Riverside winters are mild — overnight lows mostly stay in the 35-45°F range from December through February, with occasional dips into the high 20s during cold-front events. Furnaces run nightly through the cold months but accumulate moderate heating-cycle hours per season, so failure modes skew toward cold-start issues (igniter, flame sensor, pressure switch) rather than wear-out from sustained run hours. Older Wood Streets, Magnolia, and central Arlington homes often have 1990s-era 80% AFUE gas furnaces. These work but waste 20% of the gas they burn. The repair-vs-replace conversation on a 15+ year-old 80% AFUE furnace usually favors replacement with 95%+ AFUE high-efficiency equipment, which qualifies for SoCalGas rebates of $200-$800 depending on tier. Newer Mission Grove, Orangecrest, Canyon Crest tract homes typically run 90-95% AFUE condensing furnaces with cleaner failure modes — usually pressure switch or condensate trap issues, not heat exchanger cracks.