Signal vs Noise

Wind Is the Only Weather That Matters

Cold games look dramatic and play close to normal. Wind above 15 mph quietly removes the deep third of the field.

Weather is the most over-narrated variable in football. A game played in snow gets an hour of pregame coverage and a dozen shots of linemen breathing steam. A game played in a steady twenty-mile-per-hour crosswind gets a passing mention. The second one is the game that is actually different.

Look at the CPOE column, which is the one to trust. Completion percentage on its own is contaminated by play calling, since teams throw shorter when conditions are bad, and shorter throws are completed more often. CPOE controls for that by comparing each throw to what a typical quarterback completes on that exact type of throw. In a stiff wind, quarterbacks complete nearly two percentage points fewer passes than expected, even after accounting for the fact that they are already throwing more conservatively.

Wind does not just make passing harder. It makes passing harder than it looks, because the play calling has already absorbed some of the damage.

Why wind and not cold

A football in flight is a rough approximation of a gyroscope, and its stability is exactly what a crosswind attacks. The longer the ball is in the air, the more time the wind has to work, which is why the damage concentrates in the deep and intermediate game rather than spreading evenly. Kicking degrades on the same curve and for the same reason, which is why field goal range shrinks so sharply on windy afternoons.

Cold, by contrast, mostly affects the humans, and the humans are professionals who have practiced outdoors all week in the same climate. Temperature has a real but modest effect. It does not come close to the wind effect, and the two get conflated constantly because cold days are frequently windy days.

The indoor number is smaller than you would think

Domes are a real advantage, and you can see it: the highest completion percentage on the board and positive EPA. But the gap between indoors and an ordinary calm outdoor day is modest. The meaningful cliff is between calm and windy, not between inside and outside.

The CPOE value for indoor games sitting slightly below zero is worth a note rather than a theory. Dome teams throw deeper and more often, and the expectation model is calibrated league-wide, so a small negative there is more likely a reflection of aggressive play calling than of domes being bad for passing. The completion percentage and EPA columns, which both favor indoors, are the ones to trust for that row.

How to use it

Check the wind, not the temperature. A 25-degree game with calm air will look and play close to normal. A 55-degree game with a 20-mile wind off a lake will compress both offenses, shorten the passing game, shrink the kicking range, and make the whole afternoon lower-scoring and more volatile than the forecast graphic suggests. If you are setting a lineup or reading a total, that is the single weather input worth the thirty seconds it takes to look up.