CHICAGO, June 20 (Reuters) - Chicago Board of Trade corn slid on Thursday while soybeans closed at their lowest in two months as forecasts for heavy rains alleviated concerns about a heat wave in the central U.S. stressing crops.

July soybeans ended down 18-3/4 cents at $11.55-1/4 per bushel, the lowest since April 19, while corn dropped 10-1/4 cents at $4.39-3/4.

The heat is "more of an issue for people right now than crops," said Karl Setzer, partner at Consus Ag Marketing. "When corn is knee-high, it's pretty hard to stress."

Rains are expected in the six to 15 day period in the central U.S., according to Commodity Weather Group, with the heaviest rains in the Northwest Midwest in the next two weeks and showers to the south and east in the 11-15 period.

The precipitation forecast for corn and soybean growing areas actually creates ideal growing conditions, Setzer said, while it would take weeks of prolonged heat to see negative impact.

In wheat, forecasts for rains in Russia and crop estimates revised upwards also pressured prices, with consultancy IKAR saying on Wednesday it had raised its forecasts for the country's wheat crop to 82 million metric tons from 81.5 million tons.

July Chicago wheat lost 9-1/4 cents at $5.72-3/4 a bushel, also a two-month low.

Frosts and dry weather in Russia, the world's biggest wheat exporter, had led to severe harvest downgrades that raised global prices, but rain this month has eased concerns.

A slight improvement in expectations for the Russian crop probably has helped give some "negative spin" on this, said Bill Lapp, founder and president of Advanced Economic Solutions.

In Argentina, the Buenos Aires Grains Exchange also bumped up its wheat planting forecast, saying higher wheat prices and lower input costs were pushing more farmers to sow the crop despite dryness in some areas. (Reporting by Renee Hickman in Chicago; Editing by Richard Chang)