With the advent of the press came a need to report the news to the mass populace. However, sometimes there just isn't "news" left to report.

The "silly season" was coined in Britain in the 1800's. It refers to the August period when there were no parliamentary debates taking place. Newspaper editors were at the end of their wits trying to fill their papers with readable material; material that, of course, was better written and more interesting than their competitors'.

It was during these periods of the year when all kinds of "crazy" stories and opinions would be ventilated; stories of gigantic crops, monstrous births, odd accidents and the like would be plentiful. Columns would be devoted to matters and views that would not at any other time receive consideration. In short, silliness was at a premium.

However, this doesn't mean that good writing didn't occur in the newspapers at this time. The "silly season" was also the best season for satire and witty social commentary, often with a bravado not seen during the rest of the publishing year.

The term is still used by newspaper editors today. In fact, The Guardian newspaper has a whole page on their website devoted to "The Silly Season".

Source: J. C. Hotten's Slang Dictionary (2nd edition), 1902.