NEW YORK      -    A heat wave will continue to keep much of the eastern US in its grip on Sunday but a cold front that could lower temperatures in the middle of the country may be accompanied by thunderstorms that threaten flash floods.

The National Weather Service (NWS) said the “oppressive and dangerous” heat wave will abate by Monday and Tuesday. A swath of the east coast, from the Carolinas to Maine, faced the greatest heat threat on Sunday. Daytime highs were expected in the mid-to-upper 90s, which, coupled with high humidity, will feel like 100F to 110F, or 38C to 43C. Temperatures were expected to remain at or above the high 70s overnight (26C).

Strong wind and rain were expected to persist in the Midwest, and a cold front stretching between the Central Plains and the Great Lakes region was forecast to move south. In addition to cooler temperatures, the cold front was expected to carry showers and thunderstorms, which could lead to heavy rainfall and flash flooding in the Midwest.

Many in areas facing excessive heat have no air conditioning and cities have opened cooling shelters. With record- or near-record-high temperatures at night, when many air-conditioned places are closed, the weather can become especially dangerous. The risks are greater for young children, the elderly and the sick.

The heat wave has cancelled events across the affected region, including in New York City, where authorities scrubbed a Times Square commemoration of the 1969 moon landing and an outdoor festival featuring soccer star Megan Rapinoe and musician John Legend.

As animal rights activists protested, operators of the Monmouth Park horse racing track in New Jersey canceled some races and pushed back others on Saturday, including the $1m Haskell Invitational that went off after 8pm. Maximum Security, the horse that crossed the finish line first in this year’s Kentucky Derby and then was disqualified, was declared the victor after a short steward’s inquiry.