78% of flights leaving Santa Rosa (STS) arrived on time over the past 12 months, 2 points better than the national average of 76%. About 19 flights leave STS on a typical day; 2.2% were cancelled. 79% pushed back from the gate on time, so most of the lateness is already there when the flight leaves the gate.
At a glance
- Best hour to fly: 6 a.m. (84% on time). Worst: 7 p.m. (63%).
- Best month: April (81%). Worst: December (67%).
- Biggest delay cause: late-arriving aircraft (48% of delay minutes).
- Year on year: improving (75% → 78%).
How late?
The on-time rate treats a flight 20 minutes late the same as one 5 hours late. Here's the split for flights leaving STS: when a flight was late, it was under 45 minutes late 56% of the time. About 1 in 15 flights landed an hour or more late, and 1 in 96 three hours or more; 2.2% were cancelled outright.
- On time or early78%
- 15–30 min late7.5%
- 30–60 min late5.9%
- 1–2 hours late4.1%
- 2–3 hours late1.4%
- 3+ hours late1.0%
- Diverted0.2%
- Cancelled2.2%
Share of all 6,818 scheduled flights, past 12 months, by arrival time against schedule.
Best time of day to fly out of STS
Time of day matters more at STS than almost anything else you control. Flights scheduled to leave at 6 a.m. arrived on time 84% of the time; at 7 p.m. it was 63%, a 21-point gap. Taken together, early departures (5–9 a.m.) ran 83% on time against 70% for the evening bank (5–10 p.m.). Early planes usually start the day at the airport, so they haven't had a chance to pick up delays elsewhere. By evening a late inbound aircraft, a crew running out of duty hours or an afternoon thunderstorm can push one late flight into the next. Cancellations cluster too: 6 a.m. departures were cancelled 7.9% of the time, against 2.2% overall.
Hour × month
Combine the two and the spread is wider still. The most reliable combination at STS was a 7 a.m. departure in July (94% on time); the least, 7 p.m. in May (60%). If you can only move one thing, move the hour. Departure hour usually shifts the odds more than the month does.
Each cell: on-time rate for that departure hour in that calendar month, 2023–2026. Find your travel month, then look along the row for the greenest hour.
Best and worst months
December is the hardest month at STS, with 67% of flights on time across 2023–2026; April is the best at 81%. Winter costs 4 points against autumn. Cancellations peak in December (6.7% of flights).
Airlines at STS
Alaska Airlines runs 79% of departures from STS, so STS is effectively its hub. When Alaska Airlines has a bad day, so does the airport.
| Airline | Departures | On time | Left on time | Cancelled | Typical arrival |
|---|---|---|---|---|---|
| Alaska Airlines | 5,398 | 78% | 80% | 2.7% | −7 min |
| American Airlines | 878 | 74% | 76% | 0.3% | −2 min |
| Southwest Airlines | 542 | 77% | 71% | 0.2% | −7 min |
Why flights are late at STS
Airlines report a cause for every flight that arrives 15 or more minutes late. At STS, 48% of delay minutes came from late-arriving aircraft: the plane showed up late from its previous flight, so the delay started somewhere else. Next is the airlines themselves at 24%. That's why the first flight of the morning is the safest bet: it has no earlier flight to inherit a delay from. Of the 152 cancellations, 76% were blamed on weather.
The average taxi from gate to takeoff is 17 minutes, about typical for a large U.S. airport.
Month by month
Over the latest 12 months 78% of STS departures were on time, against 75% in the 12 months before, an improvement of 3 points. The best recent month was March 2026 (86%); the worst, December 2025 (57%).
Worst cancellation days
The worst single day in the past year was Sunday, Dec 14, 2025, when 44% of 18 scheduled departures were cancelled. Days like that are usually a major storm, a system outage or a holiday peak hitting bad weather. No average predicts them, so on a stormy forecast, check your airline's travel waivers.
| Date | Departures | Cancelled | On time |
|---|---|---|---|
| Dec 14, 2025 | 18 | 44% | 33% |
| Dec 30, 2025 | 18 | 39% | 11% |
| Dec 31, 2025 | 14 | 36% | 57% |
| Dec 12, 2025 | 17 | 35% | 35% |
| Dec 15, 2025 | 18 | 28% | 56% |
| Dec 8, 2025 | 18 | 28% | 50% |
| Dec 9, 2025 | 15 | 27% | 53% |
| Feb 7, 2026 | 12 | 25% | 42% |
| Dec 13, 2025 | 16 | 25% | 38% |
| Jan 31, 2026 | 12 | 25% | 75% |
Last flights of the day
The last flight of the day is a different bet. Across routes from STS, each airline's final departure was cancelled 1.1% of the time, against 3.6% for its earlier flights, so at STS the last flight is actually the steadier one. 0.9% of last flights landed 3+ hours late. The riskiest last flight out was Alaska Airlines to San Diego (2.4% cancelled).
| Last flight to | Airline | Leaves | Cancelled | 3h+ late | On time |
|---|---|---|---|---|---|
| SAN San Diego | Alaska Airlines | 5:56 p.m. | 2.4% | 0.6% | 57% |
| SEA Seattle | Alaska Airlines | 7:23 p.m. | 2.5% | 0.3% | 67% |
| PDX Portland | Alaska Airlines | 7:03 p.m. | 0.9% | 1.7% | 79% |
| BUR Burbank | Alaska Airlines | 2:17 p.m. | 0.7% | 1.3% | 72% |
| PHX Phoenix | American Airlines | 4:12 p.m. | 0.6% | 0.6% | 80% |
| LAX Los Angeles | Alaska Airlines | 5:35 p.m. | 0.3% | 0.9% | 83% |
| SNA Santa Ana | Alaska Airlines | 4:55 p.m. | 0.3% | 0.3% | 84% |
Each airline's last scheduled departure of the day on a route, on days it flies the route at least twice; past 12 months. Riskiest first.
Tips for flying out of STS
- Book the earliest departure you can live with. At STS the 6 a.m. flights do best.
- Traveling in December? Leave extra slack for anything that can't move: cruises, weddings, the last connection of the day.
- Delayed already? Most delays at STS come from late-arriving aircraft. If your inbound plane is late, your flight will be too, whatever the board says.
Routes from STS
Least reliable first. Routes with at least 365 flights a year.
| To | Flights | On time | Cancelled | Typical arrival |
|---|---|---|---|---|
| SAN San Diego | 1,166 | 68% | 4.1% | −2 min |
| PHX Phoenix | 693 | 75% | 0.4% | −2 min |
| SEA Seattle | 684 | 76% | 1.8% | −4 min |
| LAS Las Vegas | 500 | 79% | 2.0% | −6 min |
| BUR Burbank | 799 | 79% | 2.1% | −10 min |
| SNA Santa Ana | 745 | 80% | 0.7% | −6 min |
| LAX Los Angeles | 853 | 81% | 3.6% | −6 min |
| PDX Portland | 847 | 85% | 2.7% | −12 min |
Flights into STS
Arriving rather than leaving? These are the routes into Charles M. Schulz Sonoma, least reliable first. The weakest is from San Diego (71% on time).
| From | Flights | On time | Cancelled |
|---|---|---|---|
| SAN San Diego | 1,166 | 71% | 4.1% |
| LAS Las Vegas | 500 | 75% | 2.0% |
| PHX Phoenix | 693 | 80% | 0.3% |
| SNA Santa Ana | 745 | 80% | 0.5% |
| SEA Seattle | 684 | 80% | 2.6% |
| BUR Burbank | 799 | 81% | 1.9% |
| PDX Portland | 848 | 83% | 1.1% |
| LAX Los Angeles | 854 | 85% | 3.2% |
Questions about STS delays
What is the best time to fly out of STS?
Flights scheduled at 6 a.m.: over the past year 84% of STS departures at that hour arrived on time, against 63% at 7 p.m., the worst hour.
What month has the most flight delays at STS?
December (67% on time). April is the best month (81%).
Why are flights delayed at STS?
The biggest cause was late-arriving aircraft (48% of delay minutes): the plane showed up late from its previous flight, so the delay started somewhere else. Then the airlines themselves (24%).
How often are flights cancelled at STS?
2.2% of scheduled departures over the past 12 months, peaking in December at 6.7%.
Hours are scheduled local departure times. "On time" means arriving less than 15 minutes late at the destination; cancelled and diverted flights count as not on time. Method.