To find the weight of Gabriel's pumpkin, we need to add the weight of Marcos' pumpkin (1.37 pounds) to the additional weight of 0.24 pounds.
Gabriel's pumpkin weight = Marcos' pumpkin weight + Additional weight
Gabriel's pumpkin weight = 1.37 pounds + 0.24 pounds
Gabriel's pumpkin weight = 1.61 pounds
Therefore, Gabriel's pumpkin weighs 1.61 pounds.