Does it ever get hot along Lake Superior in Minnesota?

I know that inland areas of Northern Minnesota get hot a few times a year - and they average in the upper 70's for highs in July, but I was wondering if it ever gets hot in Grand Marias or Sky Harbor? For example, on July 1, DULUTH INTERNATIONAL hit 91 degrees, while at the same time, Grand Marias and Duluth Sky Harbor remained only at 51 degrees! 40 degrees colder! I was wondering if coastal areas such as these ever get hot? Is the weather of Duluth more representative of the international airport or Sky Harbor? I could not believe how cold it was on July 1st of this year in those areas. If anyone lives in Duluth and remembers July 1st, was it more like 90 degrees outside or was it in the 50's?