Snow King Mountain
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Snow King Mountain clear sky chart from 2005-11-06 to 2025-05-26.

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	5% 12% 4 9% 5% 4 4 3 5% 6% 42%	118971
	Night	4 13% 5% 10% 4 4 4 3 5% 6% 42%	119213
Transparency	Day	41% 5% 11% 20% 16% 7%	118719
	Night	41% 5% 13% 22% 15% 5%	119054
Seeing	Day	13% 19% 32% 25% 10% 2	16361
	Night	12% 11% 25% 36% 15% 1	26038

By Month

Percentage Cloud Cover SW (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	2 17% 8% 20% 7% 5% 4 4 4 5% 24%	3776
	11th to 20th	Day	3 13% 6% 16% 7% 5% 4 3 5% 6% 33%	4100
	21st to end	Day	2 19% 6% 10% 5% 3 4 3 4 6% 37%	4510
February	1st to 10th	Day	4 23% 10% 16% 5% 5% 4 3 5% 5% 20%	1800
	11th to 20th	Day	3 25% 9% 13% 7% 4 4 2 4 5% 24%	1755
	21st to end	Day	4 21% 9% 18% 7% 3 4 3 4 4 22%	1590
March	1st to 10th	Day	3 20% 6% 14% 4 4 4 3 4 4 34%	4882
	11th to 20th	Day	3 18% 7% 12% 4 4 3 2 4 5% 37%	5000
	21st to end	Day	6% 24% 8% 14% 6% 6% 5% 3 4 5% 19%	5486
April	1st to 10th	Day	7% 19% 7% 11% 5% 4 4 3 5% 6% 28%	2302
	11th to 20th	Day	7% 16% 5% 11% 7% 5% 4 3 5% 6% 30%	2508
	21st to end	Day	8% 17% 5% 10% 6% 4 4 5% 5% 7% 29%	2600
May	1st to 10th	Day	9% 17% 4 10% 5% 5% 5% 4 5% 6% 30%	4240
	11th to 20th	Day	6% 7% 2 6% 5% 5% 6% 5% 6% 8% 44%	4322
	21st to end	Day	9% 15% 4 9% 5% 4 5% 4 5% 5% 35%	4897
June	1st to 10th	Day	11% 8% 2 6% 5% 5% 5% 5% 7% 9% 39%	2660
	11th to 20th	Day	9% 8% 3 7% 5% 4 4 4 6% 6% 45%	2817
	21st to end	Day	3 3 1 4 3 4 4 4 5% 8% 63%	2850
July	1st to 10th	Day	2 2 1 3 2 2 3 3 5% 7% 70%	4740
	11th to 20th	Day	2 2 1 4 4 4 4 3 6% 7% 63%	4294
	21st to end	Day	3 3 1 5% 4 4 5% 4 6% 8% 56%	4454
August	1st to 10th	Day	3 3 2 5% 4 5% 5% 5% 7% 8% 54%	4092
	11th to 20th	Day	2 3 1 4 3 4 5% 4 5% 8% 62%	4028
	21st to end	Day	3 2 1 3 3 4 3 3 4 7% 66%	4467
September	1st to 10th	Day	4 4 2 4 4 3 3 4 5% 5% 61%	2266
	11th to 20th	Day	7% 6% 2 5% 3 4 3 3 5% 6% 55%	2090
	21st to end	Day	8% 5% 2 5% 3 3 3 2 4 5% 60%	2090
October	1st to 10th	Day	6% 7% 2 5% 3 2 3 2 3 3 63%	3216
	11th to 20th	Day	6% 9% 2 6% 3 3 3 3 4 5% 55%	3150
	21st to end	Day	6% 14% 4 8% 4 4 4 3 6% 7% 41%	3395
November	1st to 10th	Day	12% 15% 6% 8% 4 3 3 2 5% 6% 37%	1744
	11th to 20th	Day	7% 19% 5% 10% 5% 4 3 2 4 6% 36%	1600
	21st to end	Day	3 17% 8% 12% 4 5% 3 3 4 6% 37%	1600
December	1st to 10th	Day	3 13% 6% 9% 5% 3 3 2 4 6% 46%	2620
	11th to 20th	Day	4 20% 8% 17% 7% 4 3 3 4 6% 24%	3026
	21st to end	Day	5% 19% 6% 14% 7% 5% 4 4 5% 7% 24%	4004
January	1st to 10th	Night	2 12% 9% 20% 8% 5% 4 3 6% 8% 24%	6218
	11th to 20th	Night	2 16% 7% 17% 6% 5% 5% 4 5% 7% 26%	5880
	21st to end	Night	3 21% 5% 9% 4 3 3 2 4 7% 39%	6468
February	1st to 10th	Night	4 22% 9% 15% 7% 5% 4 3 4 5% 22%	2600
	11th to 20th	Night	4 21% 8% 15% 6% 4 4 3 3 4 29%	2532
	21st to end	Night	4 18% 8% 19% 6% 4 3 3 4 5% 25%	2036
March	1st to 10th	Night	2 22% 7% 14% 4 3 2 2 2 5% 35%	5010
	11th to 20th	Night	3 13% 6% 10% 5% 4 4 3 5% 7% 40%	5000
	21st to end	Night	5% 18% 8% 12% 6% 5% 5% 4 5% 5% 27%	5489
April	1st to 10th	Night	6% 16% 5% 9% 5% 4 5% 3 4 8% 34%	2097
	11th to 20th	Night	6% 13% 4 9% 6% 4 6% 4 5% 6% 37%	1835
	21st to end	Night	7% 13% 3 7% 4 3 4 4 5% 8% 42%	1800
May	1st to 10th	Night	9% 20% 3 7% 3 3 4 3 5% 5% 37%	2950
	11th to 20th	Night	4 4 2 5% 4 3 4 4 7% 10% 53%	2799
	21st to end	Night	8% 11% 3 6% 4 4 5% 4 5% 8% 43%	2806
June	1st to 10th	Night	9% 8% 2 5% 3 4 5% 3 7% 9% 45%	1520
	11th to 20th	Night	8% 7% 2 5% 3 4 3 3 5% 7% 54%	1357
	21st to end	Night	3 1 1 3 2 3 3 3 5% 7% 69%	1330
July	1st to 10th	Night	1 1 2 2 3 3 4 5% 6% 72%	2220
	11th to 20th	Night	1 1 2 2 3 3 3 6% 9% 70%	2669
	21st to end	Night	1 1 1 2 3 3 4 4 6% 9% 65%	3109
August	1st to 10th	Night	3 3 1 5% 3 4 4 4 7% 8% 60%	2847
	11th to 20th	Night	2 3 1 4 3 4 5% 4 6% 10% 58%	2811
	21st to end	Night	3 3 1 3 2 2 3 2 4 5% 72%	3198
September	1st to 10th	Night	5% 4 1 3 2 3 3 2 5% 6% 66%	1911
	11th to 20th	Night	5% 4 2 5% 3 4 3 4 6% 7% 57%	2090
	21st to end	Night	8% 6% 1 3 2 2 3 2 3 5% 64%	2090
October	1st to 10th	Night	7% 5% 2 3 3 2 2 2 3 5% 66%	3755
	11th to 20th	Night	7% 8% 3 6% 4 4 3 3 4 6% 54%	3778
	21st to end	Night	6% 12% 3 6% 3 4 3 4 5% 8% 47%	4150
November	1st to 10th	Night	11% 14% 4 9% 3 3 3 3 4 5% 39%	2535
	11th to 20th	Night	7% 16% 5% 9% 5% 4 5% 3 5% 6% 36%	2798
	21st to end	Night	4 15% 5% 10% 5% 4 3 3 5% 6% 39%	2800
December	1st to 10th	Night	4 13% 4 11% 5% 4 3 3 3 4 44%	4570
	11th to 20th	Night	4 20% 8% 15% 6% 3 4 3 5% 6% 26%	5181
	21st to end	Night	3 21% 8% 17% 7% 5% 4 3 4 5% 25%	6974

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	57% 7% 13% 14% 8% 1	3777
	11th to 20th	Day	49% 5% 14% 18% 9% 4	4100
	21st to end	Day	46% 4 12% 21% 15% 1	4510
February	1st to 10th	Day	66% 6% 11% 12% 4 1	1800
	11th to 20th	Day	63% 5% 12% 13% 5% 2	1764
	21st to end	Day	66% 5% 7% 14% 6% 2	1590
March	1st to 10th	Day	53% 4 11% 18% 12% 3	4882
	11th to 20th	Day	49% 4 15% 24% 8% 1	5000
	21st to end	Day	65% 5% 14% 14% 2	5486
April	1st to 10th	Day	56% 7% 12% 16% 7% 1	2302
	11th to 20th	Day	55% 6% 11% 19% 9% 1	2511
	21st to end	Day	53% 6% 13% 22% 6%	2600
May	1st to 10th	Day	52% 7% 9% 22% 8% 1	4240
	11th to 20th	Day	34% 8% 10% 30% 13% 4	4325
	21st to end	Day	48% 7% 9% 26% 9%	4897
June	1st to 10th	Day	39% 7% 16% 26% 11% 1	2660
	11th to 20th	Day	38% 5% 9% 21% 18% 9%	2817
	21st to end	Day	19% 6% 7% 24% 32% 12%	2850
July	1st to 10th	Day	13% 4 5% 15% 37% 26%	4666
	11th to 20th	Day	17% 5% 5% 14% 25% 34%	4218
	21st to end	Day	23% 3 8% 17% 32% 17%	4314
August	1st to 10th	Day	23% 4 7% 19% 28% 18%	4078
	11th to 20th	Day	20% 5% 7% 23% 32% 13%	4067
	21st to end	Day	18% 4 6% 20% 32% 20%	4466
September	1st to 10th	Day	25% 5% 6% 18% 34% 13%	2266
	11th to 20th	Day	31% 4 9% 22% 26% 8%	2090
	21st to end	Day	28% 4 11% 28% 24% 5%	2090
October	1st to 10th	Day	27% 3 7% 22% 32% 9%	3216
	11th to 20th	Day	31% 3 12% 34% 15% 5%	3150
	21st to end	Day	41% 5% 17% 25% 11% 1	3395
November	1st to 10th	Day	49% 5% 14% 21% 9% 2	1744
	11th to 20th	Day	51% 5% 17% 18% 8% 1	1600
	21st to end	Day	49% 6% 16% 19% 9% 1	1600
December	1st to 10th	Day	40% 4 25% 22% 7% 2	2620
	11th to 20th	Day	62% 3 21% 12% 3	3024
	21st to end	Day	55% 5% 15% 12% 7% 6%	4004
January	1st to 10th	Night	54% 6% 12% 19% 8%	6218
	11th to 20th	Night	54% 6% 13% 17% 7% 3	5880
	21st to end	Night	45% 4 13% 24% 12% 1	6468
February	1st to 10th	Night	65% 6% 10% 12% 6%	2600
	11th to 20th	Night	60% 5% 11% 16% 8% 1	2533
	21st to end	Night	62% 5% 9% 15% 6% 3	2036
March	1st to 10th	Night	53% 4 10% 19% 12% 3	5010
	11th to 20th	Night	42% 5% 16% 26% 10% 1	5000
	21st to end	Night	53% 8% 17% 20% 2	5489
April	1st to 10th	Night	47% 8% 15% 18% 10% 2	2097
	11th to 20th	Night	46% 8% 15% 21% 9% 2	1835
	21st to end	Night	40% 7% 16% 28% 8%	1800
May	1st to 10th	Night	47% 6% 10% 24% 12% 1	2950
	11th to 20th	Night	26% 6% 17% 35% 13% 3	2800
	21st to end	Night	37% 8% 12% 30% 11% 2	2806
June	1st to 10th	Night	35% 7% 19% 26% 12% 1	1520
	11th to 20th	Night	30% 6% 12% 25% 19% 8%	1357
	21st to end	Night	15% 3 10% 25% 34% 14%	1330
July	1st to 10th	Night	12% 4 6% 16% 45% 16%	2185
	11th to 20th	Night	10% 3 5% 19% 35% 28%	2622
	21st to end	Night	13% 5% 10% 23% 33% 16%	3011
August	1st to 10th	Night	19% 3 8% 20% 34% 16%	2838
	11th to 20th	Night	20% 7% 9% 25% 26% 13%	2838
	21st to end	Night	16% 3 7% 22% 36% 17%	3198
September	1st to 10th	Night	20% 5% 6% 19% 31% 18%	1911
	11th to 20th	Night	26% 4 12% 23% 26% 10%	2090
	21st to end	Night	24% 4 9% 30% 28% 6%	2090
October	1st to 10th	Night	23% 2 7% 29% 34% 6%	3755
	11th to 20th	Night	31% 3 11% 35% 17% 3	3778
	21st to end	Night	34% 5% 18% 28% 14% 1	4150
November	1st to 10th	Night	47% 6% 13% 23% 9% 2	2535
	11th to 20th	Night	47% 7% 17% 20% 8% 1	2798
	21st to end	Night	45% 7% 16% 21% 10% 2	2800
December	1st to 10th	Night	41% 5% 27% 22% 4 1	4570
	11th to 20th	Night	57% 5% 21% 12% 3	5182
	21st to end	Night	58% 5% 13% 14% 7% 4	6974

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% 21% 27% 31% 7% 1	300
	11th to 20th	Day	8% 20% 38% 22% 10% 2	300
	21st to end	Day	8% 18% 35% 31% 8%	330
February	1st to 10th	Day	16% 37% 30% 15% 2	300
	11th to 20th	Day	18% 27% 31% 20% 4	300
	21st to end	Day	15% 30% 34% 17% 5%	354
March	1st to 10th	Day	17% 32% 31% 16% 4 1	500
	11th to 20th	Day	16% 24% 33% 21% 5%	500
	21st to end	Day	21% 27% 32% 17% 3	550
April	1st to 10th	Day	20% 26% 29% 19% 5% 1	500
	11th to 20th	Day	19% 28% 34% 15% 4 1	492
	21st to end	Day	20% 23% 28% 20% 8% 2	500
May	1st to 10th	Day	16% 22% 28% 24% 8% 2	503
	11th to 20th	Day	17% 18% 31% 23% 10% 2	597
	21st to end	Day	20% 13% 26% 25% 13% 3	760
June	1st to 10th	Day	11% 17% 28% 26% 15% 3	680
	11th to 20th	Day	15% 20% 36% 21% 8%	680
	21st to end	Day	6% 13% 32% 31% 16% 2	680
July	1st to 10th	Day	3 10% 33% 37% 15% 2	671
	11th to 20th	Day	4 13% 41% 29% 11% 2	567
	21st to end	Day	5% 9% 35% 35% 13% 2	531
August	1st to 10th	Day	6% 12% 36% 33% 11% 2	487
	11th to 20th	Day	4 11% 35% 31% 14% 4	477
	21st to end	Day	7% 17% 31% 27% 14% 4	539
September	1st to 10th	Day	5% 15% 33% 27% 15% 4	490
	11th to 20th	Day	13% 16% 30% 26% 11% 4	490
	21st to end	Day	9% 16% 29% 28% 14% 3	490
October	1st to 10th	Day	12% 18% 25% 23% 17% 4	333
	11th to 20th	Day	12% 20% 20% 26% 16% 6%	300
	21st to end	Day	15% 23% 31% 25% 5% 1	330
November	1st to 10th	Day	20% 19% 30% 20% 8% 3	300
	11th to 20th	Day	15% 21% 32% 22% 8% 2	300
	21st to end	Day	7% 20% 35% 28% 8% 1	300
December	1st to 10th	Day	16% 15% 29% 27% 12% 1	300
	11th to 20th	Day	16% 22% 33% 23% 6%	300
	21st to end	Day	17% 20% 32% 20% 8% 2	330
January	1st to 10th	Night	13% 14% 28% 35% 9% 1	956
	11th to 20th	Night	12% 15% 29% 31% 11% 2	800
	21st to end	Night	11% 10% 33% 35% 10% 1	880
February	1st to 10th	Night	12% 18% 36% 29% 5% 1	800
	11th to 20th	Night	13% 13% 32% 33% 8% 1	784
	21st to end	Night	12% 17% 33% 30% 7% 1	660
March	1st to 10th	Night	11% 19% 30% 31% 7% 1	800
	11th to 20th	Night	10% 14% 29% 35% 11% 1	800
	21st to end	Night	15% 14% 30% 31% 10%	880
April	1st to 10th	Night	14% 14% 28% 32% 10% 1	697
	11th to 20th	Night	13% 12% 32% 33% 9% 1	593
	21st to end	Night	13% 10% 26% 33% 17% 2	600
May	1st to 10th	Night	14% 11% 21% 36% 17% 1	600
	11th to 20th	Night	12% 7% 27% 33% 20% 1	591
	21st to end	Night	14% 10% 21% 37% 17% 1	634
June	1st to 10th	Night	14% 9% 23% 31% 22% 1	570
	11th to 20th	Night	11% 9% 26% 40% 14%	407
	21st to end	Night	3 1 16% 49% 28% 3	380
July	1st to 10th	Night	2 2 16% 47% 31% 2	370
	11th to 20th	Night	3 3 16% 50% 28%	519
	21st to end	Night	2 2 14% 50% 31% 1	624
August	1st to 10th	Night	5% 4 13% 47% 28% 2	567
	11th to 20th	Night	3 2 14% 49% 31% 2	564
	21st to end	Night	5% 4 19% 39% 30% 3	627
September	1st to 10th	Night	6% 4 16% 43% 28% 3	581
	11th to 20th	Night	7% 5% 17% 39% 27% 4	760
	21st to end	Night	11% 4 19% 37% 25% 4	760
October	1st to 10th	Night	13% 8% 20% 36% 20% 2	760
	11th to 20th	Night	14% 9% 17% 37% 20% 2	760
	21st to end	Night	12% 10% 22% 42% 11% 3	836
November	1st to 10th	Night	19% 11% 24% 34% 10% 2	780
	11th to 20th	Night	15% 14% 32% 32% 6% 1	998
	21st to end	Night	12% 13% 29% 35% 10% 1	1000
December	1st to 10th	Night	17% 12% 29% 35% 7% 1	1000
	11th to 20th	Night	16% 15% 30% 32% 7%	1000
	21st to end	Night	18% 15% 30% 26% 9% 1	1100

Page generated at 2025-05-23 07:21:04. Version ac07

Copyright © 2025 Attilla Danko.