Which Month for a Hanoi Motorbike Trip? Reading Climate Normals Instead of Guesswork

Choosing a month for a Hanoi motorbike trip starts with reading a few tables. The World Weather Information Service (WWIS) of the World Meteorological Organization (WMO) lists 1991–2020 monthly averages for Hanoi, Lang Son and Lao Cai. This article reads those tables, adds what Hanoi’s city portal, the Lao Cai provincial portal and the national hydro-meteorological administration say about seasons, cold spells and storms, and lists what the pages leave out.

What a climate normal tells you

Each WWIS page describes its figures as monthly averages for the 30-year period 1991–2020 (Hanoi page footer: 8 April 2026). The columns are mean daily minimum and maximum temperature, total rainfall and the number of rain days (days with at least 0.1 mm of rain). WMO adds that averaging periods and rain-day definitions may differ between countries, so city tables should be compared with care. An average also hides single days: the Hanoi city portal recalls a May 1926 heat spell with a day at 42.8 °C and a January 1955 low of 2.7 °C.

Hanoi climate by month: the WMO table

The table reproduces the WWIS figures for Hanoi.

Reading across, the mean daily maximum runs from 20.0 °C (January) to 33.8 °C (June) and the minimum from 14.6 °C (January) to 26.5 °C (July). Rainfall is lowest in February (19 mm) and highest in August (335 mm); rain days peak at 18 in March, July and August.

Rainfall totals against rain days

The two rain columns do not always move together. From May to September Hanoi’s totals are 188 mm to 335 mm over 14 to 18 rain days, while November and December have 48 mm and 24 mm over 7 days each. March has 55 mm over 18 days, the same day count as August. The Hanoi city portal calls summer (May to August) hot and rainy and winter (November to January) cold and dry, but says the season boundaries are only relative because some years bring early or late cold or long heat. For wet-day decisions, see Hanoi Rainy-Season Riding: A Go-or-Postpone Decision Checklist.

Cold months and cold spells

The national hydro-meteorological administration’s explainer (1 January 2025) says cold air usually arrives from mid-September to mid-June and is strongest from December to February, when clear nights bring frost and ice and, in some years, snow on high mountains. It defines severe cold (rét đậm) as a daily mean of about 13 to 15 °C and harmful cold (rét hại) as a daily mean below 13 °C. The page adds that the daily mean counts only with cloudy or overcast weather, possibly light rain; a clear day with a very cold night and a sunny, very warm afternoon is not counted. The terms are mainly understood for the plains and midlands of northern and north-central Viet Nam and are not applied to mountains, where such cold lasts almost a whole month; the page’s example is Sa Pa, where severe cold lasts almost all of December, January and February. Travel timed to the lunar new year has its own planning questions; see Riding in Hanoi During Tet: Traffic Changes and a Backup Travel Plan.

Lang Son, Lao Cai and Sa Pa

The pages read here hold no monthly table for Sa Pa or Ha Giang, but WWIS lists Lang Son and Lao Cai on the same 1991–2020 basis. The table sets four months side by side.

Lang Son’s January minimum (10.7 °C) is below Hanoi’s (14.6 °C); Lao Cai’s (14.5 °C) is close to it. Lao Cai’s rainfall peaks at 374 mm in August and its July rain days (20.8) exceed Hanoi’s 18, while Lang Son peaks at 238 mm in July.

Sa Pa is outside these tables. The Lao Cai provincial government page (18 September 2025) gives Sa Pa’s annual mean temperature as 15.5 °C against 18.9 to 23.9 °C across the province, and annual rainfall of 2,676.6 mm at its Sa Pa station against 1,696.3 mm at Lao Cai. It describes a cold season from November to March and a hot season from May to October, names July and August as the rainiest months (300 to 500 mm a month) and December to February as the driest (18 to 38 mm a month; a later passage gives 22.0 to 35.0 mm a month for the dry season and 70.2 mm for Sa Pa), and links heavy rain on steep terrain to flash floods and landslides. For the cold season it reports that above 1,500 m there is almost no hot weather and mean temperatures stay under 20 °C, with fog, frost and ice often appearing early in the season, in December and January. For routes beyond the city, see Hanoi to Sapa: Train, Bus or a Multi-Day Motorbike Plan? and Ha Giang from Hanoi: Travel First or Begin the Ride in Hanoi?

Storm timing: one 2025 outlook

Normals do not show storms. A Viet Nam Meteorological and Hydrological Administration page dated 14 May 2025 reports a deputy director of the national forecasting centre as saying that the multi-year average is about 11 to 13 storms or tropical depressions on the East Sea, 5 to 6 of them affecting the mainland. For 2025 the page says activity could concentrate from July to September in northern Viet Nam (Bắc Bộ) and that widespread heavy rain could begin in June in the north. With the ENSO phenomenon likely to stay neutral, the page also says storms may be scattered through the season instead of peaking in a few months, and that flash floods and landslides remain possible, with high risk in vulnerable places in northern mountain provinces. The deputy director adds that this rests on climate patterns and initial conditions and that current model forecasts are usually reliable for under one week. This is a one-year outlook, not a normal.

Reading the tables when choosing dates

No page here ranks months for riding or sets a riding threshold. The tables allow three comparisons.

• Lowest rainfall: Hanoi has 19 mm in February, 24 mm in December and 28 mm in January; Lang Son has 29 mm in February and 30 mm in December; Lao Cai has 24 mm in February and 34 mm in December.
• Fewest rain days: Hanoi has 7 in November and December, Lang Son 7 in November and Lao Cai 6.4 in December.
• Cooler nights: from December to February the mean daily minimum is 14.6 to 16.2 °C in Hanoi, 10.7 to 12.7 °C in Lang Son and 14.5 to 16.6 °C in Lao Cai.

The low-rainfall months overlap with the cold-air season, and March pairs 55 mm of rain with 18 rain days, so the tables show trade-offs rather than a single answer.

What the pages leave out

• Monthly humidity values: only annual means (Hanoi 80 to 82 %; Lao Cai 86 %, Sa Pa 87 %), the Lao Cai page’s note that months differ by 3 to 5 % and its naming of February to May as the most humid months at the Lao Cai and Sa Pa stations.
• Hill towns: no month-by-month table for Sa Pa, Ha Giang or other hill towns, and the WWIS pages state no station height.
• Conflicts: the Hanoi city portal gives annual rainfall above 1,700 mm and about 114 rain days, while the WWIS Hanoi monthly figures add up, by the writer’s own arithmetic, to 164 rain days and 1,628 mm; the pages do not explain the difference, and the portal gives no rain-day definition. The Lao Cai provincial page also gives no averaging period for its climate figures, so they may not match the WWIS 1991–2020 basis.
• Missing elements: extremes, sunshine, UV, wind and visibility by month, and road or landslide conditions by month.
• Storms: only the 2025 outlook above; no storm counts by month for a normal year.
• Riding and rental: no temperature or rainfall limit for riding, and nothing on rental terms or prices.

Sources checked

• WMO World Weather: Hanoi
• WMO World Weather: Lang Son
• WMO World Weather: Lao Cai
• Hanoi city portal: geography and climate
• Lao Cai provincial portal: location and climate
• Hydro-meteorological administration: cold air explainer
• Hydro-meteorological administration: 2025 storm outlook

Thuê xe máy Nguyễn Hà is open 09:00–21:00 daily at Ngõ 5 Nguyễn Văn Cừ, Bồ Đề, Long Biên, Hà Nội (near Gia Lâm bus station). Phone: 0334 699 969.