The weather records can be downloaded here.
Armagh Observatory has been taking manual weather observations for more than 200 years, see this BBC story.
Northern Ireland has a reputation for bad weather, the climate here is cool, often cloudy and quite wet. But on the plus side we don't get hurricanes, snow storms, high humidity or freezing temperatures.
The above graph shows the seasonal variation in max temperature. Note that most of the time it is less than 20 Celcius.
Occasionally in January, February, March, November and December the temperature will drop below zero Celsius but most of the time it is above freezing.
Seasonal variation in rainfall is less noticeable than temperature - basically each season can be wet., but winters are usually wetter.
Sunshine can be a rare thing in Ireland, the seasonal variation is clear.
Evidence of climate change?
The following graphs do suggest changes possibly indicating climate change.
The above graph shows that since the mid-1970s the number of times the annual max temperature gets above 21 Celsius has increased.
The above graph shows that since 1990 the number of times air frost days per year is above 45 days has decreased.
These last two graphs might indicate a warming of the climate.