Compensation is due if you arrived 3+ hours late and it was one booking.
Check your flightThe rule that matters is that compensation is measured at your final destination, not at the airport where things went wrong. A ninety minute delay on your first leg that causes you to miss a connection and arrive eleven hours late is an eleven hour delay for the purposes of the regulation.
The condition is that the whole journey was booked as a single reservation with one booking reference. If you bought two separate tickets and the first airline made you miss the second, the regulation does not connect them, and you are generally on your own.
Distance is also measured end to end, from your original departure airport to your final destination in a straight line, not leg by leg. That often pushes a claim into a higher compensation band than passengers expect.
The reason for the original delay still matters. If the first leg was delayed by weather, the claim fails. If it was a technical fault or a late inbound aircraft, it pays.
Compensation is a flat amount set by distance, not by ticket price: €250 up to 1,500 km, €400 for longer flights inside the EU and for 1,500–3,500 km, and €600 beyond 3,500 km. The UK equivalents are £220, £350 and £520.
Distance is measured in a straight line from your original departure airport to your final destination, which on a connecting itinerary often lands you in a higher band than you would expect.
Duty of care is separate from compensation and does not depend on the cause. Once you are delayed two hours or more the airline owes you meals and drinks, two phone calls, and a hotel plus transfers if you are stuck overnight. This applies in bad weather, during ATC strikes, and in every other situation where no compensation is payable.
Airlines frequently provide none of this during major disruption. Buy your own, keep every receipt, and claim the cost back afterwards.
Work out what you are owed