xiān chá tiānqìyùbào.

先 means first or before doing something else. In Mandarin, words like 先 usually go before the main verb they modify.

So:

• 先查天气预报 = first check the weather forecast

This is a very common pattern:

• 先吃饭 = eat first
• 先回家 = go home first
• 先看看 = take a look first

So the order is:

先 + verb + object

Yes. 查 often means to check, to look up, or to investigate.

In this sentence, 查天气预报 means something like:

• check the weather forecast
• look up the weather forecast

It often suggests finding information, especially from a phone, website, app, or other source.

For example:

• 查地图 = check the map
• 查字典 = look up in a dictionary
• 查资料 = look up information

So 查 fits well when you are checking information rather than just casually watching something.

Yes, you can, but the feeling is a little different.

• 看天气预报 = watch/read the weather forecast
• 查天气预报 = check/look up the weather forecast

看 focuses more on viewing the forecast. 查 focuses more on finding out the information.

In modern everyday speech, especially when using a phone, 查天气预报 sounds very natural because people often mean check the forecast rather than literally sit and watch a weather report.

Mandarin often omits the subject when it is already clear from context.

So 先查天气预报 could mean:

• You check the weather forecast first.
• Let’s check the weather forecast first.
• I’ll check the weather forecast first.

The exact subject depends on the situation.

This is very normal in Chinese. If the listener already knows who is supposed to do the action, the subject can be left out.

It can be.

Without more context, 先查天气预报 can sound like:

• an instruction
• a suggestion
• part of a sequence of actions

For example:

• 先查天气预报，再出门。 = First check the weather forecast, then go out.

By itself, it may sound a little direct in some situations. If you want to make it softer or more conversational, you could say:

• 先查一下天气预报吧。
• 你先查一下天气预报。

Adding 一下 and/or 吧 often makes the tone gentler.

Yes. It is a compound word:

• 天气 = weather
• 预报 = forecast

So:

• 天气预报 = weather forecast

This is treated as a normal noun phrase or fixed expression. In everyday Chinese, people usually say the whole thing together as one unit.

You may also hear:

• 看天气预报 = watch/check the weather forecast
• 天气预报说... = the weather forecast says...

Pinyin:

• 先 = xiān (1st tone)
• 查 = chá (2nd tone)
• 天 = tiān (1st tone)
• 气 = qì (4th tone)
• 预 = yù (4th tone)
• 报 = bào (4th tone)

So the full sentence is:

xiān chá tiānqì yùbào

A useful rhythm is:

xiān | chá | tiānqì yùbào

Pay special attention to:

• 先 xiān: sounds like shyen but with an x sound, not English sh
• 查 chá: rising 2nd tone
• 预报 yùbào: both are 4th tone, so they sound firm and falling

Both are possible.

• 先查天气预报 = more direct, shorter
• 先查一下天气预报 = softer, more natural in many conversations

一下 often makes an action sound:

• lighter
• brief
• less abrupt

So if you are talking to a friend or making a suggestion, 先查一下天气预报 may sound more natural.

But the shorter version is still perfectly grammatical and common, especially in instructions, reminders, or notes.

Usually 先 comes after the subject and before the verb:

• 你先查天气预报。 = You check the weather forecast first.
• 我们先查天气预报。 = Let’s check the weather forecast first.

So the common order is:

subject + 先 + verb + object

This is one of the most useful sentence patterns in Mandarin.

A very common pattern is:

先 + action A，再 + action B

Examples:

• 先查天气预报，再决定要不要出去。
  First check the weather forecast, then decide whether to go out.

• 先查天气预报，再收拾行李。
  First check the weather forecast, then pack.

• 先查天气预报，再订票。
  First check the weather forecast, then book tickets.

This 先...再... pattern is extremely common in Mandarin for sequencing actions.

Yes, absolutely.

It sounds natural, especially in modern contexts where someone checks the weather on:

• a phone
• an app
• a website

Native speakers also say things like:

• 我查一下天气预报。 = I’ll check the weather forecast.
• 你查过天气预报了吗？ = Have you checked the weather forecast?
• 先查天气预报吧。 = Let’s check the weather forecast first.

So this is practical, natural everyday Chinese.