Average Weather in Sisters Oregon, United States
In Sisters, the summers are short, warm, dry, and mostly clear and the winters are very cold, 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.
Based on the tourism score, the best time of year to visit Sisters for warm-weather activities is from mid July to mid August.
The warm season lasts for 2.6 months, from June 25 to September 14, with an average daily high temperature above 75°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 13 to March 1, with an average daily high temperature below 48°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 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
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 4. 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 4 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 Categories
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 6.7 months, from October 19 to May 9, 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 5.3 months, from May 9 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
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 9, 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 9 to August 31. The least rain falls around August 3, with an average total accumulation of 0.3 inches.
Average Monthly Rainfall
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 3, 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 6.7 months, from April 3 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 length of the day in Sisters varies significantly over the course of the year. In 2018, 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 earliest sunrise is at 5:21 AM on June 15, and the latest sunrise is 2 hours, 24 minutes later at 7:46 AM on November 3. 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 2018, starting in the spring on March 11, lasting 7.8 months, and ending in the fall on November 4.
Sunrise & Sunset with Twilight and Daylight Saving Time
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
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 5.6 miles per hour. The windiest day of the year is December 1, with an average hourly wind speed of 6.7 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 9, with an average hourly wind speed of 4.5 miles per hour.
Average Wind Speed
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 60% on June 1. The wind is most often from the south for 4.3 months, from October 25 to March 2, with a peak percentage of 54% on January 1.
Best Time of Year to Visit
To characterize how pleasant the weather is in Sisters 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 Sisters for general outdoor tourist activities is from mid July to mid August, with a peak score in the last week of July.
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 Sisters for hot-weather activities is from mid July to mid August, with a peak score in the first week of August.
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.
The growing season in Sisters typically lasts for 4.0 months (122 days), from around May 28 to around September 26, rarely starting before May 6 or after June 22, and rarely ending before September 9 or after October 15.
Time Spent in Various Temperature Bands and the Growing Season
Based on growing degree days alone, the first spring blooms in Sisters should appear around April 29, only rarely appearing before April 12 or after May 19.
Growing Degree Days
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 24, with an average daily incident shortwave energy per square meter above 6.6 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 3.6 months, from October 28 to February 17, 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
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%).
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).
Time zones for aiports and weather stations are provided by AskGeo.com .