Daily occurrence of North Atlantic Tropical Cyclones
I've just been working on the latest HURDAT2 data (1851-2012) from the National Hurricane Centre and run some statistics on the daily occurrence of North Atlantic Tropical Cyclones. The graph I've put together illustrates how the season starts usually around mid-May, peaks around the start of September before petering out during December.
The y scale values look a little low and I had to check my maths a number of times, but I think its accurate. The HURDAT2 data has around 48,000 individual track location, these are produced every 6 hours and of course the series runs for 161 years, so all the aggregate totals I have for each day of the year would need dividing by 4 and then 161 to get a daily mean value. If you think different let me know!
Despite all this the shape of the each curves is true whatever the scale - so all I can think is that I had never realised how rare tropical cyclones are even in peak season.