Altitude, temperature, and your real carry numbers

Your carry distances are conditional on the air. Altitude adds roughly 1.1 to 1.2% of carry per 1,000 feet of elevation, so a 200-yard sea-level carry becomes about 212 in Denver, a gain near 6%. Thinner air also needs more spin to hold the ball up, so the optimal spin window drifts upward as you climb, by about 75 rpm per 1,000 feet. That spin drift is the one place environment actually moves a fitting target rather than just a yardage.

You will also see a 2%-per-1,000-foot figure quoted, roughly double what we encode, and it is worth being precise about why we take the lower number. Both figures come from real measurement, so this is not one source being more careful than the other. The 2% figure simply does not agree with itself: the same source that states it also gives 2.5 yards per 1,000 feet, and 2.5 yards on a 250-yard drive is about 1%, not 2%. The 1.1 to 1.2% side is internally consistent, since 200 yards becoming 212 at Denver's 5,280 feet is a clean 6%. So we encode the consistent number and note that Denver runs nearer a 6% gain than the 10% you will sometimes read.

Air temperature moves the ball too, about 2 yards of driver carry per 10°F and only about 1.3 on a wedge, which is why a cold round shrinks the top of the bag far more than the scoring clubs. In worked terms, a 250-yard drive carries about 254 at 90°F and 246 at 50°F. A percent form says the same thing, roughly 1.5% per 20°F. Humidity, which intuition insists should matter, does almost nothing.

The ball's own temperature is a separate lever from the air, and the two stack on a winter morning. A cold-soaked ball costs about 6 yards of carry on average across the bag, closer to 8 on the driver and 7 on a 7-iron, along with roughly 2.5 mph of ball speed and 500 to 700 rpm of extra iron spin, and it flies about 8% lower. Those are moderate warm-versus-cold figures. At a near-freezing extreme, a ball soaked to the low 30s can give up as much as 21 yards against a warm one, so the penalty grows quickly as the temperature drops.

This is why the warm-spare trick is a measured edge rather than a superstition. Keep a spare ball in a pocket and rotate it every couple of holes, and you hold onto that 6 yards and avoid the extra iron spin that makes cold approaches balloon and land short. It costs nothing and is worth about a club over a full round.

The practical upshot for your fitting is clean. Enter what your monitor actually said, because your session numbers travel with you. The flight windows themselves, launch and spin, stay valid wherever you play, with altitude's small spin rise the lone exception. It is the yardages that scale with the air, not the shape of the flight you are fitting.