Ag Weather Forum

Another Warm One In September

Bryce Anderson
By  Bryce Anderson , DTN Senior Ag Meteorologist
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Much of the western and northern Corn Belt saw temperatures more the 6 degrees Fahrenheit above average in September 2015. (NOAA graphic)

Following are highlights from the NOAA September 2015 State of the Climate report for the U.S. It was definitely a warm one. Note the departure from normal of almost 4 degrees Fahrenheit. That is a HUGE difference.--Bryce

TEMPERATURE

The September contiguous U.S. average temperature was 68.5 degrees F, 3.7 deg F above the 20th century average and the second warmest on record. Only September 1998 was warmer for the Lower 48 with a monthly average temperature of 69.0 deg F.

Record and near-record warmth was observed across most of the country. Thirty states had September temperatures that were much above average and nine states — Connecticut, Colorado, Maine, Michigan, Minnesota, New Mexico, Rhode Island, Utah, and Wisconsin — were record warm.

Near-average September temperatures were observed in the Southeast and in the Northwest. The near-average temperatures in the Northwest were a reprieve from the record warm summer (June-August) and aided firefighters battling the record-breaking wildfires in the region.

Alaska had its 19th coolest September with a statewide average temperature of 38.8 deg F, 1.8 deg F below average.

The September contiguous U.S. maximum (daytime) temperature was 81.3 deg F, 3.5 deg F above average, the fourth-warmest on record. Record warm maximum temperatures were observed in the Central Rockies and New England. Colorado, Wyoming, Maine, Connecticut, Massachusetts, and Rhode Island each had record warm maximum temperatures.

The September contiguous U.S. minimum (nighttime) temperature was 55.8 deg F, 3.9 deg F above average, the second-warmest on record. Only September 1998 had warmer minimum temperatures for the Lower 48. Record warm minimum temperatures were observed in the Northern Plains and Upper Midwest. Nebraska, South Dakota, Minnesota, Wisconsin, and Michigan each had record warm minimum temperatures.

During September, there were 4,506 record warm daily high (1,611) and low (2,895) temperature records, which is about five and a half times the 802 record cold daily high (461) and low (341) temperature records.

Based on NOAA's Residential Energy Demand Temperature Index (REDTI), the contiguous U.S. temperature-related energy demand during September was 80.2 percent above average and the ninth-highest in the 1895-2015 period of record.

PRECIPITATION

The September precipitation total for the contiguous U.S. was 2.09 inches, 0.40 inch below average and the 21st-driest on record.

Above-average precipitation was observed for parts of the Midwest, Mid-Atlantic, and Northeast. Below-average precipitation was observed across the Central Rockies, Southern Plains, and the Lower Mississippi River Valley. Arkansas had its 11th-driest September on record.

The remnants of Hurricane Linda in the northeast Pacific Ocean interacted with an upper-level low-pressure system bringing heavy precipitation to the Southwest on September 14th and 15th. Los Angeles had its third-wettest September on record with 2.39 inches of rainfall, all of which fell on the 15th, 2.15 inches above the monthly average. Flash flooding was observed in southern Utah which killed 13 people in Hildale and another seven in nearby Zion National Park.

Interior and southern Alaska were wetter than average, with Anchorage and Fairbanks observing their wettest September on record with precipitation totals of 7.71 inches and 3.74 inches, respectively. The normal September precipitation is 1.1 inches in Fairbanks and 2.99 inches in Anchorage. Early-season snowfall was also observed in Anchorage and Fairbanks at mid-month, marking the earliest snowfall in over 20 years for those locations. As a whole, Alaska had its 11th-wettest September on record with 5.92 inches of precipitation, 1.35 inches above average.

Record and near-record precipitation was observed across Hawaii. Honolulu observed 4.48 inches of precipitation, surpassing the previous September record set in 1947 by 2.08 inches. The normal September precipitation for Honolulu is 0.70 inch. This was the second-consecutive record wet month for Honolulu.

According to the September 29th U.S. Drought Monitor report, 31.4 percent of the contiguous U.S. was in drought, up about 1.0 percentage point compared to September 1st. Drought conditions improved across parts of the Southwest and Southeast, particularly in South Florida. Drought conditions worsened across parts of the Northeast. In the Southern Plains and Lower Mississippi River Valley, Extreme Drought (D3) expanded due to the warm and dry month. Precipitation was spotty across the West with long-term drought conditions continuing to plague the region.

Outside of the contiguous U.S., drought improved in Alaska which was wetter than average in September. Drought also improved in Hawaii where tropical cyclones passed near the Islands. Drought improved in central Puerto Rico, but Severe and Extreme Drought (D2-D3) continued across the eastern third of the island.

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