Do you need to know, when is the best time to go to Northern Ireland? Then you should take a look here, what weather you can expect there during the year.
Northern Ireland is part of United Kingdom. The climate of United Kingdom is temperate, weather is moderated by prevailing southwest winds over the North Atlantic Current. More than one-half of the days are overcast. Weather is usually quite unstable here. Generally speaking, you can expect cool and often cloudy weather. You can also expect warmer weather in the southern part of UK.
When speaking about the usual weather in this area, the information is relevant for example for these popular places: Antrim, Armagh, Ballycastle, Ballymena, Ballymoney, Banbridge, Bangor, Belcoo, Belfast, Belleek, Bushmills, Carrickfergus, Castlerock, Coleraine, Cookstown, County Antrim, County Armagh, County Down, County Fermanagh, County Londonderry, County Tyrone, Cushendall, Derry, Downpatrick, Dungannon, Enniskillen, Giant's Causeway, Hillsborough, Holywood, Irvinestown, Larne, Limavady, Lisburn, Lisnaskea, Lurgan, Magherafelt, Mourne Mountains, Newcastle, Newry, Newtownabbey, Newtownards, Omagh, Portadown, Portrush, Portstewart, Rathlin Island, Strabane, Strangford.
Let's look now what weather you can expect in the area around Belfast and in many other cities. The warmest month here is August, the average maximum temperature is 19.9 ℃ (67.82 ℉). The average minimum temperature in this month is 11.9 ℃ (53.42 ℉). The coldest month here is January, the average maximum temperature is 8.2 ℃ (46.76 ℉). The average minimum temperature in this month is 2.5 ℃ (36.5 ℉). The most rainy month here is November, the average number of rainy days is 14.5. The least rainy month here is April, the average number of rainy days is 11.2. 
When travelling around Northern Ireland, always consider the altitude of the the place as well. We should remind you, that the highest point in United Kingdom is Ben Nevis (1343 m) and the lowest point is The Fens (-4 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 Northern Ireland in January is this: The average highest temperature in Northern Ireland in January is 8.2 ℃ (46.76 ℉). 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 8.35 ℃ (47.03 ℉). At the end of January you can expect higher temperatures, the average highest temperature is around 8.4 ℃ (47.12 ℉). The average number of rainy days in January is 14.4. The average rainfall is 89.7 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 7:20 (hours and minutes), in the middle of the month 7:51 and at the end of the month 8:40.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 Northern Ireland in February is this: The average highest temperature in Northern Ireland in February is 8.6 ℃ (47.48 ℉). The average lowest temperature is 2.3 ℃ (36.14 ℉). At the beginning of February you can expect lower temperatures, the average highest temperature is around 8.4 ℃ (47.12 ℉). At the end of February you can expect higher temperatures, the average highest temperature is around 9.45 ℃ (49.01 ℉). The average number of rainy days in February is 11.5. The average rainfall is 63.9 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 8:40 (hours and minutes), in the middle of the month 9:41 and at the end of the month 10:46.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 Northern Ireland in March is this: The average highest temperature in Northern Ireland in March is 10.3 ℃ (50.54 ℉). The average lowest temperature is 3.8 ℃ (38.84 ℉). At the beginning of March you can expect lower temperatures, the average highest temperature is around 9.45 ℃ (49.01 ℉). At the end of March you can expect higher temperatures, the average highest temperature is around 11.3 ℃ (52.34 ℉). The average number of rainy days in March is 13.5. The average rainfall is 76.6 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 10:46 (hours and minutes), in the middle of the month 11:52 and at the end of the month 12:59.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 Northern Ireland in April is this: The average highest temperature in Northern Ireland in April is 12.3 ℃ (54.14 ℉). The average lowest temperature is 4.9 ℃ (40.82 ℉). At the beginning of April you can expect lower temperatures, the average highest temperature is around 11.3 ℃ (52.34 ℉). At the end of April you can expect higher temperatures, the average highest temperature is around 14.05 ℃ (57.29 ℉). The average number of rainy days in April is 11.2. The average rainfall is 65.6 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 12:59 (hours and minutes), in the middle of the month 14:05 and at the end of the month 15:08.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 Northern Ireland in May is this: The average highest temperature in Northern Ireland in May is 15.8 ℃ (60.44 ℉). The average lowest temperature is 7 ℃ (44.6 ℉). At the beginning of May you can expect lower temperatures, the average highest temperature is around 14.05 ℃ (57.29 ℉). At the end of May you can expect higher temperatures, the average highest temperature is around 17.05 ℃ (62.69 ℉). The average number of rainy days in May is 11.8. The average rainfall is 63.2 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 15:08 (hours and minutes), in the middle of the month 16:05 and at the end of the month 16:49.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 Northern Ireland in June is this: The average highest temperature in Northern Ireland in June is 18.3 ℃ (64.94 ℉). The average lowest temperature is 9.8 ℃ (49.64 ℉). At the beginning of June you can expect lower temperatures, the average highest temperature is around 17.05 ℃ (62.69 ℉). At the end of June you can expect higher temperatures, the average highest temperature is around 18.9 ℃ (66.02 ℉). The average number of rainy days in June is 11.4. 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 16:49 (hours and minutes), in the middle of the month 17:14 and at the end of the month 17:13.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 Northern Ireland in July is this: The average highest temperature in Northern Ireland in July is 19.5 ℃ (67.1 ℉). The average lowest temperature is 11.8 ℃ (53.24 ℉). At the beginning of July you can expect lower temperatures, the average highest temperature is around 18.9 ℃ (66.02 ℉). At the end of July you can expect higher temperatures, the average highest temperature is around 19.7 ℃ (67.46 ℉). The average number of rainy days in July is 12.2. The average rainfall is 65.4 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 17:13 (hours and minutes), in the middle of the month 16:47 and at the end of the month 16:02.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 Northern Ireland in August is this: The average highest temperature in Northern Ireland in August is 19.9 ℃ (67.82 ℉). The average lowest temperature is 11.9 ℃ (53.42 ℉). At the beginning of August you can expect lower temperatures, the average highest temperature is around 19.7 ℃ (67.46 ℉). At the end of August you can expect lower temperatures, the average highest temperature is around 18.7 ℃ (65.66 ℉). The average number of rainy days in August is 13.5. The average rainfall is 84.7 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 16:02 (hours and minutes), in the middle of the month 15:05 and at the end of the month 14:03.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.Typical (usual) weather in Northern Ireland in September is this: The average highest temperature in Northern Ireland in September is 17.5 ℃ (63.5 ℉). The average lowest temperature is 9.9 ℃ (49.82 ℉). At the beginning of September you can expect higher temperatures, the average highest temperature is around 18.7 ℃ (65.66 ℉). At the end of September you can expect lower temperatures, the average highest temperature is around 15.7 ℃ (60.26 ℉). The average number of rainy days in September is 12.6. The average rainfall is 78.4 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 14:03 (hours and minutes), in the middle of the month 12:58 and at the end of the month 11:52.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 Northern Ireland in October is this: The average highest temperature in Northern Ireland in October is 13.9 ℃ (57.02 ℉). The average lowest temperature is 7.3 ℃ (45.14 ℉). At the beginning of October you can expect higher temperatures, the average highest temperature is around 15.7 ℃ (60.26 ℉). At the end of October you can expect lower temperatures, the average highest temperature is around 12.25 ℃ (54.05 ℉). The average number of rainy days in October is 14.3. The average rainfall is 99.4 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 11:52 (hours and minutes), in the middle of the month 10:46 and at the end of the month 9:42.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 Northern Ireland in November is this: The average highest temperature in Northern Ireland in November is 10.6 ℃ (51.08 ℉). The average lowest temperature is 4.5 ℃ (40.1 ℉). At the beginning of November you can expect higher temperatures, the average highest temperature is around 12.25 ℃ (54.05 ℉). At the end of November you can expect lower temperatures, the average highest temperature is around 9.55 ℃ (49.19 ℉). The average number of rainy days in November is 14.5. The average rainfall is 98.5 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 9:42 (hours and minutes), in the middle of the month 8:42 and at the end of the month 7:52.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 Northern Ireland in December is this: The average highest temperature in Northern Ireland in December is 8.5 ℃ (47.3 ℉). The average lowest temperature is 2.5 ℃ (36.5 ℉). At the beginning of December you can expect higher temperatures, the average highest temperature is around 9.55 ℃ (49.19 ℉). At the end of December you can expect lower temperatures, the average highest temperature is around 8.35 ℃ (47.03 ℉). The average number of rainy days in December is 14.3. The average rainfall is 94.4 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 7:52 (hours and minutes), in the middle of the month 7:21 and at the end of the month 7:15.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.| Belfast | temperature: - | highest temperature: 8.5 ℃ (47.3 ℉) | lowest temperature: 2.5 ℃ (36.5 ℉) | rainfall: 94.4mm | rainy days: 14.3 |
| Armagh | temperature: - | highest temperature: 8 ℃ (46.4 ℉) | lowest temperature: 2.3 ℃ (36.14 ℉) | rainfall: 76.6mm | rainy days: 13.3 |
| Enniskillen | temperature: - | highest temperature: 7.7 ℃ (45.86 ℉) | lowest temperature: 2.1 ℃ (35.78 ℉) | rainfall: 119.4mm | rainy days: 16.5 |