Across seasons and calendar dates
Sydney and San Francisco can display different calendar dates for the same instant. Their daylight-saving seasons also differ. Compare dated examples on both sides of the year and use a UTC-based calendar file so that a saved event keeps its instant through each city’s clock changes.
Sydney, AU: Australia/Sydney (city ID: sydney).
San Francisco, US: America/Los_Angeles (city ID: san-francisco).
Does the difference change?
The destination-minus-source differences sampled on the 15th of each month in 2027 are −19h, −18h, −17h. These are dated examples, not a promise of fixed offsets or a complete historical range. A different reference date may have different rules.
| Source date | Sydney | San Francisco |
|---|---|---|
| 2027-01-16 | 10:00 Australian Eastern Daylight Time | 2027-01-15 · 15:00 -1 day · Pacific Standard Time |
| 2027-07-16 | 10:00 Australian Eastern Standard Time | 2027-07-15 · 17:00 -1 day · Pacific Daylight Time |
Daylight-saving rules depend on the city and date. When a local hour is missing or repeated, the converter rejects it or asks which occurrence you mean. Rules can change politically; reconfirm far-future meetings.