Althought one of our illustrious members really advises against the semi-colon in general, I'm nearly as strongly opposed. However, I would say that three in one paragraph is too many. One is usually more than enough. (No more than one per page is probably more in keeping with how often it's really needed.)
Yoong Liat is entirely correct if your only choices are commas or semi-colons, but at least two of them should be full stops instead. You can also change the middle section to "...the summer, but it was safe..."