This site explains China's weather-warning colours in two places already. The typhoon guide sets out the four-colour scale and the instrument behind it. The heat guide does the same for high temperature and notes, correctly, that heat runs on the same machinery.
Neither covers rain. Neither covers fog. Between them those are the two kinds of weather most likely to cost a traveller a day in China — one by shutting a city down where you are standing, the other by shutting the way out.
The framework, in one sentence#
It is the one you have already met: a national scale of blue, yellow, orange and red, defined for every kind of severe weather by a single instrument, with a published standard and a published set of instructions attached to each colour. The typhoon page sets out the instrument and the logic of the colours, including the trap that the more severe the warning, the less notice it carries. This page adds the two weather types it does not cover.
Rain: four colours, and they measure rate rather than depth#
Here is the part that most published guidance gets wrong by describing a rainstorm warning as a rainfall total. It is not. Read the four standards next to each other and the design becomes obvious:
| Colour | The standard |
|---|---|
| Blue | 50 mm or more within 12 hours, or already reached and likely to continue |
| Yellow | 50 mm or more within 6 hours, or already reached and likely to continue |
| Orange | 50 mm or more within 3 hours, or already reached and likely to continue |
| Red | 100 mm or more within 3 hours, or already reached and likely to continue |
Three of the four colours use the same 50 millimetres and change only the window. Blue to orange is one quantity of rain arriving three times faster each step. Only red changes the quantity, and it doubles it inside the shortest window.
So a Chinese rainstorm colour is a statement about how hard it is coming down, which is the thing that actually floods an underpass or a metro entrance. A day of steady drizzle adding up to 60 mm never earns a colour at all.
What each rain colour is meant to stop#
Each signal carries a 防御指南 (fángyù zhǐnán, defence guideline) published with it. The two upper ones are worth reading exactly, because they are where a trip gets interrupted.
Orange:
处于危险地带的单位应当停课、停业
Units in dangerous areas should suspend classes and suspend business.
Red:
停止集会、停课、停业（除特殊行业外）
Assemblies stop, classes stop, business stops — special industries excepted.
Lower down the scale the guidelines are about drainage and traffic rather than closure: blue tells schools and nurseries to take appropriate measures and asks for city, farmland and fish-pond drainage systems to be checked; yellow puts transport departments on control measures for heavily rained sections and traffic guidance where water is standing.
Fog: three colours, and that shape should look familiar#
Fog does not get a blue. The scale starts at yellow, and it runs on visibility and time rather than on any quantity:
| Colour | The standard |
|---|---|
| Yellow | Visibility below 500 m possible within 12 hours, or already below 500 m and at least 200 m, and continuing |
| Orange | Visibility below 200 m possible within 6 hours, or already below 200 m and at least 50 m, and continuing |
| Red | Visibility below 50 m possible within 2 hours, or already below 50 m and continuing |
Three colours instead of four is the same shape the heat warnings take, and for a comparable reason: there is no version of these conditions mild enough to be worth the lowest grade. The national scale has four rungs; individual hazards use as many of them as they need.
Note the red window as well. Rain red looks three hours ahead; fog red looks two. It is the least warning any of these signals gives you.
The red fog guideline is the one that eats a travel day#
The upper fog guidelines are about transport almost exclusively. Yellow tells airports, motorways and ferry terminals to tighten traffic management; orange tells them to tighten dispatch and command. Red is explicit:
有关单位按照行业规定适时采取交通安全管制措施，如机场暂停飞机起降，高速公路暂时封闭，轮渡暂时停航等
Relevant units take traffic safety control measures under their industry rules — airports suspending takeoffs and landings, motorways temporarily closed, ferries temporarily suspended.
That is the sentence to remember, because it maps onto three things this site covers separately. A red fog signal is the weather behind a Chinese flight delay you did not cause and cannot appeal; it is why a long-distance coach does not leave; and it is the condition under which driving yourself in China stops being a choice, because the road is shut rather than merely unpleasant.
Reading the two together#
The two hazards fail you in opposite directions, and the practical response differs.
- Rain hurts you where you are. Metro entrances, underpasses, riverside promenades and hill roads. The colour tells you how fast it is arriving; orange upward, stay off the transport system rather than trying to beat it.
- Fog hurts you on the way out. It is a departure problem, and it is seasonal and regional — inland winter mornings and river valleys far more than summer coasts.
- Check the operator, not only the app. The airline, the rail app and the coach station decide; the signal only tells you which way they are leaning.
- Build the buffer before the last leg. A red fog signal two hours ahead of a morning departure is not a situation you can plan your way out of on the day.
- Standing water is the actual danger in a rainstorm, not the rain. Chinese cities publish flood-point maps for exactly this reason, and an underpass with water across it is the thing that kills people.
- The cold half of the year runs on the same scale. Sandstorm and cold wave signals complete the set, and the red sandstorm guideline goes one step further than the red fog one: it suspends trains as well as flights and motorways.
- Winter has its own two signals. Snow and road ice complete the set, and the road-ice one grades the temperature of the tarmac rather than of the air — the only signal in the system that does.
- Hong Kong and Macau run their own warning systems with different names, different colours and different thresholds — the mainland scale described here does not apply there.
Checked for newer, and it is the same instrument#
The measures behind all of this are recorded on the meteorological administration's own regulations register as China Meteorological Administration Order No. 16 of 12 June 2007, with its status shown as in force and no amendment noted.
The register serves the full text only as a document I could not open from here, so the standards and guidelines quoted above are taken from the meteorological administration's own published pages for each signal rather than from the order itself. The colours, the numbers and the defence guidelines match across those pages.
Frequently asked questions#
What does a red rainstorm warning mean in China?#
That 100 mm of rain or more is expected within three hours, or has already fallen and is likely to continue. The defence guideline published with it calls for assemblies, classes and business to stop, special industries excepted. It is the top of a four-colour scale in which the three lower colours all use 50 mm and differ only in how fast it arrives.
How many levels of fog warning does China have?#
Three — yellow, orange and red. There is no blue fog warning, the same way there is no blue heat warning. Yellow is visibility below 500 m within 12 hours, orange below 200 m within 6 hours, and red below 50 m within 2 hours.
Do Chinese motorways close in fog?#
The red fog signal's defence guideline says so explicitly: relevant units take traffic control measures under their industry rules, with airports suspending takeoffs and landings, motorways temporarily closed and ferries suspended. The closure decision itself is taken by the operator or authority, not by the weather service.
Does a rainstorm warning close schools in China?#
The guideline attached to the orange signal says units in dangerous areas should suspend classes and business, and the red one says classes stop generally. Whether a particular school closes is decided locally by the authority acting on the signal — the warning indicates that closures are in play rather than executing them.
Is a Chinese weather warning legally binding?#
The signal states a meteorological fact against a published standard; the defence guideline published with it states what ought to be done. Neither closes anything by itself. Local governments and operators act on the signal under their own rules, which is why the same colour can produce different closures in different cities.
What is the difference between a rain warning and a typhoon warning in China?#
They are separate signals on the same national scale. The typhoon signals grade wind and the lead time shortens as severity rises; the rainstorm signals grade rainfall rate over three, six or twelve hours. A landfalling typhoon commonly triggers both at once, and they can be at different colours.