National Cycle Route 23: which way and when to ride
The best month for National Cycle Route 23 is September: 81% of days were dry with highs of 10–30 °C. In September, riding Ventnor → Reading meant an average tailwind of 2.7 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 | 18% | 21% | 67 | 8 °C | 0% | 72% | 8.4 † |
| February | 26% | 22% | 56 | 8 °C | 0% | 66% | 9.9 † |
| March | 48% | 23% | 52 | 10 °C | 0% | 40% | 11.7 |
| April | 72% | 21% | 46 | 14 °C | 0% | 12% | 13.8 |
| May | 75% | 24% | 61 | 17 °C | 0% | 1% | 15.5 |
| June | 78% | 21% | 60 | 20 °C | 0% | 0% | 16.5 |
| July | 76% | 22% | 58 | 22 °C | 2% | 0% | 16.1 |
| August | 76% | 23% | 60 | 21 °C | 1% | 0% | 14.5 |
| September | 81% | 19% | 54 | 19 °C | 0% | 0% | 12.5 |
| October | 75% | 23% | 80 | 15 °C | 0% | 2% | 10.6 † |
| November | 51% | 23% | 78 | 11 °C | 0% | 31% | 8.8 † |
| December | 28% | 22% | 70 | 9 °C | 0% | 58% | 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 Reading → Ventnor, km/h | Headwind > 15 km/h, Reading → Ventnor | Headwind > 15 km/h, Ventnor → Reading | Better way |
|---|---|---|---|---|
| January | −3.7 | 22% | 8% | Ventnor → Reading |
| February | −3.3 | 22% | 12% | Ventnor → Reading |
| March | −1.4 | 18% | 13% | either |
| April | −0.8 | 13% | 11% | either |
| May | −1.6 | 15% | 10% | either |
| June | −3.3 | 16% | 7% | Ventnor → Reading |
| July | −5.4 | 20% | 3% | Ventnor → Reading |
| August | −4.7 | 20% | 5% | Ventnor → Reading |
| September | −2.7 | 17% | 7% | Ventnor → Reading |
| October | −4.2 | 22% | 7% | Ventnor → Reading |
| November | −3.1 | 22% | 10% | Ventnor → Reading |
| December | −4.9 | 26% | 8% | Ventnor → Reading |
Along the route (sections of about 25 km)
| km | Heading | Tailwind in September, km/h |
|---|---|---|
| 0–25 | SW | −4.0 |
| 25–50 | S | −2.7 |
| 50–75 | SW | −4.8 |
| 75–100 | SW | −3.9 |
| 100–125 | S | −1.3 |
| 125–150 | SE | +1.1 |
| 150–157 | SW | −6.2 |
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.