Royal Canal Greenway: which way and when to ride
The best month for Royal Canal Greenway is September: 75% of days were dry with highs of 10–30 °C. In September, riding Longford → Dublin meant an average tailwind of 3.0 km/h (ERA5 2006–2025, daytime 9:00–18:00).
Weather by month
| Month | Good days | Rain days ≥ 1 mm | Rain, mm | Avg high | Days ≥ 30 °C | Days < 10 °C | Daylight, h |
|---|---|---|---|---|---|---|---|
| January | 16% | 23% | 74 | 8 °C | 0% | 76% | 8.0 † |
| February | 20% | 25% | 67 | 8 °C | 0% | 70% | 9.7 † |
| March | 37% | 28% | 67 | 10 °C | 0% | 51% | 11.7 |
| April | 62% | 28% | 59 | 12 °C | 0% | 19% | 13.9 |
| May | 69% | 30% | 68 | 15 °C | 0% | 2% | 15.9 |
| June | 69% | 31% | 78 | 18 °C | 0% | 0% | 17.0 |
| July | 68% | 32% | 83 | 19 °C | 0% | 0% | 16.5 |
| August | 70% | 30% | 87 | 18 °C | 0% | 0% | 14.8 |
| September | 75% | 25% | 75 | 17 °C | 0% | 0% | 12.6 |
| October | 70% | 26% | 83 | 14 °C | 0% | 5% | 10.4 † |
| November | 35% | 26% | 85 | 10 °C | 0% | 48% | 8.5 † |
| December | 18% | 27% | 86 | 8 °C | 0% | 68% | 7.5 † |
Best months are all months within 3 percentage points of the best one. † less than 11 hours of daylight — long stages get tight.
Wind by month
| Month | Wind Longford → Dublin, km/h | Headwind > 15 km/h, Longford → Dublin | Headwind > 15 km/h, Dublin → Longford | Better way |
|---|---|---|---|---|
| January | +3.3 | 6% | 17% | Longford → Dublin |
| February | +2.2 | 10% | 17% | Longford → Dublin |
| March | +1.9 | 9% | 16% | either |
| April | +0.5 | 10% | 12% | either |
| May | +1.7 | 8% | 14% | either |
| June | +2.6 | 4% | 13% | Longford → Dublin |
| July | +4.2 | 3% | 14% | Longford → Dublin |
| August | +4.7 | 4% | 17% | Longford → Dublin |
| September | +3.0 | 5% | 15% | Longford → Dublin |
| October | +1.2 | 8% | 13% | either |
| November | +2.9 | 6% | 14% | Longford → Dublin |
| December | +2.9 | 6% | 15% | Longford → Dublin |
Along the route (sections of about 25 km)
| km | Heading | Tailwind in September, km/h |
|---|---|---|
| 0–25 | S | −2.6 |
| 25–50 | E | +4.2 |
| 50–75 | E | +4.5 |
| 75–101 | SE | +3.8 |
| 101–128 | E | +5.1 |
| 128–131 | E | +4.1 |
| 131–134 | SE | +2.2 |
How to read the numbers
Wind is the 10 m wind of a 25-km grid cell, daytime hours 9:00–18:00 local solar time; at saddle height in a sheltered valley it is weaker, on a coast or ridge stronger. A positive value is a tailwind. ERA5 slightly over-counts days with ≥ 1 mm of rain (by about 5–7 percentage points) and underestimates daily highs by 1–2 °C. Good day = less than 1 mm of rain between 9:00 and 18:00 (riding hours, local solar time) and a high between 10 and 30 °C; rain at night or in the evening does not spoil it.