The simple answer is that airlines are always tweaking prices for airfare based on demand, timing, sales, and more. Carriers can change airfare prices at a moments' notice – and they do.

Flight prices doubling overnight is usually the result of Dynamic Pricing and "fare bucket" exhaustion. Airlines use sophisticated AI algorithms that adjust prices in real-time based on demand, remaining seat inventory, and even competitor pricing. When a flight has only a few seats left in a lower-priced "fare bucket" (e.g., Economy Light), and those are sold, the system automatically jumps to the next available bucket (e.g., Economy Standard), which can be significantly more expensive. Other factors in 2026 include browser cookies (though debated, many believe frequent searching signals high intent), major events or holidays being announced, or a sudden spike in fuel surcharges. Additionally, if a large group booking occurs or if a competitor cancels a flight on the same route, the remaining seats become a premium commodity. To avoid this, it is often recommended to use "incognito" mode for searching and to book immediately if you see a price that fits your budget, as "sleeping on it" often allows the algorithm to detect the demand and raise the price by morning.