Cologne Germany
Expected first-bloom dates for spring 2027, based on a degree-day temperature model and years of observations. 25 Apr 2027 status shown.
| Flower | Status today | Expected start | Likely range | Reliability | Model error (backtest) |
|---|---|---|---|---|---|
| Lilac | Blooming | ~22 Apr 2027 | 11 Apr – 6 May | validated | 3.5 d |
| Forsythia | Season over | ~15 Mar 2028 | 5 Mar – 3 Apr | validated | 3.97 d |
| Wood anemone | Blooming | ~23 Mar 2027 | 18 Mar – 30 Mar | validated | 4.44 d |
| Sweet cherry blossom | Season over | ~10 Apr 2028 | 3 Apr – 19 Apr | validated | 3.1 d |
| Horse chestnut | Blooming | ~24 Apr 2027 | 16 Apr – 6 May | validated | 3.47 d |
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Lilac in Cologne validated
Expected in bloom now (started ~22 Apr, ends ~12 May). Likely start range (80% of past weather years): 11 Apr 2027 – 6 May 2027. Expected flowering length: ~20 days (measured in Sweden).
Backtested against 35 years of local observations at this city (leave-one-year-out); the model beat simple climatology.
- Typical error if the weather were known (model backtest, MAE): 3.5 days; 80% of years within ±5 days.
- Typical error of a long-range estimate like this one (spread of past years at this city, MAE): ±6.17 days. Months ahead, the weather is unknown, so expect about this much.
- Observations used: 35 years at this city (1991–2025).
Observed first-bloom date by year (city median of observers) vs. model expectation:
Forsythia in Cologne validated
Season over. Next expected start ~15 Mar 2028. Likely start range (80% of past weather years): 5 Mar 2028 – 3 Apr 2028. Expected flowering length: ~14 days (assumed, not measured).
Backtested against 35 years of local observations at this city (leave-one-year-out); the model beat simple climatology.
- Typical error if the weather were known (model backtest, MAE): 3.97 days; 77% of years within ±5 days.
- Typical error of a long-range estimate like this one (spread of past years at this city, MAE): ±9.74 days. Months ahead, the weather is unknown, so expect about this much.
- Observations used: 35 years at this city (1991–2025).
Observed first-bloom date by year (city median of observers) vs. model expectation:
Wood anemone in Cologne validated
Expected in bloom now (started ~23 Mar, ends ~28 Apr). Likely start range (80% of past weather years): 18 Mar 2027 – 30 Mar 2027. Expected flowering length: ~36 days (measured in Sweden).
Backtested against 35 years of local observations at this city (leave-one-year-out); the model beat simple climatology.
- Typical error if the weather were known (model backtest, MAE): 4.44 days; 63% of years within ±5 days.
- Typical error of a long-range estimate like this one (spread of past years at this city, MAE): ±6.32 days. Months ahead, the weather is unknown, so expect about this much.
- Observations used: 35 years at this city (1991–2025).
Observed first-bloom date by year (city median of observers) vs. model expectation:
Sweet cherry blossom in Cologne validated
Season over. Next expected start ~10 Apr 2028. Likely start range (80% of past weather years): 3 Apr 2028 – 19 Apr 2028. Expected flowering length: ~13 days.
Backtested against 10 years of local observations at this city (leave-one-year-out); the model beat simple climatology.
- Typical error if the weather were known (model backtest, MAE): 3.1 days; 90% of years within ±5 days.
- Typical error of a long-range estimate like this one (spread of past years at this city, MAE): ±5.11 days. Months ahead, the weather is unknown, so expect about this much.
- Observations used: 10 years at this city (1991–2013).
Observed first-bloom date by year (city median of observers) vs. model expectation:
Horse chestnut in Cologne validated
Expected in bloom now (started ~24 Apr, ends ~8 May). Likely start range (80% of past weather years): 16 Apr 2027 – 6 May 2027. Expected flowering length: ~14 days (assumed, not measured).
Backtested against 35 years of local observations at this city (leave-one-year-out); the model beat simple climatology.
- Typical error if the weather were known (model backtest, MAE): 3.47 days; 74% of years within ±5 days.
- Typical error of a long-range estimate like this one (spread of past years at this city, MAE): ±5.35 days. Months ahead, the weather is unknown, so expect about this much.
- Observations used: 35 years at this city (1991–2025).
Observed first-bloom date by year (city median of observers) vs. model expectation:
“Start” = first flowers open (BBCH 60), not the peak. Peak is usually later; we have no open peak data. Individual gardens differ by ±4–8 days from the city median. See How it works and Sources.