In 2026, Bay Area Rapid Transit (BART) maintains a tiered start-up schedule that varies significantly depending on the day of the week. On weekdays (Monday through Friday), service typically begins at approximately 5:00 AM. On Saturdays, the system starts slightly later, usually around 6:00 AM, and on Sundays, the earliest trains do not begin running until 8:00 AM. It is important to note that these are "system-start" times; the specific arrival of the first train at your local station may be 15 to 30 minutes later depending on its position relative to the end of the line. For travelers heading to San Francisco International (SFO) or Oakland (OAK) airports, BART remains the most reliable early-morning option, though passengers with very early flights (before 6:30 AM) should always verify the specific first-train dispatch from their origin station using the official BART Trip Planner or the "Real-Time Departures" feature in the BART mobile app to avoid missing their boarding window.