The spread is not fixed
The spread — the gap between the buy and sell price — is a live number that moves with the market. A pair that shows a tight spread during busy hours can widen dramatically at quiet times or around news. If your spread suddenly looks huge, it is usually the market, not a broker bug.
Because you pay the spread on every trade, widening spreads directly raise your costs and can trip stop-losses or make a trade unprofitable before it even moves. Knowing when spreads widen lets you avoid the expensive moments.
Liquidity and time of day
Spreads are tightest when lots of buyers and sellers are active. For major currencies that means the busy overlaps of the main trading sessions. Late at night, during the daily rollover period, on weekends for products that trade then, and around holidays, activity thins out and spreads widen — sometimes several times their normal size.
The lesson is simple: the same instrument can be cheap to trade at one hour and expensive at another. If you can, trade the liquid hours for whatever you are trading and steer clear of the thin ones.
News and volatility
Right before and during major economic releases or central-bank announcements, market makers widen spreads to protect themselves from the sudden, unpredictable moves. Spreads can balloon in the seconds around the release and then settle again. Trading straight into that window means paying a much higher cost and risking slippage on top.
Less-traded instruments — exotic currency pairs, small stocks, some commodities — carry wider spreads all the time because fewer participants trade them. That is a structural cost of the instrument, not a temporary blip.
What you can do about it
Practical steps: check the live spread before entering rather than assuming the 'typical' number; favour major, heavily traded instruments during their liquid hours; and avoid opening trades in the moments around scheduled high-impact news unless that is your deliberate strategy.
If your broker's spreads are consistently far wider than others' for the same instrument at the same time, that is worth questioning — but a spread that widens at 2 a.m. or during a rate decision is normal market behaviour, and the answer is usually just to trade at a better time.