I was reading a textbook and found this sentence:
海や山もあれるそうです。
I don't understand what the や is doing there with も.
The full piece where it comes from is:
あさっての夕方ごろからくずれるそうです。気温も下がるそうです。海や山もあれるそうです。
And the person was answering to a question about weather forecasts.
Is that supposed to mean something like "Both the sea and the mountain..." or is it just a typo?
あさっての夕方ごろからくずれるそうです。気温も下がるそうです。海や山もあれるそうです。
It's using 山も to say "Adding to / Beside くずれる(=雨が降る/it will rain) and 気温が下がる(temperature will drop), 海や山 will also be rough."
The も in 気温も is being used in the same way: "Adding to / Beside くずれる(the rain), the temperature will drop, too."
The や implies that places/areas other than 海と山 will also be rough. Compare:
海と山が荒れる -- (Just) The sea and mountains will be rough.
海と山も荒れる -- Also, the sea and mountains will be rough.
海も山も荒れる -- (Also,) Both the sea and mountains will be rough.
海や山が荒れる -- The sea and mountains and other places will be rough.
海や山も荒れる -- Also, the sea and mountains and other places will be rough.
や is being used here as the "incomplete" list particle. It implies there are other things which could be included in the list. Contrast this with と、which is used for "complete" lists.
For example:
私の好物はスープやハンバーガーです。 My favorite foods are soup and hamburgers [among other things].
私の好物はスープとハンバーガーです。 My favorite foods are soup and hamburgers [and nothing else].
As for も, it is being used to emphasize that both the sea and mountains are going to be rough.
[EDIT] I'm not a native, but to me if it had said 「海も山も」that would seem to downplay whether or not there are other things that will be rough, and emphasize even more strongly that it is both that will be rough.
It tells that the weather is going bad from around afternoon the day after tomorrow, and the sea and mountains will also have bad weather.
や and も is used to add sea and mountain, to indicate the bad weather is not just there but also has wider scope and impact stretching over sea and mountains.
