Translation:The weather is not good this month.
- good; excellent; fine; nice; pleasant; agreeable
Usually written using kana alone
[Edit to add: Writing words in kanji that are not supposed to be written in kanji may be a stylistic choice, but as a learner, it may often signal to a native speaker that you don't understand the proper usage.]
I guess you could say something like よくない天気が続いています (yoku nai tenki ga tsuzuite imasu) to say "the weather has not been good", but it's literally saying "the not good weather is continuing" so it's pretty interpretive and probably not that helpful a suggestion. I feel like any translation of this sentence trying to catch the nuance of a tense that doesn't exist in Japanese is going to run into the same problem, but I'm interested to hear any other suggestions because I have a tendency to think very literally.
Yes, you do. It is considered more formal but is used in writing and is correct and quite a common character. It tends to be used more for yoi than ii because it implies more formality, that's all.
For example, if you check the headline of this article from the Asahi Shinbun, there it is.
It's pretty common IMO.
I have downloaded a few apps for kana and kanji on my phone for fun, but usually I just practise/learn by reading and writing. I also have an excellent kanji book and a sanseido waei dictionary (Japanese to English). I would recommend waei dictionaries as it gets you thinking in a Japanese mindset and helps you to learn the rank order of kana which is important for conjugating.
I don't think English speakers say "is not good" for a period as long as a month. "Has not been good" or "will not be good" or "The forecast is not good" but not "The weather is not good". Duolingo doesn't take "Has not been good" or "will not be good" though. Is this just a bad translation and it should take one of those, or am I missing something specific to the meaning of this sentence that makes it that awkward to translate to English?
It means both :)
よく is "often"
but it is also the adverbial form of 良い・よい meaning "good" (which colloquially we use いい for "good" instead with よい being more formal/literary, but the よ～ reading is still used for other inflections such as adverbial よく used to form the negative here よくない "not good")