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 2024-03-08.

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	6% 12% 5% 8% 6% 3 4 4 5% 6% 40%	79195
	Night	6% 13% 5% 9% 5% 3 4 4 4 6% 40%	80422
Transparency	Day	45% 5% 11% 19% 14% 5%	78903
	Night	45% 5% 12% 20% 13% 5%	80235
Seeing	Day	13% 19% 32% 25% 10% 2	14662
	Night	12% 11% 25% 36% 15% 1	24442

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	3 20% 10% 16% 8% 3 4 3 4 5% 25%	2634
	11th to 20th	Day	5% 17% 8% 13% 8% 3 4 3 4 5% 28%	2860
	21st to end	Day	3 26% 9% 12% 5% 2 3 3 3 5% 28%	3146
February	1st to 10th	Day	4 22% 10% 14% 6% 3 4 4 5% 6% 22%	1710
	11th to 20th	Day	4 23% 9% 12% 8% 2 4 3 4 6% 26%	1665
	21st to end	Day	5% 19% 11% 17% 9% 2 5% 4 4 4 21%	1513
March	1st to 10th	Day	5% 18% 7% 15% 6% 4 5% 5% 4 5% 27%	2022
	11th to 20th	Day	5% 16% 7% 9% 5% 3 5% 4 6% 7% 32%	1980
	21st to end	Day	7% 23% 8% 12% 6% 4 4 4 4 6% 21%	2178
April	1st to 10th	Day	9% 19% 7% 10% 6% 3 4 4 5% 6% 27%	2071
	11th to 20th	Day	8% 16% 7% 10% 8% 4 5% 4 4 6% 27%	2254
	21st to end	Day	9% 17% 5% 9% 6% 3 4 4 5% 7% 30%	2340
May	1st to 10th	Day	9% 11% 4 10% 7% 4 6% 5% 5% 7% 31%	2340
	11th to 20th	Day	9% 9% 3 6% 7% 4 7% 6% 7% 8% 33%	2362
	21st to end	Day	14% 13% 4 9% 8% 4 6% 6% 6% 7% 24%	2724
June	1st to 10th	Day	11% 7% 3 5% 5% 3 5% 6% 7% 9% 39%	2520
	11th to 20th	Day	9% 8% 3 6% 5% 3 5% 4 5% 7% 44%	2668
	21st to end	Day	3 2 2 4 4 2 4 4 5% 7% 63%	2700
July	1st to 10th	Day	2 2 1 3 4 2 4 5% 7% 9% 61%	2700
	11th to 20th	Day	2 3 1 4 4 3 5% 4 5% 6% 62%	2455
	21st to end	Day	4 3 2 4 5% 3 5% 5% 6% 7% 57%	2545
August	1st to 10th	Day	5% 4 2 4 5% 3 5% 6% 7% 7% 53%	2328
	11th to 20th	Day	2 3 2 3 4 2 4 4 6% 6% 64%	2299
	21st to end	Day	5% 3 1 4 4 3 4 5% 5% 8% 59%	2546
September	1st to 10th	Day	5% 4 2 4 5% 3 3 4 5% 5% 61%	2147
	11th to 20th	Day	7% 5% 2 4 4 3 3 4 5% 6% 56%	1980
	21st to end	Day	8% 5% 2 4 4 2 3 3 4 5% 59%	1980
October	1st to 10th	Day	10% 12% 3 7% 5% 2 3 3 4 5% 44%	1832
	11th to 20th	Day	9% 11% 3 5% 4 3 3 4 4 5% 48%	1800
	21st to end	Day	9% 13% 4 6% 4 3 4 3 4 6% 44%	1961
November	1st to 10th	Day	13% 14% 6% 8% 4 2 3 3 4 6% 37%	1655
	11th to 20th	Day	8% 18% 5% 9% 6% 3 3 3 4 6% 37%	1520
	21st to end	Day	3 16% 8% 11% 5% 3 5% 3 3 5% 37%	1520
December	1st to 10th	Day	5% 20% 8% 12% 7% 4 4 3 3 5% 28%	1520
	11th to 20th	Day	6% 23% 8% 12% 7% 3 4 4 5% 6% 23%	1926
	21st to end	Day	5% 14% 6% 11% 7% 4 5% 4 5% 8% 31%	2794
January	1st to 10th	Night	3 14% 9% 19% 8% 3 4 4 4 5% 27%	4350
	11th to 20th	Night	3 20% 10% 19% 8% 2 3 3 3 4 25%	4110
	21st to end	Night	4 29% 8% 11% 6% 2 3 3 2 4 27%	4521
February	1st to 10th	Night	3 21% 10% 14% 7% 4 5% 3 4 5% 23%	2470
	11th to 20th	Night	4 20% 9% 13% 7% 3 4 3 3 4 30%	2402
	21st to end	Night	4 16% 10% 17% 9% 4 4 3 4 5% 24%	1938
March	1st to 10th	Night	4 19% 8% 12% 7% 3 4 4 3 7% 29%	2096
	11th to 20th	Night	4 13% 5% 8% 5% 3 5% 5% 5% 7% 38%	1980
	21st to end	Night	7% 18% 7% 10% 6% 3 5% 5% 6% 6% 29%	2178
April	1st to 10th	Night	7% 15% 6% 8% 5% 3 5% 4 4 8% 34%	1888
	11th to 20th	Night	7% 13% 5% 8% 7% 3 6% 5% 5% 6% 36%	1650
	21st to end	Night	8% 11% 4 5% 5% 2 4 5% 5% 7% 44%	1620
May	1st to 10th	Night	9% 11% 3 5% 5% 3 4 4 6% 7% 43%	1620
	11th to 20th	Night	8% 5% 3 6% 6% 2 4 5% 7% 11% 44%	1529
	21st to end	Night	11% 9% 3 6% 5% 3 6% 6% 6% 9% 34%	1552
June	1st to 10th	Night	8% 8% 3 5% 4 3 4 4 7% 9% 46%	1440
	11th to 20th	Night	8% 7% 2 4 4 2 4 4 5% 8% 53%	1286
	21st to end	Night	3 1 1 2 2 1 4 4 5% 7% 70%	1260
July	1st to 10th	Night	2 1 2 3 2 4 6% 8% 8% 64%	1260
	11th to 20th	Night	1 2 2 2 2 3 4 5% 8% 71%	1499
	21st to end	Night	3 2 1 2 3 2 4 4 6% 7% 66%	1773
August	1st to 10th	Night	4 4 1 4 4 3 4 5% 6% 9% 58%	1611
	11th to 20th	Night	2 2 1 2 3 2 3 4 5% 9% 66%	1602
	21st to end	Night	4 3 1 3 3 2 4 3 4 7% 66%	1808
September	1st to 10th	Night	5% 4 1 2 3 2 3 3 5% 6% 65%	1810
	11th to 20th	Night	5% 4 2 4 3 3 3 4 6% 8% 58%	1980
	21st to end	Night	9% 6% 1 3 3 1 2 3 3 5% 63%	1980
October	1st to 10th	Night	13% 8% 3 5% 5% 2 3 4 4 7% 47%	2128
	11th to 20th	Night	9% 10% 3 5% 4 2 3 3 4 5% 53%	2160
	21st to end	Night	7% 11% 3 5% 4 3 3 4 5% 6% 49%	2394
November	1st to 10th	Night	12% 14% 4 9% 4 2 4 4 3 5% 39%	2405
	11th to 20th	Night	8% 15% 5% 7% 5% 3 5% 4 5% 6% 37%	2658
	21st to end	Night	4 14% 7% 9% 5% 3 4 3 4 6% 40%	2660
December	1st to 10th	Night	6% 19% 8% 12% 8% 4 4 3 4 5% 29%	2660
	11th to 20th	Night	6% 20% 8% 13% 7% 2 4 3 4 5% 27%	3271
	21st to end	Night	5% 18% 6% 11% 6% 3 4 4 4 6% 32%	4873

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	63% 5% 11% 16% 4 1	2635
	11th to 20th	Day	60% 4 14% 12% 8% 3	2860
	21st to end	Day	61% 5% 11% 14% 9% 1	3146
February	1st to 10th	Day	65% 6% 11% 13% 4 1	1710
	11th to 20th	Day	63% 5% 12% 13% 6% 2	1674
	21st to end	Day	67% 5% 7% 14% 5% 2	1513
March	1st to 10th	Day	61% 5% 11% 15% 6% 1	2022
	11th to 20th	Day	51% 7% 15% 16% 9% 1	1980
	21st to end	Day	65% 6% 11% 14% 3	2178
April	1st to 10th	Day	59% 7% 12% 14% 8% 1	2071
	11th to 20th	Day	58% 6% 11% 18% 7% 1	2257
	21st to end	Day	53% 6% 13% 22% 5%	2340
May	1st to 10th	Day	51% 7% 10% 23% 8% 1	2340
	11th to 20th	Day	46% 8% 12% 26% 8%	2365
	21st to end	Day	58% 7% 13% 17% 5%	2724
June	1st to 10th	Day	40% 7% 16% 25% 11% 1	2520
	11th to 20th	Day	39% 6% 9% 21% 17% 8%	2668
	21st to end	Day	20% 6% 7% 24% 32% 11%	2700
July	1st to 10th	Day	19% 6% 8% 22% 32% 14%	2626
	11th to 20th	Day	22% 5% 5% 16% 27% 25%	2379
	21st to end	Day	25% 4 7% 14% 27% 22%	2404
August	1st to 10th	Day	29% 5% 9% 19% 26% 13%	2313
	11th to 20th	Day	20% 4 7% 23% 31% 14%	2299
	21st to end	Day	24% 5% 7% 20% 32% 13%	2546
September	1st to 10th	Day	25% 5% 6% 17% 34% 13%	2147
	11th to 20th	Day	30% 4 9% 22% 26% 9%	1980
	21st to end	Day	29% 4 11% 28% 24% 4	1980
October	1st to 10th	Day	44% 4 11% 25% 13% 3	1832
	11th to 20th	Day	40% 4 15% 29% 10% 2	1800
	21st to end	Day	42% 5% 16% 24% 12% 1	1961
November	1st to 10th	Day	50% 5% 14% 21% 9% 2	1655
	11th to 20th	Day	51% 5% 17% 18% 8% 1	1520
	21st to end	Day	50% 6% 15% 19% 9% 1	1520
December	1st to 10th	Day	61% 6% 10% 11% 9% 3	1520
	11th to 20th	Day	66% 3 12% 15% 4	1924
	21st to end	Day	52% 4 11% 14% 10% 8%	2794
January	1st to 10th	Night	61% 5% 10% 17% 6%	4350
	11th to 20th	Night	65% 4 11% 12% 6% 2	4110
	21st to end	Night	63% 4 12% 13% 6% 1	4521
February	1st to 10th	Night	65% 7% 10% 12% 6%	2470
	11th to 20th	Night	60% 5% 10% 16% 8% 1	2403
	21st to end	Night	63% 5% 9% 15% 5% 3	1938
March	1st to 10th	Night	57% 6% 12% 18% 6%	2096
	11th to 20th	Night	44% 8% 15% 22% 8% 2	1980
	21st to end	Night	55% 8% 14% 18% 3 1	2178
April	1st to 10th	Night	49% 9% 15% 16% 10% 2	1888
	11th to 20th	Night	48% 8% 15% 20% 8% 1	1650
	21st to end	Night	39% 7% 17% 29% 8%	1620
May	1st to 10th	Night	39% 6% 13% 30% 12%	1620
	11th to 20th	Night	34% 8% 18% 28% 12%	1530
	21st to end	Night	46% 8% 18% 21% 6% 1	1552
June	1st to 10th	Night	35% 7% 19% 25% 12% 1	1440
	11th to 20th	Night	30% 6% 12% 25% 19% 7%	1286
	21st to end	Night	15% 3 10% 26% 34% 13%	1260
July	1st to 10th	Night	15% 6% 10% 24% 33% 12%	1225
	11th to 20th	Night	13% 3 5% 21% 32% 26%	1452
	21st to end	Night	16% 5% 8% 18% 30% 22%	1674
August	1st to 10th	Night	24% 5% 10% 19% 25% 17%	1602
	11th to 20th	Night	16% 4 7% 25% 33% 15%	1602
	21st to end	Night	20% 3 7% 21% 32% 16%	1808
September	1st to 10th	Night	21% 5% 7% 18% 31% 18%	1810
	11th to 20th	Night	25% 4 12% 23% 26% 10%	1980
	21st to end	Night	26% 4 9% 29% 27% 5%	1980
October	1st to 10th	Night	39% 4 12% 26% 16% 3	2128
	11th to 20th	Night	35% 4 13% 33% 13% 2	2160
	21st to end	Night	36% 6% 17% 27% 13% 1	2394
November	1st to 10th	Night	48% 5% 13% 23% 9% 2	2405
	11th to 20th	Night	47% 7% 16% 20% 8% 2	2658
	21st to end	Night	46% 6% 15% 21% 11% 2	2660
December	1st to 10th	Night	60% 6% 14% 11% 7% 2	2660
	11th to 20th	Night	61% 4 14% 15% 5%	3272
	21st to end	Night	54% 4 10% 16% 10% 6%	4873

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% 20% 28% 30% 8% 1	270
	11th to 20th	Day	9% 21% 37% 20% 10% 3	270
	21st to end	Day	8% 19% 36% 29% 8%	297
February	1st to 10th	Day	12% 37% 33% 16% 2	270
	11th to 20th	Day	19% 27% 30% 20% 4	270
	21st to end	Day	16% 30% 34% 16% 4	325
March	1st to 10th	Day	18% 33% 31% 15% 2	449
	11th to 20th	Day	15% 26% 34% 20% 5%	420
	21st to end	Day	20% 27% 34% 16% 2	462
April	1st to 10th	Day	22% 27% 29% 17% 5% 1	420
	11th to 20th	Day	20% 31% 33% 11% 4 1	412
	21st to end	Day	20% 24% 25% 20% 9% 2	420
May	1st to 10th	Day	15% 22% 30% 25% 6% 2	423
	11th to 20th	Day	16% 17% 30% 24% 11% 2	509
	21st to end	Day	21% 12% 26% 24% 14% 3	679
June	1st to 10th	Day	11% 17% 27% 27% 16% 3	630
	11th to 20th	Day	15% 19% 36% 21% 9%	630
	21st to end	Day	5% 12% 31% 32% 17% 3	630
July	1st to 10th	Day	3 10% 33% 37% 15% 2	621
	11th to 20th	Day	4 13% 41% 29% 11% 2	523
	21st to end	Day	5% 9% 35% 35% 13% 3	487
August	1st to 10th	Day	6% 12% 36% 33% 12% 1	447
	11th to 20th	Day	4 10% 34% 31% 16% 5%	437
	21st to end	Day	7% 15% 32% 28% 15% 4	495
September	1st to 10th	Day	6% 16% 35% 28% 14% 3	450
	11th to 20th	Day	13% 17% 29% 26% 11% 4	450
	21st to end	Day	10% 17% 29% 28% 14% 2	450
October	1st to 10th	Day	13% 19% 25% 23% 16% 4	302
	11th to 20th	Day	13% 22% 20% 27% 14% 4	270
	21st to end	Day	17% 22% 31% 24% 5% 1	297
November	1st to 10th	Day	23% 21% 28% 17% 7% 3	270
	11th to 20th	Day	14% 21% 32% 22% 8% 2	270
	21st to end	Day	7% 22% 33% 29% 9% 1	270
December	1st to 10th	Day	18% 16% 31% 24% 10% 1	270
	11th to 20th	Day	16% 22% 32% 24% 6%	270
	21st to end	Day	17% 20% 33% 20% 9% 2	297
January	1st to 10th	Night	13% 14% 28% 35% 10% 1	909
	11th to 20th	Night	13% 15% 28% 31% 11% 2	760
	21st to end	Night	12% 10% 32% 35% 10% 1	836
February	1st to 10th	Night	11% 17% 35% 30% 6% 1	760
	11th to 20th	Night	13% 14% 31% 33% 8% 1	744
	21st to end	Night	12% 17% 33% 30% 7% 1	628
March	1st to 10th	Night	12% 20% 29% 31% 7% 1	750
	11th to 20th	Night	10% 15% 27% 36% 12% 1	720
	21st to end	Night	15% 14% 29% 32% 10%	792
April	1st to 10th	Night	15% 14% 28% 32% 10% 1	628
	11th to 20th	Night	14% 13% 31% 32% 10% 1	533
	21st to end	Night	13% 10% 25% 32% 18% 2	540
May	1st to 10th	Night	13% 11% 21% 37% 17% 1	540
	11th to 20th	Night	12% 7% 23% 33% 22% 1	531
	21st to end	Night	14% 11% 21% 36% 18% 1	584
June	1st to 10th	Night	14% 8% 22% 31% 24% 1	540
	11th to 20th	Night	11% 9% 25% 40% 15%	386
	21st to end	Night	4 1 15% 48% 29% 3	360
July	1st to 10th	Night	2 2 16% 47% 31% 2	350
	11th to 20th	Night	3 3 16% 51% 27%	490
	21st to end	Night	3 2 14% 48% 32% 1	591
August	1st to 10th	Night	5% 4 12% 48% 29% 2	537
	11th to 20th	Night	3 1 12% 49% 33% 2	534
	21st to end	Night	5% 4 18% 39% 31% 3	594
September	1st to 10th	Night	6% 4 16% 43% 28% 3	550
	11th to 20th	Night	7% 5% 17% 39% 28% 4	720
	21st to end	Night	12% 4 19% 36% 25% 4	720
October	1st to 10th	Night	14% 8% 20% 35% 20% 2	720
	11th to 20th	Night	15% 9% 17% 37% 19% 2	720
	21st to end	Night	12% 10% 21% 42% 12% 3	792
November	1st to 10th	Night	20% 11% 24% 33% 11% 2	740
	11th to 20th	Night	15% 14% 31% 33% 6% 1	948
	21st to end	Night	12% 13% 28% 35% 10% 1	950
December	1st to 10th	Night	18% 12% 29% 34% 6% 1	950
	11th to 20th	Night	16% 15% 29% 33% 7%	950
	21st to end	Night	19% 15% 30% 26% 9% 2	1045

Page generated at 2024-03-05 05:23:58. Version ac07

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