Fluctuations in AdSense revenue can happen for a number of reasons, here’s of them “Advertisers with branding goals usually run cost-per-thousand impressions (CPM) flighted campaigns” to launch new, or remind people about their brand during strategic periods of time. Flighted campaigns help advertisers get most out of their budget. For e.g., instead of taking a $12,000 yearly budget and spending $1,000 p/m, an advertiser might spend $3,000 p/m during strategic periods, and not advertise at all (or as much) during rest of the year. Flighted campaigns with direct response (DR) goals usually use CPC bidding and promote an event, like a sale or a concert. Instead of focusing on engagement and building recognition, DR campaigns strive to elicit a specific response from their target audience (e.g. purchase a concert ticket, go to a holiday sale),” explain Google. Flighted campaigns can be unpredictable, but there’re steps you can take to ensure that you reap benefits when they're running on your sites: Make sure to allow image ads on your sites, as many flighted campaigns use display; Opt into placement targeting so advertisers can find and specifically target your sites; Open above the fold ad blocks since these spots are desirable to advertisers, especially during flighted campaigns; Add information about your sites to Ad Planner Publisher Center to attract advertisers and help them understand value of your sites; Understand your users. This’ll help you anticipate ‘types of advertisers’ who want to target your sites and when they intend to, which can help you to monetize it more efficiently.