How often do conditions match?

No opportunity windows are predicted in the next 14 days. Conditions can change quickly, so check back for updates.

Rule Dawn Crystals

Morning Frost in Nuuksio

Q: What conditions does Dawn Crystals look for?

Time Window: Sunrise -45m to +90m. Frost Probability: ≥ 60.0%. Dewpoint Spread: ≤ 3.0°C. Relative Humidity: ≥ 85.0%. Wind Speed: ≤ 1.5m/s

Uusimaa, Finland

Morning dew drops or frost crystals on calm mornings

No opportunities right now

Here’s what usually blocks matches

No frost conditions. Autumn and spring mornings bring delicate frost patterns to the forest floor.

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Rule requirements (key thresholds)

Time Window · Sunrise -45m to +90m Frost Probability · ≥ 60.0% Dewpoint Spread · ≤ 3.0°C Relative Humidity · ≥ 85.0%

Tip: Scroll down to the 72-hour table to see exactly which condition fails hour by hour.

Most common blockers (next 72 hours)

Wind Speed 100% failing

Time Window 88% failing

Frost Probability 26% failing

Upcoming Opportunities

When all conditions match, PhotoWeather marks an opportunity window.

Times shown in Europe/Helsinki

No opportunities in the next 14 days

See the blocker timeline above to understand which conditions are preventing matches.

What this forecast looks for

Plain-language explanation from the rule

Dawn Crystals detects conditions for dew drops and frost:

Frost Probability: Based on temperature and humidity
Dewpoint Spread: Close spread means moisture condensation
Wind Speed: Calm conditions let frost/dew form undisturbed
Timing: Around sunrise when conditions are most favorable

Perfect for macro photography of frost crystals and dew drops.

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72-hour requirements breakdown

What passed or failed, hour by hour

0matching hours in the next 72 hours

OR logic: one branch per group is enough

Meets requirement

Misses requirement

Time Europe/Helsinki	Time Window Sunrise -45m to +90m	Frost Probability OR1·B1 ≥ 60.0%	Dewpoint Spread OR1·B2 ≤ 3.0°C	Relative Humidity OR1·B2 ≥ 85.0%	Wind Speed ≤ 1.5m/s
Fri, Jan 9
08:00	✓	58%	1.7°C	87%	3.1m/s
09:00	✓	54%	1.8°C	86%	3.4m/s
10:00	✓	54%	2.2°C	83%	3.4m/s
11:00	✕	62%	3.3°C	76%	3.8m/s
12:00	✕	62%	4.3°C	70%	3.9m/s
13:00	✕	62%	5.2°C	65%	4m/s
14:00	✕	62%	5.6°C	63%	4.1m/s
15:00	✕	62%	5.8°C	62%	4m/s
16:00	✕	62%	5.9°C	61%	4m/s
17:00	✕	62%	5.9°C	61%	4m/s
18:00	✕	66%	6.1°C	60%	4m/s
19:00	✕	66%	6.7°C	57%	4m/s
20:00	✕	64%	7.1°C	55%	4.3m/s
21:00	✕	66%	7.1°C	55%	4.1m/s
22:00	✕	67%	7.3°C	54%	3.7m/s
23:00	✕	66%	7.7°C	52%	4.1m/s
Sat, Jan 10
24:00	✕	69%	8.4°C	49%	4.1m/s
01:00	✕	69%	8.9°C	47%	3.8m/s
02:00	✕	69%	8.7°C	48%	4.1m/s
03:00	✕	69%	8.8°C	48%	4.1m/s
04:00	✕	64%	6.2°C	60%	4.4m/s
05:00	✕	60%	4.2°C	71%	4.6m/s
06:00	✕	60%	3.1°C	78%	4.7m/s
07:00	✕	52%	2.6°C	81%	4.9m/s
08:00	✓	52%	2.6°C	81%	4.9m/s
09:00	✓	52%	2.6°C	81%	5.3m/s
10:00	✓	52%	2.8°C	80%	5.2m/s
11:00	✕	52%	2.9°C	79%	5.2m/s
12:00	✕	60%	3.4°C	76%	5.4m/s
13:00	✕	60%	4.1°C	72%	5.5m/s
14:00	✕	60%	4.8°C	68%	5.4m/s
15:00	✕	63%	5.4°C	65%	5.4m/s
16:00	✕	63%	5.8°C	63%	5.3m/s
17:00	✕	63%	5.8°C	63%	5.2m/s
18:00	✕	63%	5.9°C	62%	5.3m/s
19:00	✕	63%	5.9°C	62%	5.3m/s
20:00	✕	63%	5.9°C	62%	5.6m/s
21:00	✕	63%	5.9°C	62%	5.5m/s
22:00	✕	63%	5.9°C	62%	5.5m/s
23:00	✕	63%	5.8°C	63%	5.5m/s
Sun, Jan 11
24:00	✕	63%	5.4°C	65%	5.3m/s
01:00	✕	63%	5°C	67%	5.5m/s
02:00	✕	60%	4.5°C	70%	5.4m/s
03:00	✕	60%	4.1°C	72%	5.4m/s
04:00	✕	60%	3.6°C	75%	5.2m/s
05:00	✕	60%	3.5°C	76%	5.1m/s
06:00	✕	60%	3.5°C	76%	5m/s
07:00	✕	60%	3.5°C	76%	4.9m/s
08:00	✓	60%	3.5°C	76%	4.9m/s
09:00	✓	60%	3.3°C	77%	4.6m/s
10:00	✓	60%	3.3°C	77%	4.4m/s
11:00	✕	60%	3.5°C	76%	4.3m/s
12:00	✕	62%	3.5°C	76%	4.1m/s
13:00	✕	62%	3.3°C	77%	4.1m/s
14:00	✕	60%	3.2°C	78%	4.3m/s
15:00	✕	52%	2.9°C	80%	4.6m/s
16:00	✕	52%	2.4°C	83%	4.7m/s
17:00	✕	52%	2.4°C	83%	4.4m/s
18:00	✕	52%	2.4°C	83%	4.3m/s
19:00	✕	54%	2.2°C	84%	4.2m/s
20:00	✕	52%	2.2°C	84%	4.3m/s
21:00	✕	52%	2.2°C	84%	4.4m/s
22:00	✕	52%	2.4°C	83%	4.6m/s
23:00	✕	53%	2.5°C	82%	4.7m/s
Mon, Jan 12
24:00	✕	52%	2.5°C	82%	4.7m/s
01:00	✕	53%	2.4°C	83%	4.6m/s
02:00	✕	52%	2.2°C	84%	4.5m/s
03:00	✕	52%	2.2°C	84%	4.3m/s
04:00	✕	53%	2.1°C	85%	4.3m/s
05:00	✕	56%	2.1°C	85%	4.2m/s
06:00	✕	58%	2.1°C	85%	4.2m/s
07:00	✕	65%	2.1°C	85%	4.2m/s

How to read: colored cells show whether each predicate requirement is met; highlighted rows mean the full rule matched (an opportunity). For OR groups, only one branch is required, so some OR-branch predicates can be ✕ even in a matching hour.

What does Frost Probability mean?

Inputs that drive the score

This 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	Frost Probability %	Dew Point °C	Dewpoint Spread °C	Relative Humidity %	Surface Temperature °C	Temperature °C	Time Window	Total Cloud Coverage %	Vapor Pressure Deficit kPa
Fri, Jan 9 Sunrise 09:20 Sunset 15:37
09:00	54%	-16°C	1.8°C	86%	-15°C	-14°C	-	84%	0.03kPa
10:00	54%	-17°C	2.2°C	83%	-16°C	-14°C	-	99%	0.03kPa
11:00	62%	-17°C	3.3°C	76%	-16°C	-14°C	-	96%	0.05kPa
12:00	62%	-18°C	4.3°C	70%	-15°C	-13°C	-	92%	0.07kPa
13:00	62%	-18°C	5.2°C	65%	-15°C	-13°C	-	97%	0.08kPa
14:00	62%	-18°C	5.6°C	63%	-15°C	-12°C	-	99%	0.09kPa
15:00	62%	-18°C	5.8°C	62%	-15°C	-12°C	-	98%	0.09kPa
16:00	62%	-19°C	5.9°C	61%	-15°C	-13°C	-	96%	0.09kPa
17:00	62%	-19°C	5.9°C	61%	-15°C	-13°C	-	95%	0.09kPa
18:00	66%	-19°C	6.1°C	60%	-16°C	-13°C	-	100%	0.09kPa
19:00	66%	-20°C	6.7°C	57%	-16°C	-13°C	-	94%	0.09kPa
20:00	64%	-21°C	7.1°C	55%	-15°C	-14°C	-	98%	0.1kPa
21:00	66%	-21°C	7.1°C	55%	-15°C	-14°C	-	94%	0.1kPa
22:00	67%	-21°C	7.3°C	54%	-15°C	-14°C	-	80%	0.1kPa
23:00	66%	-21°C	7.7°C	52%	-16°C	-13°C	-	97%	0.1kPa
Sat, Jan 10 Sunrise 09:20 Sunset 15:37
24:00	69%	-21°C	8.4°C	49%	-16°C	-13°C	-	100%	0.11kPa
01:00	69%	-22°C	8.9°C	47%	-16°C	-13°C	-	100%	0.12kPa
02:00	69%	-21°C	8.7°C	48%	-15°C	-12°C	-	100%	0.12kPa
03:00	69%	-21°C	8.8°C	48%	-15°C	-12°C	-	99%	0.13kPa
04:00	64%	-18°C	6.2°C	60%	-14°C	-12°C	-	98%	0.1kPa
05:00	60%	-16°C	4.2°C	71%	-14°C	-11°C	-	99%	0.07kPa
06:00	60%	-14°C	3.1°C	78%	-14°C	-11°C	-	100%	0.06kPa
07:00	52%	-14°C	2.6°C	81%	-14°C	-11°C	-	100%	0.05kPa
08:00	52%	-13°C	2.6°C	81%	-14°C	-11°C	-	100%	0.05kPa
09:00	52%	-13°C	2.6°C	81%	-14°C	-10°C	-	100%	0.05kPa
10:00	52%	-13°C	2.8°C	80%	-14°C	-10°C	-	100%	0.06kPa
11:00	52%	-13°C	2.9°C	79%	-13°C	-9.8°C	-	95%	0.06kPa
12:00	60%	-13°C	3.4°C	76%	-13°C	-9.3°C	-	100%	0.07kPa
13:00	60%	-13°C	4.1°C	72%	-12°C	-8.6°C	-	100%	0.09kPa
14:00	60%	-13°C	4.8°C	68%	-12°C	-8.4°C	-	100%	0.1kPa
15:00	63%	-14°C	5.4°C	65%	-12°C	-8.3°C	-	100%	0.11kPa
16:00	63%	-14°C	5.8°C	63%	-12°C	-8.4°C	-	100%	0.12kPa
17:00	63%	-14°C	5.8°C	63%	-12°C	-8.6°C	-	100%	0.12kPa
18:00	63%	-15°C	5.9°C	62%	-12°C	-8.8°C	-	99%	0.12kPa
19:00	63%	-15°C	5.9°C	62%	-12°C	-8.9°C	-	95%	0.12kPa
20:00	63%	-15°C	5.9°C	62%	-11°C	-9°C	-	85%	0.12kPa
21:00	63%	-15°C	5.9°C	62%	-11°C	-9°C	-	100%	0.12kPa
22:00	63%	-15°C	5.9°C	62%	-11°C	-8.9°C	-	100%	0.12kPa
23:00	63%	-14°C	5.8°C	63%	-10°C	-8.7°C	-	100%	0.12kPa
Sun, Jan 11 Sunrise 09:19 Sunset 15:39
24:00	63%	-14°C	5.4°C	65%	-9.8°C	-8.6°C	-	100%	0.11kPa
01:00	63%	-13°C	5°C	67%	-9.6°C	-8.5°C	-	100%	0.11kPa
02:00	60%	-13°C	4.5°C	70%	-9.5°C	-8.3°C	-	100%	0.1kPa
03:00	60%	-12°C	4.1°C	72%	-9.4°C	-8.3°C	-	100%	0.09kPa
04:00	60%	-12°C	3.6°C	75%	-9.2°C	-8.1°C	-	100%	0.08kPa
05:00	60%	-11°C	3.5°C	76%	-9.1°C	-8°C	-	100%	0.08kPa
06:00	60%	-11°C	3.5°C	76%	-8.9°C	-7.9°C	-	100%	0.08kPa
07:00	60%	-11°C	3.5°C	76%	-8.8°C	-7.7°C	-	100%	0.08kPa
08:00	60%	-11°C	3.5°C	76%	-8.6°C	-7.7°C	-	100%	0.08kPa
09:00	60%	-11°C	3.3°C	77%	-8.3°C	-7.6°C	-	100%	0.08kPa
10:00	60%	-11°C	3.3°C	77%	-8.1°C	-7.7°C	-	100%	0.08kPa
11:00	60%	-11°C	3.5°C	76%	-7.6°C	-7.6°C	-	100%	0.08kPa
12:00	62%	-11°C	3.5°C	76%	-7.3°C	-7.5°C	-	100%	0.08kPa
13:00	62%	-10°C	3.3°C	77%	-7.2°C	-7.2°C	-	100%	0.08kPa
14:00	60%	-10°C	3.2°C	78%	-7.1°C	-7.1°C	-	100%	0.08kPa
15:00	52%	-9.9°C	2.9°C	80%	-7.1°C	-7°C	-	100%	0.07kPa
16:00	52%	-9.4°C	2.4°C	83%	-7.2°C	-7°C	-	100%	0.06kPa
17:00	52%	-9.3°C	2.4°C	83%	-7.2°C	-6.9°C	-	100%	0.06kPa
18:00	52%	-9.2°C	2.4°C	83%	-7.1°C	-6.8°C	-	100%	0.06kPa
19:00	54%	-9°C	2.2°C	84%	-7°C	-6.8°C	-	100%	0.06kPa
20:00	52%	-9°C	2.2°C	84%	-6.9°C	-6.8°C	-	100%	0.06kPa
21:00	52%	-9°C	2.2°C	84%	-6.9°C	-6.8°C	-	99%	0.06kPa
22:00	52%	-9.2°C	2.4°C	83%	-7.1°C	-6.8°C	-	88%	0.06kPa
23:00	53%	-9.4°C	2.5°C	82%	-7.2°C	-6.9°C	-	70%	0.07kPa
Mon, Jan 12 Sunrise 09:18 Sunset 15:41
24:00	52%	-9.7°C	2.5°C	82%	-7.6°C	-7.2°C	-	99%	0.06kPa
01:00	53%	-9.9°C	2.4°C	83%	-7.9°C	-7.5°C	-	80%	0.06kPa
02:00	52%	-9.6°C	2.2°C	84%	-7.8°C	-7.4°C	-	100%	0.06kPa
03:00	52%	-9.5°C	2.2°C	84%	-7.8°C	-7.3°C	-	99%	0.06kPa
04:00	53%	-9.2°C	2.1°C	85%	-7.4°C	-7.1°C	-	71%	0.05kPa
05:00	56%	-9.2°C	2.1°C	85%	-7.4°C	-7.1°C	-	51%	0.05kPa
06:00	58%	-9.2°C	2.1°C	85%	-7.3°C	-7.1°C	-	50%	0.05kPa
07:00	65%	-9.3°C	2.1°C	85%	-7.6°C	-7.2°C	-	24%	0.05kPa
08:00	0%	-9.6°C	1.9°C	86%	-8.1°C	-7.7°C	-	48%	0.05kPa

How to read: these inputs help produce the derived score; they are not requirements by themselves.

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