Strange as it may seem, Portuguese navigators were also involved in the exploration of the west coast of North America.
"In 1542-3, Portuguese-born João Rodrigues Cabrilho and his chief pilot Bartolomé (Bartolomeu) Ferrelo, who may have been Portuguese, were the first Europeans to explore the coast of the present state of California.
Sailing for the King of Spain Charles I – better known as Emperor Charles V – as Columbus and Fernão de Magalhães (Magellan) had sailed before, Cabrilho left in June of 1542 from Navidad on the west coast of Mexico and proceeded north. He reached San Diego Bay in September, becoming the first European to set foot in what is today the state of California. He continued north along the California coast but died in January 1543 from an infection resulting from a broken arm. Ferrelo continued north, possibly reaching the Oregon coast in March 1543.
Curiously enough, Magalhães had suffered a similar fate twenty years before: on the first successful attempt to sail around the entire Earth – the first circumnavigation ever – he was killed during the battle of Mactan on Cebu Island (one of the Maluku or Moluccas Islands) in the Philippines, in April 1521, taking over command of the expedition the Spaniard Juan Sebastián Elcano, who reached Spain the following year.
Little is known about Cabrilho's early years. Even his nationality is uncertain; most biographies describe him as Portuguese, but in his exhaustive 1986 biography "João Rodrigues Cabrilho", historian Harry Kelsey writes that Cabrilho appears to have been born in Spain, "probably in Seville, but perhaps in Cuellar." His date of birth and parentage are also unknown, but events in Cabrilho's life lead Kelsey to believe he was born of poor parents "around 1498 or 1500," and then worked for his keep in the home of a prominent Seville merchant."
However, if his name is João Rodrigues Cabrilho, as it seems to be the case, and not Juan Rodriguez Cabrillo, then the Portuguese hypothesis is a quite plausible one.