August had the highest global ACE value -- Accumulated Cyclone Energy -- of any August since records began in 1970. [data]
It's not a perfect metric of cyclonic energy -- it doesn't include a storm's size, for example, as I wrote about here and here-- but it does seem the most popular and the most published.
Of course, August also saw the highest sea-surface temperatures according to HadSST3 data (since 1850) and NOAA data (since 1880). Just a coincidence I'm sure.