30 second time out during post export

Upon exporting posts from my site, I’m encountering a timeout error after 30 seconds when attempting to export posts by month. This doesn’t occur for every month oddly, only 4 of the 36 months in my archive — I was able to successfully export every month other than these four problematic months.

The error text in the export XML is:

Fatal error: Maximum execution time of 30 seconds exceeded in /home/vsb/public_html/wp-includes/wp-db.php on line 1302.

The line number in the error message is variable depending on the exported file. I’m pretty stumped at this point. Can anyone provide some feedback?