Does weather affect scoring in MLB?
Yes, and cleanly. MLB games in hot weather average 9.6 total runs, versus 8.2 in the cold. That is a swing of more than a run per game, purely from the temperature, and the relationship climbs the whole way up.
It is physics as much as baseball. Warm air is less dense, so a struck ball carries farther, fly balls that die on the warning track in April clear the fence in July, and hitters' hands and muscles work better in the heat. Cold, heavy air does the opposite.
It rises the whole way, cold to hot.
A run and a half separates a frigid night from a summer scorcher. That is a meaningful chunk of a run total.
This is one of the cleanest environmental effects in the sport, and it is why our run-environment model watches first-pitch temperature closely. When you see a total that looks high for two good pitchers, check the forecast before you assume it is a mistake. A 90-degree afternoon does a lot of the work.
Every number here comes from our own game database: 6,883 MLB games since 2024, rebuilt nightly. We compute rates across all qualifying games, never a cherry-picked window. This is descriptive history, not a prediction, and it updates on its own.
Last recomputed August 22, 2026.