Weekly Weather Summary: A record-setting heat wave gripped most areas from the Plains to the East Coast. The combination of high temperatures, oppressive humidity, and a lack of overnight cooling resulted in significant stress on humans, animals, and crops. In contrast, cool weather prevailed in the Pacific Coast States. Meanwhile, little or no rain fell from the southern Plains into the lower Ohio Valley. The combination of heat and a lack of rain caused further devastation in the drought-ravaged south-central U.S. and brought the season’s first round of stress to some Midwestern crops. The Midwest’s problems were compounded by the fact that for some corn and soybeans, the heat wave coincided with the reproductive stage of development. Late in the week, however, beneficial rain fell across an area of emerging dryness from Iowa into the lower Great Lakes region. Areas to the south, however, including the middle Mississippi Valley, remained dry. Hot weather also contributed to an increase in crop stress in parts of the East. Rain tempered the heat’s effects in some areas. Farther west, beneficial monsoon showers dotted the Southwest.
click image to zoom The Midwest and Northeast: Record-setting heat affected both regions for several days. On July 18, Rochester, Minnesota, set an all-time record with a dewpoint of 83°F (previously, 82°F on July 12 and 13, 1995). On July 19, Aberdeen, South Dakota, reported its first triple-digit heat since July 7, 2007, while Moline, Illinois, registered a 100-degree day for the first time since July 17, 2006. Even more impressively, Rockford, Illinois (100°F on July 19), tallied its first high of 100°F or greater since July 10, 1989, while Indianapolis, IN (100°F on July 21), experienced its hottest day since August 16, 1988. Later, record-shattering heat spread into the East. On July 22, highs soared to 108°F in Newark, New Jersey, and downtown Baltimore, Maryland. Newark’s former all-time record of 105°F had been set on August 9, 2001, and several earlier dates. Downtown Baltimore’s reading missed the Maryland state record by 1°F. All-time-record highs were also set or tied on July 22 in locations such as Virginia’s Dulles Airport (105°F; previously, 104°F on August 20, 1983, and July 16, 1988); Bridgeport, Connecticut (103°F; tied the record set on July 22, 1957); Reading, Pennsylvania (106°F; previously, 105°F on August 7, 1918); and Georgetown, Delaware (104°F; previously, 102°F on July 31, 1954, and July 6, 2010). A July record was set in Portland, Maine (100°F on July 22), where it was the hottest day since August 2, 1975 (103°F). In Pittsburgh, Pennsylvania (96°F on July 22), it was the hottest day since August 15, 1995. In some locations, including Reading (102, 106, and 100°F from July 21-23), daily-record highs were set on 3 days in a row. At the height of the heat wave, all-time records for the highest minimum temperature were set or tied in numerous locations, including Newark (86°F on July 22); Washington, D.C. (84°F on July 23 and 24); New York’s Central Park (84°F on July 22); and Scranton, Pennsylvania (80°F on July 22). In Omaha, Nebraska, the minimum temperature remained at 80°F or higher from July 17-20, marking the second-longest such streak on record behind 8 days from July 18-25, 1934. However, as the heat relaxed, heavy rain erupted in a few areas, especially from eastern Iowa into northern Illinois. In particular, July 23 was the wettest day on record in Chicago, Illinois, where 6.86 inches fell (previously, 6.64 inches on September 13, 2008).