Autumn weather begins in Ireland this month and the weather turns cool to cold, however, Dublin is picturesque this season and the city activities and events are in full swing.
Daytime high temperatures tend to average around 18 C (64-65 F) early in the month falling to near 16 C (60-61 F) by the end of this month.
A few of the warmer afternoons, especially early in the month, can reach up near 21 C (70 F). The record high temperature in Dublin during September is 24.6 C (76.3 F).
Late night and early morning low temperatures will likely be near 11 C (52 F) early in September, falling gradually to near 9 C (48-49 F) near the end of the month.
You should expect a couple of chilly mornings, especially late in the month, when lows can dip down near 5-6 C (about 42 F). The record low temperature in Dublin during September is 1.2 C (34.2 F).
How Muc Sun and Rain?
About 14 days this month normally have clear, or at least, partly sunny skies so this month is still a great time of year to explore the city.
Some rain falls on about 15 days, however, rainfalls of 5 mm (0.2 inches) or more only occur on 4 days this month.
The amount of daylight quickly falls this month from about 13.7 hours on September 1st to 11.7 hours by the 30th.
Wind speeds during September range mostly from gentle at 8-12 mph/12-19 kph to moderate at 13-18 mph/20-28 kph but can occasionally be fresh at 19–24 mph/29-38 kph, especially near the end of the month.
Dublin lies along the western edge of the Irish Sea which during September is quite chilly with temperatures averaging near 14 C (58-57 F).
What to Wear in Dublin During September?
September brings fall weather to Dublin so dress in layers as late night and early morning temperatures can be quite chilly, especially towards the end of the month.
Afternoons, however, still remain mild so bring both short and long-sleeved shirts, warm socks and water-resistant walking shoes or boots. In addition, jeans, or other travel pants along with a light-weight jacket and a few sweaters.
Things to Do in Dublin in September
Although there will be some rain this month, there will also be several sunny days to enjoy. If you manage to visit on a nice day, we recommend taking a pay-what-you-wish walking tour of Dublin.
If you do visit on a rainy day, consider an indoors activity instead. With Oktoberfest around the corner, this might be a good time to visit Dublin's distilleries such as the Guinness Storehouse, the Jameson Distillery, or the Teelings Distillery.
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