September for Ireland report

SEPTEMBER SUMMARY
RAINFALL:   Slightly wetter overall with an estimated 5% more rainfall than is typical for September, drier to the north and west, wetter to the south and east.  Ulster Province can expect around 10% less rainfall than the norm and Connaught drier by around 15-20% less.  Leinster can expect around 10% more rainfall than the norm and the Munster around 35% wetter.

SUNSHINE:   Sunnier overall for the first month since January this year, with an estimated 36% more sunshine hours for the country as a whole.  Overall, Ulster and Leinster can expect around a 20-25% more sunshine hours, Connaught  sunnier by up to 35-40% more hours and Munster sunnier by up to 55-60% above the norm. 

TEMPERATURE:   For daily maximas:  Warmer than the September average by up to an estimated 1-1.5C warmer in Ulster and Leinster and around 1.5-2C warmer for  Connaught and Munster , with an overall estimated 1.6C warmer for the country as a whole.  Warmest spell around 8th-11th and 28th-30th, coolest around 20th-23rd.  For daily minimas:   Warmer than the September average by an estimated 0.5-1C , up to 0.5-1C warmer in Ulster , 1.5-2C warmer in Munster and around the average to 0.5C cooler for Connaught and Leinster .

AUTUMN OVERALL: 
Overall, this season will be generally wet but sunny with above average temperatures.
Wetter overall by around 16% more than is typical for the autumn season, with the Ulster and Leinster around 15% wetter than the average, Munster around 35% wetter than average while Connaught around average for the season overall, slightly wetter but only by an estimated 1%.  Sunshine hours above normal most districts and around 30-35% sunnier for the country.  Ulster and Connaught can anticipate around 30-35% more sunshine than norm, Leinster around 15-20% sunnier and Munster up to 50% sunnier than season average.  For daily maximas:  Warmer by around 1.5C for season for the country as a whole, a trend reflected in Leinster and Munster , while around 2C warmer in Connaught and around 1C warmer across Ulster .  For daily minimas:   Cooler than seasonal average by 0.7C, up to 1-1.5C cooler in Connaught , around 0.5-1C warmer in Ulster and Leinster and around average to 0.5C warmer in  Munster . 

1st Sept    Unsettled weather returns when winds turn westerly bringing outbreaks of rain or showers mostly to northern and northwestern areas with some pockets of heavy falls around 30th. 
2nd-3rd     A small depression passes close to the north coast bringing heavy rain to many places, clearing to showers, some heavy and squally.
4th     Another weak depression moves over the northern half of the country bringing outbreaks of mostly light rain.
5th-9th     A large anticyclone to the west moves onto the country bringing a spell of dry and mostly sunny conditions everywhere.  Light northerly winds keep daytime temperatures close to normal, while nighttime temperatures will be very cool with a pockets of isolated frosts  making appearances.
10th     Unsettled conditions return with the passage of a slow moving front crossing the country bringing showers to most districts and some heavy rain near the south coast, accompanied by strong southerly winds.
Over the next four weeks air pressure values will be fairly stable but below the norm for this time of year.  Conditions will be a mix of warm, summer like conditions and some very wet and windy weather typical of autumn.  Overall, it will be generally sunnier than is typical for this time of year with close to average rainfall in most places but only around half the normal rainfall in the north and northwest.   Overall, this period will be dry in the northwestern half of the country with near normal rainfall elsewhere, except in the extreme eastern region where heavy rain in the last couple of days of this period will result in above average rainfall.  While heavy rain will be seen on a number of days, the last few days of the third week and into the first half of the fourth week will be mostly dry everywhere.  Most districts will see close to the average number of rain days.  Overall maximas may be above normal almost everywhere, by up to 1-2 degrees warmer than the average, with daytime temperatures above normal for most of this outlook period except over the second week.  Similarly, mean minimas will also be above normal with the coolest spell around the third week when overnight lows may result in some brief frost pockets only on one or two nights.  Sunshine hours will be average to above average in most districts, although slightly below normal in some pockets in the southeast.  Almost cloudless days can be expected over some days in the first week and third weeks when 10 hours of sunshine or more can be enjoyed.
11th     A very warm and humid airmass over the country brings isolated heavy showers and the occasional thunderstorm, particularly in eastern parts.
11th-15th Widespread fogs.
12th-13th  A weak ridge develops to the south, extending dry and misty conditions with light winds and a few showers over the country.
14th     Freshening southeasterly winds and the passage of a front crossing northeastwards over the country brings widespread wind and rain.
15th-17th Unsettled weather.  A deep depression to the southwest, possibly the remnants of a hurricane, brings rain and strong southerly winds to the country with heavy rain in the south and southwest. 
18th-19th The depression may now be situated just off the northwest coast extending further bands of rain or showers when winds turn  southwesterly, possibly accompanied by thunderstorms.
20th     Northwesterly change as the depression tracks slowly eastward.  Temperatures drop sharply while showery conditions continue. 
21st-25th Low pressure maintains its position to the northeast of the country extending a cool northwesterly flow and continued showers, heavy and thundery at times, for most districts, but still some good sunny intervals.  Chance of hail showers around the 21st-23rd.
26th     Rising pressure over the country brings a mostly dry and sunny day.
27th-28th A warm front from a depression off the northwest coast brings some rain but clearing quickly as it moves eastward ahead of an anticyclone. 
27th-30th Some extensive fogs during this period.
29th-3rd Oct  An area of high pressure becomes established over the North Sea and remains mostly stationary allowing for a light southeasterly flow  over the country, mostly dry and sunny everywhere and becoming very warm away from the southern and eastern coasts.