What is the most suitable sleeping bag for late spring?

A down-filled sleeping bag is the most suitable choice for late spring because it offers an excellent combination of warmth, lightweight properties, and compressibility. Down insulation provides high warmth-for-weight ratio, making it effective at retaining heat even in cooler temperatures typical of late spring nights. Additionally, down-filled sleeping bags pack down small, making them easy to transport while still providing ample insulation.

While wool has good thermal properties, it can be heavier and bulkier than down, making it less favorable for backpacking or situations where weight is a concern. Foam sleeping bags typically offer less warmth and are generally used for warmer conditions or as liners rather than as standalone bags for cooler nights. Synthetic-filled sleeping bags perform well in wet conditions because they retain some insulation properties even when damp; however, they are generally heavier than comparable down bags and do not pack as small, which could make them less desirable for late spring camping, particularly when the weather can still be cool at night. Therefore, the down-filled sleeping bag is the best choice for the specific conditions of late spring camping.