352: which way and when to ride
The best month for 352 is September: 78% of days were dry with highs of 10–30 °C. In September the wind barely favours either direction — on average 1.7 km/h along the route (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 | 2% | 18% | 41 | 2 °C | 0% | 98% | 8.5 † |
| February | 7% | 15% | 31 | 3 °C | 0% | 92% | 10.0 † |
| March | 30% | 20% | 38 | 8 °C | 0% | 66% | 11.7 |
| April | 60% | 24% | 43 | 13 °C | 0% | 28% | 13.7 |
| May | 66% | 32% | 71 | 17 °C | 0% | 5% | 15.4 |
| June | 69% | 28% | 70 | 22 °C | 4% | 0% | 16.3 |
| July | 64% | 29% | 76 | 24 °C | 8% | 0% | 15.9 |
| August | 66% | 27% | 79 | 23 °C | 8% | 0% | 14.4 |
| September | 78% | 21% | 56 | 18 °C | 0% | 2% | 12.5 |
| October | 60% | 18% | 44 | 13 °C | 0% | 29% | 10.6 † |
| November | 16% | 17% | 40 | 6 °C | 0% | 81% | 8.9 † |
| December | 2% | 16% | 41 | 3 °C | 0% | 98% | 8.1 † |
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 Rokycany → Klášter, km/h | Headwind > 15 km/h, Rokycany → Klášter | Headwind > 15 km/h, Klášter → Rokycany | Better way |
|---|---|---|---|---|
| January | −3.8 | 16% | 2% | Klášter → Rokycany |
| February | −3.0 | 15% | 3% | Klášter → Rokycany |
| March | −2.6 | 14% | 5% | Klášter → Rokycany |
| April | −1.5 | 10% | 3% | either |
| May | −1.2 | 9% | 5% | either |
| June | −2.4 | 8% | 1% | Klášter → Rokycany |
| July | −4.0 | 11% | 1% | Klášter → Rokycany |
| August | −2.4 | 7% | 1% | Klášter → Rokycany |
| September | −1.7 | 8% | 2% | either |
| October | −2.1 | 10% | 2% | Klášter → Rokycany |
| November | −2.4 | 11% | 2% | Klášter → Rokycany |
| December | −3.5 | 13% | 2% | Klášter → Rokycany |
Along the route (sections of about 25 km)
| km | Heading | Tailwind in September, km/h |
|---|---|---|
| 0–25 | N | +0.2 |
| 25–50 | W | −2.3 |
| 50–76 | NW | −2.1 |
| 76–102 | W | −2.4 |
| 102–105 | W | −2.3 |
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.