Thirty-six holes into the golf tournament, weather has been one of the main characters of the week. In other words, it’s an Open Championship.

Last time the Open visited Royal Troon in 2016, the conditions produced an average scoring differential of 3.2 strokes between tee time waves, one of the biggest splits in recent major championship history. Of the 11 players who finished T-9 or better in 2016, nine came from a late-early tee time, including both winner Henrik Stenson and runner-up Phil Mickelson. With each of the nines facing primarily in the same direction – the front nine playing mostly into the wind and the back nine playing mostly downwind so far this week – Royal Troon is particularly susceptible to weather splits. The golf course plays completely differently based on the time you play it. So far this week, the golfers who have played the front nine during the worst of the winds are facing a much more difficult golf course than competitors with more fortuitous tee times.

The biggest weather advantage manifested during the middle of Friday’s round. After a relatively benign morning featuring scorable conditions, winds began to pick up in the middle of the day, creating a treacherous golf course for the players who teed off roughly between noon and early afternoon local time. Disasters ensued for that group of players. Bob MacIntyre, who teed off at 2:47 p.m. local time, started his round +8 through five holes. Joaquin Niemann recorded an 8 on the par-3 8th, one of many big numbers posted in the early afternoon. And Rory McIlroy pulled a 93-yard wedge miles left of the green on the par-5 6th on his way to a bogey, his fourth consecutive bogey or worse in the early afternoon. Per DataGolf, players who teed off in the afternoon averaged 75.3, compared to 73.4 in the morning, though it should be noted that tee times at the Open roll throughout the day as opposed to two distinct waves.

The adverse early afternoon conditions underscore the quality of a few phenomenal rounds today, including gritty performances by Jon Rahm (70) and Joaquin Niemann (71) who posted two of the handful of scores of par or better from afternoon tee times. But the round of the day belonged to Justin Rose, who fired a brilliant 68 (-3) despite facing some of the worst conditions of the day. Tied for Friday’s low round, Rose’s 68 was the only score of 69 or better shot by a player who teed off after 10:00 a.m. local time. There were 11 other rounds of 69 or better, all from tee times much earlier in the day. Rose teed off at 12:42 p.m., squarely in the window of the day’s toughest conditions. Through two rounds, Rose has made just one bogey or worse, a remarkable feat given some of the conditions he’s faced in this championship.

As the remainder of this championship unfolds, the weather forecast is worth tracking closely. Generally, winds lie down towards the late afternoon. This dynamic can increase the difficulty of making up ground on the leaders, a subtle factor that can exacerbate the importance of wave splits beyond Thursday and Friday.

This week, as much as any week, is a reminder that there is only so much within players’ control when nature plays a role. Winning an Open Championship isn’t just about flushing irons or holing putts; it’s about braving whatever elements Mother Nature sends one’s way. With 36 holes left to play in the final major championship of the season, Shane Lowry and his chasers have plenty of control over their destinies. But the golf course routing and wind patterns will also have a say in who wins on Sunday, a special characteristic of the Open.

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