A method for a vehicle, comprising: initiating an engine-off natural vacuum test based on an ambient temperature change potential over a testing duration. The ambient temperature change potential may be based on historic weather data and further based on forecast weather data. In this way, the engine-off natural vacuum test may be executed only when conditions favor an in-tank temperature change significant enough to cause a threshold change in fuel tank pressure, thus reducing the number of aborted tests and increasing the test's overall performance metrics.