Undated (AP) _ A new blast of scorching weather in the nation's midsection has increased fears about fall crops that are already wilting from thirst, and experts say the effects of the drought may extend into next year.

Despite scattered July showers, farmers say it will now take an exceptional amount of rain the rest of the year to make up for the huge moisture deficit caused by the hot, dry spring and summer.

''We've never had temperatures like this that I can recall. I'd say we're going downhill real quick if it stays hot,'' said Indiana farmer Dan Donathen, who tends 300 acres of corn and soybeans.

''I'd say we're in a real blowtorch pressure-cooker right now.''

Temperatures soared Tuesday to tie or break records in 26 cities in 12 states: Wisconsin, Minnesota, Michigan, Illinois, Ohio, Iowa, Indiana, South Carolina, North Carolina, West Virginia, Tennessee and New York, according to the National Weather Service.

In Wisconsin, the city of La Crosse broke a 24-year-old record for the date with 102 degrees, and tied a 1955 mark with its 35th day of temperatures in the 90s or hotter. Columbia Hospital in Milwaukee treated 86 heat-related cases in a 24-hour period Monday and Tuesday. Its normal amount for an entire summer is 56, hospital officials said.

Minneapolis-St. Paul set a mark of 101 degrees and Chicago hit 100 for a record the seventh time this year.

''It was so hot ... I had to go outside to breathe,'' said Willie Nabors, who abandoned his un-air-conditioned Milwaukee apartment Tuesday to join thousands of other sufferers in a cool shopping mall.

In the Detroit area, hundreds of Chrysler Corp. workers felt the same way, walking off their jobs at three factories when temperatures reached up to 140 degrees near furnaces, United Auto Workers union officials said.

Farmers, meanwhile, caught between the heat and drought, worried about what the weather conditions might do to their crop yield next year.

''The key times for recharging are late fall and early spring,'' said Ken Kunkel, director of the Midwestern Climate Center in Champaign, Ill. ''If we have a very dry fall, we will be in more danger next spring.''

That makes melting winter snow and early spring rain even more critical in 1989.

''It's going to be tough to go into the spring with adequate soil moisture,'' said Larry Dallas, who farms 560 acres in central Illinois with his brother.

''What corn there is, the rain helped and we've got some decent sized ears,'' said Dallas, who still expects no more than half a crop. ''The soybeans perked up and grew a foot, but if it gets hot and dry again, we'll lose all we've gained.''

In Carroll County, Iowa, however, some farmers with better-than-average rainfall were relishing the potential payoff from grain prices pushed higher by the parched conditions.

''We've hit the jackpot at the end of the rainbow,'' county Extension Director Dennis Molitor said Tuesday. ''It's definitely a potential gain for a lot of producers.''

Rain has soaked many fields in parts of Illinois, Indiana, Ohio, and Kentucky in recent weeks. However, other parts of Illinois, Iowa, Wisconsin, and Minnesota remained relatively dry, Kunkel said.

''Certainly, the drought is not over,'' said Kunkel. ''Soil moisture reserves are very limited.''

Late-July showers were also welcome in Kentucky and Arkansas.

''It's looking a whole lot better,'' said Kentucky farmer Homer Hurst Jr. ''We actually cut some hay yesterday. ... We reseeded 65 acres of corn and we're hoping for a late fall.''

But farmers in other drought states have not been as fortunate. In South Dakota, experts said rains came too late to save most crops and the state approved a program to help farmers and ranchers replace dried-up water supplies.

''It's the same old story: we need rain; we're not getting any,'' said Herb Halvorson, assistant agriculture commissioner in Minnesota, who indicated heat now may be causing more damage than drought.

''The impact on the corn and the soybeans and the canning crops has been devastating.''