Direct answer
Volatility is often observed as low in Forex around Sunday and, sometimes, early Monday because the market can have lower and less stable liquidity during those periods, while participant activity and order flow change when trading resumes. Also, the way volatility is measured (time window and sampling) can make weekend gaps and reopening conditions appear smoother than weekday movement.
Explanation: liquidity, market reopening, and measurement
Volatility means how much exchange rates move over time. In Forex, that movement is shaped by liquidity: how many participants are willing to trade at the prices available in the order books and matching systems.
Around Sunday, trading for many retail venues and liquidity providers resumes after the weekend. Even if quotes exist, the “effective” liquidity—how many active orders are actually interacting—may be thinner or more uneven. Lower liquidity can produce two seemingly opposite effects: (1) larger jumps when there are not enough orders to absorb demand, or (2) reduced continuous movement if fewer participants actively trade or if price updates occur less frequently in your data feed. Which one you see depends on the instrument, the broker feed, and the exact time window used.
On Monday, volatility can remain muted early because the order flow during reopening and the first active sessions may not fully match midweek conditions. As more participants return and spreads and execution conditions normalize, volatility may increase later in the day. If you look at only the earliest candles, you may capture a period where activity is still ramping up.
Finally, measurement choices matter. For example, using short candles, missing weekend data, or calculating volatility on a time series that effectively “smooths” returns can make Sunday/Monday volatility appear lower than it would using continuous, gap-aware methods.
Example or checks
Independent checks you can do without assuming outcomes:
- Compare multiple volatility definitions (e.g., high-low range per candle vs. standard deviation of returns) to see whether the “low” result is method-specific.
- Contrast early Monday candles with later Monday candles to look for a ramp-up rather than a permanent low-volatility condition.
- Review whether your data feed includes weekend gaps and how it handles illiquid hours; different feeds can change the same calculation.
Limitations and uncertainty
This explanation is general and conditional. It does not guarantee that volatility will be low for every pair, broker, or feed, and it can differ by market microstructure and data handling. Your observed “low volatility” may reflect measurement settings and session definitions rather than a true lack of price uncertainty. Treat Sunday/Monday patterns as variability in trading conditions, not as a fixed rule.