I made this comment at the end of a long thread earlier and will be reposting it as the Summer goes on:

If July ends up being very hot and rains below average, then there is a 99.5% chance that corn prices will be higher than the lows set yesterday. 

Even perfect weather will make it tough but not impossible to trade lower than that.  By perfect, we need temperatures to cool off. 

It doesn't matter how much rain falls.  After pollination, when kernels fill if it stays hot for weeks, especially very warm/muggy nights, corn yields will get hurt badly. This is an absolute law of agronomy.

The difference between widespread, long lived very cool temps for filling and widespread long duration heat during filling is as much as 25 bushels/acre for individual locations. Ask Kansas, who has dealt with heat fill for decades on his farms. 

The corn plant matures/advances based on an accumulation of growing degree days. The more heat, the faster it advances. One might think this is good for the corn to be ready for harvest/mature before the risk of an early freeze. Just the opposite. 

Corn diverts alot of its photsynthetic energy/sugars that it made during the day towards filling kernels. It can only make so much each day, regardless of the temperature. The more days that it has to fill the kernels, the plumper they get. If you have long lived heat, the plant matures very fast, greatly lessening the number of days that the plant has to fill kernels and the kernels will be small..........even if there is bountiful rains and soil moisture. 

Even if the plant looks big and green and has a high rating based on the outside appearance...........if it stays hot after pollination, with lots of rain, the kernels will be small............no exceptions.......you can't defy this absolute law of nature.

This is what happened in 2010 and it shocked the market at harvest time.

In addition. If it stays very warm and humid at night, the corn plant must respire more and uses up some of the energy/sugars it made from photosynthesis during the day to to this.....which would have otherwise gone to filling kernels.............a double whammy!!

Hot and wet in June is great for corn because its in the vegetative state. The faster and bigger it grows, with more leaf area and more potential to collect sunshine and make sugars down the road.

Intense heat with good moisture in July, can cause pollination issues if it comes at the wrong time but the corn plant can still maintain most of its yield potential if its not intense heat at the wrong time.

Once pollination is over and kernels start filling, if soil moisture is good, long lived heat is one of the worst things that can happen.

In fact, a bit dry with well below average temperatures from late July thru August WILL produce higher yields than hot and wet.