Back-to-Back Pacific Storms to Impact the West Coast; Heavy Snow in the Central Appalachians

Back-to-back powerful Pacific storm systems to impact the Pacific Northwest and northern California through the end of this week with heavy rain, flooding, strong winds, and higher elevation mountain snow. A strong, long-duration atmospheric river will accompany the Pacific storms, bringing excessive rainfall and flash flooding to southwest Oregon and northwest California through the week. Read More >

September 2020 finished close to average temperature-wise on a whole across the area. That said, there were some large temperature swings. Namely, a record cold stretch from the 7^th through the 11^th in which many observed their first frost of the season (fairly early climatologically speaking), and a much above average stretch from the 20^th through the 26^th. Very little in the way of precipitation fell, with all locations recording between 0 and 3 inches of below average rainfall, and abnormally dry and/or moderate drought conditions persisted as a result. Thanks to the dry conditions, the James River at Stratford finally fell below flood stage during the early morning of the 30^th, after a record 546 consecutive days which began on April 3^rd, 2019. Several windy days with gusts of 40-60 mph occurred towards the end of the month, which raised fire weather concerns. Smoke from significant California fires drifted aloft across the Northern Plains for many days this September as well, thanks to upper-level winds. There were a couple days where enough smoke made it to the surface to reduce visibility below 6 miles for some, including on the 20^th at Aberdeen and Watertown. Also of note this September, no reports of severe weather were logged. This was the first time since 2011 where our weather forecast office didn’t issue a single convective warning (severe thunderstorm or tornado), and only the 4^th time since 1986.

*September 2020*
Temperature Data	Aberdeen	Sisseton	Wheaton	Watertown
Warmest Temperature / Date	87 / 2, 21, 22^nd	85 / 21, 22^nd	85 / 22^nd	84 / 22^nd
Coldest Temperature / Date	32 / 9, 10^th	32 / 9^th	35 / 9, 10^th	32 / 10^th
Average High / Departure from Normal	74.0 / +1.9	71.9 / -0.3	70.1 / -1.0	70.7 / +0.1
Average Low / Departure from Normal	46.4 / +0.7	46.7 / -0.6	47.8 / +0.2	47.6 / +0.2
Monthly Average / Departure from Normal	60.2 / +1.3	59.3 / -0.4	59.0 / -0.3	59.1 / +0.1
Precipitation Data
Monthly Precipitation / Departure from Normal	1.54 / -0.65	1.05 / -1.49	0.78 / -2.31	1.05 / -1.59
Most Precipitation in 24 hours / Date	0.70 / 7^th	0.72 / 11^th	0.49 / 11^th	0.48 / 7^th
Monthly Snowfall / Departure from Normal	N/A	N/A	N/A	N/A
Most Snow in 24 hours / Date	N/A	N/A	N/A	N/A

Temperature Data	Pierre	Kennebec	Mobridge	Timber Lake
Warmest Temperature / Date	97 / 14^th	94 / 2, 14^th	96 / 2^nd	91 / 2^nd
Coldest Temperature / Date	32 / 10^th	32 / 10^th	31 / 9^th	27 / 9^th
Average High / Departure from Normal	77.8 / +1.3	81.4 / +2.2	76.0 / +2.1	75.7 / +0.7
Average Low / Departure from Normal	48.1 / -1.1	47.7 / -1.6	48.3 / +0.7	46.5 / -0.9
Monthly Average / Departure from Normal	63.0 / +0.1	64.9 / +0.6	62.2 / +1.5	61.3 / +0.1
Precipitation Data
Monthly Precipitation / Departure from Normal	0.29 / -1.58	0.43 / -1.34	1.01 / -0.53	0.82 / -0.62
Most Precipitation in 24 hours / Date	0.17 / 7^th	0.25 / 8^th	0.88 / 7^th	0.74 / 7^th
Monthly Snowfall / Departure from Normal	N/A	N/A	N/A	N/A
Most Snow in 24 hours / Date	N/A	N/A	N/A	N/A

Average September temperature departures from normal, from the Midwestern Regional Climate Center

Total September precipitation (left) and departures from normal (right), from the Midwestern Regional Climate Center

Daily high (top graphic) and low (bottom graphic) temperatures (values) and departures from normal (colors) during September for Aberdeen, Watertown and Pierre