This exact same thread shows up every time the exchange rate or the block rate changes, and lots of times when neither does.
There is no such thing as The Hash Rate
. It isn't measured. It isn't calculated. It isn't real.
Your piddly little CPU could calculate two valid hashes in a row, but that doesn't mean that you got a temporary 5 petahash/sec upgrade.
Whenever you see a graph claiming to show a network hash rate, you need to mentally cross out the graph's title, and write in your own:
How much work I would have needed to do in the past to have a good chance of having generating these blocks myself
Note that this title is 100% past-tense, and that it makes no claims about what really did happen.