Today is the 237th straight day with a high below 80° in Fargo Moorhead. That would rank as the 13th longest stretch since 1891. We should break the streak this Saturday or Sunday. meaning the streak will continue for a few more days. (The list below does not include today)
Grand Forks, including today, has gone 237 days without a high temperature at or above 80 degrees (list below does not include today). Here is the list from the University of North Dakota / NWS site for longest streaks since 1893.
It appears Bismarck has now gone 241 days without an 80° day (including today, list below goes through yesterday). Here is the list of longest streaks at that location.