I'm seeing how, in the last 2-3 weeks, the traffic towards my website increased 20%. I do not if it's due to the last Google Update or the "Back to work / back to school" effect.

However, I see also that the RPM of my AdSense ads are decreasing also around 20%. I've experienced this behaviour (high traffic + low RPM; low traffic + high RPM) more times, but always

in the weekends (I guess that visitors are more willing to buy online on Saturdays and Sundays, with more free time)

in Christmas time (lower traffic, but full of gift purchases)

I would like to know similar experiences.