The worst delay month of the year is the one everyone flies in.
132 million flights of realized history say the year fails in two different ways: winter breaks the schedule. Summer bends it. This page is the record itself — explore it.
Click any month to open its board · type a field below to read an airport's weather personality
Weather cancellations / 1,000 flights · by month · click a monthFebruary is the breaker · 17.3
dashed line = national all-month mean
WhyWinter weather removes the option to fly. Snow and ice take runways below their physical limits, de-icing capacity caps how many aircraft can launch an hour, and a flight that can't depart safely is cancelled outright. February cancels at more than 3× July's rate.
Source: U.S. federal flight-performance records and official airport surface-weather observations · 2003–2025 · national 22-season means · realized history — sourced, not forecast
Weather-delay minutes / flight · by month · click a monthJuly is the grinder · 0.69 — #1 of 12
dashed line = national all-month mean
WhySummer convection is short, violent, and local. A thunderstorm closes arrival paths for an hour, not a day — flights wait it out rather than cancel, and the cost lands as minutes stacked across every hub the storm brushes. July edges June for #1, yet ranks only #7 for cancellations.
Source: U.S. federal flight-performance records and official airport surface-weather observations · 2003–2025 · national 22-season means · realized history — sourced, not forecast
The year in two rows · break × bend · click a month
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row peak · FEB 17.32 /1k · JUL 0.692 min/flt
selected month
The whole law in one glance: the cancellation row peaks in February; the delay row peaks in July. Two failure modes, half a year apart.
National 22-season means · rows scaled independently to their own peak month · no forecast on this page — the axis ends at realized history
THE JULY BOARDwhere that month bites hardest, 2003–2025
Breakers — weather cancellations / 1,000 flights · July
· source: U.S. federal flight-performance records and official airport surface-weather observations
Grinders — weather-delay minutes / flight · July
· source: U.S. federal flight-performance records and official airport surface-weather observations
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≤20% of field peak
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peak month
spark = that field's own 12-month profile · height + luminance = share of its peak month · click a row for the field panel
FIELD LOOKUPevery figure: that airport's own 22-year record
Aviation Weather Intelligence — our team's 22-year study of how weather converts into airline disruption, airport by airport, month by month. This terminal is its first public page; more of the record is coming.
Built on U.S. federal flight-performance records and official airport surface-weather observations, 2003–2025 · 90 major airports · 132M flights. Figures are realized history — Sourced, not forecast. Monthly values are 22-season means per airport.
PAGE 001 · Airport Weather Intelligence · the seasonality terminal