Spring — March to May
Spring arrives slowly. March is still cool and often wet (5–10°C), with April and May warming gradually to a genuinely pleasant 9–15°C. Dublin's maritime climate means there's rarely a dramatic thaw — the city just becomes gradually greener and brighter, with noticeably longer daylight by late April.
Rain is a constant companion rather than an occasional visitor; expect scattered showers even on otherwise sunny days. The upside is that Dublin rarely gets truly cold or truly hot, so spring days are comfortable for walking as long as you're dressed for sudden changes.
Key events: St Patrick's Festival, centred on March 17, turns the city centre into a multi-day parade and street festival — the single busiest tourist week of the year, with accommodation prices to match. Bloomsday on June 16 (just past the spring cutoff but worth planning around) celebrates James Joyce's *Ulysses* with costumed readings and events across the city.
What to pack: a proper waterproof jacket, not just a light one — Irish rain is fine and persistent rather than heavy and short. Layers underneath, since afternoons can feel ten degrees warmer than mornings. Waterproof shoes are worth the suitcase space.
Summer — June to August
Summer in Dublin is mild by most standards — June to August average 15–20°C, with the occasional warm spell pushing into the mid-20s. What summer really offers is daylight: at the solstice, it doesn't get properly dark until close to 11pm, which makes evenings feel endless.
Rain doesn't disappear in summer, it just becomes less predictable — sunny mornings can turn showery by afternoon and back again by evening. Locals rarely check a forecast in detail; they just carry a light rain layer regardless of what the sky looks like at breakfast.
This is peak tourist season. Trinity College, the Guinness Storehouse, and Kilmainham Gaol all need advance booking, and accommodation prices rise noticeably from June through August.
Key events: Bloomsday (June 16) is a genuinely distinctive Dublin experience — costumed readings, breakfasts of kidneys, and pub crawls tracing the route of *Ulysses*. Dublin Pride (June) fills the city centre with a large parade and week of events. Longitude and other outdoor music festivals run through July and August in Marlay Park.
What to pack: layers rather than heavy clothing — a T-shirt and a packable rain jacket cover most days. Sunglasses for the good days, which do happen. Comfortable shoes for the amount of walking a Dublin visit demands.
Autumn — September to November
September holds onto summer's mildness (12–18°C) with noticeably thinner crowds than July or August, making it one of the best months to visit. October cools further (9–14°C) and the light turns gold over the Georgian squares and the canals. November is the clear transition into winter — cold, short days (5–10°C), and rain that becomes more frequent and more persistent.
Autumn is when Dublin's literary and theatre scene is at its most active, and the city's parks — Phoenix Park, St Stephen's Green, the Iveagh Gardens — turn properly colourful through October.
Key events: Dublin Theatre Festival (late September to early October) is Ireland's leading theatre event, with productions across venues citywide. Dublin Fringe Festival (September) runs alongside it with more experimental and independent work. The Dublin Marathon (late October) closes major city-centre streets and draws tens of thousands of runners and spectators.
What to pack: a warm waterproof jacket from October onward, plus layers for the still-mild September days. An umbrella is only marginally useful against Dublin's wind-driven rain — a hooded jacket works better.
Winter — December to February
Dublin winters are mild in temperature but relentlessly grey and wet — daytime highs typically sit between 5 and 9°C, rarely dropping below freezing and rarely rising much above 10°C. Snow is uncommon and usually light when it does fall. The defining feature of an Irish winter isn't the cold, it's the short days: sunset comes as early as 4:15pm in late December, and overcast skies can persist for stretches of a week or more.
This is low season for tourism, which means better hotel rates, no queues at Trinity College or the Guinness Storehouse, and a noticeably more local atmosphere in the pubs. Dublin leans into its indoor strengths in winter — this is the season for long pub sessions, traditional music nights, and museum visits that don't require booking weeks ahead.
The Christmas season, from late November through early January, is genuinely charming — Georgian streetscapes lit up, Grafton Street's lights switched on, and traditional music sessions in pubs across the city. New Year's Eve draws a large crowd to the Countdown Concert along the Liffey quays.
January and February are the quietest, wettest, and darkest months — good for a cheap city break if you don't mind carrying an umbrella everywhere and accepting that daylight is a limited resource.
What to pack: a warm, genuinely waterproof coat, plus a hat and gloves for the wind off the Liffey and Dublin Bay, which cuts more than the actual temperature suggests. Waterproof boots. Layers you can shed once you're inside a warm, crowded pub, which you will be, often.