Weather in Haiphong in May

A hard month. May is a hard month in Haiphong, and worth planning around. You should expect rain on 18 days of the month, which is more days wet than dry.

May ranks 9 of 12 in Haiphong: past the worst of the year but short of December, which is the month to book if the dates are open.

Rain on 18 days, 6 of them heavy. Enough to need a plan B, not enough to need a plan around it. Natural fibres and a second shirt for the day. At 84% nothing dries, including you.

What the averages hide

Averages flatten a month, and this one hides a few things: 21 days top 30 °C, making the heat continuous rather than occasional; the day barely swings — 5.9 °C between the overnight low and the afternoon high. Across the twenty years measured, the hottest May day reached 39.6 °C and the coldest night fell to 19.2 °C, and the wettest single day dropped 73 mm — roughly 43% of the month's rain in one day.

May is statistically steady but not small: the year-to-year variation is modest in relative terms, yet the wettest May on record still delivered 316 mm against 82 mm in the driest. In a month this wet, even a tame spread is a lot of rain in absolute terms — the 168 mm average is a reasonable planning figure, not a promise.

Wind is light at 8.2 km/h, so the temperature on the page is close to the temperature on your skin, and humidity runs at 84%, high enough to notice on the warm days without dominating them.

How May sits in the year

Temperatures hold steady either side: 28.7 °C in April, 30.8 here, 31.2 in June. Nothing about the timing within the month matters much. Rain is the thing that moves: June brings 5 days more of it, so the earlier half of a flexible trip is the safer half.

Daylight in May

May is at or near the longest days of Haiphong's year: 13.1 hours of daylight, gaining 0.4 hours across the month. Evenings are the real gain — dinner outdoors still happens in full light.

Sea temperature

The sea sits at about 27.2 °C in May — warm enough that the water offers no relief from the heat. The sea peaks at 29.9 °C in August and bottoms out at 20.4 °C — water lags the air by a month or two, which is why the best swimming often comes after the best weather.

How busy it gets

Off season. The genuine off season: cheapest by a distance, with the caveat that some tours and restaurants close entirely.

Crowd levels are estimated from climate desirability and school-holiday calendars, not from visitor numbers.

May in Haiphong versus nearby

If Haiphong is one option among several, the nearby comparison is worth making. Hanoi is close enough to be a coin toss — within a degree on temperature, the same number of rain days. Thanh Hóa is close enough to be a coin toss — within a degree on temperature, the same number of rain days.

So: May is a compromise. December is 47 points better and is what Haiphong is actually like at its best — worth moving the trip for if that is possible, and worth adjusting expectations for if it is not.

Every month in Haiphong

See all twelve months in Haiphong, or where else to go in May.