I was skeptical, but it turns out you're right! According to Wikipedia, the Northernmost point in California is 42 degrees north, and the Southernmost point in Canada is Middle Island, which is 41.7 degrees north [1], or about 0.3 degrees farther south of the Northernmost point in California.
[1]: https://en.wikipedia.org/wiki/List_of_extreme_points_of_Cana...
[2]: https://en.wikipedia.org/wiki/List_of_extreme_points_of_U.S....