July is the calmest month for weather at London Stansted, and the airport's reliability rests largely on Ryanair. The CAA doesn't publish monthly breakdowns of delays and cancellations, so only the weather data says anything about summer.
July and the weather
From January 2018 to September 2026, EUROCONTROL imposed weather restrictions on arrivals at Stansted on just 5% of July days, against 17% in December. Weather accounts for 79% of arrival delay minutes caused by restrictions here, but that averages out at 0.39 minutes per flight of waiting before departure, without cancellations. Every month is on the Stansted weather page.
Ryanair and routes
In 2025, Stansted disrupted 0.8% of flights, less than Gatwick (1.4%) and Heathrow (1.8%). About 71% of flights here belong to Ryanair, with its 0.7%: 548 delays and 352 cancellations across 126,660 flights. The worst route is Keflavik at 6.5% of 520 flights, while the busiest, Dublin, sits at 0.4%. On a 1,500–3,500 km flight like Keflavik, compensation is £350, and your right to care starts at a delay of 3 hours.