Sixty to ninety minutes before departure is enough at STS on most days.
A maps app covers the drive to STS. Bag drop, security, and the walk to your gate usually take longer, and they are the steps people misjudge.
Here is the same plan drawn to scale. The first block is travel; the next two are the airport. A checked bag grows one, a far gate grows the other.
Front door to boarding: 1hr 55min
Sixty to ninety minutes before departure is enough at STS on most days. Holiday mornings are the main exception.
STS is a small airport (a short walk from the lot, a handful of gates), and showing up 60–90 minutes out is usually enough instead of the big-airport two hours. The terminal is small enough that once you are through security there is nowhere far to walk, so the arrival number is really just the check-in and checkpoint number.
One small checkpoint means the line is usually minutes, but it also means one full flight checking in at once is the whole queue. The early-morning departures are the busy moment. There is no second checkpoint to move to, so when it backs up the only fix is having arrived earlier. Outside the departure banks it is often empty.
The plan allows 15 minutes for a standard lane on a busy but normal morning. With TSA PreCheck, that drops to 10 minutes. A checked bag lengthens the one before it.
Just off 101 north of Santa Rosa. For North Bay travelers the comparison is ~15 minutes to STS versus two-plus hours of 101 to SFO. Recheck the route map: destinations that used to mean SFO or OAK may now be nonstop from Santa Rosa.
For live waits, parking, and terminal maps, check the official STS site.
Terminals, checkpoints and transit change; the official STS site is the live source.
Sixty to ninety minutes before departure is enough at STS on most days. Holiday mornings are the main exception. The plan above works back from there through security, bag drop, parking and the drive to a leave-by time.
The plan allows 15 minutes for a busy-but-normal standard lane. With TSA PreCheck it drops to 10 minutes, and you can edit either one to what you actually see. A checked bag lengthens the step before it. Checkpoint detail for STS is under Security at STS above.
Earlier than for a domestic one. International boarding starts 45 minutes before departure instead of 30, which pulls every step earlier. Use the airline desk for bags: documents get checked and counters often close an hour out. That also covers lap infants, unaccompanied minors, and oversized bags. If your boarding pass names a boarding time, match that.
Work backward from departure: boarding, time at the gate, the walk, security, bag drop, parking, then the drive (15 minutes in the default plan). Replace the drive with your own route. The leave-by moment is the first travel row, "Drive to STS" by default.
Taking the train instead? The Amtrak station pages use the same kind of plan without security. Flying from somewhere not listed? The airport leave time calculator has the same rows with your own numbers, and the wake-up time calculator runs it back to the alarm.
Start the plan in the app, and the Lock Screen and Dynamic Island show the time left, with a bar that fills as each step passes.
Glance at it in the terminal without opening the app.
Every step also gets its own alert, and sharing the plan gives whoever is driving the same leave time, with alerts on their phone.
Live Activities are part of Premium, a one-time unlock.
Plans for the rest of the trip
More on being ready on time