NATIONAL WEATHER SUMMARY

SEPTEMBER 2021

Aug. 29-Sep. 4: Hurricane Ida cut a destructive swath from the central Gulf Coast region into the Northeast, spending parts of 5 days (August 29 – September 2) inland. Initially, primary hurricane impacts included high winds and a coastal storm surge, which resulted in extensive damage and power outages across southeastern Louisiana. Once inland, the focus turned to freshwater flooding and heavy rain, which totaled 4 inches or more in eastern Louisiana and parts of Alabama, Mississippi, and western Florida.  

 

In contrast, mostly dry covered the remainder of the country, including the northern Rockies, Far West, upper Great Lakes region, and much of Texas. Weekly temperatures averaged at least 5°F above normal across large sections of the central and southern Plains, promoting summer crop maturation. Elsewhere, nearnormal temperatures prevailed in the Southwest and most areas east of the Mississippi River, while cool air held temperatures as much as 5°F below normal in the Northwest. Late in the week, cooler air spread into the South, although heat and humidity lingered along and near the Gulf Coast. Brief heat in the Far West was knocked down following a cold front’s passage. On August 30, daily-record highs in California’s San Joaquin Valley soared to 108°F in Merced and Madera. Meanwhile, strong thunderstorms sweeping across Montana resulted in a wind gust to 79 mph (on August 30) at Bozeman Airport—a record for that location. Previously, Bozeman’s highest gust (78 mph) had occurred during a thunderstorm on July 30, 1957. Although cooler air soon overspread much of the West, heat persisted across the Deep South. In Texas, daily-record highs included 97°F (on August 30) in Galveston and 105°F (on August 31) in Del Rio. Early to mid-week heat also extended northward across the Plains, where Burlington, CO, posted a daily-record high of 100°F on the last day of August. Meanwhile, New Orleans, LA, endured temperatures ranging from 76 to 93°F during August 30 – September 5, the 7 days after Hurricane Ida hit, amid widespread power outages. In Florida, daily-record highs of the first day of September reached 96°F in Miami and 95°F in Vero Beach. Late in the week, cooler air settling into the Southeast and Northwest resulted in several dailyrecord lows. In Oregon, record-setting lows for September 3 dipped to 27°F in Burns and 32°F in Klamath Falls. The following day in Georgia, lows of 54°F in Augusta and 56°F in Macon were records for September 4.

 

5-11: Hot, dry weather soon returned across the West, limiting the overall impact of the precipitation. In fact, weekly temperatures broadly averaged at least 5°F above normal across the western half of the country—and up to 10°F above normal in parts of California, the Rockies, and the Great Basin. Meanwhile, temperatures averaged as much as 5°F below normal across portions of the interior Southeast, particularly in the Tennessee Valley. Late-summer heat gripped much of the central and western U.S., boosting temperatures to 100°F or higher as far north as California’s Central Valley and the central High Plains. However, the week had begun on a cool note across parts of the Intermountain West, where Randolph, UT, posted a daily-record low of 23°F on September 5. The parade of Western high-temperature records began on September 6, with highs of 104°F in Gilroy, CA, and 96°F in Reno, NV. Reno logged another daily-record high (98°F) on September 7. Elsewhere in Nevada, Winnemucca registered daily-record highs each day (98, 99, 99, and 101°F) from September 6-9. Death Valley, CA, collected consecutive daily-record highs (122 and 120°F, respectively) on September 7-8. In New Mexico, Farmington tallied five consecutive daily-record highs (95, 96, 94, 91, and 91°F) from September 7-11. With a high of 106°F on the 10th, Borger, TX, edged the monthly record of 105°F, originally set on September 5, 1995. A monthly record of 89°F was tied on September 10 in Alamosa, CO. Alamosa again reached 89°F on September 11, tying the record first set on September 5 and 6, 2020, while Colorado Springs, CO, achieved a new September standard (98°F; previously, 97°F on September 6, 2020). Across the High Plains, the week ended on September 10-11 with consecutive triple-digit, daily-record highs in communities such as McCook, NE (102 and 104°F); Goodland, KS (103 and 102°F); and Burlington, CO (101 and 100°F). Dodge City, KS (105°F on the 11th), achieved a 105-degree reading in September for only the third time on record, following 106°F on September 3, 1947, and 107°F on September 1, 2011. Heat also lingered across the Deep South, where Del Rio, TX, noted highs of 100°F or greater on each of the first 10 days in September. Del Rio also reported several daily-record highs, including a reading of 105°F on September 8.

 

12-18:  Scattered showers dotted the nation’s northern tier, from the upper Midwest into the Northeast. The remainder of the nation was dry. 

 

Late in the week, precipitation began to overspread the Northwest, aiding wildfire containment efforts and providing limited drought relief. Mostly dry weather continued, however, across the nation’s southwestern quadrant, including central and southern California. Near- or above-normal temperatures across most of the country favored summer crop maturation, while pockets of cooler-than-normal conditions were generally limited to the Southeast, Northwest, and upper Great Lakes region. Weekly temperatures broadly averaged at least 5°F above normal from the Great Basin and the Four Corners region into the mid-Atlantic and southern New England, encompassing the central Plains and lower Midwest. Readings averaged as much as 10°F above normal in the eastern Corn Belt and mid-Atlantic. Some of the coolest weather, relative to normal, occurred in Washington. Heat briefly retreated into the South before returning northward. Borger, TX, posted a daily-record high of 99°F on September 12, down slightly from its monthly record high of 106°F set 2 days earlier. Meanwhile in Florida, early-week records included 95°F (on September 13) in Tampa and 94°F (on September 12) in Fort Myers. During the second half of the week, scattered daily-record highs dotted the Plains, where September 16 readings rose to 97°F in Pueblo, CO, and Imperial, NE. The following day, record-setting highs for September 17 surged to 103°F in Del Rio, TX, and 101°F in Roswell, NM. On September 18, the week ended with a flurry of daily-record highs, as summer-like heat developed in advance of a cold front. On that date, Glasgow, MT, reported a daily-record high of 99°F. Other record-breaking highs for the 18th included 99°F in San Antonio, TX; 98°F in Chadron, NE; and 96°F in Dickinson, ND. In contrast, cooler air settling across the Northwest resulted in a daily-record low (37°F on September 16) in Hillsboro, OR.

 

19-25: Elsewhere, near or above-normal temperatures covered much of the country, with widespread cooler-than-normal conditions limited to the Southeast. Weekly temperatures averaged as much as 5°F above normal in northern and central California, while similar departures (at least 5°F above normal) were common across the northern Plains and the Northeast. Readings averaged up to 5°F below normal in the Southeast, where temperatures were suppressed in part by cloudiness and showers associated with the remnants of Nicholas. 

 

Early-week heat spread from the central and southern Plains into the Midwest. On the Plains, record-setting highs for September 19 soared to 99°F in Borger, TX, and McCook, NE. On the same date, Rockford, IL, collected a daily-record high of 93°F. By the 20th, triple-digit, daily-record highs in Texas soared to 106°F in Del Rio, 104°F in Abilene, 102°F in San Angelo, 101°F in Waco, and 100°F in San Antonio. Later, heat briefly affected coastal California, where record-setting highs for September 21 included 104°F in Anaheim and 101°F in Gilroy. In contrast, cooler air settled across the Northwest, where Butte, MT (21°F on September 21), registered a daily-record low. During the second half of the week, cooler air also arrived across the nation’s mid-section. Austin, TX, notched a daily-record low of 50°F on September 24, just 4 days after posting a high of 99°F.

 

26-30: A multi-day rain event across the nation’s mid-section slowed fieldwork but delivered much-needed moisture for newly planted winter wheat. However, rainfall coverage was uneven, leaving some areas with ongoing soil moisture shortages. In addition, precipitation completely bypassed some of the northern High Plains’ hardest-hit drought areas. 

 

Widespread cooler-than-normal conditions were limited to the Southwest, while near- or above-normal temperatures covered the remainder of the country. Weekly temperatures averaged 10 to 15°F above normal across the north-central U.S., stretching from eastern Montana into the upper Midwest. Warmer-thannormal weather also prevailed most areas between the Rockies and Appalachians. In contrast, readings averaged at least 5°F below normal in parts of Arizona and New Mexico. Early in the week, precipitation lingered across the Pacific Northwest.

 

Late-September temperatures surged across the Plains, followed by slightly cooler conditions. On September 26-27, consecutive dailyrecord highs were established in locations such as Hill City, KS (99 and 97°F), and McCook, NE (99 and 97°F). On those dates, Waterloo, IA (88 and 89°F, respectively), also notched a pair of daily-record highs. Heat briefly shifted northward, where Dickinson, ND, logged consecutive daily-record highs (96 and 100°F, respectively) on September 27-28. The previous latest occurrence of a reading of 100°F or higher in Dickinson had been September 15, 1948, when the temperature reached 102°F. Elsewhere in North Dakota, record-setting highs for September 28 soared to 98°F in Bismarck and 96°F in Minot. With 50 days of 90-degree heat so far this year, Bismarck trails only 53 such days in 1936. Warmth lingered for a few days in the Great Lakes States, where daily-record highs included 84°F (on September 29) in Brainerd, MN, and 83°F (on October 1) in Merrill, WI. Meanwhile, cooler weather in the West resulted in a few daily-record lows, including 20°F (on September 29) in Burns, OR, and 26°F (on September 30) in South Lake Tahoe, CA.

 

 

Jim G. Munley, jr.
http://www.jimmunleywx.com