I’m not sure if anyone else noticed this kind of pattern. I’ve looked back at my adsense earning back since 2005 and there were always something similar. Adsense earnings started to rise steadily since end of April, bringing May, June and July as being the highest adsense earning months during the year. Things will cool down and get back to normal again at the end of July and start of August.
My own thoughts on why this might be happening:
1. Some businesses in United States and other countries (ex. Australia) have their financial year ends on June and they start to spend heavily in online advertising in May and June each year so that they can write off their profit margins? Knowing that they can claim some of these PPC expenses from tax, businesses/individuals starts spending heavily on PPC?
2. After getting back some tax refunds, businesses/individuals start to see some extra money in hand and decide to run more PPC campaigns?
Anyone else has more ideas on this?