Do you need to know, when is the best time to go to Laos? Then you should take a look here, what weather you can expect there during the year.
The climate of Laos is tropical monsoon. The rainy season is from May to November, dry season is from December to April. Stronger rains is usually in Bolovens Plateau in Champasak Province, much less rainfall is in Luang Prabang province. Temperatures in the mountains are considerably lower than in lowlands.
When speaking about the usual weather in this state, the information is relevant for example for these popular places: Ban Nahin, Ban Nakasang, Bokeo Nature Reserve, Bolaven Plateau, Central Laos, Champasak, Don Det, Don Khon, Don Khong, Houay Xai, Luang Namtha, Luang Prabang, Muang Khua, Muang Long, Muang Ngeun, Muang Ngoi Neua, Muang Sing, Muang Xay, Nong Khiaw, Northern Laos, Oudomxai, Pak Lay, Pakbeng, Paksan, Pakse, Paksong, Phongsali, Phonsavan, Phou Khao Khouay National Protected Area, Plain of Jars, Sam Neua, Saravan, Savannakhet, Sayabouly, Si Phan Don, Southern Laos, Tadlo, Tha Khaek, Vang Vieng, Vieng Phoukha, Vieng Xai, Vientiane, Xieng Kok.
Let's look now what weather you can expect in the area around the capital and in many other cities. The warmest month here is April, the average maximum temperature is 34.4 ℃ (93.92 ℉). The average minimum temperature in this month is 24.5 ℃ (76.1 ℉). The coldest month here is December, the average maximum temperature is 28.8 ℃ (83.84 ℉). The average minimum temperature in this month is 17.1 ℃ (62.78 ℉). The most rainy month here is August, the average number of rainy days is 20.6. The least rainy month here is January, the average number of rainy days is 1. 
When travelling to some places in Laos, always consider the altitude of the the place as well. The highest point here is Phu Bia (2817 m) and the lowest point is Mekong River (70 m). So there are quite big differences in altitudes in this country, so you can expect the weather to be different in different altitudes as well. Keep in mind, that the temperature usually decreases by 1.2 - 1.9 ℃ (2.2 - 3.5 ℉) per 200 m (656 ft), depending on the other conditions. (And we should add, that in the very special condition named thermal inversion even the temperature may be higher in higher altitudes.)
Typical (usual) weather in Laos in January is this: The average highest temperature in Laos in January is 29.3 ℃ (84.74 ℉). The average lowest temperature is 16.4 ℃ (61.52 ℉). At the beginning of January you can expect lower temperatures, the average highest temperature is around 29.05 ℃ (84.29 ℉). At the end of January you can expect higher temperatures, the average highest temperature is around 29.55 ℃ (85.19 ℉). The average number of rainy days in January is 1. The average rainfall is 7.6 mm (look here, what this number means). When planning your travel, please, keep in mind, that actual weather may differ from these average values. The length of the day at the beginning of this month is approximately 11:04 (hours and minutes), in the middle of the month 11:10 and at the end of the month 11:20.These numbers above are valid primarily for the capital and the area around it. It is important to say, that the weather may differ significantly in different altitudes, especially in mountains.Typical (usual) weather in Laos in February is this: The average highest temperature in Laos in February is 29.8 ℃ (85.64 ℉). The average lowest temperature is 18.8 ℃ (65.84 ℉). At the beginning of February you can expect lower temperatures, the average highest temperature is around 29.55 ℃ (85.19 ℉). At the end of February you can expect higher temperatures, the average highest temperature is around 31.7 ℃ (89.06 ℉). The average number of rainy days in February is 2. The average rainfall is 13.2 mm (look here, what this number means). When planning your travel, please, keep in mind, that actual weather may differ from these average values. The length of the day at the beginning of this month is approximately 11:20 (hours and minutes), in the middle of the month 11:33 and at the end of the month 11:47.These numbers above are valid primarily for the capital and the area around it. It is important to say, that the weather may differ significantly in different altitudes, especially in mountains.Typical (usual) weather in Laos in March is this: The average highest temperature in Laos in March is 33.6 ℃ (92.48 ℉). The average lowest temperature is 21.3 ℃ (70.34 ℉). At the beginning of March you can expect lower temperatures, the average highest temperature is around 31.7 ℃ (89.06 ℉). At the end of March you can expect higher temperatures, the average highest temperature is around 34 ℃ (93.2 ℉). The average number of rainy days in March is 4. The average rainfall is 33.6 mm (look here, what this number means). When planning your travel, please, keep in mind, that actual weather may differ from these average values. The length of the day at the beginning of this month is approximately 11:47 (hours and minutes), in the middle of the month 12:02 and at the end of the month 12:18.These numbers above are valid primarily for the capital and the area around it. It is important to say, that the weather may differ significantly in different altitudes, especially in mountains.Typical (usual) weather in Laos in April is this: The average highest temperature in Laos in April is 34.4 ℃ (93.92 ℉). The average lowest temperature is 24.5 ℃ (76.1 ℉). At the beginning of April you can expect lower temperatures, the average highest temperature is around 34 ℃ (93.2 ℉). At the end of April you can expect lower temperatures, the average highest temperature is around 33.55 ℃ (92.39 ℉). The average number of rainy days in April is 7.8. The average rainfall is 86.7 mm (look here, what this number means). When planning your travel, please, keep in mind, that actual weather may differ from these average values. The length of the day at the beginning of this month is approximately 12:18 (hours and minutes), in the middle of the month 12:32 and at the end of the month 12:46.These numbers above are valid primarily for the capital and the area around it. It is important to say, that the weather may differ significantly in different altitudes, especially in mountains.Typical (usual) weather in Laos in May is this: The average highest temperature in Laos in May is 32.7 ℃ (90.86 ℉). The average lowest temperature is 25.4 ℃ (77.72 ℉). At the beginning of May you can expect higher temperatures, the average highest temperature is around 33.55 ℃ (92.39 ℉). At the end of May you can expect lower temperatures, the average highest temperature is around 32.05 ℃ (89.69 ℉). The average number of rainy days in May is 14.8. The average rainfall is 243.6 mm (look here, what this number means). When planning your travel, please, keep in mind, that actual weather may differ from these average values. The length of the day at the beginning of this month is approximately 12:46 (hours and minutes), in the middle of the month 12:58 and at the end of the month 13:07.These numbers above are valid primarily for the capital and the area around it. It is important to say, that the weather may differ significantly in different altitudes, especially in mountains.Typical (usual) weather in Laos in June is this: The average highest temperature in Laos in June is 31.4 ℃ (88.52 ℉). The average lowest temperature is 24.7 ℃ (76.46 ℉). At the beginning of June you can expect higher temperatures, the average highest temperature is around 32.05 ℃ (89.69 ℉). At the end of June you can expect higher temperatures, the average highest temperature is around 31.45 ℃ (88.61 ℉). The average number of rainy days in June is 17.8. The average rainfall is 278.5 mm (look here, what this number means). When planning your travel, please, keep in mind, that actual weather may differ from these average values. The length of the day at the beginning of this month is approximately 13:07 (hours and minutes), in the middle of the month 13:11 and at the end of the month 13:11.These numbers above are valid primarily for the capital and the area around it. It is important to say, that the weather may differ significantly in different altitudes, especially in mountains.Typical (usual) weather in Laos in July is this: The average highest temperature in Laos in July is 31.5 ℃ (88.7 ℉). The average lowest temperature is 24.8 ℃ (76.64 ℉). At the beginning of July you can expect lower temperatures, the average highest temperature is around 31.45 ℃ (88.61 ℉). At the end of July you can expect lower temperatures, the average highest temperature is around 30.9 ℃ (87.62 ℉). The average number of rainy days in July is 19.9. The average rainfall is 278.7 mm (look here, what this number means). When planning your travel, please, keep in mind, that actual weather may differ from these average values. The length of the day at the beginning of this month is approximately 13:11 (hours and minutes), in the middle of the month 13:06 and at the end of the month 12:57.These numbers above are valid primarily for the capital and the area around it. It is important to say, that the weather may differ significantly in different altitudes, especially in mountains.Typical (usual) weather in Laos in August is this: The average highest temperature in Laos in August is 30.3 ℃ (86.54 ℉). The average lowest temperature is 25.2 ℃ (77.36 ℉). At the beginning of August you can expect higher temperatures, the average highest temperature is around 30.9 ℃ (87.62 ℉). At the end of August you can expect higher temperatures, the average highest temperature is around 30.6 ℃ (87.08 ℉). The average number of rainy days in August is 20.6. The average rainfall is 332.8 mm (look here, what this number means). When planning your travel, please, keep in mind, that actual weather may differ from these average values. The length of the day at the beginning of this month is approximately 12:57 (hours and minutes), in the middle of the month 12:46 and at the end of the month 12:32.These numbers above are valid primarily for the capital and the area around it. It is important to say, that the weather may differ significantly in different altitudes, especially in mountains.Typical (usual) weather in Laos in September is this: The average highest temperature in Laos in September is 30.9 ℃ (87.62 ℉). The average lowest temperature is 24.1 ℃ (75.38 ℉). At the beginning of September you can expect lower temperatures, the average highest temperature is around 30.6 ℃ (87.08 ℉). At the end of September you can expect higher temperatures, the average highest temperature is around 31.2 ℃ (88.16 ℉). The average number of rainy days in September is 17.2. The average rainfall is 295.8 mm (look here, what this number means). When planning your travel, please, keep in mind, that actual weather may differ from these average values. The length of the day at the beginning of this month is approximately 12:32 (hours and minutes), in the middle of the month 12:17 and at the end of the month 12:02.These numbers above are valid primarily for the capital and the area around it. It is important to say, that the weather may differ significantly in different altitudes, especially in mountains.Typical (usual) weather in Laos in October is this: The average highest temperature in Laos in October is 31.5 ℃ (88.7 ℉). The average lowest temperature is 22.6 ℃ (72.68 ℉). At the beginning of October you can expect lower temperatures, the average highest temperature is around 31.2 ℃ (88.16 ℉). At the end of October you can expect lower temperatures, the average highest temperature is around 30.45 ℃ (86.81 ℉). The average number of rainy days in October is 9.1. The average rainfall is 78.9 mm (look here, what this number means). When planning your travel, please, keep in mind, that actual weather may differ from these average values. The length of the day at the beginning of this month is approximately 12:02 (hours and minutes), in the middle of the month 11:47 and at the end of the month 11:33.These numbers above are valid primarily for the capital and the area around it. It is important to say, that the weather may differ significantly in different altitudes, especially in mountains.Typical (usual) weather in Laos in November is this: The average highest temperature in Laos in November is 29.4 ℃ (84.92 ℉). The average lowest temperature is 19.5 ℃ (67.1 ℉). At the beginning of November you can expect higher temperatures, the average highest temperature is around 30.45 ℃ (86.81 ℉). At the end of November you can expect lower temperatures, the average highest temperature is around 29.1 ℃ (84.38 ℉). The average number of rainy days in November is 2. The average rainfall is 11.1 mm (look here, what this number means). When planning your travel, please, keep in mind, that actual weather may differ from these average values. The length of the day at the beginning of this month is approximately 11:33 (hours and minutes), in the middle of the month 11:20 and at the end of the month 11:10.These numbers above are valid primarily for the capital and the area around it. It is important to say, that the weather may differ significantly in different altitudes, especially in mountains.Typical (usual) weather in Laos in December is this: The average highest temperature in Laos in December is 28.8 ℃ (83.84 ℉). The average lowest temperature is 17.1 ℃ (62.78 ℉). At the beginning of December you can expect higher temperatures, the average highest temperature is around 29.1 ℃ (84.38 ℉). At the end of December you can expect higher temperatures, the average highest temperature is around 29.05 ℃ (84.29 ℉). The average number of rainy days in December is 1. The average rainfall is 2.5 mm (look here, what this number means). When planning your travel, please, keep in mind, that actual weather may differ from these average values. The length of the day at the beginning of this month is approximately 11:10 (hours and minutes), in the middle of the month 11:04 and at the end of the month 11:03.These numbers above are valid primarily for the capital and the area around it. It is important to say, that the weather may differ significantly in different altitudes, especially in mountains.| Vientiane | temperature: - | highest temperature: 28.8 ℃ (83.84 ℉) | lowest temperature: 17.1 ℃ (62.78 ℉) | rainfall: 2.5mm | rainy days: 1 |
| Luangphrabang | temperature: - | highest temperature: 26.3 ℃ (79.34 ℉) | lowest temperature: 14.4 ℃ (57.92 ℉) | rainfall: 12.7mm | rainy days: 1 |
| Savannakhet | temperature: - | highest temperature: 27.5 ℃ (81.5 ℉) | lowest temperature: 14.6 ℃ (58.28 ℉) | rainfall: 2.4mm | rainy days: 1 |
| Pakse | temperature: - | highest temperature: 30.8 ℃ (87.44 ℉) | lowest temperature: 18.5 ℃ (65.3 ℉) | rainfall: 2mm | rainy days: 1 |
| Luangnamtha | temperature: - | highest temperature: 25.7 ℃ (78.26 ℉) | lowest temperature: 14.4 ℃ (57.92 ℉) | rainfall: 34.1mm | rainy days: 6.8 |
| Xiengkhuang | temperature: - | highest temperature: 22.4 ℃ (72.32 ℉) | lowest temperature: 8 ℃ (46.4 ℉) | rainfall: 8.2mm | rainy days: 2 |