Do you need to know, when is the best time to go to Solomon Islands? Then you should take a look here, what weather you can expect there during the year.
The climate of Solomon Islands is tropical monsoon. Weather is warm and very humid throughout the year, but there are few temperature and weather extremes. The season from November to April has more rainfall.
When speaking about the usual weather in this state, the information is relevant for example for these popular places: East Rennell, Guadalcanal, Honiara, Rennell and Bellona, Santa Cruz Islands.
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 November, the average maximum temperature is 31.2 ℃ (88.16 ℉). The average minimum temperature in this month is 23.7 ℃ (74.66 ℉). The coldest month here is September, the average maximum temperature is 29.6 ℃ (85.28 ℉). The average minimum temperature in this month is 22.6 ℃ (72.68 ℉). The most rainy month here is March, the average number of rainy days is 23. The least rainy month here is August, the average number of rainy days is 16.8. 
When travelling to some places in Solomon Islands, always consider the altitude of the the place as well. The highest point here is Mount Popomanaseu (2335 m) and the lowest point is Pacific Ocean (0 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 Solomon Islands in January is this: The average highest temperature in Solomon Islands in January is 30.6 ℃ (87.08 ℉). The average lowest temperature is 23.8 ℃ (74.84 ℉). At the beginning of January you can expect lower temperatures, the average highest temperature is around 30.6 ℃ (87.08 ℉). At the end of January you can expect higher temperatures, the average highest temperature is around 30.85 ℃ (87.53 ℉). The average number of rainy days in January is 20.7. The average rainfall is 403.9 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 12:37 (hours and minutes), in the middle of the month 12:34 and at the end of the month 12:29.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 Solomon Islands in February is this: The average highest temperature in Solomon Islands in February is 31.1 ℃ (87.98 ℉). The average lowest temperature is 24.1 ℃ (75.38 ℉). At the beginning of February you can expect lower temperatures, the average highest temperature is around 30.85 ℃ (87.53 ℉). At the end of February you can expect lower temperatures, the average highest temperature is around 30.8 ℃ (87.44 ℉). The average number of rainy days in February is 22. The average rainfall is 382.1 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 12:29 (hours and minutes), in the middle of the month 12:23 and at the end of the month 12:16.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 Solomon Islands in March is this: The average highest temperature in Solomon Islands in March is 30.5 ℃ (86.9 ℉). The average lowest temperature is 23.3 ℃ (73.94 ℉). At the beginning of March you can expect higher temperatures, the average highest temperature is around 30.8 ℃ (87.44 ℉). At the end of March you can expect higher temperatures, the average highest temperature is around 30.55 ℃ (86.99 ℉). The average number of rainy days in March is 23. The average rainfall is 431.6 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 12:16 (hours and minutes), in the middle of the month 12:08 and at the end of the month 12:01.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 Solomon Islands in April is this: The average highest temperature in Solomon Islands in April is 30.6 ℃ (87.08 ℉). The average lowest temperature is 23.8 ℃ (74.84 ℉). At the beginning of April you can expect lower temperatures, the average highest temperature is around 30.55 ℃ (86.99 ℉). At the end of April you can expect higher temperatures, the average highest temperature is around 30.85 ℃ (87.53 ℉). The average number of rainy days in April is 21.1. The average rainfall is 259.3 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 12:01 (hours and minutes), in the middle of the month 11:54 and at the end of the month 11:48.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 Solomon Islands in May is this: The average highest temperature in Solomon Islands in May is 31.1 ℃ (87.98 ℉). The average lowest temperature is 22.9 ℃ (73.22 ℉). At the beginning of May you can expect lower temperatures, the average highest temperature is around 30.85 ℃ (87.53 ℉). At the end of May you can expect lower temperatures, the average highest temperature is around 30.9 ℃ (87.62 ℉). The average number of rainy days in May is 19. The average rainfall is 225.9 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 11:48 (hours and minutes), in the middle of the month 11:42 and at the end of the month 11:38.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 Solomon Islands in June is this: The average highest temperature in Solomon Islands in June is 30.7 ℃ (87.26 ℉). The average lowest temperature is 22.9 ℃ (73.22 ℉). At the beginning of June you can expect higher temperatures, the average highest temperature is around 30.9 ℃ (87.62 ℉). At the end of June you can expect lower temperatures, the average highest temperature is around 30.3 ℃ (86.54 ℉). The average number of rainy days in June is 21.5. The average rainfall is 176.1 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 11:38 (hours and minutes), in the middle of the month 11:36 and at the end of the month 11:36.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 Solomon Islands in July is this: The average highest temperature in Solomon Islands in July is 29.9 ℃ (85.82 ℉). The average lowest temperature is 22.8 ℃ (73.04 ℉). At the beginning of July you can expect higher temperatures, the average highest temperature is around 30.3 ℃ (86.54 ℉). At the end of July you can expect lower temperatures, the average highest temperature is around 29.85 ℃ (85.73 ℉). The average number of rainy days in July is 19.8. The average rainfall is 240.3 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 11:36 (hours and minutes), in the middle of the month 11:39 and at the end of the month 11:43.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 Solomon Islands in August is this: The average highest temperature in Solomon Islands in August is 29.8 ℃ (85.64 ℉). The average lowest temperature is 22 ℃ (71.6 ℉). At the beginning of August you can expect higher temperatures, the average highest temperature is around 29.85 ℃ (85.73 ℉). At the end of August you can expect lower temperatures, the average highest temperature is around 29.7 ℃ (85.46 ℉). The average number of rainy days in August is 16.8. The average rainfall is 232.6 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 11:43 (hours and minutes), in the middle of the month 11:48 and at the end of the month 11:54.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 Solomon Islands in September is this: The average highest temperature in Solomon Islands in September is 29.6 ℃ (85.28 ℉). The average lowest temperature is 22.6 ℃ (72.68 ℉). At the beginning of September you can expect higher temperatures, the average highest temperature is around 29.7 ℃ (85.46 ℉). At the end of September you can expect lower temperatures, the average highest temperature is around 29.6 ℃ (85.28 ℉). The average number of rainy days in September is 19. The average rainfall is 216.9 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 11:54 (hours and minutes), in the middle of the month 12:01 and at the end of the month 12:08.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 Solomon Islands in October is this: The average highest temperature in Solomon Islands in October is 29.6 ℃ (85.28 ℉). The average lowest temperature is 23.2 ℃ (73.76 ℉). 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 30.4 ℃ (86.72 ℉). The average number of rainy days in October is 18.7. The average rainfall is 225.5 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 12:08 (hours and minutes), in the middle of the month 12:16 and at the end of the month 12:23.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 Solomon Islands in November is this: The average highest temperature in Solomon Islands in November is 31.2 ℃ (88.16 ℉). The average lowest temperature is 23.7 ℃ (74.66 ℉). At the beginning of November you can expect lower temperatures, the average highest temperature is around 30.4 ℃ (86.72 ℉). At the end of November you can expect lower temperatures, the average highest temperature is around 30.9 ℃ (87.62 ℉). The average number of rainy days in November is 17.8. The average rainfall is 224.1 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 12:23 (hours and minutes), in the middle of the month 12:29 and at the end of the month 12:34.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 Solomon Islands in December is this: The average highest temperature in Solomon Islands in December is 30.6 ℃ (87.08 ℉). The average lowest temperature is 24.2 ℃ (75.56 ℉). At the beginning of December you can expect higher temperatures, the average highest temperature is around 30.9 ℃ (87.62 ℉). At the end of December you can expect lower temperatures, the average highest temperature is around 30.6 ℃ (87.08 ℉). The average number of rainy days in December is 19.1. The average rainfall is 295.6 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 12:34 (hours and minutes), in the middle of the month 12:37 and at the end of the month 12:37.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.