Direct answer
The “London forex session” is generally the period when major trading activity is associated with London market hours. In practical terms, many traders describe it using a time window in London local time or by converting that window to their own time zone. Because daylight saving time can shift the relationship between London time and other regions, the exact clock times you see depend on the time-zone conversion you apply.
If you need a single, actionable statement: use London time as your reference and confirm the exact session window for your specific broker/platform, since platforms may display times in server time or a different reference.
Explanation: what determines the “time”
A forex “session” is a convention that groups trading activity by geography. The London session is tied to the London trading day rather than to a fixed global moment. Two common assumptions that affect “what time” you mean are:
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Time zone reference: London operates on a local time that changes with daylight saving time. When you convert to another region, the session’s start and end can move by an hour relative to your clock.
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Instrument and trading schedule: Forex pairs trade nearly continuously, but liquidity and spreads can vary during different local market hours. Some brokers/platforms also publish a trading calendar and may reflect server-time conventions.
To make the concept operational, pick one reference you trust (for example, London local time) and then convert consistently.
Example checks (without assuming live data)
To independently verify the timing you’re using:
- Convert time zones explicitly: If your device or platform shows times in your local zone, determine the offset to London for the date you care about.
- Cross-check a “session open” definition: Some pages or tools define session start as a specific hour; others describe it as the window when London liquidity is typically strongest. Treat these as definitions, not guarantees.
- Check holidays: Bank holidays and market closures can reduce liquidity even during “usual” hours.
Limitations and uncertainty
This explanation is informational and bounded. It does not provide real-time or broker-specific session schedules, and it cannot predict future liquidity or market behavior. “London session time” can vary depending on which time zone reference you use and how your platform defines and displays session hours. For any time-critical use, rely on the current primary schedule and your platform’s time conventions rather than a one-time fixed number.