Grimsby, who for eighteen years was seen on ABC's flagship station WABC in New York City, is known as one of the pioneers of local television broadcast news.

After graduating from Denfeld High School in 1946, he attended St. Olaf College in Northfield, Minnesota before studying history at Columbia University in New York.

For most of his years at WABC, Grimsby also wrote and delivered a daily weekday afternoon radio newscast on the ABC Entertainment Network, which he considered his "read-in" to the news of the day.

[5] Beginning in June, his role was almost exclusively as a commentator, as Grimsby would be featured as part of the station's daily Live at Five newscast in a brief segment where he offered his take on a news story of the day with his usual deadpan style.

[6] In 1990, he relocated to California, where he and George Reading of KMST (now KION-TV) in Monterey became the first anchor team on San Diego television station KUSI's newly-launched 10:00 p.m.

[8][9] After his retirement, Grimsby returned to New York City and lived on Manhattan's Upper West Side with his wife, Maria, whom he had married in 1989.