Opening Day temps in Detroit rise in recent decades due to global warming Temperatures rose by average of 3.3 degrees since 1970 Tags: DETROIT – Last year, Opening Day was sweltering in Detroit -- which probably has something to do with it being held in July because of the coronavirus pandemic. This year, Opening Day is unfolding on time, but with much colder temperatures in addition to new health and safety restrictions. Related: Ad Since 1970, Opening Day temps have increased by an average 3.3 degrees -- a statistically significant upward trend. See the trend in the video above. Opening Day in Detroit will look much different this year compared to other years due to the pandemic. In addition to a limited number of ticket holders being welcomed into Comerica Park, there will also be no large crowds or crowded bars and restaurants.