Heat waves are not particularly unusual in September, especially early in the month. Think about it, early September is equivalent to early March. In early March there can be intensely cold periods. And in September, it can still feel like mid-summer on occasion. One of the greatest early ninth-month hot spells occurred from September 2-4, 1929. Ironwood residents felt record highs of 92, 93 and 92 degrees on the 2nd, 3rd and 4th, while Iron Mountain set records of 92, 95 and 91 on the same days.
Heat was not a consistent feature of September 1929 because records show Marquette actually wound up 0.4 degrees below average for the month. In 2012, our warm start will give way to a cooling trend starting tomorrow in the western U. P. The weather will likely be coolest Friday into Saturday (Image 1 above). In fact it may be cool enough for some scattered light lake-effect showers during this time.