For longer shoots we can have more flower buds on the shoots. When growth starts in the spring the terminal buds begin growth first, then the lateral buds begin growth with the buds further down the shoot beginning growth later than those closer to the tip. The first buds out are more susceptible to frost damage and the even in the flowers in the bud we see differences to frost susceptibility. Early frosts will kill more of the early flowers which are most advanced in the cluster and early clusters will have more flowers die than later developing clusters. This means that frost damage will kill more of the buds that have the potential to develop the largest fruit.
Blueberries have a small root system adapted for moist soil conditions.
If they dry out over the course of the growing season the damaging effects can be both immediate and long lasting. Early drought will reduce this years growth and fruit size while late drought will decrease next years crop and growth.