Sweet cherry blossom Prunus avium
Expected first-bloom dates for spring 2027 in 16 cities.
| City | Status | Expected start | Likely range | Label | Model MAE (d) | Climatology MAE (d) | Obs. years |
|---|---|---|---|---|---|---|---|
| Berlin | Season over | ~14 Apr 2027 | 6 Apr – 22 Apr | validated | 3.71 | 4.01 | 12 |
| Hamburg | Season over | ~16 Apr 2027 | 9 Apr – 24 Apr | validated | 3.14 | 5.3 | 21 |
| Munich | Season over | ~16 Apr 2027 | 8 Apr – 26 Apr | validated | 3.11 | 3.53 | 9 |
| Cologne | Season over | ~10 Apr 2027 | 3 Apr – 19 Apr | validated | 3.1 | 5.11 | 10 |
| Frankfurt | Season over | ~10 Apr 2027 | 3 Apr – 18 Apr | validated | 4.23 | 5.36 | 11 |
| Stuttgart | Season over | ~10 Apr 2027 | 3 Apr – 21 Apr | validated | 4.35 | 5.03 | 10 |
| Dresden | Season over | ~15 Apr 2027 | 6 Apr – 23 Apr | validated | 2.73 | 4.7 | 11 |
| Hanover | Season over | ~14 Apr 2027 | 5 Apr – 21 Apr | validated | 3.75 | 5.03 | 24 |
| Leipzig | Season over | ~14 Apr 2027 | 5 Apr – 22 Apr | validated | 3.53 | 5.79 | 19 |
| Nuremberg | Season over | ~14 Apr 2027 | 6 Apr – 24 Apr | validated | 3.1 | 4.65 | 24 |
| Stockholm | Season over | ~10 May 2027 | 2 May – 16 May | approximate | 3 | 3 | 4 |
| Uppsala | Season over | ~10 May 2027 | 4 May – 15 May | approximate | 3 | n/a | 1 |
| Gothenburg | Season over | ~28 Apr 2027 | 19 Apr – 9 May | approximate | 4 | 8.67 | 4 |
| Malmö | Season over | ~23 Apr 2027 | 11 Apr – 3 May | approximate | 6.5 | 10.1 | 5 |
| Linköping | Season over | ~4 May 2027 | 26 Apr – 12 May | validated | 1.94 | 5.49 | 9 |
| Örebro | Season over | ~6 May 2027 | 28 Apr – 14 May | validated | 1.96 | 5.61 | 13 |
Backtest (leave-one-year-out)
| Country | City-years | Model MAE | Simple climatology MAE | Within ±5 days |
|---|---|---|---|---|
| Germany | 151 | 3.45 d | 4.94 d | 78% |
| Sweden | 36 | 2.96 d | 6.27 d | 81% |
Model parameters
- Germany: sum of daily mean temperature above 0 °C from 1 Mar; bloom when the sum reaches 281 °C·days (fitted on 151 city-years)
- Sweden: sum of daily mean temperature above 2 °C from 1 Feb; bloom when the sum reaches 212 °C·days (fitted on 36 city-years)
MAE = mean absolute error in days. “Climatology” = just using the average date of the other years. Details and limits: How it works.