CLIMATE OF LAOS: WET AND DRY SEASONS, REGIONAL VARIATIONS

CLIMATE OF LAOS

Climate map for map from 1930 to 1960

Just south of Tropic of Cancer, Laos is a hot, tropical country with a monsoon climate and a rainy season (May to November) and dry season (December to April). The yearly average temperature is about 28̊̊°C (82̊°F), rising to a maximum of 38̊ C (100°F) during April and May. Rainfall is often less than five centimeters (two inches) a month in the dry season and reaches up to 30 centimeters a month in the rainy season. March and April are often the hottest months with temperatures often topping 40̊ C (104̊ F). In the wet season the rains help cool things down.

Humidity is high throughout the year, even during the season of drought. Average daily temperatures in Vientiane range from 14–28°C (57–82°F) in January, the coolest month, and from 23–34°C (73–93°F) in April, the hottest. [Source: Worldmark Encyclopedia of Nations, Thomson Gale, 2007]

Temperatures range from highs of 40°C (104°F) along the Mekong in March-April to lows of 5°C (41°F) in the mountains in January. Humidity averages 70 to 80 percent. Annual rainfall in Laos averages 175 centimeters (69 inches). Most of this rain occurs during the southwest monsoon between May and October. Rainfall ranges from 27 to 229 centimeters (50 to 90 inches) during this period. [Source: Geo-Data: The World Geographical Encyclopedia, Gale Group Inc., 2003]

In April, the hottest month, temperatures in Vientiane normally range between 22°C and 34°C (72°F and 93°F), and in January, the coolest month, between 14°C and 28 °C (57°F and 83°F). However, temperature extremes of 39°C (103°F) (April) and 4°C (39°F) (January) have been recorded. Vientiane's climate is more varied, drier and cooler than that found in Singapore; Jakarta; Indonesia; or Bangkok, Thailand.

The best times to visit are in the cool season from November to February. The hot season from March to May is very dry and certain river trips are not possible. The main holiday seasons when foreign travelers are visible are around Christmas and New Year, early spring and the summer holiday in July and August. Tet-Chinese New Year in late January and February and the May-Day-Golden Week holiday in May are big travel times with Vietnamese, Chinese and other Asians.

Seasons in Laos

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Laos has three major seasons: the hot, the cool, and the wet monsoon seasons. The pronounced rainy season extends from May through October. The cool dry season runs from November through February, and a hot dry season is in March and April. the hot season brings substantially higher temperatures and little rain. Temperatures often reach 40̊ Celsius (104̊ F) throughout the country. Dust, during the dry period, and mud in the wet season, are common but tolerable obstacles.

The climate of Laos roughly divides the year in half. Beginning in late May are five months of heavy tropical rains. Five more months, beginning in December, have high temperatures and little rain. A short spring and autumn connect these rainy and dry seasons. The seasons is Laos are overlapping to some degree. In October, the rains start to taper off and the cool season begins in November, and lasts through February.

The "cool" dry months (December-February) are the best time to travel in Laos as a whole. The temperatures are relatively mild, the days are bright and sunny, and humidity is low. In the mountains, however, it sometimes is cold at night. In the winter a cold high-pressure zone over Tibet clashes with a low pressure zone over the Indian Ocean, bringing cold, dry winds. In Vientiane a minimum temperature of 19 degrees Celsius occurs during January. In mountainous areas, however, temperature drops to as low as 14-15 degrees Celsius during the winter months, and during cold nights, can easily reach the freezing point, especially in December and January in places loke Xieng Khouuane Province.

In the dry season, road travel is easier but the countryside is often brown, hazy and dusty, and smoky from slash and burn agriculture. In most parts of Laos the hot dry season is very hot especially in April and May, before the arrival of the monsoons, when temperatures are often above 100 degrees F everyday. This a good time of year to visit the mountains.

Rainy Season in Laos

In rainy season is from May through October rainfall averages 127 to 229 centimeters (50 to 90 inches). Rainfall can be heavy, particularly in the southern lowlands, resulting in severe flooding. However, without this period of intense precipitation, rice cultivation — the staple of Lao agriculture — would be impossible. [Source: “Culture and Customs of Laos” by Arne Kislenko, Greenwood Press, 2009]

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During the rainy season air masses from the Indian Ocean pass over Southeast Asia, releasing moisture they have picked along the way. Rains tend to fall in short afternoon downpours during the rainy season, when the countryside is lush and green and beautiful but the jungles are full of leeches and dirt roads in remote areas become impassable. It is not unusual for the Mekong River to overflow its banks in late August and early September. With the construction of dikes, however, the incidence of flooding in Vientiane has decreased.

Rainfall is not always adequate for rice cultivation, however, and the relatively high average precipitation conceals years where rainfall may be only half or less of the norm, causing significant declines in rice yields. Such droughts often are regional, leaving production in other parts of the country unaffected.

The rainy season in Laos coincides more or less with the rainy seasons in Vietnam, Cambodia and Burma, but is different from the rainy season on the west coast of Malaysia (from September to November) and rainy season in Singapore, Borneo, Indonesia and the east coast of Malaysia (November to January). The rainy season in southern China is generally most intense in June and July.

Regional Climate Differences in Laos

The temperatures are generally cooler in the highlands and in the north. In the lowlands humidity is generally high and the high temperatures are usually around 32̊C (90̊ F) . The temperatures often drop into the single digits C (40s F) at night in the winter in the northern highlands. In addition, mountainous areas are almost always drier than the low-lying plains.

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Generally, monsoons occur at the same time across the country, although that time may vary significantly from one year to the next. Rainfall also varies regionally, with the highest amounts— 3,700 millimeters annually—recorded on the Bolovens Plateau in Champasak Province. City rainfall stations have recorded that Savannakhét averages 144 centimeters (57 inches) of rain annually; Vientiane receives about 170 centimeters (67 inches) and Luang Prabang receives about 136 centimeters (53 inches), Temperatures range from highs around 40̊ C (104̊ F) along the Mekong in March and April to lows of 5̊C (41F) or less in the uplands of Xiangkhoang and Phôngsali in January.

About 80 percent of the annual rainfall falls in the wet season, with the rainfall amounts varying according to altitude and latitude with the highlands of central Laos and the peaks of the Annamite Chain in southern Laos getting the most rain. Less rain falls in the north The average precipitation is highest in Southern Laos, where the Annamite Mountains receive over 300 centimeters and the Bolovens Plateau gets 250 centimeters annually. In Vientiane rainfall is about 150 to 300 centimeters, Luang Prabang gets about 125 centimeters a year, and the Northern provinces only 100 to 150 centimeters annually.

Storms, Floods and Typhoons in Laos

Natural hazards in Laotian include mainly floods and droughts. Disastrous floods affected Laos, Cambodia and Vietnam during September–October 2000. United Nations agencies determined that deforestation in the upper Mekong region was the main cause of the flooding. [Source: Geo-Data: The World Geographical Encyclopedia, Gale Group Inc., 2003]

Although Laos is a landlocked country, it is regularly affected by tropical storms and typhoons that develop over the western Pacific Ocean and the South China Sea. These systems typically make landfall in Vietnam before moving westward into Laos. By the time they reach Laos, they have usually weakened, but they can still produce heavy rainfall, strong winds, and severe weather.

The typhoon season traditionally begins in July—but large storms can churn up as early as May—and ends in October or November. Although Laos sometimes experiences heavy rain this time of the year it is protected from the high winds by Vietnam (typhoons approach Southeast Asia from the Pacific). The greatest typhoon-related activity occurs during August and September. During these months, storms moving inland from the South China Sea frequently affect northern and central Laos. Even weakened tropical systems can bring large amounts of rain over a short period of time.

Flooding is the most common hazard associated with these storms. Heavy rainfall can cause rivers and streams to rise rapidly, leading to flash floods in valleys and low-lying areas. Floodwaters may damage homes, farmland, roads, and other infrastructure. Landslides are another major threat, particularly in the mountainous regions that cover much of the country. Saturated soils can become unstable after prolonged rainfall, causing mudslides and slope failures. These events can destroy property, block transportation routes, and isolate communities. Tropical storms can also disrupt transportation and communication networks. Flooded roads, damaged bridges, and landslides frequently interrupt travel and the movement of goods. Airports, highways, and rail lines may experience temporary closures during severe weather events.

In recent years, storms such as Typhoons Yagi, Wipha, and Kalmaegi have caused significant flooding and damage in parts of Laos. These events highlight the country's vulnerability to tropical weather systems despite its location away from the coast. Heavy rainfall associated with tropical storms remains one of the most important natural hazards affecting Laos.

Image Sources: Wikimedia Commons

Text Sources: Laos-Guide-999.com,, “Encyclopedia of World Cultures Volume 5: East/Southeast Asia:” edited by Paul Hockings, 1993; National Geographic, New York Times, Washington Post, Los Angeles Times, Smithsonian magazine, Encyclopedia.com, Library of Congress, Live Science, The Conversation, The New Yorker, Time, BBC, CNN, Reuters, Associated Press, AFP, Lonely Planet Guides, Google AI, Wikipedia, The Guardian and various websites, books and other publications.

Last updated June 2026