August is the so-called silly season in the media world, when there is a lack of news from usual sources - debates in Parliament, large court cases, and so on - and the press fills its pages with silly, frivolous stories.
A Dutch acquaintance was telling me that in Dutch the term was 'cucumber time', and this expression exists in German, too (Gurkenzeit). Indeed, cucumber time is in the Oxford English Dictionary, although they link it to tailors. Cucumber was, between the late 17th and the early 19th century, a slang word for a tailor. Cabbage is another vegetable associated with tailors (see this old post).
The summer months were a quiet time for tailors, since their well-to-do clients all left the cities for their country estates. Cucumbers are in season in summer, and presumably were cheap at this time, so the reference is probably that tailors ate a lot of cucumbers at this time of low income. Partridge's Dictionary of Historical Slang also cites the saying 'tailors are vegetarians'.