If a STEM field PhD student is not able to be funded for the summer, what do they typically do? I'd imagine they can't afford to take an entire summer off from their research - or they would probably risk not graduating in the standard 5 years in a U.S. program - but at the same time it would be hard for them to support themselves, eg, cover rent and living expenses, if they aren't supported by their parents / family.
Depending on your specific field, and when you've found out summer funding isn't guaranteed or available, I present main options in no particular order:
- Research internship in 'industry' ($ to $$$$$)
- Apply for summer grants to work in another University in different, but hopefully related, research ($ to $$)
- Get a summer job or non-research internship - ideal if it uses some set of related skills to your PhD, but if not, oh well, bills to pay ($ to $$$+)
- As Dawn suggested, a sub-set of summer job is to seek the option to be an instructor, summer teaching assistant, or grader in your University (or a nearby institution), or even being an adjunct for the summer if that option is available to you ($ to $$)
- Vacation, travel, relax rejuvenate, try some hobbies, spend time with friends and family (-$ to -$$$$)
- Focus on your own personal research, free of official obligations (at least -$, due to living expenses)
- Have an existential crisis due to the lack of driving structure which otherwise distracts you from your morality/mortality and the uncertainty inherent in life itself (free, and can stack with other options)
- Choose your own adventure
Above all, I suggest planning ahead - if not for this summer, then for the next one. Most outcomes are uncertain, so judicious planning for multiple applications, budgeting (so you have options on how to spend your summer), and trying to develop a number of options will be important.
Note also that many of the options don't need to - and perhaps should not - take up the entire summer, so you should have the option to try out multiple things. Remember: academic life is a marathon, which extends off into the unknown future until you fade away (go Emeritus) or leave ("go into industry"). That makes the longest ultra-marathon on earth seem short by comparison. No matter what you do, try to change things up a bit, work in some rest and contemplation, friends and family, and a bit of fun for yourself too. If academic life starts to resemble a 24/7/365.25 prison sentence, you might want to reconsider your worldview.
Is the school trying to tell you something? Like go away? If so leave. Assuming not Change Advisors If your advisor is so poorly funded that he can't afford a summer stipend, there is no chance he can afford to equip his lab, and this really does not bode well for his future, and you're probably going down in flames with him if you stay