American Family Field weather

What the research says

The published studies behind the read on this page at American Family Field. Every figure is season-adjusted, with sample sizes and t-statistics shown.

• MLB Playoff Roof Rules

  In the postseason MLB decides roof movement. Late-season October open-air games averaged 1.91 HR vs 2.33 in September (n=92, p=0.004); runs not significant (p=0.13).

  92 October and 1,470 September open-air regular-season games, 2021–2026

• Wind Blowing Out vs the Line

  Games with wind blowing out at 10+ mph finished +0.07 runs vs the closing total compared with all other games (t=0.53); 597 Overs, 612 Unders. The market already prices it.

  11,547 outdoor games with a closing total, 2021–2026; 1,250 with wind out at 10+ mph

• Wrigley Field Wind

  At Wrigley Field, wind blowing out vs in is worth +4.04 runs (t=6.62, 95% CI +2.84 to +5.25) and +2.06 home runs per game, season-adjusted. The April lake-breeze pattern does not show up in how often wind blows in.

  475 Wrigley Field games, 2021–2026; 106 wind out, 176 wind in

• Windiest MLB Stadiums

  Oracle Park is the windiest outdoor park at about 14 mph at game time, but Wrigley Field is where wind moves scoring most (+4.04 runs out vs in). Only 4 of 18 measurable parks show a real wind gap.

  Outdoor MLB games, 2021–2026, every open-air park

• Coors Field Humidor & Altitude

  Coors Field games averaged 2.43 more runs than other parks (2021–2026) but only 0.25 more home runs; games went over the closing total 48.8% of the time.

  471 Coors Field and 13,628 other MLB regular-season games, 2021–2026

• MLB Rain Delays

  The median recorded MLB rain delay since 2021 is 65 minutes; 6.6% of open-air games were delayed against 0.2% under retractable roofs, and 242 games were postponed for weather.

  Every scheduled MLB regular-season game, 2021–2026

• MLB Ballpark Wind Sensitivity

  Wind sensitivity is concentrated in a few parks: at Wrigley Field wind blowing out vs in is worth +4.0 runs (t=6.62), park- and season-adjusted; at most parks the gap is a run or less.

  11,581 outdoor games at 30 parks, 2021–2026; parks ranked only with 40+ out and 40+ in games

• MLB Retractable Roofs

  At the seven retractable-roof parks, roof-open games scored +0.13 runs (t=0.87) and +0.07 home runs (t=1.26) vs closed, park- and season-adjusted; against the closing total the gap was -0.10 (t=-0.66).

  3,281 games at 7 retractable-roof parks, 2021–2026; 3,278 with closing totals

• MLB Roof Open vs Closed

  At retractable-roof parks, roof-open games scored +0.13 runs (t=0.87) and +0.07 home runs (t=1.26) vs closed, park- and season-adjusted; against the closing total the gap was -0.10 (t=-0.66).

  3,281 games at 7 retractable-roof parks, 2021–2026; 3,278 with closing totals

• MLB Wind Direction & Scoring

  Wind blowing in costs 0.24 home runs and 0.34 runs per game against calm. Wind blowing out lifts home runs (+0.16) but not total runs.

  11,581 outdoor games, 2021–2026, resolved against each park's own field bearing

• MLB Temperature & Scoring

  Cold is the cleaner signal: under 50°F a game loses 1.14 runs and 0.72 home runs against mild weather. Heat helps less — 90°F+ adds 0.64 runs and 0.38 home runs. Against the closing total, cold games lean under versus mild conditions, but no band clears our bar (t between -1.74 and -1.87) — directional only.

  10,717 dry outdoor games, 2021–2026, season- and park-adjusted against the 70–79°F control; closing-line check on 6,000+ games

• Highest-Elevation MLB Stadiums

  Coors Field is the highest MLB ballpark at about 5,200 feet, more than 4,000 feet above #2 Chase Field (about 1,090 ft); only three parks sit above 1,000 feet.

  Elevations at venue coordinates for all 30 MLB ballparks, snapshot 2026-10-19

• Marine Layer Baseball

  Across 2,232 games at five coastal parks since 2021, West Coast parks score 8.45 runs per game vs 9.06 elsewhere, but home runs are identical (2.31) and night games show no significant drop in runs or home runs. Coastal games finished +0.38 vs the closing total — the market prices it in.

  2,232 open-air games at Oracle, T-Mobile, Petco, Dodger and Angel Stadium (2021–2026) vs 9,205 at other parks

• How Temperature Affects Baseball

  Across 10,422 open-air games since 2021, home runs climb from 1.64 per game below 50°F to 2.76 at 85°F+ (cold vs mild: t = −10.1) and runs from 8.18 to 9.90 — about +0.24 home runs and +0.43 runs per 10°F. Versus closing totals the band differences are not significant (hot vs mild t = 0.97): the market prices temperature in.

  10,422 open-air MLB games (2021–2026) with game-time temperature at each park's coordinates; 10,389 with closing totals

• April Baseball and Early-Season Scoring

  April averaged 2.07 home runs versus 2.37 in May–September across 2021–2025 open-air games. The home-run dip repeats in all five seasons, but April 2023 scored more runs than later that year. Equal-weight same-park/season differences are −0.32 home runs and −0.43 runs; exploratory, not causal.

  1,389 April and 7,333 May–September open-air regular-season games, 2021–2025; 110 park-season pairs

• Yankee Stadium vs Citi Field

  Across 808 games since 2021, the two New York parks share nearly identical game-time weather (71.5°F vs 71.4°F, 8.5 mph wind at both) but not scoring: Yankee Stadium averages 2.74 home runs per game versus 2.25 at Citi Field (t ≈ 4.1), a gap that repeats in all five seasons. Total runs are closer (8.70 vs 8.33, not significant), and both parks finish slightly over their closing totals — the park effect is priced in.

  808 regular-season games at Yankee Stadium (405) and Citi Field (403), 2021–2025; 794 with closing totals

All weather research · How our leans are derived