To build on the good answers from superkret and nemo…
The survival Rule of 3’s says that, depending on your situation, you can generally survive:
- three weeks without food.
- three days without drinkable water.
- three hours in a harsh environment (extreme heat or cold).
- three minutes without breathable air, or in icy water.
Finding a way to stay warm and dry at night should probably be your primary concern. Hypothermia kills fast.
This is basically how the city of Richland, Washington came into its present form. During the Manhattan Project the federal government took over the town and some adjacent villages, evicting about 300 people, and built it into a bedroom community that eventually housed about 25,000 people for the nearby Hanford site.