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      Latest 90 in Iron Mountain: September 18, 1955

      The exceptional heat of 1955 was focused over the northeastern quarter of the U.S.

      It reached 90 degrees in Iron Mountain on September 18, 1955â??the latest 90-degree temperature on record. Itâ??s not surprising that this record occurred in 1955. The summer of 1955 was a hot, long one. Weather historian David Ludlum in his â??American Weather Bookâ?? states â??Never did so many Americans swelter under such high temperatures through such a long summer asâ?|in July and August 1955.â??

      For Iron Mountain, July 1955 was the hottest seventh month in 53 years of record keeping. Chicago residents endured one of its hottest summers in a string of hot summers in the late 1940s and 1950s. In early September, the locus of the heat shifted west. Los Angeles recorded a killer heat wave early in the month.

      In the Upper Peninsula, Marquette had temperatures well above average in June, July and August. The heat of 1955 was known for its persistence and lack of extremely high temperatures. Ironwoodâ??s temperature record illustrates this lack of extreme heat. While it was a very warm summer on the Gogebic range and throughout the Great Lakes, the summer of 1955 featured only one record high at Ironwoodâ??a 92-degree high on August 18.

      In Marquette, there was one last gasp of heat in September that coincided with Iron Mountainâ??s record-setter. From the 16th to the 18th of September, the mean temperature was 17 degrees above average. The high on September 18 in Marquette also topped out at 90 degrees. The summer of 1955 was one of the warmest on record over the Upper Midwest and Northeast (Image 1 above). September did cool back in relation to average (Image 2). In fact, the U.S. Weather Bureau in Marquette measured near average temperatures for the month.

      So far, September 2013 is running a bit below average. We are now in the process of warming up again. However, highs in the 90s are most likely over with this warm season. Thursday will likely be the warmest day this stretch ahead of the next cold front. This front should pass through Upper Michigan Thursday night into Friday morning. Behind the front, it looks like a seasonably cool start to the weekend.