Sharknado 2: The Second One, the second installment in Syfy‘s campy disaster franchise, whirled into the ratings last night with 3.9 million viewers and 1.6 million adults 18-49, becoming the channels most watched original movie ever. It dwarfed last summer’s original, which became a surprise hit, soaring 183% in total viewers and 190% among adults 18-49. In the demo, Sharknado 2 topped several broadcast shows last night, including CBS’ Extant, Fox’s So You Think You Can Dance and ABC’s Motive.

The sequel also continued to be a social-media hit, drawing even bigger numbers on Twitter than last year. According to Nielsen’s Twitter TV ratings, it generated 581,000 related tweets from 188,000 unique authors, up from 318,000 tweets by 112,000 users for the original movie just over a year ago.

Syfy estimates that the sequel was the most social movie on TV ever, delivering one billion impressions in Twitter conversations, though Nielsen’s Twitter TV ratings suggest a considerably smaller number, a still very substantial 67.2 million impressions. The movie outstripped all other shows last night in terms of Twitter impact, and by an order of magnitude in every category.

A third Sharknado installment is already in the works.

Twitter TV Ratings Sharknado Night final

Nielsen issues caveats to its numbers for Twitter TV, to wit:

Nielsen Social captures relevant Tweets from three hours before, during and three hours after an episode’s initial broadcast, local time. Unique Audience measures the audience of relevant Tweets ascribed to an episode from when the Tweets were sent until the end of the broadcast day at 5am. The data includes new/live primetime and late fringe episodes only and excludes sports events. For multicast events, networks are listed alphabetically and metrics reflect the highest Unique Audience across all airing networks, denoted with an asterisk.