3, with an average hourly wind speed of 3.6 miles per hour.

The calmer time of year lasts for 5.2 months, from May 17 to October 23. The calmest day of the year is August 10, with an average hourly wind speed of 2.4 miles per hour.

Average Wind Speed

Average Wind Speed in Sisterswindywindy0.0 mph0.5 mph1.0 mph1.5 mph2.0 mph2.5 mph3.0 mph3.5 mph4.0 mph4.5 mph5.0 mph5.5 mph6.0 mphJanFebMarAprMayJunJulAugSepOctNovDecDec 33.6 mphDec 33.6 mphAug 102.4 mphAug 102.4 mphOct 233.0 mphOct 233.0 mphMay 173.0 mphMay 173.0 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 in Sisters varies throughout the year.

The wind is most often from the west for 7.7 months, from March 2 to October 25, with a peak percentage of 62% on June 8. The wind is most often from the south for 4.3 months, from October 25 to March 2, with a peak percentage of 55% on January 1.

Wind Direction

Wind Direction in SistersSWS0%20%40%60%80%100%JanFebMarAprMayJunJulAugSepOctNovDecwestsoutheastnorth
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).

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 3.2 months, from May 18 to August 25, with an average daily incident shortwave energy per square meter above 6.5 kWh. The brightest day of the year is July 14, with an average of 7.8 kWh.

The darker period of the year lasts for 3.7 months, from October 27 to February 18, with an average daily incident shortwave energy per square meter below 2.7 kWh. The darkest day of the year is December 15, with an average of 1.4 kWh.

Average Daily Incident Shortwave Solar Energy

Average Daily Incident Shortwave Solar Energy in Sistersbrightdarkdark0 kWh1 kWh2 kWh3 kWh4 kWh5 kWh6 kWh7 kWh8 kWh9 kWh10 kWhJanFebMarAprMayJunJulAugSepOctNovDecJul 147.8 kWhJul 147.8 kWhDec 151.4 kWhDec 151.4 kWhMay 186.6 kWhMay 186.6 kWhAug 256.5 kWhAug 256.5 kWhOct 272.7 kWhOct 272.7 kWhFeb 182.7 kWhFeb 182.7 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.

Topography

For the purposes of this report, the geographical coordinates of Sisters are 44.291 deg latitude, -121.549 deg longitude, and 3,205 ft elevation.

The topography within 2 miles of Sisters contains only modest variations in elevation, with a maximum elevation change of 305 feet and an average elevation above sea level of 3,201 feet. Within 10 miles contains only modest variations in elevation (4,541 feet). Within 50 miles also contains extreme variations in elevation (9,642 feet).

The area within 2 miles of Sisters is covered by shrubs (81%) and trees (11%), within 10 miles by shrubs (57%) and trees (42%), and within 50 miles by shrubs (48%) and trees (46%).

Data Sources

This report illustrates the typical weather in Sisters, 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 6 weather stations near enough to contribute to our estimation of the temperature and dew point in Sisters.

For each station, the records are corrected for the elevation difference between that station and Sisters 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 Sisters is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Sisters and a given station.

The stations contributing to this reconstruction are: Roberts Field-Redmond Municipal Airport (45%, 33 kilometers, east); Bend Municipal Airport (39%, 35 kilometers, southeast); McNary Field (4.1%, 134 kilometers, northwest); Mahlon Sweet Field Airport (4.2%, 135 kilometers, west); Corvallis Municipal Airport (4.0%, 140 kilometers, west); and The Dalles Municipal Airport (3.7%, 151 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 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.