José Antonio de Evia was born in La Graña, Spain, in July 1740, the son of master mariner Simón de Evia and Felipa de Gantes y Pravio. He studied at the Royal Naval School of El Ferrol and on January 1, 1753, began serving on naval vessels as a pilot. After serving in the coast guard of Cartagena de Indias in 1760 he sailed around Spain's mare nostrum, the Gulf of Mexico. He made the round trip from Havana to New Orleans, Veracruz, and Mobile several times. In 1779 he commanded a launch at New Orleans and captured the English ship that tried to bring reinforcements and supplies to Manchak. He was shipwrecked in the Volante off Mobile in February 1780 but nevertheless captured the English ship and crew he was chasing. He also commanded the port of Mobile during its siege and capture by Bernardo de Gálvez. After convoying troop ships back to Havana, he served as courier between Gálvez, Gabriel de Aristízabal, and Juan Bautista Bonet. He served in the royal arsenal of Havana from March 1782 until May 1783, when he was assigned to the warship San Cristóbal. He was promoted to frigate ensign in 1783 and commissioned by Gálvez to draw up detailed plans of the entire Gulf Coast from West Florida to Tampico.
Evia made an unsuccessful attempt in 1783, then embarked again in 1785 to explore by lugger and canoe the rivers and inlets of Florida, Alabama, Mississippi, Louisiana, Texas, and Mexico-an arduous task that he completed at Tampico in September 1786. He explored San Bernardo Bay and named Galveston Bay for his patron after taking detailed soundings of it. Supported by Gálvez, he was rewarded on July 2, 1787, with the post of captain of the port and commander of the coast guard of New Orleans at an annual salary of $2,000. He left Havana with his wife, Francisca Ruiz Delgado, and his two sons for New Orleans, where he changed the spelling of his name to Hevia. In 1792 he was commissioned by Governor General Carondelet to capture William Augustus Bowles, who had used Seminole Indians to attack and take the post of San Marcos de Apalache. Upon the successful completion of the assignment, Evia returned to New Orleans, where he exercised the functions of port master throughout the Spanish occupation of Louisiana. His accurate and detailed charts, diaries, and descriptions of the Gulf area were the best by any navigator of the eighteenth century. They served as the basis of subsequent charts drawn by the Hydrographic Service of Spain, as well as key documents in the Spanish case against American claims to the Neutral Ground between Louisiana and Texas.