Updated 1st August.
Summary June 2018
There were intense thunderstorms especially on the 1st and 8th June, but in general the dry, settled weather from the end of May continued for the first two weeks of June with high pressure dominating producing and a slack easterly flow. The north Atlantic jet stream stayed well to the north. There was a break in the fine weather for the third week of that month. Storm Hector passed close to the Northwest, giving two days of rain and gales on the 13th and 14th followed by frontal systems crossing the country from the west up to the 20th. Even during this unsettled spell, rainfall totals were very low everywhere but especially in the South and East. From the 21st, the remainder of the month and the first part of July was settled and exceptionally dry due to an area of high pressure building over Ireland. For June and July, heat wave, partial drought and absolute drought conditions were reported in many locations (See tables below).
On June 21st, an intense area of high pressure of was centred to the west of Ireland bringing a northwesterly air flow across Ireland. In the days that followed, an easterly airflow dominated our weather. It brought the warmest conditions, with the highest maximum temperature of 32.0°C recorded at Shannon Airport, Co Clare (13.7°C above its LTA) on the 28th.
Over three days, 27th, 28th and 29th, five stations in counties Clare, Tipperary, Roscommon, Galway and Mayo recorded maximum screen air temperatures over 30°C. On the 27th, Shannon Airport recorded 30.8°C (12.5°C above its LTA) and Mount Dillon, Co Roscommon recorded 30.5°C (12.4°C above its LTA). On the 28th, Shannon Airport (mentioned above), 30.3°C was recorded at Mount Dillon, Co Roscommon (12.2°C above its LTA), 30.2°C was recorded at both Claremorris, Co Mayo (12.7°C above its LTA) and at Athenry, Co Galway (12.2°C above its LTA) and 30.1°C recorded at Moore Park, Co Cork (11.8°C above its LTA).
On 29th June, Shannon Airport, Co Clare and Gurteen, Co Tipperary recorded temperatures above 30°C with a temperatures of 31.1°C (12.8°C above its LTA) and 30.1°C (11.8°C above its LTA) respectively. The highest (minimum) night-time temperature was 18.8°C recorded on the 29th at Mace Head, Co Galway (8.1°C above its LTA).
Summary July 2018
High temperatures and drought conditions, most prolonged in the East and South, were also experienced during July. The first half of the month was characterised by a large area of blocking high pressure stretching from the Azores to Scandinavia pushing the north Atlantic Jet Stream well to the north away from Ireland. This gave dry and very warm conditions with a lot of sunshine and light variable winds, with heat wave conditions continuing for a few days at the beginning of the month. For the second half of the month, up to the 26th, pressure stayed relatively high, but Atlantic weather fronts broke through on some occasions, giving somewhat cooler conditions with some rain at times to Western and Northern areas and more generally on the 15th, 20th and 23rd . An area of low pressure to the northwest became dominant from the 26th to the end of the month, with associated frontal troughs bringing wind, rain or heavy thundery showers.
The latter part of July saw temperatures drop back to near normal levels for the time of year. There was also some rainfall recently which ended the Absolute drought status and Partial drought status in all areas.
For July, rainfall was about 80% of normal in the west and about 47% of normal in the east. Gurteen, Co Tipperary had only 35% of normal rainfall in July. This follows on from a dry and warm May and June. Phoenix Park recorded its lowest combined two-monthly rainfall total of 34.5 mm for June and July since records began in 1850.
More information is available in the full report (PDF): Warm and Dry weather June July 2018