Average Weather in December in Heppner Oregon, United States
Daily high temperatures decrease by 4°F, from 41°F to 37°F, rarely falling below 24°F or exceeding 52°F. The lowest daily average high temperature is 37°F on December 29.
Daily low temperatures decrease by 3°F, from 29°F to 26°F, rarely falling below 13°F or exceeding 40°F. The lowest daily average low temperature is 26°F on December 23.
For reference, on July 31, the hottest day of the year, temperatures in Heppner typically range from 56°F to 87°F, while on December 23, the coldest day of the year, they range from 26°F to 37°F.
Average High and Low Temperature in December
The figure below shows you a compact characterization of the hourly average temperatures for the quarter of the year centered on December. The horizontal axis is the day, 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 December
Las Navas del Marqués, Spain (5,282 miles away); Sarajevo, Bosnia & Herzegovina (5,761 miles); and Aydıncık, Turkey (6,336 miles) are the far-away foreign places with temperatures most similar to Heppner (view comparison).
The month of December in Heppner experiences essentially constant cloud cover, with the percentage of time that the sky is overcast or mostly cloudy remaining about 62% throughout the month.
The clearest day of the month is December 17, with clear, mostly clear, or partly cloudy conditions 39% of the time.
For reference, on January 16, the cloudiest day of the year, the chance of overcast or mostly cloudy conditions is 64%, while on July 29, the clearest day of the year, the chance of clear, mostly clear, or partly cloudy skies is 84%.
Cloud Cover Categories in December
A wet day is one with at least 0.04 inches of liquid or liquid-equivalent precipitation. In Heppner, the chance of a wet day over the course of December is gradually decreasing, starting the month at 24% and ending it at 21%.
For reference, the year's highest daily chance of a wet day is 24% on November 28, and its lowest chance is 5% on August 5.
Over the course of December in Heppner, the chance of a day with only rain decreases from 18% to 13%, the chance of a day with mixed snow and rain remains an essentially constant 3% throughout, and the chance of a day with only snow remains an essentially constant 4% throughout.
Probability of Precipitation in December
The average sliding 31-day rainfall during December in Heppner is essentially constant, remaining about 0.9 inches throughout, and rarely exceeding 1.9 inches or falling below 0.1 inches.
Average Monthly Rainfall in December
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. As with rainfall, we consider the liquid-equivalent snowfall accumulated over a sliding 31-day period centered around each day.
The average sliding 31-day liquid-equivalent snowfall during December in Heppner is essentially constant, remaining about 0.3 inches throughout, and rarely exceeding 0.9 inches or falling to 0.0 inches.
The highest average 31-day liquid-equivalent accumulation is 0.3 inches on December 30.
Average Monthly Liquid-Equivalent Snowfall in December
Over the course of December in Heppner, the length of the day is essentially constant. The shortest day of the month is December 21, with 8 hours, 43 minutes of daylight and the longest day is December 1, with 8 hours, 59 minutes of daylight.
Hours of Daylight and Twilight in December
The earliest sunrise of the month in Heppner is 7:17 AM on December 1 and the latest sunrise is 20 minutes later at 7:37 AM on December 31.
The earliest sunset is 4:15 PM on December 10 and the latest sunset is 10 minutes later at 4:25 PM on December 31.
Daylight saving time is observed in Heppner during 2018, but it neither starts nor ends during December, so the entire month is in standard time.
For reference, on June 21, the longest day of the year, the Sun rises at 5:10 AM and sets 15 hours, 40 minutes later, at 8:50 PM, while on December 21, the shortest day of the year, it rises at 7:34 AM and sets 8 hours, 43 minutes later, at 4:18 PM.
Sunrise & Sunset with Twilight and Daylight Saving Time in December
The chance that a given day will be muggy in Heppner is essentially constant during December, remaining around 0% throughout.
For reference, on August 24, the muggiest day of the year, there are muggy conditions 0% of the time, while on January 1, the least muggy day of the year, there are muggy conditions 0% of the time.
Humidity Comfort Levels in December
The average hourly wind speed in Heppner is gradually decreasing during December, decreasing from 10.0 miles per hour to 9.4 miles per hour over the course of the month.
For reference, on December 1, the windiest day of the year, the daily average wind speed is 10.0 miles per hour, while on September 9, the calmest day of the year, the daily average wind speed is 7.4 miles per hour.
The highest daily average wind speed during December is 10.0 miles per hour on December 1.
Average Wind Speed in December
Wind Direction in December
The growing season in Heppner typically lasts for 5.5 months (167 days), from around April 29 to around October 13, rarely starting before April 6 or after May 19, and rarely ending before September 23 or after November 1.
The month of December in Heppner is reliably fully outside of the growing season.
Time Spent in Various Temperature Bands and the Growing Season in December
The average accumulated growing degree days in Heppner are essentially constant during December, remaining within 1°F of 2,332°F throughout.
Growing Degree Days in December
The average daily incident shortwave solar energy in Heppner is essentially constant during December, remaining within 0.1 kWh of 1.4 kWh throughout.
The lowest average daily incident shortwave solar energy during December is 1.3 kWh on December 26.
Average Daily Incident Shortwave Solar Energy in December
For the purposes of this report, the geographical coordinates of Heppner are 45.353 deg latitude, -119.558 deg longitude, and 2,425 ft elevation.
The topography within 2 miles of Heppner contains very significant variations in elevation, with a maximum elevation change of 951 feet and an average elevation above sea level of 2,291 feet. Within 10 miles contains very significant variations in elevation (2,598 feet). Within 50 miles contains large variations in elevation (6,010 feet).
The area within 2 miles of Heppner is covered by shrubs (91%), within 10 miles by shrubs (78%) and grassland (17%), and within 50 miles by shrubs (71%) and cropland (15%).
This report illustrates the typical weather in Heppner year round, 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 5 weather stations near enough to contribute to our estimation of the temperature and dew point in Heppner.
For each station, the records are corrected for the elevation difference between that station and Heppner 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 Heppner is computed as the weighted average of the individual contributions from each station, with weights proportional to the inverse of the distance between Heppner and a given station.
The stations contributing to this reconstruction are: Hermiston Municipal Airport (30%, 57 kilometers, northeast); Eastern Oregon Regional Airport (34%, 67 kilometers, northeast); John Day State Airport (16%, 116 kilometers, southeast); The Dalles Municipal Airport (12%, 129 kilometers, west); and Roberts Field-Redmond Municipal Airport (9%, 175 kilometers, southwest).
Time zones for aiports and weather stations are provided by AskGeo.com .