Do you need to know, when is the best time to go to USA - United States of America? Then you should take a look here, what weather you can expect there during the year.
The climate of USA is very varied, as United States of America is a large country. The climate is mostly temperate, but tropical in Hawaii and Florida, and arctic in Alaska. This is not all. The climate is semiarid in the great plains west of the Mississippi River, and arid in the Great Basin of the southwest. You can expect low winter temperatures in the northwest, but they are sometimes moderated in January and February by warm winds. Winters in the south are warmer. Don? forget, that temperatures are usually significantly lower in mountains.
As USA - United States of America has a really huge area, the information below relate mostly only to the area around the capital of this country. To see information about other places, please, choose one of these areas: Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, Florida, Georgia (state), Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York (state), North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington (state), West Virginia, Wisconsin, Wyoming, Washington D.C. (details about the weather are below).
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 July, the average maximum temperature is 31.3 ℃ (88.34 ℉). The average minimum temperature in this month is 19 ℃ (66.2 ℉). The coldest month here is January, the average maximum temperature is 5.9 ℃ (42.62 ℉). The average minimum temperature in this month is -4.2 ℃ (24.44 ℉). The most rainy month here is May, the average number of rainy days is 11.9. The least rainy month here is October, the average number of rainy days is 7.6. 
When travelling to some places in USA - United States of America, always consider the altitude of the the place as well. The highest point here is Denali (Mount McKinley) (6190 m) and the lowest point is Death Valley (-86 m). So there are huge differences in altitudes in this country and the weather is very different in them therefore. 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 USA - United States of America in January is this: The average highest temperature in USA - United States of America in January is 5.9 ℃ (42.62 ℉). The average lowest temperature is -4.2 ℃ (24.44 ℉). At the beginning of January you can expect higher temperatures, the average highest temperature is around 7.05 ℃ (44.69 ℉). At the end of January you can expect higher temperatures, the average highest temperature is around 7.1 ℃ (44.78 ℉). The average number of rainy days in January is 9.8. The average rainfall is 66.6 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 9:29 (hours and minutes), in the middle of the month 9:44 and at the end of the month 10:10.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 USA - United States of America in February is this: The average highest temperature in USA - United States of America in February is 8.3 ℃ (46.94 ℉). The average lowest temperature is -3 ℃ (26.6 ℉). At the beginning of February you can expect lower temperatures, the average highest temperature is around 7.1 ℃ (44.78 ℉). At the end of February you can expect higher temperatures, the average highest temperature is around 10.9 ℃ (51.62 ℉). The average number of rainy days in February is 9. The average rainfall is 68 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 10:10 (hours and minutes), in the middle of the month 10:43 and at the end of the month 11:19.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 USA - United States of America in March is this: The average highest temperature in USA - United States of America in March is 13.5 ℃ (56.3 ℉). The average lowest temperature is 0.7 ℃ (33.26 ℉). At the beginning of March you can expect lower temperatures, the average highest temperature is around 10.9 ℃ (51.62 ℉). At the end of March you can expect higher temperatures, the average highest temperature is around 16.45 ℃ (61.61 ℉). The average number of rainy days in March is 10.4. The average rainfall is 84.5 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 11:19 (hours and minutes), in the middle of the month 11:57 and at the end of the month 12:35.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 USA - United States of America in April is this: The average highest temperature in USA - United States of America in April is 19.4 ℃ (66.92 ℉). The average lowest temperature is 5.8 ℃ (42.44 ℉). At the beginning of April you can expect lower temperatures, the average highest temperature is around 16.45 ℃ (61.61 ℉). At the end of April you can expect higher temperatures, the average highest temperature is around 21.95 ℃ (71.51 ℉). The average number of rainy days in April is 10.9. The average rainfall is 88.3 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 12:35 (hours and minutes), in the middle of the month 13:13 and at the end of the month 13:47.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 USA - United States of America in May is this: The average highest temperature in USA - United States of America in May is 24.5 ℃ (76.1 ℉). The average lowest temperature is 11.1 ℃ (51.98 ℉). At the beginning of May you can expect lower temperatures, the average highest temperature is around 21.95 ℃ (71.51 ℉). At the end of May you can expect higher temperatures, the average highest temperature is around 26.7 ℃ (80.06 ℉). The average number of rainy days in May is 11.9. The average rainfall is 114 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 13:47 (hours and minutes), in the middle of the month 14:17 and at the end of the month 14:40.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 USA - United States of America in June is this: The average highest temperature in USA - United States of America in June is 28.9 ℃ (84.02 ℉). The average lowest temperature is 16.1 ℃ (60.98 ℉). At the beginning of June you can expect lower temperatures, the average highest temperature is around 26.7 ℃ (80.06 ℉). At the end of June you can expect higher temperatures, the average highest temperature is around 30.1 ℃ (86.18 ℉). The average number of rainy days in June is 11. The average rainfall is 100.7 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 14:40 (hours and minutes), in the middle of the month 14:52 and at the end of the month 14:51.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 USA - United States of America in July is this: The average highest temperature in USA - United States of America in July is 31.3 ℃ (88.34 ℉). The average lowest temperature is 19 ℃ (66.2 ℉). At the beginning of July you can expect lower temperatures, the average highest temperature is around 30.1 ℃ (86.18 ℉). 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 10.7. The average rainfall is 92.9 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 14:51 (hours and minutes), in the middle of the month 14:39 and at the end of the month 14:16.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 USA - United States of America in August is this: The average highest temperature in USA - United States of America in August is 30.5 ℃ (86.9 ℉). The average lowest temperature is 18.4 ℃ (65.12 ℉). 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 lower temperatures, the average highest temperature is around 28.65 ℃ (83.57 ℉). The average number of rainy days in August is 9.2. The average rainfall is 89.3 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 14:16 (hours and minutes), in the middle of the month 13:46 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 USA - United States of America in September is this: The average highest temperature in USA - United States of America in September is 26.8 ℃ (80.24 ℉). The average lowest temperature is 13.4 ℃ (56.12 ℉). At the beginning of September you can expect higher temperatures, the average highest temperature is around 28.65 ℃ (83.57 ℉). At the end of September you can expect lower temperatures, the average highest temperature is around 23.4 ℃ (74.12 ℉). The average number of rainy days in September is 8.9. The average rainfall is 100.5 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 13:11 (hours and minutes), in the middle of the month 12:35 and at the end of the month 11:57.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 USA - United States of America in October is this: The average highest temperature in USA - United States of America in October is 20 ℃ (68 ℉). The average lowest temperature is 6.8 ℃ (44.24 ℉). At the beginning of October you can expect higher temperatures, the average highest temperature is around 23.4 ℃ (74.12 ℉). At the end of October you can expect lower temperatures, the average highest temperature is around 17.1 ℃ (62.78 ℉). The average number of rainy days in October is 7.6. The average rainfall is 82.8 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 11:57 (hours and minutes), in the middle of the month 11:20 and at the end of the month 10:44.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 USA - United States of America in November is this: The average highest temperature in USA - United States of America in November is 14.2 ℃ (57.56 ℉). The average lowest temperature is 2 ℃ (35.6 ℉). At the beginning of November you can expect higher temperatures, the average highest temperature is around 17.1 ℃ (62.78 ℉). At the end of November you can expect lower temperatures, the average highest temperature is around 11.2 ℃ (52.16 ℉). The average number of rainy days in November is 9.2. The average rainfall is 86.1 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 10:44 (hours and minutes), in the middle of the month 10:11 and at the end of the month 9:45.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 USA - United States of America in December is this: The average highest temperature in USA - United States of America in December is 8.2 ℃ (46.76 ℉). The average lowest temperature is -2.6 ℃ (27.32 ℉). At the beginning of December you can expect higher temperatures, the average highest temperature is around 11.2 ℃ (52.16 ℉). At the end of December you can expect lower temperatures, the average highest temperature is around 7.05 ℃ (44.69 ℉). The average number of rainy days in December is 10.1. The average rainfall is 77.1 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 9:45 (hours and minutes), in the middle of the month 9:29 and at the end of the month 9:26.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.| Washington DC | temperature: - | highest temperature: 8.2 ℃ (46.76 ℉) | lowest temperature: -2.6 ℃ (27.32 ℉) | rainfall: 77.1mm | rainy days: 10.1 |