Holidaymakers concerned about the fall in the value of the pound are being urged to "watch rate movements carefully".
Nick Boden, head of foreign currency provider Post Office Travel Money, warned that "sterling's volatility makes it impossible to predict how exchange rates will behave in the coming weeks". Purchasing 500 US dollars cost around £480 at some points on Monday, compared with approximately £440 on the same day last week.
Mr Boden said: "Our advice for people planning overseas trips is to watch rate movements carefully in the weeks leading up to their departure, and change money at times when the rate rises." Mr Boden noted that sterling's drop in value is "much smaller" against currencies used by European countries.
