More than 1,200 cattle died during a three-day blast of heat and humidity in northeast South Dakota, ranchers, feedlot owners and authorities reported, though the weather was expected to ease Thursday.

The high Wednesday in Aberdeen was 96, at least the third straight day the city's temperature was in the 90s. The heat index, which is related to humidity, hit 109.

Thursday's forecast called for a high in the low 80s and a 50 percent chance of rain, but agriculture authorities worried the heat wave might have caused long-term disabilities to some livestock.

"I've never seen anything like it," said feedlot operator Ivan Sjovall, 67, of Langford.

Veterinarians and livestock specialists recommended owners spray herds with water at night to cool the animals' body temperature. And the Farm Service Agency, part of the U.S. Department of Agriculture, encouraged cattle owners to document their losses in case the agency authorizes disaster relief funds.