Translation:It will rain the whole day tomorrow.
yes you can MayKuroi, it's perfectly natural Danish! Your sentence is more natural/common than the DL-sentence! "Kommer til" can indicate futurum, a prediction. But more frequently it is used in the context of something that just happens: Jeg kom uheldigvis til at skære mig i fingeren (I unfortunately cut my own finger).
"Vil" is used in two different ways. In this case the "vil" indicates futurum - it's a prediction that it will rain tomorrov. Like "Solen vil stå op i morgen klokken 7 og den vil gå ned klokken 6, og så vil jeg spise aftensmad". (The sun will rise at 7 and set at 6 and then I shall have supper).
Another "vil" derives from the verb "at ville". Examples: Jeg vil ikke finde mig i den tone! (I will not accept that tone!), Jeg vil ikke gøre det, jeg hader det (I will not do it, I hate it!), Jeg VIL have den bolle nu! (I WILL have that bun now!).
The latter "predictions" are of a different kind, yes? I think you have the exact same in English: "I will die some day and my will is ... " (I'm a native Dane).
I think having it in the continuous, rather than the passive, doesn't really change its meaning. I can't even think if "to rain" even works in passive, other than maybe "It is being rained on". But I don't think there's a difference between "It will rain" and "It will be raining"
The fixed expression "at komme til" means the following verb occurs in the future. It breaks down to:
Det | kommer til | at regne....
I know it may seem weird to a native English speaker and feels a bit awkward (especially when the literal translation is "to to"), but it's one of those things your have to get used to. There's a few phrasal verbs like this that have the proposition "til" which is then followed by the infinitive marker "at", both having their own functions in the sentence.