Arguably some people might think the what version is more appropriate when the speaker is specifically interested in knowing what the weather actually is (or perhaps will be, later in the day). Conversely, the how version might be more likely if what the speaker wants to know is how the addressee feels about the weather.

0 You can think of it this way: weather is usually referred to as "it" Today it is cold so, the singular be verb gets used It was cold today. I wish it wasn't so cold. I wish it weren't so cold today. is still understandable.

Both foggy and snowing are weather conditions. Roughly speaking both foggy and snowing mean the sky is filled with fog or snow respectively. Snowy, however, is not a weather condition. Snowy is a more general term than snowing, meaning things are covered with snow. It can be snowy and snowing or it can be snowy but not snowing.

0 I wish the weather would improve tomorrow=grammatical. I wish the weather were going to be good tomorrow.=grammatical For it to be grammatical with regard to the future, you have to introduce the expectation, which is expressed using the past continuous subjunctive or regular past continuous to express an unreal situation in the present.

The reason is that in the first sentence, "today is rainy", today is the object being described directly, so you don't need the pronoun 'it'. In the second however, there is a comma so after the comma, the 'it' pronoun is needed to make the sentence correct (hence the 'it's').

Today is a rainy day. In your first sentence, either rainy or raining could fit, depending on what you actually want to say; "... because it is raining" indicates that water is physically falling from the sky right now, while "because it is rainy" indicates that it is the sort of day where rain is extremely likely to happen, but doesn't ...

2. How is the weather forecast? This is asking for the methods used by people who predict the weather. In other words: Can you tell me what charts and formulas are used by people who work in weather offices?

The reason this sentence is confusing is the ambiguous "it is". Depending on what the listener believes you are referring to, the sentence may take on different meanings. "The forecast for today is 'rain' again." "If it (the forecast) is 'rain' tomorrow, we won't go to the park." In this case, "rain" is a quote about the weather. Since it is a quote, it does not have a tense and is correct ...

He need worry about the weather today. He needs worry about the weather today. Mostly we see the use of 'need' as modal verb in negative or interrogative sentences where it takes bare infinitive w...

We say, for example, "It looks like rain today", meaning something along the lines of "From what I can see [of the weather right now], I think it will probably rain later". By the same token, "What does the weather look like?" would usually mean "Based on what you see now, what do you think the weather will be like later today?".