This got me wondering how could one prove they were from the future (opposite of being able to bring technology with you) if the Butterfly Effect is real and your return changed things?
Natural disasters? Meteor strikes on planets/moons in the solar system and their time and date?
You can know about meteor strikes without time travel. Natural disasters might also be predictable. It only proves you know something others don't. I don't think that even bringing technology from the future is a very good proof – secret government technological developments and international conspiracies, as crazy as they are, are more likely than time travel.
On the other hand, for predicting the future, the butterfly effect doesn't matter at all. It only spoils major events. If you went to the 19th century, even if, say, World War II didn't happen, you can still predict personal computers, cellphones, television shows, spaceflight, the Internet, same-sex marriage, women wearing trousers, medical advances, universal suffrage, skyscrapers, global warming and HIV. Even if you meddle with history, those will still come true, and predicting them all without pre-knowledge is nearly impossible.
Unless you were visited by aliens and read their history books...
ETA: Go tell Charles Babbage that in the future people will have a differential engine in their pocket dedicated to doing discrete Fourier transforms on the colours of moving pictures of other people's cats they sent you over the wireless telegraph to recreate them for you to watch while you take a doody. Totally unthinkable, yet completely inevitable.