An interest rate announcement is one of the key market moving event in the forex market. When the central bank raises the interest rate, it increases the value of the currency. When the interest rate is decreased, the value the currency also goes down.
For example, the US dollar sold off after Donald Trump won the 2016 elections. However, it recovered, and rallied again because of the possibility of rising interest rates. So, it is important that you check your economic calendar for an interest rate statement from the central banks.
Interest rate announcements create huge volatility and hence huge spikes in the forex market. So, you need to be prepared for it, and play the market accordingly.