"Winter only"
This short statement implies that whatever this comes with is only for use in the 'winter' seasons, by putting 'only' this implies that this is the 'only' time to use it.
"Winter special"
by using 'special' this also implies that it is not always available, by putting 'winter' before this suggests it is a special only for winter months.
Winter special!
Using the season is very specific, then people will know that it is only served in that season.
Limited to winter only!
Limited winter special!
Using the word "limited" specifies that something is not permanent, it is only available for a short time.
The best way is to say that the menu is Seasonal which means that you only have that menu during whatever season it is. This is important because some foods aren't available during all seasons, and some foods you don't want in the summer or winter.
ベストな方法は、 the menu is Seasonal、つまりそのメニューがその季節のかかわらず、季節限定と言うことです。これは全ての季節食べられない食べ物もあれば、夏や冬に食べたくない食べ物もあるので大事なことです。
You can simply using the heading 'Winter Menu' or alternatively 'Winter Special' as using the word 'special' indicates it is only available at certain times.
-Winter only
-Winter Special
Some restaurants change their menus in the different times of the year as maybe some goods/items are not available in the other seasons so a simple way to explain the menu is availabel in the winter only is simply 'winter only' although you could write 'only available in the winter' both would explain what you mean
レストランによって季節ごとにメニューを変える所もあります。その季節にしか食べられないものがあるからかもしれません。
それが冬限定のメニューであるなら、シンプルに 'winter only'（冬季限定）と言えます。他に、'only available in the winter'（冬季限定）と書くこともできます。どちらも「冬季限定」を伝えます。
On a restaurant menu, you want to write that a certain menu is only available in the winter. In this situation, it may be better to be precise (example 2) rather than vague (example 1). What are winter months exactly? Who knows? There are some appropriate example suggestions above.
Often a restaurant likes to provide seasonal food. Seasonal means those foods are only available at certain times of the year. If it was written 'Only available in Winter' on a menu, in the Northern Hemisphere that would mean those foods would be available between approximately October to March and in the Southern Hemisphere it would be between approximately April to September.
レストランではしばしば 'seasonal food'（季節の料理）が提供されます。
'seasonal' はその季節にしか食べられないものを表します。
もし 'Only available in Winter' とメニューに書かれていたら、これは北半球では「だいたい10月から3月まで利用できる」、南半球では「だいたい4月から9月まで利用できる」を意味します。
英会話講師のKOGACHIです(^^)/
おっしゃられている内容は、
winter specialと言えます。
他にも
available only in winter
「冬だけ入手可能である」
のように表現できます(*^_^*)
以上ですm(_)m
少しでも参考になれば幸いです(#^^#)
お困りの時は、いつでも気軽にご質問ください(^0^)/
★★どうぞよろしくお願いもうしあげます★★
see you soon♪
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