Ag Weather Forum              06/10 09:48

   Past 10 Months Were Driest in Almost 50 Years in Contiguous US

   Late summer 2025 through spring 2026 was the sixth driest on record in the 
Lower 48 states.

Bryce Anderson
Ag Meteorologist Emeritus

   The past 10-month period in the Lower 48 U.S. states has been remarkable for 
dryness. In fact, it's been so dry that August 2025 through May 2026 now ranks 
as the sixth driest such period on record for the contiguous United States. 
This analysis is featured in the USDA Weekly Weather and Crop Bulletin posted 
June 9 for the week of May 31-June 6.

   The report noted that, "Across the contiguous United States, August-May 
precipitation averaged just 20.78 inches, well below the 20th century mean of 
24.23 inches. It was the nation's driest August-May period since 1976-77, when 
an average of 20.20 inches fell." This dryness landed easily in the Top 10 
despite near-normal precipitation in the Lower 48 states during May 2026.

   Historically, the first half of the 20th century featured a cluster of dry 
August-to-May periods. The driest August-through-May period on record is 
1917-18, with 19.97 inches. This dry stretch is closely followed by 1933-34, 
with 20 inches from August through May. The 1976-77 period is third driest with 
its 20.20 inches. Then we find 1930-31 fourth with 20.23 inches, and 1924-25 in 
fifth place with 20.30 inches precipitation. The first half of the 20th century 
certainly had chronic dryness.

   That extensive and lingering dryness has made a sizeable impact on the U.S. 
Drought Monitor. The USDA analysis noted that "drought coverage -- as reported 
by the U.S. Drought Monitor -- topped 60% of the area of the Lower 48 States 
each week from April 7 to May 26, 2026."

   The impact of dryness was made even worse by record-setting high 
temperatures for the contiguous U.S. The USDA report noted that the U.S. 
August-May period was by far the warmest such period on record. "Across the 
Lower 48 States, the August 2025-May 2026 average temperature of 52.38 (degrees 
Fahrenheit) was 4.16 degrees F above the 1901-2000 mean value of 48.22 F," the 
report said. "Prior to 2025-2026, the warmest August-May period had occurred in 
2011-12, with an average temperature of 51.74 F."

   This dry 10-month time frame's positioning in the history ledger of 
contiguous U.S. is also a culmination of significant smaller periods of dryness 
during the past 10 months. And, as we have seen with such occurrences as 
record-level rangeland fires and winter wheat crop loss, the consequences of 
such a period of dryness and warmth can be extreme.

   The full U.S. Weekly Weather and Crop Bulletin is available here: 
https://www.usda.gov/sites/default/files/documents/wwcb.pdf

   Bryce Anderson can be reached at bryce.anderson@dtn.com




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