Help me look at the English translation.

People need to wear heavy clothes.

But the winter in northern China is very warm, so people don't need to wear thick clothes. In Chongqing and Wuhan, it is very hot in summer.

And Beijing, but only for a short time.

Need is not a modal verb here, so we shouldn't add not negation directly, but add the negative negation of the auxiliary verb do.

Still wrong, the penultimate line should be But in the northern China, and an adjective should be used to modify China.