Why is this incorrect?

If it is rain tomorrow, we won't go to the park.

and why should it be this?

If it rains tomorrow, we won't go to the park.

[edit]Now I added 'Why' in hope it's understood as needing help. Well, I didn't know the sentence is so obviously incorrect, and I still don't understand why. Please help me.

  • Both the sentences are grammatically correct.
    – Khan
    Mar 29, 2015 at 19:09
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    @Khan: I beg to differ - the first one is certainly not.
    – Stephie
    Mar 29, 2015 at 19:18
  • @karlalou I think someone might've mistaken your question as a proofreading question. To me, it's quite clear that it's a grammar question. Mar 29, 2015 at 19:29
  • 4
    @Stephie: I beg to differ. There would obviously be at least an implicit reference to a weather forecast, but grammatically I can't see anything wrong with It's rain tomorrow, but then it'll be sunny for the rest of the week. And even if someone can find an argument to support the idea of that not being "grammatical", the fact of the matter is it's used all the time by native speakers. Many of whom (myself included) would not balk at the minor changes involved in OP's version above. Mar 29, 2015 at 20:44
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    @Stephie I agree with Fumble. "It's rain tomorrow" isn't a common way to express the idea, but it is probably grammatically ok. The first thing I thought of was the expression "rain or shine".
    – ColleenV
    Mar 29, 2015 at 22:03

5 Answers 5


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.

"(The sky) is raining."

"If it (the sky) rains tomorrow, we won't go to the park."

Now we are talking about an action that the sky is taking - it has rained, it will rain, or it is raining. Since we are talking about a state that the sky will be in for some time, we say "it rains".

The reason that the first sentence ("if it is rain") sounds wrong to a native speaker is that they are assuming rain is a verb associated with "it" and thus should be conjugated as such.

  • I got it. Thanks. So when 'it' is used as the subject of the sentence when talking about the weather, the 'it' is the sky! and the weather is the sky's action. Thus 'rain' should be in verb form.
    – karlalou
    Mar 29, 2015 at 23:23
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    Yes, but I think it's worth pointing out that strictly speaking, the "it" in "it's raining" isn't actually "the sky", just as it's not "the air" in "it's foggy", or "the sun" in "it's sunny". And that nobody actually says "the sky is raining" in normal circumstances. Mar 29, 2015 at 23:25
  • @FumbleFingers Absolutely correct! I am also open to suggestions as to what "it" means in this context, because for the life of me I have no idea...
    – user11628
    Mar 29, 2015 at 23:43
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    It's the "generic it", or whatever you want to call it. It's not always necessary that you should be able to identify what it actually is in any given usage (you'd have real problems trying to do that with the first word of this very sentence! :) Mar 30, 2015 at 0:00
  1. *If it is rain tomorrow, we won't go to the park. (ungrammatical)

  2. If it rains tomorrow, we won't go to the park.

Example (1) is ungrammatical when RAIN is a verb. Usually, when we talk about the weather tomorrow, we use a verb, NOT a noun. We don't say:

  • *Tomorrow is rain. (ungrammatical, uses a noun)

Talking about the present

The verb RAIN usually uses the word it as a subject:

  • It's raining today.

In this example we see the Present Continuous is raining. This is because the raining action is happening NOW. Notice that we use is and an -ing form of the verb together.

If we want to say that it rains generally, usually, or often, we use the Present Simple:

  • It rains a lot in London.

Notice that the verb rain has an 'S' here. Also, there is no verb is in this sentence. We don't use BE (am/is/are) as an extra verb in the Present Simple.

Talking about the future

When we want to say that the weather will be rainy tomorrow, there are different ways to do this. If we saw the weather forecast on the television, then we can say:

  • It's raining tomorrow.

If we saw the weather forecast, OR if we just have an idea that it's going to rain, or someone told us, we can say:

  • It'll rain tomorrow. (It will ...)

[There are some other ways too, but they aren't very important for us now.]

Conditionals (The future and if)

In sentences beginning with if or time prepositions like when, before, after, until the sentence often has two parts, two clauses:

  • If A, B.
  • When A, B.
  • After A, B.

We can also make these sentences the other way:

  • B if A.
  • B when A.
  • B after A.

The important grammar here is that we do not like to use will in the A section. We don't like to use will after words like if, after, when. We usually use a normal present tense of the verb.

We can use will in the B section:

  • When I see you tomorrow, I will buy you dinner.
  • After the concert finishes, I will go home.
  • If you're coming tomorrow, we will have a great time.

The Original Poster's examples

The original Poster wants to say they won't go to the park in rainy weather. They are using a sentence with if to talk about the future. If they have seen the weather forecast they can say:

  1. If it's raining tomorrow, I won't go to the park.

Notice that this example uses the present continuous. We need the verb BE ('s) and the -ing form of RAIN.

If the speaker wants to say:

  • If + [It will rain tomorrow] = I won't go to the park

... then they need to change the first sentence, because we don't like to use will after if. We need to use the present simple:

  1. If it rains, I won't go to the park.

Notice that we have two choices. Sentence (3) uses is raining, the Present Continuous. Sentence (4) uses rains, the Present Simple. We can use "is + -ing" OR we can use just the main verb "rains". But! We cannot mix them. We cannot use the verb BE ('s) and -ing! The following example is wrong:

  • If it is rains ..... (ungrammatical. It uses BE, but doesn't use -ing)

Hope this is helpful!

  • Yes it's helpful. So you say "If it's raining tomorrow, …" because you believe the weatherman and almost sure it will rain, right? It's nice to know the way progressive tense is used. Even I know that 'If it is rains' is no good though. Now I'm wondering how to say it when it's sunny in the same way like 'If it rains'. 'If it shines'? I guess I have to post another query.
    – karlalou
    Mar 31, 2015 at 7:22
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    @karlalou No, we usually say if it's sunny. So we usually use the adjectives sunny, cloudy, windy. There is an adjective rainy, but we hardly ever use it! We use the verb RAIN instead! :) Mar 31, 2015 at 10:20
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    I would have corrected the first example simply by adding an -y. "If it is rainy (sunny, windy, cloudy etc.) tomorrow" sounds grammatical to me.
    – Mari-Lou A
    Jun 14, 2015 at 10:52
  • @Mari-LouA Yes, that's a good point! Jun 14, 2015 at 11:05
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    @Mari-LouA Just because I don't think we say it very much, really. That and the fact that it's quite difficult to explain the difference between ascriptive and specifying uses of BE, eg "this is heat" versus "this is hot" :) Jun 14, 2015 at 11:18

As said in the comments, both are fine. However, I would say that the second one:

If it rains tomorrow, we won't go to the park.

sounds much more natural to me. I would be happy with, and would understand

If it is rain tomorrow, we won't go to the park.

but I would always favour the prior (the first one).

  • 2
    Or alternatively, "if it's raining tomorrow, we won't go to the park."
    – Jim
    Mar 30, 2015 at 4:47

((Why is this incorrect?

If it is rain tomorrow, we won't go to the park. and why should it be this?

If it rains tomorrow, we won't go to the park.))

In the sense of "rain" falling from the sky you should say "it rains", where the word rain is a verb. "It is rain tomorrow" is an incorrect sentence; a "day" cannot be "rain"! You should say here "it'll rain tomorrow". However, with conditional "if" you don't use "will" in the same clause. So the correct sentence is "if it rains tomorrow, we won't go out", "if clause" takes the present simple when talking about the possible future.


I don't think it's necessarily "incorrect", the ambiguity comes from the word "it" in this sentence.

"What is the weather forecast for tomorrow?" "It is rain" --> the weather forecast is rain.

It's not regularly used this way though, a "normal" response would be "I've heard it'll be raining tomorrow"

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