wet_dry

The probability is calculated as

where $P_i(W⁄D)$ is the probability of a wet day following a dry day in month $i$, $days_{W⁄D,i}$ is the number of times a wet day followed a dry day in month $i$ for the entire period of record, and $days_{dry,i}$ is the number of dry days in month $i$ during the entire period of record. A dry day is a day with 0 mm of precipitation. A wet day is a day with > 0 mm precipitation.