A hood assembly for a vehicle includes a hood having a vehicle-rearward edge, a vehicle-forward edge, and a top side. The hood assembly includes an airbag supported by the hood and inflatable to an inflated position. The airbag extends vehicle-forward from the vehicle-rearward edge toward the vehicle-forward edge along the top side in the inflated position. The hood assembly includes a spooler supported by the hood, the airbag being between the vehicle-rearward edge and the spooler. The hood assembly includes a tether extending from the spooler to the airbag.