Here are some reasons I have found that can result in fig drop:

1. Unusual weather change

2. Too little water, conversely, too much water

3. Major elementary deficiency: N-P-K, or the minor elements

4. Animals: squirrels and chipmunks in particular; birds of many types either pull/bite off green, unripe figs or partially eat and then drop ripe figs

5. Wind storm

6. Fungal disease

7. Some varieties of figs are just more prone to drop figs, either as: green, unripe figs; soon to be fully ripe; or fully ripe figs

8. High humidity, excessive dampness

9. Fig trees grown in too much shade, or fig fruits growing on the shady side of the tree, especially a large, wide tree

10. No logical reason/explanation; it just happens

If you find a few fallen figs at any time of the year, expect it. Even under the best of all conditions, you will find dropped figs on the ground. Actually, it would be the rare fig tree, in ground or pot cultured, that did not drop a fig from time to time.

Moses