CHICAGO (Reuters) -- The U.S. corn belt is enjoying one of its best growing seasons in years, according to a Reuters analysis of government temperature data, that looks likely to boost yields and deliver a record crop.

The number of growing degree days, a method of measuring temperatures between 50 and 86 degrees Fahrenheit considered to provide the best growing conditions, in top corn states Iowa and Illinois were running 18 to 35 percent above normal.

The growing degree days heat index, tracking temperatures from March 1 through June 5 is showing that heat levels in some major corn states ...