High Knob Overlook
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the High Knob Overlook clear sky chart from 2005-11-06 to 2026-04-17.

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	17% 10% 4 8% 5% 4 4 4 5% 7% 32%	131832
	Night	17% 11% 4 8% 5% 4 4 3 5% 6% 33%	130311
Transparency	Day	50% 7% 11% 20% 11% 1	135403
	Night	50% 6% 11% 19% 12% 2	134825
Seeing	Day	25% 18% 29% 17% 8% 2	16550
	Night	22% 18% 30% 22% 8% 1	25996

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	14% 16% 7% 14% 6% 4 4 3 5% 5% 22%	4661
	11th to 20th	Day	11% 15% 8% 18% 7% 5% 4 3 4 5% 20%	4889
	21st to end	Day	15% 12% 7% 9% 7% 4 4 3 5% 6% 29%	5780
February	1st to 10th	Day	15% 16% 5% 9% 6% 6% 5% 5% 4 5% 26%	1890
	11th to 20th	Day	14% 14% 6% 10% 6% 5% 4 4 4 6% 27%	1880
	21st to end	Day	18% 15% 4 9% 6% 4 4 2 5% 6% 29%	1730
March	1st to 10th	Day	20% 14% 4 8% 4 4 4 2 3 4 34%	4800
	11th to 20th	Day	13% 12% 4 8% 5% 4 4 3 5% 5% 37%	5090
	21st to end	Day	14% 12% 4 8% 5% 4 4 4 5% 6% 34%	5768
April	1st to 10th	Day	19% 13% 3 9% 4 4 4 3 4 5% 32%	2520
	11th to 20th	Day	17% 12% 3 7% 5% 5% 4 4 6% 6% 33%	2446
	21st to end	Day	18% 9% 3 7% 4 4 5% 4 5% 6% 36%	2408
May	1st to 10th	Day	27% 9% 3 7% 5% 4 4 4 5% 6% 27%	6067
	11th to 20th	Day	25% 9% 3 8% 4 5% 4 3 5% 6% 26%	6318
	21st to end	Day	23% 6% 2 6% 4 5% 5% 4 6% 8% 31%	6949
June	1st to 10th	Day	15% 7% 2 6% 6% 5% 6% 4 6% 8% 34%	2800
	11th to 20th	Day	18% 7% 2 6% 5% 5% 5% 5% 6% 7% 34%	2800
	21st to end	Day	15% 6% 2 6% 5% 4 6% 5% 7% 9% 37%	2800
July	1st to 10th	Day	9% 6% 3 7% 6% 6% 5% 5% 7% 9% 38%	6360
	11th to 20th	Day	12% 6% 3 7% 5% 6% 6% 5% 8% 11% 32%	6360
	21st to end	Day	13% 6% 3 7% 5% 5% 6% 4 6% 8% 38%	6703
August	1st to 10th	Day	20% 8% 3 7% 5% 5% 4 4 5% 7% 31%	4234
	11th to 20th	Day	17% 7% 2 6% 5% 5% 6% 5% 7% 9% 32%	4047
	21st to end	Day	17% 5% 2 5% 4 4 5% 4 7% 8% 39%	4312
September	1st to 10th	Day	17% 6% 2 6% 4 4 4 3 4 9% 41%	2400
	11th to 20th	Day	14% 5% 2 5% 4 3 4 4 5% 6% 47%	2400
	21st to end	Day	24% 8% 3 6% 4 3 3 3 5% 7% 34%	2119
October	1st to 10th	Day	19% 8% 2 5% 4 4 4 3 5% 7% 40%	2000
	11th to 20th	Day	21% 8% 2 7% 4 4 5% 3 5% 6% 34%	2000
	21st to end	Day	21% 11% 3 6% 5% 4 4 4 5% 6% 31%	2181
November	1st to 10th	Day	14% 10% 3 7% 4 4 4 4 5% 6% 40%	1851
	11th to 20th	Day	16% 14% 3 7% 5% 3 4 4 5% 5% 33%	1795
	21st to end	Day	19% 14% 3 6% 5% 4 4 5% 5% 6% 30%	1680
December	1st to 10th	Day	16% 17% 7% 11% 5% 5% 4 3 3 5% 23%	2680
	11th to 20th	Day	22% 15% 4 7% 3 4 3 3 4 5% 29%	3066
	21st to end	Day	18% 17% 6% 12% 5% 5% 4 3 5% 6% 20%	4048
January	1st to 10th	Night	13% 15% 5% 16% 6% 4 4 3 4 5% 23%	8234
	11th to 20th	Night	11% 15% 7% 16% 6% 5% 4 4 5% 5% 23%	7983
	21st to end	Night	13% 12% 5% 10% 8% 5% 4 3 4 5% 29%	8401
February	1st to 10th	Night	14% 13% 4 8% 6% 6% 5% 4 5% 6% 29%	2730
	11th to 20th	Night	14% 13% 5% 11% 6% 5% 5% 4 5% 6% 27%	2624
	21st to end	Night	16% 14% 4 11% 6% 4 5% 3 5% 6% 28%	2076
March	1st to 10th	Night	20% 14% 5% 7% 5% 3 3 3 4 5% 32%	5256
	11th to 20th	Night	13% 11% 5% 7% 4 4 3 3 5% 6% 39%	5089
	21st to end	Night	16% 12% 3 8% 5% 5% 4 3 4 4 36%	5405
April	1st to 10th	Night	20% 14% 3 7% 5% 4 4 3 4 6% 29%	2100
	11th to 20th	Night	18% 9% 3 6% 4 4 4 4 5% 7% 36%	2036
	21st to end	Night	18% 7% 3 6% 4 4 4 3 5% 6% 40%	2000
May	1st to 10th	Night	32% 10% 2 6% 4 3 3 3 5% 6% 26%	3881
	11th to 20th	Night	26% 10% 2 6% 4 4 4 3 4 5% 31%	3575
	21st to end	Night	23% 7% 2 6% 4 4 4 3 5% 7% 34%	3926
June	1st to 10th	Night	16% 5% 2 6% 4 4 5% 4 5% 7% 41%	1600
	11th to 20th	Night	15% 7% 2 6% 5% 5% 5% 4 6% 9% 38%	1600
	21st to end	Night	14% 6% 2 5% 4 4 5% 4 7% 8% 41%	1600
July	1st to 10th	Night	13% 7% 3 7% 5% 4 4 4 5% 8% 40%	3600
	11th to 20th	Night	17% 7% 3 6% 4 4 5% 4 6% 9% 36%	3600
	21st to end	Night	14% 5% 2 6% 4 3 4 3 5% 7% 48%	4145
August	1st to 10th	Night	21% 7% 2 7% 4 4 4 4 5% 7% 34%	2915
	11th to 20th	Night	18% 8% 3 5% 4 3 3 2 4 6% 43%	2969
	21st to end	Night	14% 5% 2 5% 3 4 4 4 6% 8% 45%	3586
September	1st to 10th	Night	16% 7% 2 6% 4 4 4 3 4 6% 45%	2000
	11th to 20th	Night	13% 5% 2 6% 3 3 3 3 4 7% 50%	2000
	21st to end	Night	21% 7% 2 6% 4 4 3 3 5% 6% 39%	2277
October	1st to 10th	Night	20% 7% 3 5% 3 3 3 3 5% 5% 44%	2400
	11th to 20th	Night	19% 8% 3 5% 4 3 3 3 4 6% 41%	2400
	21st to end	Night	21% 10% 3 7% 4 3 4 3 4 6% 35%	2657
November	1st to 10th	Night	13% 9% 3 5% 4 4 4 4 5% 6% 43%	2667
	11th to 20th	Night	19% 12% 4 7% 5% 4 4 4 5% 6% 31%	2821
	21st to end	Night	16% 14% 3 7% 5% 4 4 3 6% 6% 30%	2940
December	1st to 10th	Night	14% 15% 7% 11% 5% 5% 4 3 6% 6% 24%	4720
	11th to 20th	Night	22% 14% 4 8% 5% 4 4 3 4 5% 29%	5348
	21st to end	Night	20% 17% 6% 8% 4 4 3 3 4 5% 24%	7150

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% 6% 10% 15% 5% 1	4662
	11th to 20th	Day	67% 4 5% 12% 9% 2	4920
	21st to end	Day	56% 5% 9% 19% 11%	5780
February	1st to 10th	Day	59% 6% 10% 15% 9% 1	1890
	11th to 20th	Day	58% 6% 6% 21% 8% 1	1889
	21st to end	Day	57% 5% 8% 20% 8% 2	1730
March	1st to 10th	Day	54% 5% 9% 18% 10% 4	4803
	11th to 20th	Day	45% 7% 16% 20% 7% 4	5090
	21st to end	Day	50% 7% 8% 15% 17% 3	5768
April	1st to 10th	Day	54% 6% 9% 18% 11% 3	2520
	11th to 20th	Day	50% 7% 11% 18% 13% 2	2446
	21st to end	Day	47% 7% 9% 20% 14% 3	2408
May	1st to 10th	Day	58% 6% 10% 17% 9% 1	6076
	11th to 20th	Day	57% 8% 9% 18% 8% 1	6322
	21st to end	Day	48% 9% 11% 20% 11% 1	6949
June	1st to 10th	Day	45% 9% 12% 20% 13% 1	2800
	11th to 20th	Day	47% 9% 13% 19% 11% 1	2800
	21st to end	Day	41% 9% 14% 25% 11%	2800
July	1st to 10th	Day	42% 9% 13% 25% 12%	6290
	11th to 20th	Day	42% 9% 16% 22% 10%	6285
	21st to end	Day	41% 8% 12% 22% 16% 1	6510
August	1st to 10th	Day	51% 7% 13% 18% 10%	4221
	11th to 20th	Day	45% 9% 13% 25% 7%	4086
	21st to end	Day	40% 7% 11% 32% 9% 1	4312
September	1st to 10th	Day	41% 6% 12% 24% 15% 2	2400
	11th to 20th	Day	37% 6% 11% 24% 21% 2	2400
	21st to end	Day	49% 6% 10% 17% 16% 1	2119
October	1st to 10th	Day	41% 6% 9% 23% 19% 3	3260
	11th to 20th	Day	44% 5% 7% 24% 15% 5%	3240
	21st to end	Day	37% 5% 15% 28% 14% 1	3507
November	1st to 10th	Day	44% 6% 12% 20% 15% 3	1851
	11th to 20th	Day	52% 7% 10% 19% 10% 2	1795
	21st to end	Day	54% 7% 12% 20% 6% 1	1680
December	1st to 10th	Day	64% 5% 9% 17% 5% 1	2680
	11th to 20th	Day	58% 5% 11% 16% 9%	3066
	21st to end	Day	64% 6% 11% 12% 7%	4048
January	1st to 10th	Night	62% 7% 9% 14% 7% 1	8234
	11th to 20th	Night	61% 6% 9% 12% 10% 2	8026
	21st to end	Night	56% 6% 7% 16% 15% 1	8401
February	1st to 10th	Night	55% 7% 10% 18% 9% 1	2730
	11th to 20th	Night	57% 7% 9% 17% 10% 1	2626
	21st to end	Night	56% 5% 9% 18% 11% 2	2076
March	1st to 10th	Night	55% 5% 11% 15% 11% 3	5266
	11th to 20th	Night	42% 8% 17% 20% 8% 4	5090
	21st to end	Night	50% 6% 7% 16% 17% 4	5405
April	1st to 10th	Night	55% 5% 9% 17% 11% 2	2100
	11th to 20th	Night	47% 7% 12% 20% 14% 1	2036
	21st to end	Night	44% 7% 11% 20% 16% 2	2000
May	1st to 10th	Night	59% 5% 9% 18% 7% 2	3888
	11th to 20th	Night	53% 8% 11% 15% 10% 1	3576
	21st to end	Night	47% 10% 11% 19% 11% 2	3927
June	1st to 10th	Night	42% 7% 11% 25% 14% 1	1600
	11th to 20th	Night	41% 8% 14% 25% 10% 2	1600
	21st to end	Night	37% 9% 14% 26% 13% 1	1600
July	1st to 10th	Night	42% 6% 13% 23% 14% 1	3560
	11th to 20th	Night	43% 8% 15% 24% 10%	3552
	21st to end	Night	35% 7% 13% 23% 21% 1	4023
August	1st to 10th	Night	48% 8% 15% 21% 8% 1	2904
	11th to 20th	Night	42% 5% 14% 26% 13%	2996
	21st to end	Night	36% 7% 12% 33% 11% 1	3586
September	1st to 10th	Night	40% 7% 10% 26% 16% 2	2000
	11th to 20th	Night	34% 5% 12% 28% 20% 2	2000
	21st to end	Night	45% 5% 11% 22% 16% 1	2277
October	1st to 10th	Night	44% 5% 9% 21% 18% 1	3920
	11th to 20th	Night	37% 5% 11% 24% 17% 6%	3899
	21st to end	Night	37% 4 15% 26% 15% 2	4281
November	1st to 10th	Night	40% 7% 12% 22% 16% 3	2667
	11th to 20th	Night	53% 6% 10% 18% 11% 3	2821
	21st to end	Night	52% 6% 14% 20% 7% 1	2940
December	1st to 10th	Night	58% 7% 12% 19% 4	4720
	11th to 20th	Night	58% 4 11% 16% 10%	5348
	21st to end	Night	60% 7% 8% 15% 9% 1	7150

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	33% 26% 30% 9% 1	220
	11th to 20th	Day	42% 29% 25% 3	264
	21st to end	Day	30% 33% 27% 8% 2	363
February	1st to 10th	Day	37% 27% 29% 6% 1	330
	11th to 20th	Day	37% 28% 31% 3	367
	21st to end	Day	34% 28% 30% 7%	446
March	1st to 10th	Day	35% 24% 28% 11% 2	540
	11th to 20th	Day	32% 27% 28% 10% 2 1	540
	21st to end	Day	34% 26% 26% 9% 3 2	594
April	1st to 10th	Day	35% 26% 25% 10% 4	540
	11th to 20th	Day	28% 29% 25% 11% 5% 2	516
	21st to end	Day	26% 24% 34% 12% 3 2	500
May	1st to 10th	Day	33% 17% 31% 11% 7% 2	503
	11th to 20th	Day	26% 18% 31% 16% 7% 2	527
	21st to end	Day	24% 13% 27% 20% 13% 3	573
June	1st to 10th	Day	20% 16% 31% 23% 9% 1	530
	11th to 20th	Day	20% 16% 29% 25% 9% 1	530
	21st to end	Day	16% 13% 37% 24% 9% 1	530
July	1st to 10th	Day	13% 9% 31% 29% 14% 4	525
	11th to 20th	Day	9% 9% 32% 31% 14% 4	524
	21st to end	Day	14% 9% 34% 28% 13% 3	576
August	1st to 10th	Day	14% 9% 26% 28% 17% 5%	526
	11th to 20th	Day	16% 7% 27% 32% 13% 6%	519
	21st to end	Day	17% 9% 28% 26% 12% 8%	583
September	1st to 10th	Day	21% 11% 24% 23% 17% 5%	530
	11th to 20th	Day	13% 8% 27% 24% 19% 9%	530
	21st to end	Day	27% 12% 29% 18% 11% 4	530
October	1st to 10th	Day	25% 12% 25% 21% 12% 5%	530
	11th to 20th	Day	26% 17% 33% 16% 6% 1	530
	21st to end	Day	29% 21% 29% 16% 5%	572
November	1st to 10th	Day	25% 22% 29% 18% 5% 1	425
	11th to 20th	Day	29% 24% 29% 14% 3	335
	21st to end	Day	36% 25% 32% 6% 1	220
December	1st to 10th	Day	36% 30% 24% 7% 2 1	220
	11th to 20th	Day	38% 26% 27% 9%	220
	21st to end	Day	34% 25% 34% 5% 1	242
January	1st to 10th	Night	22% 29% 37% 10% 2	840
	11th to 20th	Night	24% 25% 34% 15% 2	840
	21st to end	Night	21% 29% 35% 14% 1	924
February	1st to 10th	Night	24% 25% 35% 15% 1	840
	11th to 20th	Night	26% 28% 36% 10%	823
	21st to end	Night	29% 22% 35% 13% 1	692
March	1st to 10th	Night	26% 27% 32% 14% 2	840
	11th to 20th	Night	28% 24% 30% 16% 4	840
	21st to end	Night	25% 25% 33% 12% 5%	924
April	1st to 10th	Night	25% 25% 31% 16% 3	840
	11th to 20th	Night	22% 23% 31% 17% 6%	816
	21st to end	Night	23% 19% 33% 21% 5%	800
May	1st to 10th	Night	29% 14% 24% 25% 9%	532
	11th to 20th	Night	19% 11% 36% 26% 7% 1	394
	21st to end	Night	19% 9% 28% 30% 13% 1	433
June	1st to 10th	Night	17% 8% 27% 36% 13% 1	400
	11th to 20th	Night	17% 7% 27% 37% 12%	400
	21st to end	Night	15% 5% 32% 38% 11% 1	400
July	1st to 10th	Night	12% 5% 25% 38% 17% 2	390
	11th to 20th	Night	11% 2 27% 39% 19% 2	388
	21st to end	Night	14% 5% 18% 43% 18% 1	530
August	1st to 10th	Night	13% 2 20% 43% 20% 1	597
	11th to 20th	Night	15% 5% 16% 36% 25% 3	649
	21st to end	Night	13% 6% 21% 36% 20% 3	880
September	1st to 10th	Night	16% 9% 24% 32% 17% 2	800
	11th to 20th	Night	15% 7% 22% 29% 24% 4	800
	21st to end	Night	23% 10% 23% 28% 15% 2	800
October	1st to 10th	Night	22% 11% 24% 23% 18% 2	800
	11th to 20th	Night	24% 14% 31% 25% 6% 1	800
	21st to end	Night	27% 15% 33% 21% 5%	880
November	1st to 10th	Night	18% 19% 33% 23% 6%	820
	11th to 20th	Night	27% 20% 30% 18% 4 1	840
	21st to end	Night	25% 21% 33% 18% 3	840
December	1st to 10th	Night	26% 25% 32% 14% 3	840
	11th to 20th	Night	24% 25% 33% 15% 3	840
	21st to end	Night	28% 23% 34% 13% 2	924

Page generated at 2026-04-14 02:44:29. Version ac07

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