9am in Buenos Aires is 5am in San Francisco

Buenos Aires is 4 hours ahead of San Francisco. Buenos Aires runs on America/Argentina/Buenos_Aires (UTC-3); San Francisco runs on America/Los_Angeles (UTC-7). The difference is measured right now; it can shift by one hour during daylight-saving-time transitions.

San Francisco observes daylight saving time — shifting between PST (UTC-8) and PDT (UTC-7) — while Buenos Aires stays on GMT-3 (UTC-3) year-round. The difference is 5 hours in San Francisco’s winter and 4 hours in San Francisco’s summer. Transitions happen in late March and late October for most Northern-Hemisphere DST zones, and late September/early April for Southern-Hemisphere ones — check the current date against the city’s DST schedule before anchoring a meeting at the edge of those windows.

Standard 9-to-5 business hours in Buenos Aires and San Francisco overlap for roughly 4 hours a day. That window lands at 13:00–17:00 in Buenos Aires and 09:00–13:00 in San Francisco. Teams with real-time coordination needs anchor cross-city calls inside it: long enough to cover handovers, short enough that it forces crisp agendas. Outside that window, async is the default — shared docs, recorded updates, and scheduled follow-ups rather than live meetings.

When planning recurring meetings across Buenos Aires and San Francisco, pin them to one city’s local time rather than UTC or the other city’s clock. That way, the meeting time stays stable for the person anchoring the schedule, and the other side absorbs the one-hour drift during DST transitions. The alternative — a meeting pinned to the non-DST city — means the DST city sees the meeting time “move” twice a year, which is how recurring calendar invites end up at 7am on someone’s calendar in October.