Hottest month in Vietnam: April, June or July, by region

Here's a late-May day in the 2026 heatwave, pieced together from people who were out in it. In Hanoi just after noon on 25 May, a temperature sign on Lang Ha Street read 40 degrees and the streets had emptied; the few people outside were covered head to toe. That afternoon someone posted on r/Hanoi that the city was so hot they thought they'd melted, and asked where to go that night. The top reply said it felt like lying on a grill while someone fanned the coals, bún chả style; another answered: "In your room with AC on." In Hue during the same heatwave, traffic on Truong Tien Bridge thinned to a trickle around 1 p.m., and some residents slung hammocks under the bridge for a midday nap. A month later, someone who had visited Da Nang wrote that going outside after 8 a.m. was unbearable.

The hottest month in Vietnam, place by place

Each line gives the month with the highest average temperature at the place's weather station, then our call.

• Ho Chi Minh City: April. Its April mean ties for the warmest on the list. If your dates are fixed, put the walking sights before late morning and the museums after.
• Mekong Delta: April. April is the warmest month at the Can Tho station and also the month of its record high. May is barely cooler, so moving a week won't help; moving the trip will.
• Phu Quoc and Con Dao: May. The islands peak a month after the mainland south, but their record highs stay below the Delta's. If you want beach days in the hot months, we'd pick these islands.
• Da Lat: May, barely. The warmest month here still averages under 20°C. This is the south's escape from April; see the Da Lat dry-season guide for when it's also dry.
• Nha Trang: June, by a hair. May to August sit within a fraction of a degree of each other, so in practice the whole early summer is the hot season.
• Quy Nhon: June and July. The other half of the tie for the warmest mean on the list.
• Hue, Da Nang and Hoi An: June. Hue has the highest average daily high of any place in the table, so it's the stop we'd take out of June first.
• Phong Nha: June and July. The station is in Đồng Hới, not at the caves, and its record high came in April.
• Hanoi and Ninh Binh: July, with June a fraction behind. Hanoi's record high came in June.
• Ha Long Bay: July. Warm, but its record high is the lowest of our northern places apart from Sa Pa.
• Ha Giang: July, with the hottest afternoons and the record high in August, which matters if you're riding the loop.
• Sa Pa: June and July. Like Da Lat, its warmest month stays that cool. This is where to send a northern trip in July.

The mean includes the nights, so it runs well below the afternoon high; compare the two columns. The peak average high is the month with the hottest typical afternoon, which isn't always the warmest month. Both cool outliers are mountain stations: Sa Pa's sits at 1,570 m and Da Lat's at 1,513 m.

On the central coast, the worst days come in May

Average heat peaks in June on the central coast, but the record highs at Hue, Da Nang and Quy Nhon were all set in May, and Phong Nha's in April. Ninh Binh's record came in May too. For a late-spring trip, read the record column as well as the mean.

The 2026 season showed how that plays out. In late May, Vietnam's forecast centre put that heatwave down to a low-pressure area to the west plus the foehn wind, gió Lào in Vietnamese (literally the "Lao wind"), which loses its moisture crossing the Truong Son mountains and comes down hot and dry. The heat built from 8 or 9 in the morning and held until 7 in the evening. Hanoi's Lang station hit 40.7°C on 25 May, and the Ha Dong station reached 41.1°C the next day. The threshold for a heatwave in Vietnam is 35°C.

Those days still fell short of Hanoi's records. Lang's record is 41.8°C, set on 4 June 2017, and the same figure is the June record in the national station tables we used. Ha Dong reached 42.5°C that same day. The national record is higher again: 44.2°C, recorded in Nghe An province on 7 May 2023.

VTV's weather channel (in Vietnamese) covered the peak of that May 2026 heatwave and how long it would last:

Dry heat in the centre, sticky heat in the north

The central coast's hottest months are also its least humid. Mean relative humidity at Hue bottoms out at 74.1% in July, against 90.2% in December, and Da Nang, Quy Nhon and Phong Nha's station all reach their lowest in July or August. Hanoi works the other way: summer humidity sits around 80%, and its least humid month is December.

"Dry" is relative, though. A traveller on r/VietNam described July in Da Nang as "very hot and dry (around 34 to 37) with clear skies", while someone comparing it with California's dry heat said: "Here the humidity is making it awful." Both fit the record: July is the least humid month at the Da Nang station, and its mean relative humidity is still 75.8%.

In the Mekong Delta, April's humidity is close to the yearly low, and it climbs sharply from May. For month-by-month humidity and rain on the coast, see the Hoi An weather guide and the Nha Trang weather guide.

What the forecast number leaves out

The temperature in a forecast is air temperature in a shaded, ventilated box about 2 m off the ground. Vietnam's forecasters warn that on concrete and asphalt it can feel 2 to 4 degrees hotter than that, sometimes more. Their advice for heatwave days is to stay out of direct sun between 11:00 and 16:00, drink before you're thirsty, and avoid stepping straight from the heat into a cold air-conditioned room.

One r/VietNam user's verdict on a summer trip:

"I’d never go to Vietnam again during summer. I spent the entire vacation planning where to go that has air conditioning."

u/bdtv75702 on r/VietNam

In the north, the heat also arrives with the rain: Hanoi's wettest months are June to August. The Vietnam rainy season guide has the months by region.

Our take

Don't build a first trip around the hottest month in Vietnam if you can help it. If April is your month, do the south first and the north last, while Hanoi is still warming up. If it's June or July, there's no lowland escape, so give a few days to Sa Pa or Da Lat, the two mountain stations, where even the warmest month is mild. And if June is fixed, Hue is the stop we'd shorten: it has the hottest afternoons in the table. For the cool end of the year, read our coldest places in Vietnam ranking; for rain, the driest month in Vietnam table; and for the whole split between Hanoi and the south, north vs south Vietnam weather. The when-to-go planner puts it on one route.

How we checked this

On 23 October 2026 we downloaded QCVN 02:2022/BXD, Vietnam's national technical regulation on climate data for construction, and read the mean temperature (A.2), average daily maximum (A.3), record maximum (A.5) and relative humidity (A.10) rows for the 14 stations we use for these places. For each one we found the warmest month, the peak average high and the record month from the twelve monthly values. Ho Chi Minh City has no row in those tables, so its mean comes from the Japan Meteorological Agency's normals for Tan Son Hoa. We checked the 2026 heatwave figures and the forecasters' advice against the Vietnam Meteorological and Hydrological Administration's own bulletins, and the 2023 record against the JMA's annual extremes report.

What this does not tell you

These are station averages and single-day records, not a forecast for your dates. The regulation does not state the period its tables cover, and it was issued in 2022, so it can't include the 2023 national record. Phong Nha uses the Đồng Hới station, not one at the caves, and the Da Nang station stands in for Hoi An. Humidity here is a monthly mean; it doesn't measure how a given afternoon feels.

References

• QCVN 02:2022/BXD, National technical regulation on natural physical and climatic data for construction, tables A.1, A.2, A.3, A.5, A.10: https://datafiles.chinhphu.vn/cpp/files/vbpq/2022/10/02-bxd.pdf. Checked 2026-10-23.
• JMA ClimatView monthly normals, Tan Son Hoa (48900): https://ds.data.jma.go.jp/tcc/tcc/products/climate/climatview/graph_mkhtml_nrm.php?n=48900&y=2026&m=8&e=7&r=1&s=1&k=0. Checked 2026-10-23.
• JMA, Annual Report on Global Extreme Climate Events 2023: https://www.data.jma.go.jp/tcc/tcc/products/climate/annual/annual_2023e.html. Checked 2026-10-23.
• Vietnam Meteorological and Hydrological Administration, "Nắng nóng đặc biệt gay gắt, chuyên gia đưa ra khuyến cáo", 25 May 2026: https://vnmha.mae.gov.vn/nang-nong-dac-biet-gay-gat-chuyen-gia-dua-ra-khuyen-cao-17520.htm. Checked 2026-10-23.
• Vietnam Meteorological and Hydrological Administration, "Diễn biến đợt nắng nóng gay gắt và đặc biệt gay gắt ở Bắc Bộ và các tỉnh thành phố miền Trung", 27 May 2026: https://vnmha.mae.gov.vn/dien-bien-dot-nang-nong-gay-gat-va-dac-biet-gay-gat-o-bac-bo-va-cac-tinh-thanh-pho-mien-trung-17533.htm. Checked 2026-10-23.
• VnExpress International, "Vietnam heatwave to last 2-3 more days as Hanoi hits 40.7 C", 26 May 2026: https://e.vnexpress.net/news/news/environment/vietnam-heatwave-to-last-2-3-more-days-as-hanoi-hits-40-7-c-5078464.html. Checked 2026-10-23.
• VnExpress International, "Vietnam's heatwave hits 40 C, emptying streets as tourists retreat", May 2026: https://e.vnexpress.net/photo/environment/vietnams-heatwave-hits-40-c-emptying-streets-as-tourists-retreat-5078101.html. Checked 2026-10-23.

Photo (cover): Tran Trong Nhan / Wikimedia Commons, CC BY-SA 3.0

Data checked: October 2026.