The climate of Guangzhou (or Canton), the main city of the Pearl River Delta area, is subtropical, with very mild winters and hot summers, which are rainy and muggy as well.
Here are the average temperatures.
Guangzhou - Average temperatures
MonthJanFebMarAprMayJunJulAugSepOctNovDec
Min (°C)101115192325252524211611
Max (°C)181822262931333331292421
Min (°F)505259667377777775706152
Max (°F)646472798488919188847570

Rainfall is abundant, in fact it is around 1,700 millimetres (68 inches) per year. The rainiest period is from May to September, when the rainfall exceeds 200 mm (8 in) per month, while the least rainy period is from November to January, when the rainfall drops below 50 mm (2 in) per month. Here is the average precipitation.
Guangzhou - Average precipitation
MonthJanFebMarAprMayJunJulAugSepOctNovDecYear
Prec.(mm)4565851802852602302201708040251685
Prec.(in)1.82.63.37.111.210.29.18.76.73.11.6166.3
Days81115161819161613765150

Winter, from December to February, is very mild, with highs around 18/21 °C (64/70 °F). The sun, which shines for roughly half the time in December, gradually becomes less frequent, so that there are more and more days with cloudy skies, fog and drizzle. There may also be windy days. Some days can be pleasantly warm, while in others the temperature can drop to around 10/15 °C (50/59 °F) during the day, and the wind can increase the feeling of cold. Occasionally it can even get cold, with lows close to freezing and highs around 10 °C (50 °F). On 24 January 2016, for the first time since 88 years, there was even a slight snowfall, more abundant on Mount Baiyun, the 382 metre (1,253 feet) high hill overlooking the city, or on the 459 metres (1,505 ft) of the Canton Tower rooftop.

Spring, from March to May, is very mild or pleasantly warm, but the sky is almost always cloudy. In March, a cold wind can still blow, with highs around 13/15 °C (55/59 °F), especially in the first half of the month. Starting from mid-March, with the increase in temperature, the first thunderstorms occur. Already in May, there's a sultry heat, with highs around 29 °C (84 °F), even though it's less intense than in the summer months; moreover, the rains become significant.

The long summer, from June to September, is hot, humid and rainy, with heavy showers or thunderstorms, although the sun shines on average for a few hours per day. Typically, daytime temperatures are around 32/33 °C (89/31 °F), but they quite easily reach 35/36 °C (95/97 °F). The heat is felt because of the urban heat island effect, together with moisture coming from the sea. Luckily, there is widespread use of air conditioning. Usually, the heat remains muggy even at night: lows rarely drop below 23 °C (73 °F), but they can also remain around 26/27 °C (79/81 °F). In the hills around the city and in the cities of the metropolitan area near the sea, at least sea breezes blow. In July, there is often a pause, a period of good weather lasting a week or two.
The probability of typhoons, which bring heavy rains and strong winds for a few days, with the risk of flooding and landslides, is highest in this season.

In the short autumn, in October and November, the rains are rare and generally not abundant, and the sun is a bit more frequent than in the other seasons. In the first part of October the heat can still be muggy, but gradually becomes more pleasant; in this month, however, and sometimes even in the first half of November, tropical cyclones can still arrive. In November, the temperature is generally pleasant, with highs around 24 °C (75 °F), but cool and windy days gradually become more likely, and sometimes, in the second part of the month, it can get a bit cold.

Guangzhou

The amount of sunshine in Guangzhou is not great all year round, and it's scarce from February to April, when the sky is often overcast, while in the rainy season it improves a little because there is an alternation of sun and cloud banks, which can lead to showers and thunderstorms. In autumn, the sunshine amount remains acceptable or improves slightly, however, cloudy days are possible in this season as well.
Guangzhou - Sunshine
MonthJanFebMarAprMayJunJulAugSepOctNovDec
Hours432235766665

The sea is warm enough for swimming April to November, and is definitely warm from May to October. In winter, the South China Sea is cool but not cold: it drops to 18.5/19 °C (64/66 °F) in January and February.
Guangzhou - Sea temperature
MonthJanFebMarAprMayJunJulAugSepOctNovDec
Temp (°C)191820232728292928262421
Temp (°F)666468738182848482797570

Typhoons


As mentioned earlier, Guangzhou can be hit by typhoons, the tropical cyclones of Southeast Asia. Typically, typhoons occur in this area from June to early November, but sometimes they have affected this area outside of this period, as happened in April 2008 with Typhoon Neoguri (or Ambo), and in May 2006 with Typhoon Chanchu (or Caloy).

When to go


It's not easy to find the best time to visit Guangzhou. Winter can be a good period, although especially in the second part the sky is often cloudy; moreover, it can be windy, and sometimes, though rarely, it can be a little cold. Spring is pleasantly warm, but it's still cloudy, and when the sun becomes a little more frequent, the rains begin as well, then by May the air is muggy and there is some risk (though still low) of typhoons. In theory, autumn is the best season, but in October a typhoon can still affect this area, while in November there can be the first cool and windy days, and sometimes at the end of the month, it can already be a little cold. All in all, the best times are from mid-March to mid-April, and from mid-October to late November.

What to pack


In winter: spring/autumn clothes, a sweatshirt or sweater, a jacket, a raincoat or umbrella, a hat for colder days.
In summer: tropics-friendly, lightweight clothing, a light sweatshirt for air-conditioned places, a light raincoat or umbrella.