Stockholm Sweden
Expected first-bloom dates for spring 2027, based on a degree-day temperature model and years of observations. 16 Oct 2026 status shown.
| Flower | Status today | Expected start | Likely range | Reliability | Model error (backtest) |
|---|---|---|---|---|---|
| Lilac | Season over | ~25 May 2027 | 20 May – 31 May | validated | 4.18 d |
| Forsythia | Season over | ~20 Apr 2027 | 9 Apr – 4 May | approximate | n/a |
| Wood anemone | Season over | ~12 Apr 2027 | 1 Apr – 26 Apr | approximate | 6.68 d |
| Sweet cherry blossom | Season over | ~10 May 2027 | 2 May – 16 May | approximate | 3 d |
| Horse chestnut | Season over | ~26 May 2027 | 21 May – 1 Jun | approximate | n/a |
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Lilac in Stockholm validated
Season over. Next expected start ~25 May 2027. Likely start range (80% of past weather years): 20 May 2027 – 31 May 2027. Expected flowering length: ~20 days.
Backtested against 11 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): 4.18 days; 73% of years within ±5 days.
- Typical error of a long-range estimate like this one (spread of past years at this city, MAE): ±4.71 days. Months ahead, the weather is unknown, so expect about this much.
- Observations used: 11 years at this city (2009–2020).
Observed first-bloom date by year (city median of observers) vs. model expectation:
Forsythia in Stockholm approximate
Season over. Next expected start ~20 Apr 2027. Likely start range (80% of past weather years): 9 Apr 2027 – 4 May 2027. Expected flowering length: ~14 days (assumed, not measured).
No (or far too few) usable open observations in this country for this flower; the model parameters were fitted on German data and transferred and are unchecked here. In our lilac test, transferring the German model to Sweden was off by about 4 days on average (bias about +3.8 days). Model parameters: transferred from Germany.
- Typical error if the weather were known (model backtest, MAE): not measured.
- Typical error of a long-range estimate like this one (spread of past years at this city, MAE): not measured. Months ahead, the weather is unknown, so expect about this much.
- Observations used: 0 years at this city.
No local observation series to show for this flower here.
Wood anemone in Stockholm approximate
Season over. Next expected start ~12 Apr 2027. Likely start range (80% of past weather years): 1 Apr 2027 – 26 Apr 2027. Expected flowering length: ~36 days.
Not called validated: backtest error 6.68 days is above our 5-day bar; the model did not beat simple climatology here.
- Typical error if the weather were known (model backtest, MAE): 6.68 days; 41% of years within ±5 days.
- Typical error of a long-range estimate like this one (spread of past years at this city, MAE): ±5.78 days. Months ahead, the weather is unknown, so expect about this much.
- Observations used: 17 years at this city (2008–2024).
Observed first-bloom date by year (city median of observers) vs. model expectation:
Sweet cherry blossom in Stockholm approximate
Season over. Next expected start ~10 May 2027. Likely start range (80% of past weather years): 2 May 2027 – 16 May 2027. Expected flowering length: ~16 days.
Not called validated: only 4 years of local observations for this city; the model did not beat simple climatology here.
- Typical error if the weather were known (model backtest, MAE): 3 days; 100% of years within ±5 days.
- Typical error of a long-range estimate like this one (spread of past years at this city, MAE): ±3 days. Months ahead, the weather is unknown, so expect about this much.
- Observations used: 4 years at this city (2010–2018).
Observed first-bloom date by year (city median of observers) vs. model expectation:
Horse chestnut in Stockholm approximate
Season over. Next expected start ~26 May 2027. Likely start range (80% of past weather years): 21 May 2027 – 1 Jun 2027. Expected flowering length: ~14 days (assumed, not measured).
No (or far too few) usable open observations in this country for this flower; the model parameters were fitted on German data and transferred and are unchecked here. In our lilac test, transferring the German model to Sweden was off by about 4 days on average (bias about +3.8 days). Model parameters: transferred from Germany.
- Typical error if the weather were known (model backtest, MAE): not measured.
- Typical error of a long-range estimate like this one (spread of past years at this city, MAE): not measured. Months ahead, the weather is unknown, so expect about this much.
- Observations used: 2 years at this city (2021–2024).
No local observation series to show for this flower here.
“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.