Rank Since: This value indicates the historical rank of the period of interest among analogous periods in the climate division's history. For example, a 60-day precip value ending on March 21st, 2003 may rank as "23rd driest of 83 periods on record". This means that the 2003 rainfall total was compared to 82 other 60-day periods that ended on March 21st and was 23rd smallest value of the group. Ties are indicated by a "t-" preceding the rank.

Percentile Rank: Similar to the "Rank Since" column, except that the rank is given as a percentile ranking. Drier events are nearer to 0th percentile and wetter events are nearer to 100th percentile. For example, a percentile ranking of "72nd" means that the period of interest was wetter than 72 percent of all such periods on record.