Happy Valley, Oregon Weather: September 2019
TEMPERATURES
Mean Temperatures were slightly below normal this month; Average Maxima were actually noticeably cooler than average (about 4°) but were balanced by milder-than-normal Minima. It was a typical September in that the warmest weather occurred at the beginning and mostly gradually cooled as the month progressed. The month would likely have averaged above normal had it not been for very chilly air invading the last few days. In fact, the Portland Airport (PDX) only made it to 52° on Sept. 29th, not only breaking its daily Low Maximum record of 56°, set in 1971, but also tying the all-time September record (also set on Sept. 26, 1948). Official airport temperature records back to 1938.
Even colder was the official downtown station at KGW-TV that only reached 49°, setting its all-time coldest September Low Maximum, barely surpassing the previous record of 50° from Sept. 23, 1934. This was also the earliest sub-50° reading, besting the former earliest of 49° set October 12, 1881 a full 13 days earlier. This 49° Maximum on Sept. 29, 2019 also broke that date’s former daily Low Maximum record of 54° set in 1971 and 1891. Official Downtown temperature records date back to Nov. 1871
Minimum Temperatures during this unseasonably chilly outbreak were not much lower than the maxima as the overcast skies and associated rain kept temperature fairly equable. The month’s highest diurnal range was 29.6° on the 5th (87.3°/57.7°), the lowest only 2.7° on the chilly 29th (45.3°/42.6°).
PRECIPITATION
It was a very wet September for the area as more than 4 inches of rain was measured, far above the Normal of 1.79″ for this location. What was even more out-of-whack this month were the 17 calendar days with measurable rain (20 days when using the morning observation measurements), hardly feeling much like the end of summer/beginning of Autumn here. The month started off with the usual dry weather as no rain fell through the first 6 days, continuing the dry pattern from August. This was followed by 4 wet days, then two consecutive dry days on the 11th & 12th, the last such days through the end of the month as there was never more than a 1-day break from measurable rain. There was never a huge single-day amount, just an even distribution of the rain after the 6th of the month. The maximum daily amount was 0.74″ (15th), with 3 other days recording ≥0.50″.
≥0.25″: 7
≥0.50″: 4
≥1.00″: 0
MISCELLANEOUS
Sky Cover: August recorded 1 Clear, 18 Partly Cloudy, and 11 Cloudy days.
Barometric Pressure ranged from 30.30″ (24th) to 29.74″ (15th).
Relative Humidity peaked at 100% (8th, 9th, 18th, 23rd), and reached a Minimum of 40% (1st).
Dew Point went from 66° (3rd, 5th, 6th, 13th) to 39° (30th).
HAPPY VALLEY WEATHER FORM: SEPTEMBER 2019
Cover Photo: Towering Cumulus with Rain, looking to the southwest_Sept. 28, 2019 at 1407 Hrs.