Korkki Road
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Korkki Road clear sky chart from 2005-11-06 to 2025-11-03.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.

Observation Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(no limit)	Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

By Month

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

		Occurrence of each Forecast	Data Points
Cloud Cover	Day	13% 9% 3 7% 5% 4 4 4 5% 7% 38%	127845
	Night	13% 10% 3 8% 5% 4 4 4 5% 6% 38%	122441
Transparency	Day	29% 38% 10% 16% 7% 1	131321
	Night	31% 38% 8% 15% 7% 1	127052
Seeing	Day	16% 9% 30% 30% 13% 3	17522
	Night	17% 8% 31% 31% 12% 1	27358

By Month

Percentage Cloud Cover NE (2006-)
Color Meanings: Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	7% 11% 5% 11% 6% 4 4 3 4 6% 39%	3617
	11th to 20th	Day	5% 13% 6% 11% 8% 6% 5% 4 7% 8% 25%	3589
	21st to end	Day	5% 13% 7% 12% 7% 6% 5% 4 6% 7% 27%	4143
February	1st to 10th	Day	8% 11% 5% 11% 6% 5% 5% 4 5% 7% 34%	1800
	11th to 20th	Day	9% 11% 4 8% 4 4 5% 3 5% 7% 39%	1754
	21st to end	Day	7% 13% 4 8% 6% 4 5% 4 6% 7% 35%	1580
March	1st to 10th	Day	11% 8% 3 7% 4 5% 4 4 5% 8% 41%	4588
	11th to 20th	Day	8% 10% 4 9% 6% 5% 5% 4 6% 8% 35%	4980
	21st to end	Day	20% 12% 3 7% 3 3 4 3 4 5% 34%	5687
April	1st to 10th	Day	16% 11% 3 9% 6% 5% 5% 3 4 6% 32%	2400
	11th to 20th	Day	17% 11% 3 9% 4 5% 5% 4 5% 6% 31%	2374
	21st to end	Day	21% 10% 3 7% 5% 4 4 4 5% 6% 32%	2626
May	1st to 10th	Day	16% 7% 2 5% 4 3 3 2 4 5% 49%	6348
	11th to 20th	Day	16% 7% 2 5% 5% 4 4 4 5% 7% 41%	6319
	21st to end	Day	14% 7% 3 7% 5% 4 4 3 5% 7% 40%	6949
June	1st to 10th	Day	11% 6% 2 5% 4 4 5% 4 7% 9% 43%	2800
	11th to 20th	Day	15% 6% 2 6% 5% 4 5% 3 6% 8% 38%	2880
	21st to end	Day	14% 6% 2 5% 5% 5% 6% 5% 8% 9% 35%	3000
July	1st to 10th	Day	10% 5% 2 5% 4 5% 5% 4 7% 10% 43%	6623
	11th to 20th	Day	12% 4 1 5% 3 4 4 4 6% 9% 47%	6360
	21st to end	Day	9% 4 2 5% 3 4 4 4 7% 10% 48%	6926
August	1st to 10th	Day	9% 5% 2 6% 5% 5% 5% 5% 7% 9% 42%	4481
	11th to 20th	Day	15% 4 2 5% 4 4 4 4 6% 8% 46%	4171
	21st to end	Day	16% 6% 2 6% 4 3 4 3 5% 8% 41%	4421
September	1st to 10th	Day	10% 5% 2 6% 4 4 5% 4 5% 8% 46%	2400
	11th to 20th	Day	16% 6% 2 6% 5% 4 4 4 5% 7% 41%	2400
	21st to end	Day	16% 8% 3 6% 4 4 4 3 5% 6% 42%	2108
October	1st to 10th	Day	16% 7% 3 7% 5% 4 6% 4 6% 6% 36%	2000
	11th to 20th	Day	16% 11% 4 7% 5% 4 4 3 6% 7% 34%	2000
	21st to end	Day	20% 11% 3 8% 5% 5% 4 3 5% 5% 31%	2054
November	1st to 10th	Day	14% 11% 3 8% 6% 5% 5% 4 5% 7% 32%	1671
	11th to 20th	Day	14% 14% 6% 10% 7% 5% 5% 3 5% 4 27%	1600
	21st to end	Day	13% 12% 5% 9% 6% 5% 5% 4 5% 8% 29%	1600
December	1st to 10th	Day	11% 14% 5% 12% 7% 6% 5% 3 6% 7% 25%	2610
	11th to 20th	Day	12% 18% 6% 8% 5% 4 4 3 4 4 30%	3004
	21st to end	Day	22% 20% 7% 13% 5% 4 3 2 3 4 19%	3982
January	1st to 10th	Night	8% 10% 5% 11% 6% 5% 5% 4 5% 6% 36%	6348
	11th to 20th	Night	7% 10% 5% 11% 7% 6% 7% 5% 6% 7% 29%	6316
	21st to end	Night	7% 16% 6% 11% 5% 5% 4 3 5% 7% 32%	6830
February	1st to 10th	Night	7% 12% 4 10% 5% 4 4 5% 5% 6% 36%	2600
	11th to 20th	Night	7% 10% 4 8% 5% 5% 4 4 5% 7% 42%	2533
	21st to end	Night	10% 12% 4 10% 5% 5% 3 4 6% 7% 37%	2050
March	1st to 10th	Night	9% 8% 3 6% 4 4 5% 3 5% 7% 47%	5281
	11th to 20th	Night	11% 10% 3 10% 6% 5% 6% 4 6% 7% 31%	4979
	21st to end	Night	21% 14% 4 7% 5% 4 3 2 4 4 32%	5243
April	1st to 10th	Night	15% 13% 3 7% 5% 4 4 3 6% 6% 34%	2000
	11th to 20th	Night	18% 10% 2 6% 5% 3 4 4 5% 6% 36%	1975
	21st to end	Night	21% 10% 2 7% 4 4 4 4 4 5% 35%	1769
May	1st to 10th	Night	16% 5% 2 5% 3 3 3 3 4 6% 49%	3613
	11th to 20th	Night	15% 6% 2 6% 4 4 4 3 5% 6% 46%	3596
	21st to end	Night	15% 8% 2 6% 4 4 4 4 5% 7% 40%	3949
June	1st to 10th	Night	14% 6% 1 6% 5% 4 4 3 6% 9% 42%	1600
	11th to 20th	Night	13% 8% 2 5% 4 5% 4 4 7% 7% 40%	1512
	21st to end	Night	12% 7% 2 6% 4 4 4 4 6% 9% 43%	1400
July	1st to 10th	Night	8% 6% 2 5% 3 3 4 4 5% 9% 50%	3350
	11th to 20th	Night	11% 3 2 4 3 3 3 3 5% 7% 57%	3620
	21st to end	Night	10% 5% 2 6% 4 4 4 4 6% 8% 48%	3948
August	1st to 10th	Night	11% 3 1 5% 3 5% 4 4 5% 8% 50%	2662
	11th to 20th	Night	14% 5% 2 4 3 3 3 3 6% 8% 50%	2888
	21st to end	Night	21% 6% 2 5% 3 3 3 3 4 7% 42%	3479
September	1st to 10th	Night	10% 5% 2 5% 4 4 4 3 5% 7% 51%	2000
	11th to 20th	Night	13% 5% 2 5% 3 3 4 4 5% 7% 49%	2000
	21st to end	Night	15% 6% 2 5% 4 4 4 3 5% 6% 45%	2268
October	1st to 10th	Night	16% 5% 2 7% 4 5% 3 3 5% 6% 44%	2400
	11th to 20th	Night	16% 7% 3 6% 5% 4 4 4 5% 7% 37%	2400
	21st to end	Night	19% 9% 3 7% 5% 4 4 4 5% 6% 33%	2785
November	1st to 10th	Night	14% 9% 3 6% 4 6% 5% 4 6% 7% 35%	2668
	11th to 20th	Night	16% 12% 3 7% 5% 5% 5% 3 6% 7% 31%	2800
	21st to end	Night	13% 10% 3 7% 4 5% 5% 5% 6% 6% 35%	2800
December	1st to 10th	Night	11% 12% 4 11% 6% 6% 7% 5% 7% 6% 24%	4580
	11th to 20th	Night	11% 16% 5% 10% 5% 5% 5% 4 5% 5% 27%	5203
	21st to end	Night	24% 19% 6% 10% 3 3 2 2 3 4 23%	6996

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	36% 27% 7% 17% 13%	3618
	11th to 20th	Day	43% 28% 5% 18% 5%	3620
	21st to end	Day	43% 31% 7% 14% 5%	4143
February	1st to 10th	Day	21% 62% 5% 8% 3 1	1800
	11th to 20th	Day	18% 60% 4 11% 5%	1763
	21st to end	Day	18% 62% 5% 8% 7%	1580
March	1st to 10th	Day	28% 30% 10% 18% 9% 4	4590
	11th to 20th	Day	35% 30% 10% 14% 10% 1	4980
	21st to end	Day	37% 30% 8% 15% 10% 1	5687
April	1st to 10th	Day	22% 63% 4 7% 4 1	2400
	11th to 20th	Day	20% 63% 4 8% 4 1	2374
	21st to end	Day	20% 62% 3 9% 5%	2626
May	1st to 10th	Day	25% 29% 12% 20% 14%	6357
	11th to 20th	Day	31% 30% 11% 16% 7% 4	6323
	21st to end	Day	31% 30% 7% 20% 11%	6949
June	1st to 10th	Day	13% 63% 8% 10% 6% 1	2800
	11th to 20th	Day	19% 63% 7% 8% 4	2880
	21st to end	Day	20% 61% 6% 10% 3	3000
July	1st to 10th	Day	28% 27% 18% 21% 5%	6554
	11th to 20th	Day	26% 27% 15% 26% 6%	6285
	21st to end	Day	24% 25% 15% 26% 10%	6728
August	1st to 10th	Day	25% 36% 14% 17% 8%	4466
	11th to 20th	Day	23% 37% 16% 21% 3	4210
	21st to end	Day	31% 37% 12% 15% 4	4420
September	1st to 10th	Day	18% 58% 8% 12% 3	2400
	11th to 20th	Day	20% 58% 9% 11% 2	2400
	21st to end	Day	20% 57% 7% 11% 5%	2108
October	1st to 10th	Day	22% 35% 13% 20% 8% 1	3260
	11th to 20th	Day	24% 36% 7% 22% 11%	3240
	21st to end	Day	34% 35% 12% 14% 4	3292
November	1st to 10th	Day	27% 56% 5% 10% 3	1671
	11th to 20th	Day	26% 57% 5% 8% 4	1600
	21st to end	Day	28% 57% 4 7% 3 1	1600
December	1st to 10th	Day	41% 36% 7% 14% 2	2610
	11th to 20th	Day	40% 32% 5% 11% 11%	3005
	21st to end	Day	56% 28% 4 9% 3	3982
January	1st to 10th	Night	39% 28% 9% 13% 12%	6348
	11th to 20th	Night	42% 27% 10% 16% 5%	6360
	21st to end	Night	41% 29% 9% 16% 4	6830
February	1st to 10th	Night	19% 62% 6% 9% 4	2600
	11th to 20th	Night	18% 61% 5% 11% 4	2534
	21st to end	Night	18% 62% 4 10% 6% 1	2050
March	1st to 10th	Night	24% 30% 11% 14% 16% 5%	5292
	11th to 20th	Night	41% 30% 8% 13% 7%	4980
	21st to end	Night	43% 28% 5% 11% 11% 1	5243
April	1st to 10th	Night	20% 61% 4 8% 6%	2000
	11th to 20th	Night	19% 63% 4 8% 5% 1	1975
	21st to end	Night	19% 61% 3 11% 6%	1769
May	1st to 10th	Night	24% 30% 11% 24% 11%	3620
	11th to 20th	Night	28% 30% 7% 17% 12% 5%	3597
	21st to end	Night	31% 31% 7% 21% 9%	3950
June	1st to 10th	Night	15% 62% 6% 10% 7% 1	1600
	11th to 20th	Night	19% 63% 5% 8% 5%	1512
	21st to end	Night	17% 60% 6% 14% 3 1	1400
July	1st to 10th	Night	27% 27% 16% 22% 7%	3312
	11th to 20th	Night	21% 25% 15% 33% 5%	3572
	21st to end	Night	29% 26% 11% 24% 9% 1	3832
August	1st to 10th	Night	24% 36% 12% 15% 12% 1	2653
	11th to 20th	Night	24% 36% 11% 26% 3	2915
	21st to end	Night	34% 36% 11% 16% 3	3479
September	1st to 10th	Night	17% 57% 10% 12% 3 1	2000
	11th to 20th	Night	16% 57% 11% 12% 3	2000
	21st to end	Night	20% 57% 6% 13% 5%	2268
October	1st to 10th	Night	16% 34% 7% 25% 15% 2	3920
	11th to 20th	Night	25% 35% 6% 20% 13%	3899
	21st to end	Night	36% 36% 8% 13% 6%	4497
November	1st to 10th	Night	23% 56% 7% 11% 3	2668
	11th to 20th	Night	21% 57% 9% 8% 4	2800
	21st to end	Night	24% 57% 8% 8% 3	2800
December	1st to 10th	Night	40% 37% 10% 11% 2	4580
	11th to 20th	Night	42% 33% 6% 15% 4	5201
	21st to end	Night	51% 28% 4 14% 3	6996

Seeing (when cloud cover <= 80%)
Color Meanings: Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	13% 9% 38% 29% 10% 1	300
	11th to 20th	Day	15% 8% 35% 31% 11%	300
	21st to end	Day	12% 12% 35% 31% 9% 1	330
February	1st to 10th	Day	12% 14% 43% 24% 6% 1	300
	11th to 20th	Day	11% 16% 43% 20% 8% 1	300
	21st to end	Day	14% 14% 43% 28% 2	249
March	1st to 10th	Day	15% 10% 34% 32% 7% 1	300
	11th to 20th	Day	14% 9% 42% 25% 9% 1	300
	21st to end	Day	24% 10% 32% 25% 8% 2	424
April	1st to 10th	Day	21% 13% 33% 26% 6% 1	500
	11th to 20th	Day	23% 11% 27% 29% 10% 1	492
	21st to end	Day	24% 9% 28% 27% 11% 1	680
May	1st to 10th	Day	20% 10% 33% 27% 7% 3	703
	11th to 20th	Day	18% 8% 30% 28% 13% 3	725
	21st to end	Day	18% 7% 27% 32% 14% 2	789
June	1st to 10th	Day	11% 7% 30% 35% 14% 3	730
	11th to 20th	Day	16% 9% 29% 35% 11% 1	730
	21st to end	Day	14% 6% 29% 32% 16% 3	730
July	1st to 10th	Day	9% 4 22% 37% 22% 6%	721
	11th to 20th	Day	9% 5% 27% 32% 20% 6%	718
	21st to end	Day	7% 4 24% 40% 20% 6%	794
August	1st to 10th	Day	11% 5% 23% 37% 20% 5%	726
	11th to 20th	Day	14% 5% 20% 33% 24% 4	715
	21st to end	Day	17% 6% 20% 33% 21% 4	653
September	1st to 10th	Day	11% 5% 27% 35% 19% 3	530
	11th to 20th	Day	18% 6% 24% 31% 19% 3	530
	21st to end	Day	21% 8% 27% 23% 16% 4	394
October	1st to 10th	Day	18% 9% 31% 27% 13% 2	330
	11th to 20th	Day	17% 15% 36% 25% 5% 1	330
	21st to end	Day	24% 12% 35% 23% 5% 1	363
November	1st to 10th	Day	21% 11% 33% 24% 10%	306
	11th to 20th	Day	20% 12% 39% 22% 6%	300
	21st to end	Day	19% 14% 33% 27% 6%	300
December	1st to 10th	Day	15% 15% 35% 26% 7% 1	300
	11th to 20th	Day	20% 14% 40% 21% 6%	300
	21st to end	Day	27% 11% 32% 25% 5%	330
January	1st to 10th	Night	14% 10% 38% 31% 7% 1	1000
	11th to 20th	Night	16% 8% 43% 25% 8% 1	1000
	21st to end	Night	16% 9% 40% 27% 7% 1	1100
February	1st to 10th	Night	12% 10% 41% 29% 7% 1	1000
	11th to 20th	Night	12% 11% 41% 26% 10% 1	979
	21st to end	Night	16% 8% 37% 30% 8%	730
March	1st to 10th	Night	15% 8% 35% 34% 8% 1	771
	11th to 20th	Night	17% 8% 37% 28% 9% 1	600
	21st to end	Night	22% 7% 29% 27% 12% 2	660
April	1st to 10th	Night	21% 9% 35% 28% 8%	600
	11th to 20th	Night	24% 8% 25% 31% 10% 1	593
	21st to end	Night	25% 6% 25% 31% 12% 2	600
May	1st to 10th	Night	18% 7% 32% 31% 11% 2	600
	11th to 20th	Night	19% 6% 23% 36% 14% 2	591
	21st to end	Night	18% 5% 19% 39% 18% 1	650
June	1st to 10th	Night	16% 4 24% 39% 17% 1	600
	11th to 20th	Night	17% 4 23% 44% 12% 1	600
	21st to end	Night	16% 4 19% 39% 20% 2	600
July	1st to 10th	Night	7% 2 18% 41% 29% 3	585
	11th to 20th	Night	10% 1 25% 36% 26% 2	582
	21st to end	Night	8% 1 20% 43% 25% 3	657
August	1st to 10th	Night	9% 3 22% 39% 26% 1	597
	11th to 20th	Night	15% 3 18% 36% 25% 4	594
	21st to end	Night	17% 4 18% 35% 24% 2	660
September	1st to 10th	Night	11% 5% 24% 37% 21% 3	600
	11th to 20th	Night	15% 4 20% 38% 20% 2	600
	21st to end	Night	19% 6% 25% 28% 20% 2	735
October	1st to 10th	Night	18% 8% 29% 30% 15% 1	800
	11th to 20th	Night	19% 10% 35% 28% 8% 1	800
	21st to end	Night	23% 11% 31% 27% 8%	880
November	1st to 10th	Night	18% 11% 33% 29% 8%	894
	11th to 20th	Night	20% 14% 32% 24% 9% 1	1000
	21st to end	Night	18% 14% 35% 27% 6%	1000
December	1st to 10th	Night	18% 13% 35% 28% 6%	1000
	11th to 20th	Night	21% 12% 37% 23% 8% 1	1000
	21st to end	Night	28% 10% 33% 21% 6% 1	1100

Page generated at 2025-10-31 01:02:39. Version ac07

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