Swiss chard bolted

Having the same problem with the same variety first time growing chard.
Had this happen with spinach last year.
Maybe its the local weather 

Yeah, one of my chard plants (oriole) has bolted and I'm concerned about the rest. My Swiss chard last year didn't bolt at all. It kept growing and growing leaves until I yanked it out.

It's weird that they've all bolted like that though. I was under the impression that you could grow chard the whole summer through without having to make seasonal sowings like with spinach. We have had some dramatic fluctuations in temperature this year though so that could be a a factor. I'd sow some more if I were you!