NCN National Route 18: which way and when to ride
The best month for NCN National Route 18 is June: 81% of days were dry with highs of 10–30 °C. In June, riding Royal Tunbridge Wells → Canterbury meant an average tailwind of 3.6 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 | 14% | 22% | 63 | 7 °C | 0% | 76% | 8.4 † |
| February | 24% | 22% | 55 | 8 °C | 0% | 69% | 9.9 † |
| March | 46% | 21% | 48 | 10 °C | 0% | 45% | 11.7 |
| April | 69% | 21% | 41 | 13 °C | 0% | 15% | 13.8 |
| May | 76% | 23% | 58 | 16 °C | 0% | 2% | 15.5 |
| June | 81% | 19% | 52 | 19 °C | 0% | 0% | 16.5 |
| July | 77% | 21% | 55 | 22 °C | 2% | 0% | 16.1 |
| August | 77% | 22% | 62 | 21 °C | 1% | 0% | 14.6 |
| September | 80% | 20% | 52 | 19 °C | 0% | 0% | 12.5 |
| October | 75% | 23% | 70 | 15 °C | 0% | 2% | 10.6 † |
| November | 47% | 25% | 73 | 11 °C | 0% | 35% | 8.8 † |
| December | 26% | 22% | 69 | 8 °C | 0% | 62% | 7.9 † |
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 Canterbury → Royal Tunbridge Wells, km/h | Headwind > 15 km/h, Canterbury → Royal Tunbridge Wells | Headwind > 15 km/h, Royal Tunbridge Wells → Canterbury | Better way |
|---|---|---|---|---|
| January | −7.6 | 30% | 6% | Royal Tunbridge Wells → Canterbury |
| February | −5.8 | 30% | 11% | Royal Tunbridge Wells → Canterbury |
| March | −2.7 | 23% | 15% | Royal Tunbridge Wells → Canterbury |
| April | 0.0 | 17% | 16% | either |
| May | −2.2 | 21% | 13% | Royal Tunbridge Wells → Canterbury |
| June | −3.6 | 24% | 11% | Royal Tunbridge Wells → Canterbury |
| July | −7.7 | 31% | 4% | Royal Tunbridge Wells → Canterbury |
| August | −7.8 | 31% | 5% | Royal Tunbridge Wells → Canterbury |
| September | −4.7 | 24% | 9% | Royal Tunbridge Wells → Canterbury |
| October | −5.7 | 28% | 7% | Royal Tunbridge Wells → Canterbury |
| November | −6.7 | 27% | 5% | Royal Tunbridge Wells → Canterbury |
| December | −8.5 | 33% | 5% | Royal Tunbridge Wells → Canterbury |
Along the route (sections of about 25 km)
| km | Heading | Tailwind in June, km/h |
|---|---|---|
| 0–25 | SW | −3.0 |
| 25–50 | SW | −4.7 |
| 50–76 | W | −4.3 |
| 76–101 | NW | −2.0 |
| 101–109 | SW | −5.3 |
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.