Weather Overview for Sapa Vietnam
Sa Pa is a highland town in the northern Vietnamese frontier province of Lao Cai. Lying in the Hoang Lien Son mountain range, in the eastern extremities of the Himalayas, Sapa enjoys pleasant weather common to all of Vietnam.
Situated at around 1650 m (5413 ft) above sea level, the town of Sa Pa and its surrounding areas has a highly seasonal climate, from a sub-tropical climate during summer seasons to temperate conditions during the winter months.
Dubbed by the French colonist as the ‘Tonkinese Alps’ for its climate and natural beauty, the small village of Sa Pa was transformed into a military convalescent area for ailing French military and civilian personnel, thus paving the way to its present status as a destination for local and foreign tourists.
Lying in the shadows of Vietnam’s highest peak, Pang-Xi-Păng (Fan Si Pan, elevation: 3143m or 10,312ft above sea level), Sapa enjoys relatively cool. Weather throughout the year, averaging at around 15°C-18°C (59°F-64.4°F) mean temperature.
The annual predominant wind that blows from west to east leads to cloud formation at the upper reaches of the Fan Si Pan and produces extremely high humidity. The town of Sa Pa, although less humid than the slopes of the Fan Si Pan Massif, has an annual mean average of 8 percent of humidity, which ranges from a low of 75 percent to a high of 91 percent humidity.
In the highlands of Sa Pa and its surrounding area, the climate can change dramatically within the course of a day. Sa Pa can have weather similar to spring in the morning, midsummer’s warmth and sunshine in midday, an autumnal climate late in the afternoon and the coldness of winter at night.
Sa Pa lies on the tropical region of the planet where summer is marked by rainy season. With a total in mean average rainfall of 2,763mm (108.8in) annually, this area can experience a total maximum average rainfall of 4023mm (158.3in) annually and a total minimum average rainfall of 2,064mm (81.3in) yearly. The wettest months are July and August.
Summer weather in Sa Pa is generally more pleasant than the hot and humid conditions in low lying plains. It is during the summer that people, who come to see the beauty of Sa Pa, may experience its occurring fast changing climate.
Although usually humid, the climate in Sa Pa is tempered by the prevalent cool temperature of the highlands. People who come to Sa Pa to trek the nearby Hoang Lien Son National Park find the area’s summer climate cool and mild, which is very suitable for hiking and trekking. Summer temperatures seldom reach a maximum of 30°C (86°F) even in high summer.
Summer weather in Sa Pa can come as early as the month of May and can last until September. During this five month period, the total precipitation can amount to 1,995mm (78.5in) or about 70 percent of the annual total precipitation.
During the month of July and August, the wettest months of the year, monthly precipitation readings average at 490mm (19.3in) and 670mm (26.4in) respectively. These precipitations transmute to rainfall that is welcomed by local farmers to water their terraced rice paddies along the down slopes of Sa Pa.
Autumn in the highlands of Sa Pa comes as the rains diminish in frequency during the month of October. Autumn does not even last long, barely two months, and at times passes unnoticed except to the local inhabitants of the area. There is a dramatic drop in temperature by four to six degrees.
Winter in the highland town of Sa Pa is from mid-November to late February. The coldest of these months are from December to February when snow falls for one to three days at the Fan Si Pan’s ridges.
Sa Pa’s winter can be best described as, cold, foggy and wet. During winter cloud, fog, drizzle, and frost are common occurrences in Sa Pa. At times even snow can make an appearance like in 2011, when about 10cm of snow fell in the Sa Pa town.
Fog is common during winters in the highlands of Sa Pa occurring 137 days a year on average. There are incidents that some hikers were trapped by heavy fog for a week in the nearby Hoang Lien Son National Park, after starting to hike on a fine sunny day in Sa Pa.
It is common to the indigenous inhabitants of Sa Pa to experience sun mid-morning to noon and later experience wet weather brought about by cold drizzle or mist from the low cloud or fog hanging over the town itself.
During this season, it is uncommon to see the summit of Fan Si Pan Massif peeks through its thick shroud of fog and mist. The low cloud or fog hides the grand vista of Sa Pa during this season. At times, this foggy shroud covers not just the town, but even the valley down below, all the way to the foot of Fan Si Pan Mountain.
Most people stay indoors much of the winter season. The terrace rice paddies are empty, brown and largely obscured. The beautiful scenery is not especially visible at this time; even the vista of the Fan Si Pan is hidden behind a blanket of cloud.
Temperature can go as low as 1°C (34°F) during the night time and at times can plummet to sub-zero temperatures condensing frost along the way.
Precipitation during winter is at its highest during the month of January when there is 140mm (5.5in) precipitation that can be attributed to the drizzle, mist, frost and even snow.
Spring in Sa Pa arrives early in March and signals the start of planting season. Soon the terraced rice paddies on the slopes of Sa Pa will be filled with farmers.
The average temperature by this time is gradually rising until it reaches a maximum of 20°C (68°F) by early May. In early spring, early morning drizzle can happen. The average temperature in spring is around 16°C (60.8°F) with 18°C (64.4°F).
More detail at: http://www.holiday-weather.com/sapa