Sigma has announced that it will repair cameras and lenses that are still under warranty for any damages incurred from Hurricanes Harvey, Irma and Maria. If your item cannot be repaired in a cost effective manner, Sigma will offer a discount on a replacement lens.
From Fstoppers:
Sigma hereby extends the warranty coverage of Sigma products still under warranty for damages incurred as a result of Hurricane Harvey, Irma and Maria. If your equipment is under warranty, Sigma will provide either (a) complimentary service to get your equipment running, or (b) a trade-in option. Just ship your damaged equipment to Sigma, and we will ship the equipment back to you without charge. All terms of your Sigma warranty coverage still apply, so when sending in your Sigma product, please be sure to include a copy of the original sales receipt as proof of purchase date. If you do not have appropriate documentation as a result of the Hurricanes, please contact us. Eligibility for this offer is subject to Sigma’s sole discretion. This offer is open through December 31, 2017 (we must receive your damaged equipment by that date).
So if you're affected, be sure to get in contact with Sigma as soon as possible.