METEOROLOGICAL SUMMER HAS begun but the weather at the moment will be far from summery over the course of the bank holiday weekend. There is a battle of air mass and pressure systems with the models favoring low pressure and rain to develop on Saturday, Sunday and later on Monday but the timing on the rain arriving on Saturday is still uncertain.
The current models are suggesting heavy rain to develop over the southwest sometime on Saturday morning/afternoon and spread countrywide with heavy falls expected over Munster and Leinster but this rain could be delayed and lighter. There will be an update to this forecast early Friday evening as each run has varied with the arrival of the rain.
Friday will be a mostly cloudy day with patchy light rain and drizzle a a front over the country weakens. It will however feel muggy under the cloud. Later on, some brightness will break through and where this occurs it will feel very warm and humid. The best of the bright weather over the south and south west where temperatures may reach 21 or 22C in any sunshine but further north and east, temperatures will hover around the high teens. Some bright spells may occur here in the evening. Winds will be easterly and remain light but could be fresh off the northwest and southwest coast in the evening.
Present indications are for a dry and sunny start but cloud quickly moving into the southwest with rain developing before noon. The rain is predicted to be heavy and persistent spreading slowly northeast into Leinster and Connaught during the afternoon. The very far north may hold onto some bright weather before cloud rolls in here from the south during the late afternoon and early evening but it may stay dry over the very far north. Saturday night looks like being wet over the southern half of the country but it may dry out close to the south coast later for a time. Winds throughout will be cyclonic variable or from the southeast. Temperatures will range 15 to 19C. Low cloud and hill fog will develop from early on Saturday.
A cloudy and wet start across much of Connaught and Leinster. The weather front bringing the rain looks like returning south with the very far north remaining dry with perhaps some brightness here. Cooler weather will filter into Ulster as the day wears on while the rain in the south will become more patchy with drizzle at times. Once again low cloud and hill fog will affect much of the southern half of the country and around the coast. Later in the day, brighter weather and cooler temperatures will move into northern parts of Leinster and Connaught but it will remain mostly cloudy over the south as the front is reluctant to clear. A cooler night across the much of the northern half with some breaks in cloud with lows of 7 to 10C.
At this moment, it looks cloudy with patchy light rain but some bright weather. More general cloud again moving in off the Atlantic with rain developing in the southwest in the afternoon. This is too far away to be certain at this time.
Temperatures will continue to fall back with highs of 13 to 16C. It looks unsettled for the following couple of days.
Karl Mehlhorn is the founder of the Irish Weather Network. Follow on Twitter @Irelandsweather.
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