Average Weather in Sunnyside Washington, United States
In Sunnyside, the summers are hot, arid, and mostly clear and the winters are short, very cold, dry, and partly cloudy. Over the course of the year, the temperature typically varies from 26°F to 94°F and is rarely below 13°F or above 103°F.
Based on the tourism score, the best time of year to visit Sunnyside for warm-weather activities is from late June to late August.
The hot season lasts for 3.0 months, from June 12 to September 12, with an average daily high temperature above 82°F. The hottest day of the year is July 30, with an average high of 94°F and low of 62°F.
The cold season lasts for 2.9 months, from November 18 to February 15, with an average daily high temperature below 48°F. The coldest day of the year is December 23, with an average low of 26°F and high of 37°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 Sunnyside, 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 Sunnyside begins around June 6 and lasts for 4.0 months, ending around October 8. On August 4, the clearest day of the year, the sky is clear, mostly clear, or partly cloudy 83% of the time, and overcast or mostly cloudy 17% of the time.
The cloudier part of the year begins around October 8 and lasts for 8.0 months, ending around June 6. On January 16, the cloudiest day of the year, the sky is overcast or mostly cloudy 65% of the time, and clear, mostly clear, or partly cloudy 35% of the time.
Cloud Cover Categories
0% clear 20% mostly clear 40% partly cloudy 60% mostly cloudy 80% overcast 100%
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. The chance of wet days in Sunnyside varies throughout the year.
The wetter season lasts 5.0 months, from October 19 to March 20, with a greater than 13% chance of a given day being a wet day. The chance of a wet day peaks at 23% on December 1.
The drier season lasts 7.0 months, from March 20 to October 19. The smallest chance of a wet day is 2% on August 16.
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 Sunnyside changes throughout the year.
Rain alone is the most common for 12 months, from January 3 to December 26. The highest chance of a day with rain alone is 18% on November 10.
Snow alone is the most common for 1.1 weeks, from December 26 to January 3. The highest chance of a day with snow alone is 8% on January 5.
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. Sunnyside experiences some seasonal variation in monthly rainfall.
The rainy period of the year lasts for 7.8 months, from October 12 to June 6, with a sliding 31-day rainfall of at least 0.5 inches. The most rain falls during the 31 days centered around November 18, with an average total accumulation of 0.9 inches.
The rainless period of the year lasts for 4.2 months, from June 6 to October 12. The least rain falls around August 8, with an average total accumulation of 0.1 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. Sunnyside experiences some seasonal variation in monthly liquid-equivalent snowfall.
The snowy period of the year lasts for 3.2 months, from November 13 to February 20, 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 30, with an average total liquid-equivalent accumulation of 0.5 inches.
The snowless period of the year lasts for 8.8 months, from February 20 to November 13. The least snow falls around July 7, with an average total liquid-equivalent accumulation of 0.0 inches.
Average Liquid-Equivalent Monthly Snowfall
The length of the day in Sunnyside varies significantly over the course of the year. In 2018, the shortest day is December 21, with 8 hours, 36 minutes of daylight; the longest day is June 21, with 15 hours, 48 minutes of daylight.
Hours of Daylight and Twilight
The earliest sunrise is at 5:07 AM on June 15, and the latest sunrise is 2 hours, 37 minutes later at 7:44 AM on November 3. The earliest sunset is at 4:13 PM on December 10, and the latest sunset is 4 hours, 43 minutes later at 8:56 PM on June 26.
Daylight saving time (DST) is observed in Sunnyside 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 Sunnyside, 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
dry 55°F comfortable 60°F humid 65°F muggy 70°F oppressive 75°F miserable
The average hourly wind speed in Sunnyside experiences mild seasonal variation over the course of the year.
The windier part of the year lasts for 5.3 months, from February 4 to July 14, with average wind speeds of more than 8.0 miles per hour. The windiest day of the year is March 31, with an average hourly wind speed of 8.7 miles per hour.
The calmer time of year lasts for 6.6 months, from July 14 to February 4. The calmest day of the year is September 9, with an average hourly wind speed of 7.3 miles per hour.
Average Wind Speed
The predominant average hourly wind direction in Sunnyside varies throughout the year.
The wind is most often from the west for 9.0 months, from February 22 to November 22, with a peak percentage of 71% on June 23. The wind is most often from the north for 3.0 months, from November 22 to February 22, with a peak percentage of 46% on January 1.
Best Time of Year to Visit
To characterize how pleasant the weather is in Sunnyside 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 Sunnyside for general outdoor tourist activities is from late June to late August, with a peak score in the first week of August.
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 Sunnyside 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 Sunnyside typically lasts for 6.2 months (188 days), from around April 13 to around October 19, rarely starting before March 24 or after May 4, and rarely ending before October 1 or after November 5.
Time Spent in Various Temperature Bands and the Growing Season
Based on growing degree days alone, the first spring blooms in Sunnyside should appear around April 2, only rarely appearing before March 23 or after April 13.
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 3.3 months, from May 12 to August 21, with an average daily incident shortwave energy per square meter above 6.5 kWh. The brightest day of the year is July 13, 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 2.6 kWh. The darkest day of the year is December 26, with an average of 1.2 kWh.
Average Daily Incident Shortwave Solar Energy
For the purposes of this report, the geographical coordinates of Sunnyside are 46.324 deg latitude, -120.009 deg longitude, and 778 ft elevation.
The topography within 2 miles of Sunnyside contains only modest variations in elevation, with a maximum elevation change of 308 feet and an average elevation above sea level of 768 feet. Within 10 miles contains only modest variations in elevation (2,116 feet). Within 50 miles contains large variations in elevation (5,597 feet).
The area within 2 miles of Sunnyside is covered by cropland (55%) and artificial surfaces (45%), within 10 miles by cropland (61%) and shrubs (25%), and within 50 miles by shrubs (60%) and cropland (27%).
This report illustrates the typical weather in Sunnyside, 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 4 weather stations near enough to contribute to our estimation of the temperature and dew point in Sunnyside.
For each station, the records are corrected for the elevation difference between that station and Sunnyside 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 Sunnyside is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Sunnyside and a given station.
The stations contributing to this reconstruction are: Hanford (43%, 41 kilometers, northeast); Yakima Air Terminal Airport (32%, 49 kilometers, northwest); Hermiston Municipal Airport (16%, 80 kilometers, southeast); and The Dalles Municipal Airport (9%, 119 kilometers, southwest).
Time zones for aiports and weather stations are provided by AskGeo.com .