* Showers forecast over the next week
* Rain to slow final corn, soybean planting
* Rain and warmth positive for seeds already sown
CHICAGO, June 7 (Reuters) - Rain showers over the next week will present a challenge to U.S. farmers trying to finish up planting this season's corn and soybean crops, an agricultural meteorologist said on Friday.
"There will be three separate systems bringing from 0.3 inch to 0.8 inch of rain each over the next week. They will be faster moving systems than we've been seeing, so it won't be raining for a long time," said John Dee, meteorologist for Global Weather Monitoring.
Dee said showers would move through most of the U.S. Midwest crop region Saturday into Monday, next Wednesday and Thursday, and the following weekend. "It will be warmer next week so for crops that are in the ground it will be pretty much ideal, but still a little bit of a challenge to plant crops," he said.
Commodity Weather Group (CWG) on Friday also said there would be short windows of opportunity for farmers to plant crops over the next week to 10 days due to rain.
"The best chance for plantings will be in Missouri and southwestern Illinois," said CWG meteorologist Joel Widenor. "Minnesota, North Dakota, Wisconsin and central and northeastern Iowa will struggle with the most frequent interruptions."
Widenor said warmer weather during the next two weeks would be good for corn and soybean growth, with high temperatures reaching the 80s to low 90s (degrees Fahrenheit).
Rains kept farmers out of the fields for most of last week, limiting their ability to finish planting corn or catch up on soybeans, the U.S. Department of Agriculture (USDA) said in its weekly crop progress report released on Monday.
The USDA said that as of Sunday, the corn crop was 91 percent planted and soybeans 57 percent planted. Planting progress was the slowest for both crops at this point in the year since 1996. (Reporting by Sam Nelson; Editing by John Wallace)