NATIONAL WEATHER SUMMARY

SEPTEMBER 2018

1-8: Very warm, mostly dry weather dominated the northern High Plains and much of the West. Late-season heat wave, accompanied by mostly dry weather, covered the East for much of the week, hastening summer crop maturation.  Temperatures averaged 5 to 10°F above normal from the middle Mississippi Valley eastward into the middle and northern Atlantic States, and regularly topped 90°F as far north as New England.

 After reaching or exceeding the 100-degree mark each day from August 6 – September 4, and posting a daily-record high of 106°F on the 2nd, McAllen, TX, only attained 99°F on September 5.  Meanwhile, late-season heat spread across the Northeast.  In New England, record-setting highs for September 3 (Labor Day) rose to 94°F in Manchester, NH, and 93°F in Burlington, VT.  Burlington logged another daily-record high of 93°F on September 5.  From September 4-6, a trio of daily-record highs (93, 95, and 95°F) were set in Philadelphia, PA.  September 6 also featured daily-record highs in Newark, NJ (98°F), and Boston, MA (97°F).  In contrast, cool air settling into Minnesota led to daily-record lows for September 6 in locations such as International Falls (28°F) and Hibbing (29°F).  Later, heat intensified across the Desert Southwest, where Thermal, CA, closed the week with consecutive daily-record highs (115 and 118°F) on September 7-8.  Other daily-record highs in southern California on September 8 included 120°F in Death Valley and 115°F in Needles. Dry weather accompanied the Western heat.  September 8 marked the 83rd consecutive day without measurable rain in Eugene, OR, tying a record originally set in 1998.  Elsewhere in Oregon, Salem’s streak without measurable rain stretched to 89 days (June 12 – September 8), obliterating its 1967 standard of 79 days.

 

9-15: Many other areas of the country, including the Plains, Midwest, and much of the West, experienced warm, dry weather, favoring summer crop maturation and harvesting, and winter wheat planting.  Following a spate of late-August and early-September rainfall, the warm, dry Midwestern conditions were ideal for corn and soybeans, which continued to mature at a faster-than-normal pace.  In contrast, heavy rain soaked the western Gulf Coast region, hampering harvest activities but eradicating any remaining drought.  Elsewhere, very warm, breezy weather in the West hampered wildfire containment efforts. Warm weather prevailed across the Southeast in advance of Florence’s arrival and around the periphery of the storm.  Cape Hatteras, NC, collected a daily-record high of 93°F on September 10.  Two days later, on September 12, daily-record highs in Florida reached 95°F in Tampa and 94°F in Sarasota-Bradenton.  September 14 featured daily-record

highs of 96°F in Gainesville, FL, and Mobile, AL.  Gainesville logged another record high on September 15, reaching 97°F.  Other record-setting highs on the 15th included 97°F in Pensacola, FL, and New Iberia, LA.  Farther west, portions of the High Plains also experienced late-season heat.  In Colorado, Pueblo posted a high of 99°F on September 13—not a record for the date—along with daily-record highs of 97°F on September 11, 12, and 14.  Sidney, NE, registered daily-record highs of 98 and 96°F, respectively, on September 11 and 15.  Elsewhere in Nebraska on the 11th, Valentine noted a daily-record high of 99°F.  Record-setting heat also extended into the Southwest, where daily-record highs in Arizona included 113°F (on September 14) in Yuma and 105°F (on September 15) in Tucson.  In contrast, a mid-month cool spell in the Northwest resulted in daily-record lows in Oregon locations such as Meacham (27°F on September 15) and Klamath Falls (28°F on September 14).  Earlier, cool weather had also affected the Northeast, where daily-record lows dipped to 26°F (on September 9) in Saranac Lake, NY, and 28°F (on September 10) in Houlton, ME.

 

16-22: Weekly temperatures averaged at least 5°F above normal in a broad area covering the Southwest, the central Plains, and much of the eastern half of the country.  The protracted late-season warm spell boosted weekly temperatures as much as 10°F above normal in some locations, particularly in the Ohio and Tennessee Valleys.  In contrast, cooler-than-normal conditions dominated northern California and the Pacific Northwest, as well as the northernmost Plains.

 

23-29:  Warm, mostly dry weather also prevailed along the southern Atlantic Coast. Cool air also settled across the Plains, where showers were generally light and scattered, except for briefly heavy midweek rain in parts of Oklahoma and Texas.  Weekly temperatures averaged at least 5 to 10°F below normal in parts of the north-central U.S., where late-week freezes ended the growing season in most areas from Montana to Wisconsin.  Widespread freezes also affected large sections of the northern and central Rockies, the northern Intermountain West, and the northern Great Basin.  Elsewhere, mostly dry weather in the western U.S. favored fieldwork, including Northwestern winter wheat planting and Arizona cotton harvesting.  Summer-like heat in the Southwest boosted temperatures 5 to 10°F above normal. In advance of a cold front, early-week temperatures briefly spiked across the Plains.  In Nebraska, daily-record highs for September 23 included 95°F in Chadron and 93°F in Scottsbluff.  Heat later shifted into the Southeast, where Tampa, FL, registered consecutive daily record highs of 95°F on September 24-25.  Subsequently, Tampa attained 97°F on September 29 and 30.  Previously, Tampa’s highest September reading had been 96°F, set on September 20, 2018, and ten earlier dates.  Elsewhere in Florida, Gainesville’s high temperatures reached 90°F or greater each day during the month except the 3rd, eclipsing the city’s September 1921 standard of 26 such days.  Gainesville also experienced at least 112 consecutive days (June 11 – September 30) with minimum temperatures remaining at or above 70°F, easily surpassing the former record of 87 days set from June 24 – September 18, 1941.  Finally, Gainesville had its hottest September on record, with a monthly average temperature of 83.5°F, or 5.3°F above normal (previously, 82.2°F in 1925).  Other locations reporting their hottest September on record included, Tampa (85.9°F), Key West (85.8°F), Melbourne (83.6°F), and Daytona Beach (82.6°F).  September 2018 was also Tampa’s hottest month on record, edging 85.6°F in June 1998.  In contrast, progressively cooler air settled across the Rockies, Plains, and upper Midwest.  Lake Yellowstone, WY, noted consecutive low temperatures of 20°F on September 2526.  North Platte, NE, reported its first freeze of the season with a low of 31°F on September 26.  The following day, Joplin, MO, notched a daily-record low (40°F) for September 27.  Farther north, September 28-29 featured the season’s first two freezes in locations such as Grand Forks, ND (23 and 27°F), and Sisseton, SD (27 and 26°F).

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