August 5, 2001 began an extended heat wave in Upper Michigan. The pattern that produced the heat wave was a familiar one. A huge, hot upper-level ridge poked toward the Great Lakes from the southwest (Image 1 above). This ridge can be likened to a pool of very warm air. Its movement into the Upper Midwest helped produce the sizzling summer weather.
The temperature soared to a daily-record 92 at the National Weather Service (NWS) near Negaunee. Record highs in the mid-90s were registered on August 6th and 7th. In Iron Mountain, record daily highs were also set on three consecutive days when the mercury soared to 96 on August 6 and then 98 on both August 7-8 (there were four straight days with temperatures in the 90s starting on the 5, but there was no record high on that date. The record as well as the hottest day in August was back in 1947 with a high of 101.).
This level of heat??where temperatures reach 90 or above on three consecutive days??is a relatively rare occurrence at the NWS site. In fact, the last time it happened was July 15-17, 2005. On the other hand, a three-or-more 90-degree-day stretch has occurred quite late in the season. On August 26-29, 1991, the NWS sizzled with four consecutive 90-degree days. Finally, there were three 90-degree days as late as September 7-9, 2002.There is no 90-degree days so far this summer and none are expected in the immediate future. More U.P. Summer Weather is on tap as high pressure lingers over the area through the week. That means temperatures close to average for highs with comfortably cool nights.