Daylight saving mismatches shift the whole schedule for a few weeks

[Amanhasnoname]

The United States and Europe change their clocks on different dates, so for a few weeks each year the gap between London and New York is an hour different from normal. Session overlaps move, and so does the timing of the best liquidity.

For a scalper who trades the London-New York overlap, that means the high-volume window is now an hour shorter or longer in terms of the usual clock. News releases at 8:30 am New York land at 12:30 or 1:30 pm London instead of the regular time. Anyone running fixed schedules or EAs with hard-coded hours gets caught.

Broker server time adds another layer. Most brokers use a server clock tied to New York closing, with the offset changing in sync with US daylight saving. Platforms showing GMT plus 2 or plus 3 shift without warning, and indicators using time-of-day logic break unless they adjust.

The simplest defence is writing sessions down in a single timezone, ideally UTC, and checking them twice a year against the calendar.

Have clock changes ever broken an EA or schedule, and how long did it take to notice?