N.Y. Comp. Codes R. & Regs. tit. 9, § 458.15 – Seasonal signs.

(a) Seasonal signs are signs which inform the highway user of conditions or regulations which are present or in effect for less than the full 12 months of the year. It is not practical to consider a period shorter than two months as a season. The following are acceptable methods of displaying seasonal signs:
1. (1) Erect the sign as a permanent sign and remove or cover it when it is not required.
2. (2) Hinge the sign along its horizontal axis so that one portion may be folded over the other portion to obscure the message.
(b) The height, lateral and longitudinal placements of seasonal signs should comply with the erection specifications for permanently mounted signs.