Polar Storm's central mechanic is temperature - your base drifts toward its location's temperature, modified by your personal Furnace, the Alliance Furnace, City heat, and events. Push too far toward the map's center and you'll drop below -20°C, at which point you lose the ability to rally or teleport entirely.
Upgrade your personal High-Heat Furnace first - it raises both temperature and Virus Resistance together, making it the single best early investment. Reinforce the shared Alliance Furnace too; it extends warmth across a wider radius for everyone in the alliance, not just you.
Check the temperature before every advance, especially early on when it's tempting to push toward valuable Dig Sites near the map's center. Losing a march to a cold-lockout is one of the most common early-season mistakes.