Wind and AFL scoring

Wind below about 20 km/h does nothing measurable to an AFL total. At 20 km/h and above it costs roughly 5.2 combined points, across 382 dry matches (t = -3.44) — a clearly significant result, not a rounding artefact. Below that line the same sample runs +0.9 points against the season average, which is noise.

The shape is a threshold, not a straight line: the light and moderate bands sit on top of the season average, and the damage starts in the 20–24 km/h band. The 30 km/h+ row holds 36 matches — below our pre-set 40-match minimum. That minimum was fixed before this study was run; the row is shown for completeness as directional evidence only and is excluded from our headline, our summary numbers and any lean or pricing claim.

The league-wide number is the finding. It is not evenly spread, and pretending otherwise would be the easiest way to mislead with this table.

The MCG carries by far the largest set of windy matches and shows almost no effect, which is consistent with a big, deep bowl. The SCG and Optus Stadium rows are enormous and both sit below the minimum sample, so they are marked and should not be priced. Grounds with fewer than ten windy matches are left out of the table entirely.

• Source: AFL match archive joined to hourly Open-Meteo reanalysis at each venue's coordinates, in venue-local time. 2,640 dry matches, 2004–2026, 26 grounds.
• Measure: combined final score, compared with the average total of the same season so the long-term decline in AFL scoring cannot masquerade as weather.
• Excluded: any match with 0.1 mm or more of rain in the window, all roofed Docklands/Marvel matches, matches without a resolvable venue, and matches without a final score. Nothing is excluded on the basis of its result.
• Minimum sample: 40 matches, set before this study was run and unchanged for it. Rows under that threshold are labelled and never used in headlines or pricing.
• Not controlled: wind direction relative to the goals, gusts as distinct from average speed, temperature, team strength and finals context. Direction needs verified field bearings for every ground, which we do not yet hold to a standard we would publish.
• No closing totals are available for these matches, so this study reports scoring, not Over/Under hit rates. We will not publish hit rates without the lines.
• Spread inside the sample is ±32.6 points, so wind moves the average without deciding any single match.

Data generated 2026-09-21. Numbers refresh as the weekly venue-weather top-up runs; corrections are dated and published on this page.

• Open-Meteo ERA5 historical reanalysis — archive-api.open-meteo.com (hourly game-window weather at each venue’s own coordinates)
• AFL Tables — afltables.com (AFL match archive, venues and final scores)
• Internal AFL match archive — venue coordinates, local start times and final scores.
• Every dated change we have made to a published study is listed on our corrections log.