ISHPEMING, Mich.—On Sunday, Carl Pellonpaa is marking the end of an era in television history with two words: “siinä kaikki”—that’s it.

After 53 years and more than 2,650 straight weekly episodes of hosting “Finland Calling,” Mr. Pellonpaa will cap a career that far outpaces David Letterman, Johnny Carson and “Saturday Night Live.” Some might say he is Finnished.

Mr. Pellonpaa isn’t some yokel with a program on public-access. In the sprawling tundra of Michigan’s Upper Peninsula, his Sunday morning show about music, history, politics, travel and anything else Finnish has built the one-time weatherman into a legend, stirring debate over whether he can be replaced.

Known as a land of “Yoopers”—often stereotyped as talking with a Scandinavian brogue and living on baked meat pies—Michigan’s U.P. is packed with ethnic Finns. And Mr. Pellonpaa is the link to their homeland, also hosting Finnish dance parties and leading dozens of trips to Finland (but not before pre-taping episodes to be aired in his absence).

“The guy’s an icon,” said Kim Parker, a marketing executive at the NBC affiliate, TV6, that airs “Finland Calling.” Mr. Parker worked on the show as a cameraman in the 1970s and says “for a while, people thought he owned the station because he was so ubiquitous.”