Dublin Half Marathon

Half marathon in Dublin, normally held in September. A rolling half marathon course — Run largely inside Phoenix Park, with rolling parkland terrain.

The Dublin Half Marathon at a glance

Distances	Half marathon
Main distance	21.1 km (half marathon)
Usually held	September
Course	Rolling
City	Dublin, Ireland
Typical conditions	16.8°C high / 11.3°C low, rain on ~43% of days

Run largely inside Phoenix Park, with rolling parkland terrain.

Entering the Dublin Half Marathon

Entry fees, closing dates and start times are set by the organiser and change every year, so they are not reproduced here — a stale deadline is worse than none. The organiser’s own site and its social channels are the authoritative source for the current year, and are where entry opens.

What is stable, and what this page covers: the month the race is held, what the course is like, the conditions you should expect, and how long a build-up the distance needs.

Weather at previous Dublin Half Marathon races

Across the last ten years, Dublin in September has averaged a daily high of 16.8°C and a low of 11.3°C, with at least a millimetre of rain on about 43% of days.

These are recorded observations for the race month averaged over ten years, not a forecast and not a single past race day — race dates move, so one day’s figures would mislead. Source: Open-Meteo historical archive.

How to prepare for the Dublin Half Marathon

How long to train

Build for 12 to 14 weeks from a base you already hold rather than from nothing. For half marathon the block should peak at a longest run of 18–20 km, reached at least two weeks before race day so there is time to taper. Ten days of reduced volume is enough of a taper at this distance; keep one short session at race pace in the final week.

Training for this course

The course rolls, so pace will drift either side of your average and that is fine. Run your long efforts on undulating ground and practise cresting a rise without spiking your effort — the usual mistake is attacking the ups and freewheeling the downs.

Conditions in September

Conditions are usually good for racing: highs average 16.8°C and lows 11.3°C in September, which is close to ideal for half marathon running. Dress for the temperature about ten degrees warmer than it actually is, since you will warm up within two kilometres. Rain is common — around 43% of days that month see at least a millimetre — so do some training runs wet and know which kit does not chafe.

Fuelling

A half marathon needs one gel or its equivalent around the hour mark for most runners, and a normal breakfast two to three hours before the start. Practise the same timing in at least three long runs so race morning is a repeat, not an experiment.

Race week

Sleep matters most two nights before, not the night before, so protect that one. Keep eating normally with a modest tilt toward carbohydrate, lay out kit the night before, and do nothing new: no new shoes, no new breakfast, no new socks. Plan to arrive at the start with time to spare — half marathon fields move slowly through bag drop and security.

Distances and where the race is run

Half marathon — 21.1 km

The pin marks Dublin city centre, the area the Dublin Half Marathon starts and finishes in. This is not the course line: the route is set by the organiser and changes between editions, so the official course map for the current year is theirs to publish. The routes below are for training on the same roads.

Train on these roads: 10K routes in Dublin · long runs in Dublin · GPS art routes

Other races in Dublin

Dublin Marathon — Marathon, October

Full Dublin race calendar