The corn around Hettinger didn't appreciate what Mother Nature delivered overnight Tuesday to Wednesday.

While sunflowers in the area of the southwest North Dakota town seem to have been unaffected by the nippy 29-degree low, the leaves of the corn were frosted, said Eric Eriksmoen, research agronomist at the Hettinger Research Extension Center.

"It hit the corn," he said. "It's pretty much done."

The official low in Hettinger, according to the National Weather Service, was 28 degrees, though it was 29 at the research center. Other places in North Dakota, mostly in the southwest, hit the low 30s, but Hettinger was the only place to freeze.

Eriksmoen said the temperature may have spiked at the low temperatures. "I don't know how long it was that cold," he said.

Eriksmoen hasn't heard from many farmers in the area about what the cold spell meant to the crops farther from Hettinger. National Weather Service meteorologist Kevin Birk didn't know if the cold temperatures spread to other towns around Hettinger in Adams County.

"Hettinger always seems to run a little cool,"he said.

The weather service issued a frost advisory for southwest North Dakota Tuesday evening when they began expecting some cold temperatures. The advisory warned that frost could damage anything standing higher than grass. Birk said the damage could "pretty much end the growing season."

It pretty much ended the corn growing season around Hettinger.

While ears could still mature a little if the corn stalks didn't freeze, the crop wasn't very far along, Eriksmoen said. Crops, generally, looked pretty good until about a month ago, then a hot, dry spell hit. Now yields on many crops are expected to be "fair," he said. The wheat crop in the area ran 10 to 35 bushels an acre, with 30 to 50 bushels being the normal range most years, he said.

He expects much of the corn crop in the Hettinger area to be chopped for silage rather than combined. The sunflowers don't look like they were adversely affected by the frost. Many crops are killed by temperatures at or below 32 degrees, but sunflowers can survive until 28 degrees, he said.

The cold spell came on the heels of a weekend where Bismarck hit 100 degrees for the first time all summer. Birk said the area averages one or two triple-digit-temperature days a year. From 1992 to 1998, the temperature never reached 100. But from 1998 to this year, at least one day each summer has topped the century mark.

July was 1.8 degrees above normal and August was 2.5 degrees above normal in the Bismarck area, but the early summer was cooler than normal. June was 2.7 degrees below normal, and May was 3 degrees below normal.

The cool weather kept some crops from taking off early in the growing season. Burleigh County Extension Agent ElRoy Haadem said crops such as wheat, barley and flax have had the opportunity to mature enough that they should be fine. However, crops like corn, soybeans and sunflowers, which have longer growing seasons and are harvested later, might not be mature enough to prosper if an early frost hits.

According to a crop report from the U.S. Department of Agricultureissued on Tuesday, many North Dakota producers of late-season crops, such as corn and sunflowers, are concerned about the possibility of an early frost, because many crops are behind normal. The report said crop conditions declined last week, except for canola and sunflowers. Corn is about a week behind compared to last year, it said.

Once the weather heated up and some timely rains fell, much of the corn took off this summer, Haadem said. He said the growing season will need to extend into late September or early October for many farmers' crops to survive a frost. If there's a hard freeze in the coming weeks - if the temperature were to drop to 28 degrees - many crops would be damaged, he said.

"Some of the crops, for example, the corn, did not have the growing-degree days to grow as we probably would have liked to have seen,"Haadem said. "The season wasn't normal."

But if frost holds off in other parts of the state for at least a couple weeks, the crops could be better than previous years, Kevin Knodel, manager of the Prairie Cooperative Elevator in Cleveland, said. Most of the farmers who bring crops to the Cleveland elevator are from Steele on east, and other than a few spots in the area, most are expecting a good crop, he said.

"If we get another 20 days of frost-free weather, we're going to have a better crop than we had last year," Knodel said.

Birk said the coming days will be cool, though next week could warm up to above normal temperatures. However, the average high temperatures drop daily this time of year, he said. The highs next week are expected to be in the 70s or 80s, he said.

"We have a slow warming trend toward the middle of next week," he said.

But for this week, it will be cooler and pleasant, he said.

"If you like the cool weather, we are going to be seeing it for the next few days," Birk said.

(Reach reporter Jenny Michael at 250-8225 or jenny.michael@bismarcktribune.com.)