OPTION A: Currently, Shanghai is experiencing the rainy seasona rainy spell known as the "plum rain season."¶
OPTION B: Currently, Shanghai is in rainy spell season, which in Chinese is known as the "plum rain period."

VOCABULARY: a rainy spell → a rainy period of time→ 一场雨季 (?)

It sfeemls thatas if we are living in a steam pot, y. You can feel the steam even in the morning when you get out of yourleaving home.

During this period, the humidity wouldcan be so huge that couldigh (/ extreme) that it can make people feel listless, even ill. ¶
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Today is a sunny day, but it's still humid, and hot.

People would normally just call humidity "high". Huge is more for physical size, or in certain situations, occasionally quantity. If you want something more superlative, you could use "extreme".

It sfeemls thatlike we are living in a steam pot, you can feel the steam even in the morning when you get out of your home.

I think those delicious fruits in this season, such as waxberry, peach, and litchi, are compensation from the heavens for the bad weather we have been experiencing.

"the" is better than "those" here as it's your first time mentioning the fruits.

During this period, the humidity wouldcan be so hugeigh that could make people may feel listless, even ill. ¶
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Today is a sunny day, but it's still humid, and hot.

It seems thatas if we are living in a steam pot,; you can feel the steam even in the morning when you get out of your home.

I think those delicious fruits inthat we get this season, such as waxberry, peach, and litchi, are compensations from the heavens for the bad weather we have beenare experiencing.

During this period, the humidity would be so hugebad that could make people feel listless, even ill. ¶
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Today iwas a sunny day, but it's still humid, and hot.

1. We don’t normally talk about conditions with the words “huge” or “big”, instead, we use words like “bad”, “extreme”, or “awful”.
2. “Today is” is normally used when talking about the day currently, normally in conversation, but in this context “today was”, sounds more natural. I’m not to sure how to explain it.

I’m not quite sure what you mean by “listless”, it sounds a little strange but I can understand why you said it. Maybe you meant “lightheaded”? I’m not sure.

It seems that we are living in a steam pot, you can feel the steam even in the morning when you get out of your homo outside.

“Go outside” sounds more natural

I think those deliciouse fruits in this season are delicious, such as waxberryies, peaches, and litchi,es. They are compensations from the heavens for the bad weather we have been experiencing.

1. You haven’t mentioned any fruits up until this point, so you should refer to them as “the fruits”, not “those fruits”.
2. Since you are talking about multiple fruits being delicious, you should make them plural.
3. Since I restructured this sentence, I needed to make the “they are compensations” part its own sentence. Just wanted to say that just in case you were confused, I wanna be as detailed as I can :)

Currently, Shanghai is experiencing thein its rainy season, also known as the plum rain period.

During this period, the humidity would beis so hugeigh that could makit makes some people feel listless, even ill. ¶
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Today is a sunny day, but it' is still humid, and hot.

Using it is, instead of it's lends a bit more weight to your point.

It seems that we ar's like living in a steam pot, you can feel the steam even in the morning whenas you getwalk out of your home.

You could also say, "As you walk out of your home in the morning, the hot, wet air hits your face, like opening a steamer basket" as a way to be more descriptive if you wanted. If you do that make "It's like living in a steam pot" its own sentence.

I think thoseHowever, delicious fruits in this season, such as waxberry, peach, and litchi, areare in season right now: waxberry, peach, lychee. I think this is compensation from the heavens for the bad weather we have been experiencingmisery of the plum rain period.

Concluding with words from your first sentence could tie up everything nicely. You could perhaps connect the name "plum rain period" with the abundance of delicious fruits.

Currently, Shanghai is experiencing the rainy season, also known as the plum rain period.

During this period, the humidity would be so hugeigh that couldit can make people feel listless, even ill. ¶
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Today is a sunny day, but it's still humid, and hot.

It seems thatis as if we are living in a steam pot,; you can feel the steam even in the morning when you get out ofleave your home.

I think those delicious fruits inof this season, such as waxberry, peach, and litchi, are compensation from the heavens for the bad weather we have been experiencing.