According to science, humans sleep best when nighttime temperatures are between 60 and 67 degrees. I personally like it another five degrees cooler, much the same way wheat, barley, oats, rye prefer it. Cooler nights slow down respiration and are more influential than the daytime high temperatures on final grain yield.
This is well illustrated in Figure 1 in the following article. The differences between the two top rows of graphs in Figure 1 are much less dramatic than those in the third row of graphs: The length of the kernel fill was reduced by only a few days as daytime temperatures increased but nearly cut in half when nighttime temperatures increased from 17C (62F) to 28C (82F). Likewise, average kernel weight was cut in half as well when nighttime temperatures rose to 28C.
It is therefore that I wasn’t too worried about the daytime highs this past week, but rather the uncomfortable sleeping weather. The immediate forecast, however, looks better across all but the most southern part of the State.
Source: University of Minnesota Extension: Minnesota Crop News