Do you need to know, when is the best time to go to Holy See (Vatican City)? Then you should take a look here, what weather you can expect there during the year.
The climate of Holy See (Vatican City) is the same as the climate of Rome. You can expect mild and quite rainy winters - from September to May, and usually hot and dry summers - from May to September. The temperatures are affected by the fact, that this is a city - and cities are usually warmer.
When speaking about the usual weather in this state, the information is relevant for example for these popular places: Holy See (Vatican City).
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 August, the average maximum temperature is 32.2 ℃ (89.96 ℉). The average minimum temperature in this month is 17.9 ℃ (64.22 ℉). The coldest month here is January, the average maximum temperature is 12.6 ℃ (54.68 ℉). The average minimum temperature in this month is 2.5 ℃ (36.5 ℉). 
Typical (usual) weather in Holy See (Vatican City) in January is this: The average highest temperature in Holy See (Vatican City) in January is 12.6 ℃ (54.68 ℉). The average lowest temperature is 2.5 ℃ (36.5 ℉). At the beginning of January you can expect higher temperatures, the average highest temperature is around 13.05 ℃ (55.49 ℉). At the end of January you can expect higher temperatures, the average highest temperature is around 13.55 ℃ (56.39 ℉). The average rainfall is 83.3 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 9:10 (hours and minutes), in the middle of the month 9:27 and at the end of the month 9:57.These numbers above are valid primarily for the capital and the area around it.
Typical (usual) weather in Holy See (Vatican City) in February is this: The average highest temperature in Holy See (Vatican City) in February is 14.5 ℃ (58.1 ℉). The average lowest temperature is 3.6 ℃ (38.48 ℉). At the beginning of February you can expect lower temperatures, the average highest temperature is around 13.55 ℃ (56.39 ℉). At the end of February you can expect higher temperatures, the average highest temperature is around 15.55 ℃ (59.99 ℉). The average rainfall is 76.4 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 9:57 (hours and minutes), in the middle of the month 10:33 and at the end of the month 11:14.These numbers above are valid primarily for the capital and the area around it.Typical (usual) weather in Holy See (Vatican City) in March is this: The average highest temperature in Holy See (Vatican City) in March is 16.6 ℃ (61.88 ℉). The average lowest temperature is 5 ℃ (41 ℉). At the beginning of March you can expect lower temperatures, the average highest temperature is around 15.55 ℃ (59.99 ℉). At the end of March you can expect higher temperatures, the average highest temperature is around 18.4 ℃ (65.12 ℉). The average rainfall is 67.7 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 11:14 (hours and minutes), in the middle of the month 11:56 and at the end of the month 12:39.These numbers above are valid primarily for the capital and the area around it.Typical (usual) weather in Holy See (Vatican City) in April is this: The average highest temperature in Holy See (Vatican City) in April is 20.2 ℃ (68.36 ℉). The average lowest temperature is 7.6 ℃ (45.68 ℉). At the beginning of April you can expect lower temperatures, the average highest temperature is around 18.4 ℃ (65.12 ℉). At the end of April you can expect higher temperatures, the average highest temperature is around 22.2 ℃ (71.96 ℉). The average rainfall is 68.4 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 12:39 (hours and minutes), in the middle of the month 13:20 and at the end of the month 13:59.These numbers above are valid primarily for the capital and the area around it.
Typical (usual) weather in Holy See (Vatican City) in May is this: The average highest temperature in Holy See (Vatican City) in May is 24.2 ℃ (75.56 ℉). The average lowest temperature is 11.3 ℃ (52.34 ℉). At the beginning of May you can expect lower temperatures, the average highest temperature is around 22.2 ℃ (71.96 ℉). At the end of May you can expect higher temperatures, the average highest temperature is around 26.35 ℃ (79.43 ℉). The average rainfall is 47.7 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 13:59 (hours and minutes), in the middle of the month 14:33 and at the end of the month 14:58.These numbers above are valid primarily for the capital and the area around it.
Typical (usual) weather in Holy See (Vatican City) in June is this: The average highest temperature in Holy See (Vatican City) in June is 28.5 ℃ (83.3 ℉). The average lowest temperature is 14.7 ℃ (58.46 ℉). At the beginning of June you can expect lower temperatures, the average highest temperature is around 26.35 ℃ (79.43 ℉). At the end of June you can expect higher temperatures, the average highest temperature is around 29.8 ℃ (85.64 ℉). The average rainfall is 40 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 14:58 (hours and minutes), in the middle of the month 15:12 and at the end of the month 15:12.These numbers above are valid primarily for the capital and the area around it.Typical (usual) weather in Holy See (Vatican City) in July is this: The average highest temperature in Holy See (Vatican City) in July is 31.1 ℃ (87.98 ℉). The average lowest temperature is 17.4 ℃ (63.32 ℉). At the beginning of July you can expect lower temperatures, the average highest temperature is around 29.8 ℃ (85.64 ℉). At the end of July you can expect higher temperatures, the average highest temperature is around 31.65 ℃ (88.97 ℉). The average rainfall is 23.2 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 15:12 (hours and minutes), in the middle of the month 14:57 and at the end of the month 14:31.These numbers above are valid primarily for the capital and the area around it.Typical (usual) weather in Holy See (Vatican City) in August is this: The average highest temperature in Holy See (Vatican City) in August is 32.2 ℃ (89.96 ℉). The average lowest temperature is 17.9 ℃ (64.22 ℉). At the beginning of August you can expect lower temperatures, the average highest temperature is around 31.65 ℃ (88.97 ℉). At the end of August you can expect lower temperatures, the average highest temperature is around 30.5 ℃ (86.9 ℉). The average rainfall is 35.3 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 14:31 (hours and minutes), in the middle of the month 13:58 and at the end of the month 13:19.These numbers above are valid primarily for the capital and the area around it.Typical (usual) weather in Holy See (Vatican City) in September is this: The average highest temperature in Holy See (Vatican City) in September is 28.8 ℃ (83.84 ℉). The average lowest temperature is 14.6 ℃ (58.28 ℉). At the beginning of September you can expect higher temperatures, the average highest temperature is around 30.5 ℃ (86.9 ℉). At the end of September you can expect lower temperatures, the average highest temperature is around 26.05 ℃ (78.89 ℉). The average rainfall is 74.1 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 13:19 (hours and minutes), in the middle of the month 12:38 and at the end of the month 11:56.These numbers above are valid primarily for the capital and the area around it.Typical (usual) weather in Holy See (Vatican City) in October is this: The average highest temperature in Holy See (Vatican City) in October is 23.3 ℃ (73.94 ℉). The average lowest temperature is 11.1 ℃ (51.98 ℉). At the beginning of October you can expect higher temperatures, the average highest temperature is around 26.05 ℃ (78.89 ℉). At the end of October you can expect lower temperatures, the average highest temperature is around 20.45 ℃ (68.81 ℉). The average rainfall is 107.1 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 11:56 (hours and minutes), in the middle of the month 11:15 and at the end of the month 10:34.These numbers above are valid primarily for the capital and the area around it.Typical (usual) weather in Holy See (Vatican City) in November is this: The average highest temperature in Holy See (Vatican City) in November is 17.6 ℃ (63.68 ℉). The average lowest temperature is 6.8 ℃ (44.24 ℉). At the beginning of November you can expect higher temperatures, the average highest temperature is around 20.45 ℃ (68.81 ℉). At the end of November you can expect lower temperatures, the average highest temperature is around 15.55 ℃ (59.99 ℉). The average rainfall is 117.8 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 10:34 (hours and minutes), in the middle of the month 9:58 and at the end of the month 9:28.These numbers above are valid primarily for the capital and the area around it.Typical (usual) weather in Holy See (Vatican City) in December is this: The average highest temperature in Holy See (Vatican City) in December is 13.5 ℃ (56.3 ℉). The average lowest temperature is 3.5 ℃ (38.3 ℉). At the beginning of December you can expect higher temperatures, the average highest temperature is around 15.55 ℃ (59.99 ℉). At the end of December you can expect lower temperatures, the average highest temperature is around 13.05 ℃ (55.49 ℉). The average rainfall is 91.9 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 9:28 (hours and minutes), in the middle of the month 9:10 and at the end of the month 9:07.These numbers above are valid primarily for the capital and the area around it.