Daylight saving: the weeks when the session clock lies
Posted: Fri Oct 30, 2026 6:16 am
US clocks change on one weekend in March and one in November. Europe changes on different weekends, a few weeks apart in spring and a week or so apart in autumn. For those short gaps, the time difference between London and New York shifts, and the overlap between the two sessions grows or shrinks by an hour.
Consequences: the London open lands at a different time relative to the US data releases, and a strategy built around a fixed clock time can suddenly be an hour out of sync with the market.
Example: a scalper trades the first fifteen minutes after the London open, using the platform's server time. When Europe changes its clocks but the broker's server time follows the US schedule, the setup drifts by an hour without anyone noticing. The result is trades taken in a quiet window, mistaken for the open.
Also, the Sydney and Tokyo sessions don't change clocks in the northern hemisphere's pattern, so Asian open times shift relative to everything else.
The fix is dull but important: use UTC or a market-based reference for all session rules, and check the calendar twice a year.
Anyone been caught out by a daylight saving shift? What was the symptom?
Consequences: the London open lands at a different time relative to the US data releases, and a strategy built around a fixed clock time can suddenly be an hour out of sync with the market.
Example: a scalper trades the first fifteen minutes after the London open, using the platform's server time. When Europe changes its clocks but the broker's server time follows the US schedule, the setup drifts by an hour without anyone noticing. The result is trades taken in a quiet window, mistaken for the open.
Also, the Sydney and Tokyo sessions don't change clocks in the northern hemisphere's pattern, so Asian open times shift relative to everything else.
The fix is dull but important: use UTC or a market-based reference for all session rules, and check the calendar twice a year.
Anyone been caught out by a daylight saving shift? What was the symptom?