Rule
Morning Frost
Repovesi - Morning Frost - Southern Finland
Repovesi Nationalpark, Kymenlaakso, Finland
Frost crystals on calm, cold mornings near sunrise
Currently
Real-time conditionsSoil Temperature-5.8°C
Dew Point-10.6°C (low dew point)
Wind Speed4.5m/s (calm conditions)
Cloud Cover5%
Upcoming Opportunities
When all conditions match, PhotoWeather marks an opportunity window.
Times shown in Europe/Helsinki
Next opportunity
Moderate Frost (radiative) at Sunrise
Repovesi
Wed, Feb 25 · 06:41–08:56 · 2h window
Medium confidence
48%
❄️Frost Probability75-84%
Soil Temperature: -5.5°C
Dew Point: -6.9°C (low dew point)
Wind Speed: 1.2m/s (calm conditions)
Cloud Cover: 5%
What this forecast looks for
Plain-language explanation from the ruleThis forecast tracks the conditions that create Southern Finland's dramatic frost photography opportunities. From November through March, the region's lakes, forests, and wetlands transform under hoar frost and ice formations, with temperatures regularly dropping to -15°C or colder.
What makes Southern Finland special for frost photography:
- Lake ice formations - Vesijärvi and Saimaa develop intricate ice patterns and frozen shoreline details
- Torronsuo's frozen bog - The region's largest raised bog becomes an otherworldly landscape of frosted sphagnum and ice-covered pools
- Nuuksio forest frost - Hoar frost on birch trees and frozen forest streams create intimate woodland scenes
- Accessible winter locations - All major frost photography sites within 2 hours of Helsinki
Peak frost conditions occur during stable high-pressure systems when clear nights drop temperatures well below freezing while daytime sun creates backlit opportunities. Nuuksio's mixed forests develop heavy hoar frost on birch branches, transforming familiar trails into sparkling winter scenes. Torronsuo National Park's boardwalks traverse frosted bog landscapes where every sedge and shrub carries ice crystals. The region's thousands of lakes create endless shoreline compositions—ice formations along reed beds, frozen spray patterns, and geometric crack patterns in smooth ice. The forecast identifies calm, clear nights with appropriate temperature drops, then tracks morning visibility to ensure you can photograph the frost before midday sun melts the formations.
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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 | Time Window Sunrise -45m to +90m | Frost Probability ≥ 60.0% | Wind Speed ≤ 1.5m/s |
|---|---|---|---|
| Sat, Feb 21 | |||
| 21:00 | ✕ | 48% | 5m/s |
| 22:00 | ✕ | 48% | 4.8m/s |
| 23:00 | ✕ | 48% | 4.8m/s |
| Sun, Feb 22 | |||
| 24:00 | ✕ | 48% | 4.7m/s |
| 01:00 | ✕ | 48% | 4.4m/s |
| 02:00 | ✕ | 50% | 4.1m/s |
| 03:00 | ✕ | 50% | 4m/s |
| 04:00 | ✕ | 50% | 3.7m/s |
| 05:00 | ✕ | 50% | 3.4m/s |
| 06:00 | ✓ | 50% | 2.9m/s |
| 07:00 | ✓ | 52% | 2.3m/s |
| 08:00 | ✓ | 52% | 1.9m/s |
| 09:00 | ✓ | 52% | 2.1m/s |
| 10:00 | ✕ | 48% | 4.3m/s |
| 11:00 | ✕ | 48% | 5.3m/s |
| 12:00 | ✕ | 52% | 5.4m/s |
| 13:00 | ✕ | 50% | 6m/s |
| 14:00 | ✕ | 50% | 6m/s |
| 15:00 | ✕ | 61% | 6.1m/s |
| 16:00 | ✕ | 73% | 6m/s |
| 17:00 | ✕ | 73% | 5.9m/s |
| 18:00 | ✕ | 65% | 5.6m/s |
| 19:00 | ✕ | 67% | 5.4m/s |
| 20:00 | ✕ | 67% | 5m/s |
| 21:00 | ✕ | 67% | 4.5m/s |
| 22:00 | ✕ | 69% | 4.1m/s |
| 23:00 | ✕ | 69% | 3.8m/s |
| Mon, Feb 23 | |||
| 24:00 | ✕ | 69% | 3.3m/s |
| 01:00 | ✕ | 69% | 3m/s |
| 02:00 | ✕ | 71% | 2.7m/s |
| 03:00 | ✕ | 67% | 2.3m/s |
| 04:00 | ✕ | 59% | 2.3m/s |
| 05:00 | ✕ | 67% | 2.1m/s |
| 06:00 | ✓ | 63% | 2m/s |
| 07:00 | ✓ | 63% | 1.8m/s |
| 08:00 | ✓ | 58% | 1.5m/s |
| 09:00 | ✓ | 63% | 1.7m/s |
| 10:00 | ✕ | 73% | 1.5m/s |
| 11:00 | ✕ | 65% | 1.4m/s |
| 12:00 | ✕ | 62% | 1.4m/s |
| 13:00 | ✕ | 69% | 1.3m/s |
| 14:00 | ✕ | 70% | 1.2m/s |
| 15:00 | ✕ | 69% | 1m/s |
| 16:00 | ✕ | 75% | 0.55m/s |
| 17:00 | ✕ | 71% | 0.75m/s |
| 18:00 | ✕ | 69% | 0.87m/s |
| 19:00 | ✕ | 58% | 1.2m/s |
| 20:00 | ✕ | 55% | 1.1m/s |
| 21:00 | ✕ | 55% | 1.1m/s |
| 22:00 | ✕ | 55% | 1.3m/s |
| 23:00 | ✕ | 55% | 1.3m/s |
| Tue, Feb 24 | |||
| 24:00 | ✕ | 54% | 1.3m/s |
| 01:00 | ✕ | 54% | 1.3m/s |
| 02:00 | ✕ | 54% | 1.3m/s |
| 03:00 | ✕ | 54% | 1.2m/s |
| 04:00 | ✕ | 54% | 1.4m/s |
| 05:00 | ✕ | 54% | 1.3m/s |
| 06:00 | ✓ | 54% | 1.2m/s |
| 07:00 | ✓ | 54% | 1.1m/s |
| 08:00 | ✓ | 54% | 1.2m/s |
| 09:00 | ✕ | 54% | 1.2m/s |
| 10:00 | ✕ | 58% | 1.2m/s |
| 11:00 | ✕ | 58% | 1.1m/s |
| 12:00 | ✕ | 58% | 1.1m/s |
| 13:00 | ✕ | 58% | 0.94m/s |
| 14:00 | ✕ | 58% | 1m/s |
| 15:00 | ✕ | 58% | 0.98m/s |
| 16:00 | ✕ | 58% | 0.81m/s |
| 17:00 | ✕ | 54% | 0.86m/s |
| 18:00 | ✕ | 54% | 1.1m/s |
| 19:00 | ✕ | 54% | 1m/s |
| 20:00 | ✕ | 54% | 1m/s |
| 21:00 | ✕ | 54% | 1.2m/s |
| 22:00 | ✕ | 54% | 1.2m/s |
| 23:00 | ✕ | 54% | 1m/s |
| Wed, Feb 25 | |||
| 24:00 | ✕ | 54% | 0.93m/s |
| 01:00 | ✕ | 54% | 0.9m/s |
| 02:00 | ✕ | 54% | 0.99m/s |
| 03:00 | ✕ | 59% | 0.8m/s |
| 04:00 | ✕ | 67% | 0.62m/s |
| 05:00 | ✕ | 75% | 0.43m/s |
| 06:00 | ✓ | 75% | 0.7m/s |
| 07:00 | ✓ | 81% | 0.96m/s |
| 08:00 | ✓ | 84% | 1.2m/s |
| 09:00 | ✕ | 65% | 1.2m/s |
| 10:00 | ✕ | 59% | 1.2m/s |
| 11:00 | ✕ | 54% | 1.2m/s |
| 12:00 | ✕ | 54% | 1.4m/s |
| 13:00 | ✕ | 54% | 1.5m/s |
| 14:00 | ✕ | 54% | 1.7m/s |
| 15:00 | ✕ | 52% | 1.8m/s |
| 16:00 | ✕ | 52% | 2m/s |
| 17:00 | ✕ | 52% | 2.1m/s |
| 18:00 | ✕ | 52% | 2.3m/s |
| 19:00 | ✕ | 52% | 2.4m/s |
How to read: colored cells show whether each predicate requirement is met; highlighted rows mean the full rule matched (an opportunity).
What does Frost Probability 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 | Dew Point °C | Surface Temperature °C | Temperature °C | Time Window | Total Cloud Coverage % | Vapor Pressure Deficit kPa |
|---|---|---|---|---|---|---|
| Sun, Feb 22
Sunrise 07:35
Sunset 17:18 | ||||||
| 21:00 ☾ | -11°C | -5.8°C | -8.3°C | - | 5% | 0.05kPa |
| 22:00 ☾ | -11°C | -5.9°C | -9°C | - | 5% | 0.04kPa |
| 23:00 ☾ | -11°C | -5.9°C | -9.7°C | - | 5% | 0.04kPa |
| Mon, Feb 23
Sunrise 07:35
Sunset 17:18 | ||||||
| 24:00 ☾ | -12°C | -5.9°C | -10°C | - | 5% | 0.03kPa |
| 01:00 ☾ | -13°C | -5.9°C | -11°C | - | 5% | 0.02kPa |
| 02:00 ☾ | -14°C | -6°C | -13°C | - | 5% | 0.02kPa |
| 03:00 ☾ | -15°C | -6°C | -14°C | - | 5% | 0.01kPa |
| 04:00 ☾ | -15°C | -6.1°C | -15°C | - | 29% | 0.01kPa |
| 05:00 ☾ | -16°C | -6.1°C | -15°C | - | 5% | 0.01kPa |
| 06:00 ☾ | -17°C | -6.2°C | -16°C | - | 11% | 0.01kPa |
| 07:00 ☾ | -17°C | -6.3°C | -17°C | - | 19% | 0kPa |
| 08:00 | -18°C | -6.4°C | -18°C | - | 43% | 0kPa |
| 09:00 | -14°C | -6.4°C | -13°C | - | 16% | 0.01kPa |
| 10:00 | -11°C | -6.4°C | -9.2°C | - | 5% | 0.04kPa |
| 11:00 | -9°C | -6.4°C | -6.5°C | - | 30% | 0.06kPa |
| 12:00 | -7.6°C | -6.4°C | -4.8°C | - | 52% | 0.08kPa |
| 13:00 | -6.8°C | -6.4°C | -3.8°C | - | 11% | 0.09kPa |
| 14:00 | -6.4°C | -6.3°C | -3.3°C | - | 41% | 0.1kPa |
| 15:00 | -6°C | -6.3°C | -3.3°C | - | 11% | 0.09kPa |
| 16:00 | -5.7°C | -6.2°C | -4.6°C | - | 5% | 0.03kPa |
| 17:00 | -9.4°C | -6.2°C | -8.7°C | - | 5% | 0.02kPa |
| 18:00 ☾ | -12°C | -6.2°C | -12°C | - | 5% | 0.01kPa |
| 19:00 ☾ | -14°C | -6.2°C | -14°C | - | 58% | 0kPa |
| 20:00 ☾ | -15°C | -6.2°C | -15°C | - | 66% | 0kPa |
| 21:00 ☾ | -16°C | -6.3°C | -16°C | - | 67% | 0kPa |
| 22:00 ☾ | -16°C | -6.4°C | -16°C | - | 71% | 0kPa |
| 23:00 ☾ | -17°C | -6.5°C | -17°C | - | 78% | 0kPa |
| Tue, Feb 24
Sunrise 07:32
Sunset 17:20 | ||||||
| 24:00 ☾ | -18°C | -6.5°C | -18°C | - | 93% | 0kPa |
| 01:00 ☾ | -18°C | -6.6°C | -18°C | - | 100% | 0kPa |
| 02:00 ☾ | -19°C | -6.7°C | -19°C | - | 100% | 0kPa |
| 03:00 ☾ | -18°C | -6.8°C | -18°C | - | 100% | 0kPa |
| 04:00 ☾ | -17°C | -6.8°C | -18°C | - | 100% | 0kPa |
| 05:00 ☾ | -14°C | -6.9°C | -14°C | - | 100% | 0kPa |
| 06:00 ☾ | -15°C | -6.9°C | -15°C | - | 100% | 0kPa |
| 07:00 ☾ | -15°C | -7°C | -15°C | - | 100% | 0kPa |
| 08:00 | -14°C | -7°C | -14°C | - | 100% | 0.01kPa |
| 09:00 | -11°C | -7°C | -10°C | - | 100% | 0.02kPa |
| 10:00 | -9.8°C | -7°C | -8.4°C | - | 100% | 0.03kPa |
| 11:00 | -8.7°C | -7°C | -6.7°C | - | 100% | 0.05kPa |
| 12:00 | -8°C | -6.9°C | -5.6°C | - | 100% | 0.07kPa |
| 13:00 | -7.5°C | -6.8°C | -4.8°C | - | 100% | 0.08kPa |
| 14:00 | -7.2°C | -6.8°C | -4.4°C | - | 100% | 0.08kPa |
| 15:00 | -6.8°C | -6.7°C | -4.3°C | - | 100% | 0.08kPa |
| 16:00 | -6°C | -6.6°C | -4.7°C | - | 100% | 0.04kPa |
| 17:00 | -7°C | -6.6°C | -6.4°C | - | 100% | 0.02kPa |
| 18:00 ☾ | -8.8°C | -6.6°C | -8.3°C | - | 100% | 0.01kPa |
| 19:00 ☾ | -10°C | -6.5°C | -9.5°C | - | 100% | 0.01kPa |
| 20:00 ☾ | -11°C | -6.5°C | -11°C | - | 100% | 0.01kPa |
| 21:00 ☾ | -12°C | -6.5°C | -11°C | - | 100% | 0.01kPa |
| 22:00 ☾ | -12°C | -6.5°C | -12°C | - | 100% | 0.01kPa |
| 23:00 ☾ | -12°C | -6.6°C | -12°C | - | 100% | 0.01kPa |
| Wed, Feb 25
Sunrise 07:29
Sunset 17:23 | ||||||
| 24:00 ☾ | -13°C | -6.6°C | -13°C | - | 92% | 0.01kPa |
| 01:00 ☾ | -14°C | -6.6°C | -14°C | - | 98% | 0.01kPa |
| 02:00 ☾ | -14°C | -6.7°C | -14°C | - | 100% | 0.01kPa |
| 03:00 ☾ | -12°C | -6.3°C | -11°C | - | 68% | 0.02kPa |
| 04:00 ☾ | -10°C | -5.9°C | -8.5°C | - | 37% | 0.04kPa |
| 05:00 ☾ | -8.3°C | -5.6°C | -5.7°C | - | 5% | 0.07kPa |
| 06:00 ☾ | -7.9°C | -5.6°C | -5°C | - | 5% | 0.08kPa |
| 07:00 ☾ | -7.4°C | -5.5°C | -4.2°C | - | 5% | 0.1kPa |
| 08:00 | -6.9°C | -5.5°C | -3.4°C | - | 5% | 0.11kPa |
| 09:00 | -7.5°C | -5.5°C | -5°C | - | 36% | 0.07kPa |
| 10:00 | -8.1°C | -5.4°C | -6.5°C | - | 66% | 0.04kPa |
| 11:00 | -8.8°C | -5.4°C | -8.1°C | - | 97% | 0.02kPa |
| 12:00 | -10°C | -5.4°C | -9.5°C | - | 98% | 0.02kPa |
| 13:00 | -11°C | -5.4°C | -11°C | - | 99% | 0.01kPa |
| 14:00 | -13°C | -5.4°C | -12°C | - | 100% | 0.01kPa |
| 15:00 | -12°C | -5.4°C | -12°C | - | 100% | 0.01kPa |
| 16:00 | -12°C | -5.4°C | -11°C | - | 100% | 0.01kPa |
| 17:00 | -11°C | -5.4°C | -10°C | - | 100% | 0.02kPa |
| 18:00 ☾ | -10°C | -5.4°C | -9.3°C | - | 100% | 0.02kPa |
| 19:00 ☾ | -9°C | -5.4°C | -8.3°C | - | 100% | 0.02kPa |
| 20:00 ☾ | -8°C | -5.4°C | -7.4°C | - | 100% | 0.02kPa |
How to read: these inputs help produce the derived score; they are not requirements by themselves.
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