**Thin, warm layers under the car-seat harness, with a blanket over the buckled harness, are the usual solution.** Your approach of clothing plus blankets can work well—as long as the blankets go on after he is strapped in.

**Avoid bulky snowsuits or puffy coats under the harness.** Their padding compresses in a crash, leaving the straps dangerously loose, even when they seemed snug before. A larger car seat doesn’t solve that problem. [NHTSA’s winter car-seat guidance](https://www.nhtsa.gov/keep-your-little-ones-warm-and-safe-their-car-seats)

For everyday trips, you have two practical options:

- **If you carry him in a removable infant car seat:** Keep the seat indoors before departure. Dress him in close-fitting clothing, a thin fleece layer, a hat, mittens, and socks or booties. Buckle him indoors, tighten the harness, then tuck a blanket over him for the walk to the car. Keep his face uncovered. At your destination, carry the seat inside with the blanket still over him.
- **If the seat stays in the car:** Carry him to the car wearing his coat, or wrapped in a blanket with a secure hold. Remove the bulky outer layer, buckle him in, then place the blanket or coat over the harness. At your destination, unbuckle him and put his coat on or wrap him before stepping outside.

The American Academy of Pediatrics recommends thin layers, blankets over the harness, and removing outer coverings as the car warms up. Avoid padded inserts or bunting that goes beneath him or between him and the straps; follow your seat manufacturer’s instructions for accessories. [AAP winter safety tips](https://www.healthychildren.org/English/safety-prevention/on-the-go/Pages/Winter-Car-Seat-Safety-Tips.aspx)

Wanting to keep him warm is reasonable. **Dress for the temperature, wind, and length of the outdoor walk.** A short transfer needs less insulation than an extended walk or outdoor play. For longer exposure, put his full outdoor clothing on before leaving the car. One additional layer compared with a comfortable adult is a useful starting point. [AAP cold-weather guidance](https://www.healthychildren.org/English/safety-prevention/at-play/Pages/Cold-Weather-Safety.aspx)

At around a year old, also check that he still fits the removable seat’s height and weight limits. Keep him rear-facing within his seat’s limits. [NHTSA rear-facing guidance](https://www.nhtsa.gov/car-seats-and-booster-seats/how-install-rear-facing-car-seats)