Do you need to know, when is the best time to go to Samoa? Then you should take a look here, what weather you can expect there during the year.
The climate of Samoa is tropical. You can usually expect warm and sunny weather around the year. But keep in mind, that rainy season is from November to April, dry season is from May to October.
When speaking about the usual weather in this state, the information is relevant for example for these popular places: Apia, Savaii, Upolu.
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 December, the average maximum temperature is 31.1 ℃ (87.98 ℉). The average minimum temperature in this month is 23.5 ℃ (74.3 ℉). The coldest month here is September, the average maximum temperature is 29.4 ℃ (84.92 ℉). The average minimum temperature in this month is 23.8 ℃ (74.84 ℉). The most rainy month here is January, the average number of rainy days is 0. The least rainy month here is January, the average number of rainy days is 0. 
When travelling to some places in Samoa, always consider the altitude of the the place as well. The highest point here is Mount Silisili (1857 m) and the lowest point is Pacific Ocean (0 m). So the differences in altitudes in this country are not negligible and you should expect the weather to be different in places in different altitudes. 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 Samoa in January is this: The average highest temperature in Samoa in January is 30.9 ℃ (87.62 ℉). The average lowest temperature is 23.8 ℃ (74.84 ℉). At the beginning of January you can expect higher temperatures, the average highest temperature is around 31 ℃ (87.8 ℉). At the end of January you can expect lower temperatures, the average highest temperature is around 30.5 ℃ (86.9 ℉). The average number of rainy days in January is 0. The average rainfall is 491 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 12:55 (hours and minutes), in the middle of the month 12:50 and at the end of the month 12:43.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 Samoa in February is this: The average highest temperature in Samoa in February is 30.1 ℃ (86.18 ℉). The average lowest temperature is 24.3 ℃ (75.74 ℉). At the beginning of February you can expect higher temperatures, the average highest temperature is around 30.5 ℃ (86.9 ℉). At the end of February you can expect higher temperatures, the average highest temperature is around 30.15 ℃ (86.27 ℉). The average number of rainy days in February is 0. The average rainfall is 364.3 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 12:43 (hours and minutes), in the middle of the month 12:33 and at the end of the month 12:21.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 Samoa in March is this: The average highest temperature in Samoa in March is 30.2 ℃ (86.36 ℉). The average lowest temperature is 23.7 ℃ (74.66 ℉). At the beginning of March you can expect lower temperatures, the average highest temperature is around 30.15 ℃ (86.27 ℉). At the end of March you can expect lower temperatures, the average highest temperature is around 30.2 ℃ (86.36 ℉). The average number of rainy days in March is 0. The average rainfall is 350.9 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 12:21 (hours and minutes), in the middle of the month 12:10 and at the end of the month 11:58.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 Samoa in April is this: The average highest temperature in Samoa in April is 30.2 ℃ (86.36 ℉). The average lowest temperature is 24.6 ℃ (76.28 ℉). At the beginning of April you can expect lower temperatures, the average highest temperature is around 30.2 ℃ (86.36 ℉). At the end of April you can expect higher temperatures, the average highest temperature is around 30.35 ℃ (86.63 ℉). The average number of rainy days in April is 0. The average rainfall is 210 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 11:58 (hours and minutes), in the middle of the month 11:47 and at the end of the month 11:37.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 Samoa in May is this: The average highest temperature in Samoa in May is 30.5 ℃ (86.9 ℉). The average lowest temperature is 23.4 ℃ (74.12 ℉). At the beginning of May you can expect lower temperatures, the average highest temperature is around 30.35 ℃ (86.63 ℉). At the end of May you can expect lower temperatures, the average highest temperature is around 30.1 ℃ (86.18 ℉). The average number of rainy days in May is 0. The average rainfall is 189.5 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 11:37 (hours and minutes), in the middle of the month 11:28 and at the end of the month 11:22.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 Samoa in June is this: The average highest temperature in Samoa in June is 29.7 ℃ (85.46 ℉). The average lowest temperature is 23.6 ℃ (74.48 ℉). At the beginning of June you can expect higher temperatures, the average highest temperature is around 30.1 ℃ (86.18 ℉). At the end of June you can expect higher temperatures, the average highest temperature is around 30.05 ℃ (86.09 ℉). The average number of rainy days in June is 0. The average rainfall is 121.5 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 11:22 (hours and minutes), in the middle of the month 11:18 and at the end of the month 11:18.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 Samoa in July is this: The average highest temperature in Samoa in July is 30.4 ℃ (86.72 ℉). The average lowest temperature is 23.2 ℃ (73.76 ℉). At the beginning of July you can expect lower temperatures, the average highest temperature is around 30.05 ℃ (86.09 ℉). At the end of July you can expect lower temperatures, the average highest temperature is around 30.05 ℃ (86.09 ℉). The average number of rainy days in July is 0. The average rainfall is 123.5 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 11:18 (hours and minutes), in the middle of the month 11:22 and at the end of the month 11:28.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 Samoa in August is this: The average highest temperature in Samoa in August is 29.7 ℃ (85.46 ℉). The average lowest temperature is 23.3 ℃ (73.94 ℉). At the beginning of August you can expect higher temperatures, the average highest temperature is around 30.05 ℃ (86.09 ℉). At the end of August you can expect lower temperatures, the average highest temperature is around 29.55 ℃ (85.19 ℉). The average number of rainy days in August is 0. The average rainfall is 115.2 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 11:28 (hours and minutes), in the middle of the month 11:37 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 Samoa in September is this: The average highest temperature in Samoa in September is 29.4 ℃ (84.92 ℉). The average lowest temperature is 23.8 ℃ (74.84 ℉). At the beginning of September you can expect higher temperatures, the average highest temperature is around 29.55 ℃ (85.19 ℉). At the end of September you can expect higher temperatures, the average highest temperature is around 29.6 ℃ (85.28 ℉). The average number of rainy days in September is 0. The average rainfall is 151.1 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 11:47 (hours and minutes), in the middle of the month 11:58 and at the end of the month 12:10.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 Samoa in October is this: The average highest temperature in Samoa in October is 29.8 ℃ (85.64 ℉). The average lowest temperature is 23.4 ℃ (74.12 ℉). At the beginning of October you can expect lower temperatures, the average highest temperature is around 29.6 ℃ (85.28 ℉). At the end of October you can expect higher temperatures, the average highest temperature is around 29.9 ℃ (85.82 ℉). The average number of rainy days in October is 0. The average rainfall is 228.4 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 12:10 (hours and minutes), in the middle of the month 12:21 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 Samoa in November is this: The average highest temperature in Samoa in November is 30 ℃ (86 ℉). The average lowest temperature is 24.1 ℃ (75.38 ℉). At the beginning of November you can expect lower temperatures, the average highest temperature is around 29.9 ℃ (85.82 ℉). At the end of November you can expect higher temperatures, the average highest temperature is around 30.55 ℃ (86.99 ℉). The average number of rainy days in November is 0. The average rainfall is 255.4 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 12:42 and at the end of the month 12:50.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 Samoa in December is this: The average highest temperature in Samoa in December is 31.1 ℃ (87.98 ℉). The average lowest temperature is 23.5 ℃ (74.3 ℉). At the beginning of December you can expect lower temperatures, the average highest temperature is around 30.55 ℃ (86.99 ℉). At the end of December you can expect lower temperatures, the average highest temperature is around 31 ℃ (87.8 ℉). The average number of rainy days in December is 0. The average rainfall is 366.4 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 12:50 (hours and minutes), in the middle of the month 12:55 and at the end of the month 12:56.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.