The PGA of America made the decision in response to forecasts predicting thunderstorms and up to two inches of rain, citing safety concerns for fans on the grounds.
Despite the closure to spectators, players were still permitted to practice as scheduled. The tournament itself - the second men's major of the year - is still set to begin Thursday as planned.
To accommodate those affected, the PGA of America has introduced flexible arrangements for ticket holders. Fans with Monday practice tickets can now use them to attend either Tuesday or Wednesday's practice sessions instead. Parking passes issued for Monday will also be honored on those days.
While many appreciated the precaution, some fans voiced their frustration on social media, expressing disappointment about missing out on Monday's action.
Weather forecasts suggest that rain and thunderstorms could persist into Tuesday, with a chance of additional showers on Wednesday morning.
Conditions are expected to improve by the opening round on Thursday, with drier skies and temperatures climbing into the high 80s, but more rain is possible again on Friday and Saturday.
Bryson DeChambeau has emerged as a popular pick to win his first PGA Championship this week, with fans and analysts backing the LIV Golf standout for a breakthrough performance.
Fresh off his Masters triumph and ending his decade-long wait to complete the career Grand Slam, Rory McIlroy is ready to shift focus to this week's Truist Championship on the PGA Tour.
LIV Golf superstar Dustin Johnson is set to join the high-quality field for the upcoming PGA Championship at Quail Hollow Club.
Rory McIlroy has revealed he will skip this week's CJ Cup Byron Nelson to recharge his batteries after his dramatic Masters triumph earlier this month.
