The currency exchange rate for the Cuban Convertible Peso (CUC) is at any given moment the exact same as the exchange rate for the American Dollar (USD). For a point of reference, we will use the Euro.
The exchange rate is 1.107138 CUC per Euro (EUR). The average exchange rate was 1.1218 CUC per EUR over the last 90 days. With the high being 1.1456 per EUR and the low 1.0865 EUR for the past three months.
The volatility of the CUC against the Euro was 0.29% over the last 90 days. Perhaps because the CUC is attached to the USD, this is a very low volatility rate. The CUC has fluctuated against the EUR only mildly over the last two years. You can reasonably expect exchange rates to continue to fluctuate at around these levels, barring unforeseen circumstances.