Castillo, a sophomore at Valencia High School in Placentia, California, was named a first-team Rolex Junior All-American after posting three top-three finishes in AJGA events. The University of Florida verbal commit captured a win in his first event of the year at the Winn Grips Heather Farr Classic hosted by Longbow Golf Club. Finishing second at the Callaway Golf Junior Championship and third at The PING Invitational helped Castillo earn a spot on the Wyndham Cup West Team roster and the No. 6 spot in the Polo Golf Rankings.
|3||2016 The PING Invitational||72||73||70||215|
|T31||2016 Bobby Chapman Junior Invitational||75||69||144|
|T22||2016 The Junior PLAYERS Championship presented by TaylorMade-adidas Golf||72||73||74||219|
|2||2016 Callaway Golf Junior Championship||63||74||72||209|
|T35||2016 Thunderbird International Junior||73||73||79||225|
|1||2016 Winn Grips Heather Farr Classic hosted by Longbow Golf Club||69||67||72||208|