Rule
Blue Hour
Porvoo - Blue Hour - Southern Finland
Porvoo, Uusimaa, Finland
When city lights balance with the deep blue twilight sky
Currently
Real-time conditionsCloud Cover6%
Moon Altitude16.3°
Upcoming Opportunities
When all conditions match, PhotoWeather marks an opportunity window.
Times shown in Europe/Helsinki
Next opportunity
Good Blue Hour (clear) at Sunset
Porvoo
Today · 22:56–23:00 · 1h window
Medium confidence
60%
🌉Blue Hour Quality74.4%
Cloud Cover: 0%
Moon Illumination: 61%
Moon Altitude: 29.9°
Good Blue Hour (clear) at Sunset
Porvoo
Tomorrow · 22:59–23:00
🌉Blue Hour Quality:77.6%
High
Good Blue Hour (clear) at Dusk
Porvoo
Tomorrow · 23:00–23:34
🌉Blue Hour Quality:77.3%
High
Good Blue Hour (clear) at Dawn
Porvoo
Tue, May 26 · 02:53–03:00
🌉Blue Hour Quality:70.8%
Medium
Good Blue Hour (clear) at Sunrise
Porvoo
Tue, May 26 · 03:00–03:28
🌉Blue Hour Quality:69.6%
Medium
What this forecast looks for
Plain-language explanation from the ruleSouthern Finland's architectural heritage and long Nordic twilight create exceptional blue hour photography opportunities. The extended transition between day and night—lasting up to 90 minutes in spring and autumn—provides ample time to work with artificial lighting balanced against deep blue skies.
What makes Southern Finland special for blue hour photography:
- Helsinki architecture - Senate Square's neoclassical buildings, Temppeliaukio Church, and Uspenski Cathedral lit against twilight skies
- Harbor scenes - Suomenlinna fortress and Helsinki's waterfront combine maritime elements with urban lighting
- Porvoo old town - Historic colored warehouses along Porvoonjoki river create postcard scenes during twilight
- Long twilight duration - Extended blue hour window compared to southern European locations
The combination of Baltic maritime influence and Nordic latitude means twilight lasts significantly longer than mid-latitude cities, giving you time to refine compositions as the light evolves. Helsinki's compact center allows photographers to move between multiple architectural subjects during a single blue hour session. Porvoo's riverside warehouses—painted in traditional ochre, red, and yellow—become luminous during twilight when building lights reflect in the river. The forecast tracks clear sky conditions and civil twilight timing to identify optimal blue hour opportunities.
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72-hour requirements breakdown
What passed or failed, hour by hourAND logic: all conditions required
Meets requirement
Misses requirement
Time Europe/Helsinki | Blue Hour Any | Blue Hour Quality ≥ 65.0% | Precipitation Chance ≤ 15.0% |
|---|---|---|---|
| Sun, May 24 | |||
| 07:00 | ✕ | 12% | 28% |
| 08:00 | ✕ | 11% | 25% |
| 09:00 | ✕ | 18% | 22% |
| 10:00 | ✕ | 14% | 33% |
| 11:00 | ✕ | 13% | 17% |
| 12:00 | ✕ | 13% | 0% |
| 13:00 | ✕ | 13% | 7.4% |
| 14:00 | ✕ | 16% | 15% |
| 15:00 | ✕ | 13% | 22% |
| 16:00 | ✕ | 19% | 15% |
| 17:00 | ✕ | 22% | 7.4% |
| 18:00 | ✕ | 25% | 0% |
| 19:00 | ✕ | 25% | 0% |
| 20:00 | ✕ | 25% | 0% |
| 21:00 | ✕ | 25% | 0% |
| 22:00 | ✓ | 74% | 7.9% |
| 23:00 | ✓ | 78% | 16% |
| Mon, May 25 | |||
| 24:00 | ✕ | 52% | 24% |
| 01:00 | ✕ | 45% | 25% |
| 02:00 | ✓ | 58% | 27% |
| 03:00 | ✓ | 37% | 28% |
| 04:00 | ✕ | 30% | 19% |
| 05:00 | ✕ | 15% | 9.4% |
| 06:00 | ✕ | 15% | 0% |
| 07:00 | ✕ | 13% | 0% |
| 08:00 | ✕ | 15% | 0% |
| 09:00 | ✕ | 20% | 0% |
| 10:00 | ✕ | 27% | 0% |
| 11:00 | ✕ | 27% | 0% |
| 12:00 | ✕ | 33% | 0% |
| 13:00 | ✕ | 29% | 0% |
| 14:00 | ✕ | 29% | 0% |
| 15:00 | ✕ | 26% | 0% |
| 16:00 | ✕ | 26% | 0% |
| 17:00 | ✕ | 26% | 0% |
| 18:00 | ✕ | 25% | 0% |
| 19:00 | ✕ | 28% | 0% |
| 20:00 | ✕ | 25% | 0% |
| 21:00 | ✕ | 28% | 0% |
| 22:00 | ✓ | 78% | 0% |
| 23:00 | ✓ | 77% | 0% |
| Tue, May 26 | |||
| 24:00 | ✕ | 78% | 0% |
| 01:00 | ✕ | 55% | 0% |
| 02:00 | ✓ | 71% | 0% |
| 03:00 | ✓ | 70% | 0% |
| 04:00 | ✕ | 51% | 6.9% |
| 05:00 | ✕ | 22% | 14% |
| 06:00 | ✕ | 22% | 21% |
| 07:00 | ✕ | 24% | 29% |
| 08:00 | ✕ | 25% | 37% |
| 09:00 | ✕ | 25% | 46% |
| 10:00 | ✕ | 25% | 47% |
| 11:00 | ✕ | 22% | 49% |
| 12:00 | ✕ | 13% | 51% |
| 13:00 | ✕ | 13% | 55% |
| 14:00 | ✕ | 13% | 59% |
| 15:00 | ✕ | 14% | 63% |
| 16:00 | ✕ | 12% | 49% |
| 17:00 | ✕ | 13% | 36% |
| 18:00 | ✕ | 13% | 22% |
| 19:00 | ✕ | 13% | 20% |
| 20:00 | ✕ | 14% | 19% |
| 21:00 | ✕ | 15% | 17% |
| 22:00 | ✕ | 1.3% | 19% |
| 23:00 | ✓ | 28% | 20% |
| Wed, May 27 | |||
| 24:00 | ✕ | 22% | 22% |
| 01:00 | ✕ | 15% | 23% |
| 02:00 | ✓ | 27% | 25% |
| 03:00 | ✓ | 27% | 26% |
| 04:00 | ✕ | 20% | 32% |
| 05:00 | ✕ | 1.8% | 37% |
| 06:00 | ✕ | 1.6% | 42% |
| 07:00 | ✕ | 1.6% | 50% |
| 08:00 | ✕ | 1.6% | 57% |
| 09:00 | ✕ | 1.6% | 64% |
| 10:00 | ✕ | 1.6% | 54% |
| 11:00 | ✕ | 1.6% | 45% |
| 12:00 | ✕ | 1.6% | 35% |
| 13:00 | ✕ | 1.6% | 36% |
| 14:00 | ✕ | 1.6% | 36% |
How to read: colored cells show whether each predicate requirement is met; highlighted rows mean the full rule matched (an opportunity).
What does Blue Hour Quality mean?
Inputs that drive the scoreThis derived score summarizes multiple raw weather signals. The table below shows the supporting inputs hour by hour, so you can see what's pushing the score up or down.
| Time Europe/Helsinki | Blue Hour | High Clouds % | Low Clouds % | Mid-Level Clouds % | Relative Humidity % | Solar Elevation ° | Total Cloud Coverage % | Visibility m | Wind Speed m/s |
|---|---|---|---|---|---|---|---|---|---|
| Sun, May 24
Sunrise 04:17
Sunset 22:12 | |||||||||
| 16:00 | - | 0% | 6% | 0% | 57% | 41° | 6% | 24135m | 5.6m/s |
| 17:00 | - | 0% | 8% | 0% | 51% | 34° | 8% | 24135m | 5.8m/s |
| 18:00 | - | 0% | 1% | 0% | 53% | 27° | 1% | 24134m | 5.8m/s |
| 19:00 | - | 0% | 0% | 0% | 56% | 20° | 0% | 24134m | 5.8m/s |
| 20:00 | - | 0% | 0% | 0% | 60% | 13° | 0% | 24134m | 5.7m/s |
| 21:00 | - | 0% | 0% | 0% | 64% | 6.1° | 0% | 24134m | 5.2m/s |
| 22:00 | - | 0% | 0% | 0% | 66% | 0.69° | 0% | 24135m | 4.9m/s |
| 23:00 ☾ | - | 2% | 0% | 0% | 69% | -4.2° | 2% | 24134m | 5m/s |
| Mon, May 25
Sunrise 04:17
Sunset 22:12 | |||||||||
| 24:00 ☾ | - | 100% | 0% | 0% | 72% | -7.3° | 100% | 24135m | 4.6m/s |
| 01:00 ☾ | - | 100% | 0% | 38% | 72% | -8.6° | 100% | 24134m | 5.3m/s |
| 02:00 ☾ | - | 100% | 5% | 100% | 71% | -8.1° | 100% | 24135m | 5.1m/s |
| 03:00 ☾ | - | 100% | 100% | 100% | 64% | -5.8° | 100% | 24135m | 5.4m/s |
| 04:00 ☾ | - | 100% | 92% | 97% | 65% | -1.9° | 100% | 24135m | 5.2m/s |
| 05:00 | - | 100% | 40% | 100% | 67% | 3.4° | 100% | 24135m | 4.8m/s |
| 06:00 | - | 100% | 73% | 51% | 64% | 9.5° | 100% | 24135m | 5.1m/s |
| 07:00 | - | 100% | 100% | 100% | 81% | 16° | 100% | 7069m | 5.3m/s |
| 08:00 | - | 100% | 6% | 5% | 82% | 24° | 100% | 24134m | 4.3m/s |
| 09:00 | - | 7% | 24% | 28% | 69% | 31° | 35% | 24134m | 4.7m/s |
| 10:00 | - | 99% | 5% | 5% | 54% | 38° | 99% | 24135m | 5.5m/s |
| 11:00 | - | 99% | 5% | 5% | 46% | 44° | 99% | 24134m | 6m/s |
| 12:00 | - | 4% | 5% | 5% | 41% | 48° | 5% | 24135m | 6m/s |
| 13:00 | - | 5% | 5% | 0% | 37% | 51° | 5% | 24135m | 6.3m/s |
| 14:00 | - | 0% | 5% | 0% | 34% | 50° | 5% | 24134m | 6.6m/s |
| 15:00 | - | 0% | 5% | 0% | 34% | 46° | 5% | 24135m | 6.6m/s |
| 16:00 | - | 0% | 5% | 0% | 35% | 41° | 5% | 24134m | 6.3m/s |
| 17:00 | - | 0% | 2% | 0% | 37% | 35° | 2% | 24134m | 6.3m/s |
| 18:00 | - | 0% | 5% | 0% | 38% | 27° | 5% | 24134m | 6.2m/s |
| 19:00 | - | 0% | 3% | 0% | 41% | 20° | 3% | 24134m | 5.9m/s |
| 20:00 | - | 0% | 3% | 0% | 44% | 13° | 3% | 24135m | 5.9m/s |
| 21:00 | - | 0% | 3% | 0% | 48% | 6.3° | 3% | 24134m | 5.8m/s |
| 22:00 | - | 0% | 0% | 0% | 51% | 0.85° | 0% | 24135m | 4.9m/s |
| 23:00 ☾ | - | 0% | 0% | 0% | 56% | -4° | 0% | 24134m | 4.6m/s |
| Tue, May 26
Sunrise 04:15
Sunset 22:14 | |||||||||
| 24:00 ☾ | - | 1% | 0% | 0% | 61% | -7.1° | 1% | 24135m | 4.3m/s |
| 01:00 ☾ | - | 0% | 0% | 3% | 64% | -8.4° | 3% | 24134m | 5m/s |
| 02:00 ☾ | - | 0% | 2% | 0% | 68% | -8° | 2% | 24134m | 4.5m/s |
| 03:00 ☾ | - | 0% | 5% | 0% | 72% | -5.7° | 5% | 24135m | 4.1m/s |
| 04:00 ☾ | - | 0% | 5% | 0% | 74% | -1.7° | 5% | 24134m | 3.9m/s |
| 05:00 | - | 0% | 5% | 0% | 77% | 3.5° | 5% | 24135m | 3.7m/s |
| 06:00 | - | 0% | 5% | 0% | 75% | 9.7° | 5% | 24134m | 3.5m/s |
| 07:00 | - | 0% | 5% | 0% | 70% | 17° | 5% | 24134m | 3.7m/s |
| 08:00 | - | 0% | 5% | 1% | 62% | 24° | 5% | 24134m | 4.1m/s |
| 09:00 | - | 0% | 5% | 0% | 53% | 31° | 5% | 24135m | 4.2m/s |
| 10:00 | - | 0% | 5% | 0% | 44% | 38° | 5% | 24134m | 4.7m/s |
| 11:00 | - | 0% | 22% | 0% | 40% | 44° | 22% | 24135m | 5m/s |
| 12:00 | - | 0% | 98% | 5% | 38% | 49° | 98% | 24134m | 5.1m/s |
| 13:00 | - | 0% | 100% | 0% | 40% | 51° | 100% | 24135m | 5.1m/s |
| 14:00 | - | 0% | 100% | 0% | 45% | 50° | 100% | 24134m | 4.3m/s |
| 15:00 | - | 0% | 66% | 0% | 48% | 47° | 66% | 24134m | 3.5m/s |
| 16:00 | - | 0% | 84% | 0% | 34% | 41° | 84% | 24134m | 4.9m/s |
| 17:00 | - | 0% | 57% | 0% | 36% | 35° | 57% | 24135m | 5.2m/s |
| 18:00 | - | 0% | 78% | 1% | 38% | 28° | 78% | 24135m | 4.6m/s |
| 19:00 | - | 0% | 100% | 1% | 44% | 20° | 100% | 24134m | 3.6m/s |
| 20:00 | - | 0% | 71% | 10% | 48% | 13° | 71% | 24135m | 3.2m/s |
| 21:00 | - | 0% | 62% | 89% | 58% | 6.4° | 89% | 15700m | 4.7m/s |
| 22:00 | - | 0% | 74% | 90% | 69% | 1° | 92% | 18332m | 4.3m/s |
| 23:00 ☾ | - | 0% | 86% | 90% | 79% | -3.9° | 96% | 20963m | 3.9m/s |
| Wed, May 27
Sunrise 04:13
Sunset 22:16 | |||||||||
| 24:00 ☾ | - | 0% | 98% | 91% | 89% | -6.9° | 99% | 23595m | 3.5m/s |
| 01:00 ☾ | - | 0% | 67% | 90% | 82% | -8.3° | 95% | 20731m | 4.1m/s |
| 02:00 ☾ | - | 0% | 36% | 89% | 74% | -7.8° | 91% | 17868m | 4.7m/s |
| 03:00 ☾ | - | 0% | 5% | 88% | 66% | -5.5° | 88% | 15004m | 5.3m/s |
| 04:00 ☾ | - | 5% | 9% | 92% | 56% | -1.5° | 92% | 18048m | 5.4m/s |
| 05:00 | - | 11% | 12% | 96% | 46% | 3.7° | 96% | 21091m | 5.6m/s |
| 06:00 | - | 16% | 16% | 100% | 36% | 9.8° | 100% | 24135m | 5.7m/s |
| 07:00 | - | 35% | 44% | 100% | 35% | 17° | 100% | 24135m | 5.8m/s |
| 08:00 | - | 54% | 72% | 100% | 34% | 24° | 100% | 24135m | 5.8m/s |
| 09:00 | - | 73% | 100% | 100% | 33% | 31° | 100% | 24135m | 5.9m/s |
| 10:00 | - | 50% | 83% | 100% | 34% | 38° | 100% | 24135m | 5.7m/s |
| 11:00 | - | 28% | 66% | 100% | 36% | 44° | 100% | 24135m | 5.5m/s |
| 12:00 | - | 5% | 48% | 100% | 37% | 49° | 100% | 24135m | 5.3m/s |
| 13:00 | - | 36% | 34% | 99% | 38% | 51° | 99% | 24135m | 5.3m/s |
| 14:00 | - | 67% | 19% | 98% | 39% | 50° | 98% | 24135m | 5.4m/s |
| 15:00 | - | 98% | 4% | 97% | 40% | 47° | 98% | 24135m | 5.4m/s |
How to read: these inputs help produce the derived score; they are not requirements by themselves.
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