If you’ve been growing a backyard garden, you already know 2017 has been a productive summer for Central Oregon.
Still in the midst of one of its warmest summers ever, Bend has not seen the temperature hit the freezing mark since May 18, 117 days ago. According to records going back to 1911 maintained by the National Weather Service, 2017 is only the seventh year June, July and August have been entirely frost-free in Bend.
The current streak is not the longest Bend has gone without a freezing day, but it’s getting there. The current stretch above 32 degrees is now the sixth-longest on record. The longest period above freezing in Bend came in 2015, lasting 139 days between May 10 and Sept. 27.
Amy Jo Detweiler with the OSU Extension Service in Redmond said although an unexpected freeze is the worst thing that can happen to tender plants, cooler but above-freezing nights still stunt their growth.
That hasn’t been much of a problem in Central Oregon this year — last month was the hottest August ever recorded in Bend, and July 2017 tied as the fourth-warmest July recorded.
“The advantage, of course, is that people can have more harvests than they typically would get,” she said. “We are seeing some plants that are more vigorous this season, and plants mature quicker, too, because we haven’t had the colder evening temperatures that slow down plant growth at night.”
Detweiler said warm nights have been a boon for tomatoes, winter squashes and other cold-sensitive plants favored by local gardeners. Watermelons have been thriving at the extension service demonstration garden, she said. The watermelon is a notoriously hard plant to grow under typical Central Oregon conditions.
A hot summer comes with trade-offs for gardeners and farmers, Detweiler said. Water use increases with heat, and many plants don’t do so well once temperatures get past 90 degrees or so.
There have been a handful of absurdly short growing seasons in Bend in past decades, none more so than in 1955. That year, the temperature dipped to freezing or below seven times in July, and the longest frost-free stretch was the 36 days between Aug. 13 and Sept. 19.
Rob Brooks, forecaster with the National Weather Service in Pendleton, said although cooler air is moving into the region later this week, Bend appears to be on track to stay above the freezing mark through the weekend. Temperatures are forecast to hit 40 degrees early Friday morning.
The National Weather Service forecast calls for slightly warmer weather in Central Oregon over the next week than some other forecasts available to the public. Brooks said forecasters generally work from the same set of observations but will draw different conclusions from the same data.
The longer-term National Weather Service forecast suggests there’s a 70 to 80 percent chance of a warmer-than-average September for most of Eastern Oregon and Washington.
If Bend breaks the 139-days-without-a-freeze record this year, it will happen Oct. 5. The latest first freeze measured in the city came in 2014, when Bend stayed above freezing until Nov. 1.
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