JSTOR access has been restored, and should be operating normally.
JSTOR posted an update:
Service Update – October 14, 2015
We are continuing to make progress restoring full access to JSTOR. Users should be able to search, browse, and access most journal articles and primary sources… Access to books as well as journal content published in the most recent few years may be intermittent.
JSTOR is currently experiencing access and authentication issues for a large number of their clients – Temple included. Their technical support is working on the problem, but has not yet provided an ETA for resolution. JSTOR will be posting any updates on this support page.