Lack of rainfall and high temperatures are causing significant damage to corn and soybeans that are going through key stages when it comes to defining yields. The heat does not let up and rain is just forecast for Wednesday or Thursday of next week.

"The worst days of the heat wave are yet to come. The losses compared to what was estimated up to 15 days ago, I don't think they will escape 20 to 30 percent if it rains in less than 10 days, otherwise it will be worse," says one producer.