Happy Valley, Oregon, Weather: September 2017

Happy Valley, Oregon, Weather: September 2017

TEMPERATURES: The normal steady monthly decline in temperatures occurred through this September. The Average Maximum/Minimum/Mean Temperatures for Sept 1st-15th vs. 16th-30th were thus: 82.9°/59.1°/71.0° vs. 68.1°/51.8°/60.0°. There were 5 days with Max. Temps. ≥90°, all occurring over the first 11 days of the month. A brief warm-up occurred at month’s end with 2 days reaching ≥80°, otherwise Maximum readings mostly stayed in the 50’s and 60’s over the latter half of the month. As far as Minimum Temperatures, there were 8 consecutive days remaining ≥60° (2nd-9th), the longest such streak since this station was established on May 29, 2014. (These elevated Minimums were likely due to the excessive smoke resulting from the nearby Eagle Creek wildfire, acting like cloud cover.) Five days fell into the 40’s (seven when not rounding values). The greatest diurnal temperature range was 35.8° (11th), the least only 7.1° (18th) during the rainiest period of the month.

Average Monthly Maximum: 75.5°
Average Monthly Minimum: 55.5°
Monthly Mean: 65.5°


Monthly High Maximum: 94.9° (2nd)
Monthly Low Maximum: 58.5° (18th)
Monthly Low Minimum: 46.3° (24th)
Monthly High Minimum: 69.6° (5th)


Number of Days:
Maximums ≥95°: 1
Maximums ≥90°: 5
Maximums ≥80°: 11
Maximums ≥70°: 20
Minimums ≤65°: 29
Minimums ≤60°: 21
Minimums ≤55°: 16
Minimums ≤50°: 10


PRECIPITATION: Though the month had nearly 4 inches of rain, 82% of the total fell from 17th-20th (3.18″). This single event bested my previous September monthly totals back to 2014. In all, 9 days recorded measurable rain (≥0.01″), with 4 of these days reaching ≥0.50″. After only 0.15″ of rain falling from June 17th through Sept. 8th, a period of 84 days, the moisture was more than welcome, helping with numerous wildfires burning here in the Pacific Northwest.

Total Precipitation: 3.90″
Maximum Calendar Day: 0.95″ (18th)


Number of Days:
≥0.01″: 9
≥0.25″: 5
≥0.50″: 4
≥0.75″: 3


MISCELLANEOUS: The month saw 15 clear days, 9 partly cloudy days, and just 6 cloudy days. There were 7 days with Fog but none of these were heavy (<1/4 Mile visibility).


Photo by Jeff Taylor, 9/15/2017 – smoke from Eagle Creek Wildfire in the Columbia River Gorge partially obscuring the rising sun (Mt. Hood in the background).

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