Knob Lakes
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Knob Lakes clear sky chart from 2005-11-06 to 2024-11-02.

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	10% 12% 5% 12% 8% 7% 7% 5% 7% 7% 20%	103189
	Night	5% 11% 5% 13% 9% 8% 7% 6% 7% 7% 22%	95879
Transparency	Day	50% 17% 15% 12% 5% 1	102882
	Night	45% 17% 15% 12% 8% 2	95834
Seeing	Day	14% 7% 21% 27% 21% 9%	17741
	Night	8% 4 19% 36% 25% 8%	22256

By Month

Percentage Cloud Cover NW (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	6% 3 11% 10% 9% 12% 9% 11% 9% 18%	1269
	11th to 20th	Day	2 8% 4 10% 10% 10% 11% 7% 6% 6% 27%	1563
	21st to end	Day	1 6% 4 13% 10% 9% 10% 10% 10% 8% 20%	2090
February	1st to 10th	Day	1 8% 4 12% 9% 8% 8% 5% 9% 8% 28%	1265
	11th to 20th	Day	1 8% 6% 14% 10% 8% 8% 7% 10% 7% 22%	1479
	21st to end	Day	1 7% 4 15% 9% 9% 6% 6% 5% 8% 28%	1306
March	1st to 10th	Day	6% 6% 19% 14% 9% 7% 5% 5% 5% 23%	3114
	11th to 20th	Day	1 5% 4 15% 12% 11% 8% 5% 6% 6% 28%	3242
	21st to end	Day	1 8% 6% 20% 12% 9% 7% 5% 7% 6% 20%	4155
April	1st to 10th	Day	1 11% 6% 11% 8% 8% 6% 6% 10% 9% 23%	2368
	11th to 20th	Day	2 11% 5% 11% 8% 5% 6% 4 8% 9% 31%	2587
	21st to end	Day	3 12% 4 11% 7% 5% 5% 5% 8% 7% 33%	2764
May	1st to 10th	Day	5% 17% 5% 14% 8% 7% 7% 6% 7% 6% 19%	4937
	11th to 20th	Day	6% 12% 4 10% 7% 7% 7% 6% 8% 7% 26%	5162
	21st to end	Day	12% 18% 5% 12% 7% 6% 7% 5% 6% 6% 17%	5953
June	1st to 10th	Day	18% 12% 4 10% 8% 7% 6% 5% 6% 6% 17%	3420
	11th to 20th	Day	25% 12% 4 10% 7% 6% 5% 3 5% 5% 16%	3420
	21st to end	Day	25% 11% 3 10% 6% 6% 6% 5% 6% 6% 16%	3420
July	1st to 10th	Day	17% 10% 4 10% 7% 7% 7% 6% 7% 8% 17%	5700
	11th to 20th	Day	16% 12% 5% 13% 9% 7% 7% 6% 7% 7% 12%	5646
	21st to end	Day	21% 13% 4 10% 7% 5% 6% 5% 6% 8% 15%	5545
August	1st to 10th	Day	17% 12% 4 11% 7% 6% 6% 4 5% 6% 19%	5046
	11th to 20th	Day	15% 10% 3 9% 6% 6% 6% 5% 9% 8% 24%	4478
	21st to end	Day	19% 16% 5% 11% 6% 5% 6% 5% 7% 6% 14%	4835
September	1st to 10th	Day	19% 14% 4 12% 7% 6% 6% 3 6% 7% 17%	2399
	11th to 20th	Day	13% 14% 5% 12% 7% 6% 5% 4 6% 7% 22%	2233
	21st to end	Day	11% 18% 6% 11% 6% 6% 5% 5% 5% 6% 20%	2085
October	1st to 10th	Day	10% 17% 5% 14% 6% 5% 5% 3 6% 7% 23%	1824
	11th to 20th	Day	5% 15% 7% 16% 8% 5% 6% 4 6% 6% 23%	1710
	21st to end	Day	4 15% 6% 15% 8% 6% 5% 4 6% 7% 25%	1598
November	1st to 10th	Day	2 14% 6% 18% 13% 8% 6% 4 6% 5% 17%	1309
	11th to 20th	Day	2 12% 4 15% 10% 11% 10% 4 5% 7% 20%	1093
	21st to end	Day	1 8% 6% 17% 10% 11% 8% 5% 6% 7% 21%	950
December	1st to 10th	Day	2 10% 5% 14% 11% 6% 8% 7% 8% 10% 18%	860
	11th to 20th	Day	1 9% 6% 14% 11% 8% 11% 8% 9% 8% 16%	967
	21st to end	Day	1 5% 4 9% 9% 7% 9% 9% 11% 15% 21%	1397
January	1st to 10th	Night	1 9% 4 12% 10% 12% 10% 6% 8% 8% 18%	5686
	11th to 20th	Night	2 7% 4 12% 9% 9% 10% 7% 7% 8% 27%	5341
	21st to end	Night	1 7% 4 11% 9% 8% 8% 8% 11% 10% 22%	5577
February	1st to 10th	Night	1 9% 4 11% 8% 7% 7% 6% 7% 7% 32%	2913
	11th to 20th	Night	1 7% 5% 14% 10% 10% 8% 6% 6% 8% 25%	2588
	21st to end	Night	2 7% 4 14% 9% 7% 7% 6% 6% 8% 30%	2146
March	1st to 10th	Night	8% 5% 18% 9% 9% 7% 6% 6% 6% 25%	3740
	11th to 20th	Night	1 5% 5% 14% 12% 9% 8% 6% 8% 10% 23%	3716
	21st to end	Night	8% 6% 20% 11% 8% 7% 6% 8% 7% 20%	3473
April	1st to 10th	Night	1 10% 6% 14% 8% 7% 7% 5% 7% 8% 25%	1812
	11th to 20th	Night	2 10% 5% 10% 7% 6% 7% 6% 7% 8% 32%	1541
	21st to end	Night	4 11% 4 11% 7% 6% 6% 5% 6% 8% 33%	1416
May	1st to 10th	Night	4 17% 6% 12% 10% 8% 7% 6% 7% 6% 17%	2033
	11th to 20th	Night	10% 15% 6% 10% 6% 6% 6% 4 6% 7% 23%	1738
	21st to end	Night	14% 14% 4 10% 6% 5% 5% 5% 6% 6% 25%	1611
June	1st to 10th	Night	19% 9% 6% 9% 5% 5% 8% 4 7% 6% 21%	760
	11th to 20th	Night	23% 9% 5% 10% 4 4 5% 5% 6% 7% 22%	760
	21st to end	Night	19% 12% 4 9% 7% 7% 6% 4 6% 6% 20%	760
July	1st to 10th	Night	22% 11% 3 9% 6% 7% 7% 5% 7% 7% 16%	1270
	11th to 20th	Night	16% 14% 5% 12% 8% 6% 5% 5% 6% 6% 17%	1322
	21st to end	Night	25% 12% 4 10% 7% 5% 4 4 5% 5% 17%	2003
August	1st to 10th	Night	16% 15% 4 11% 7% 7% 5% 5% 4 6% 21%	1894
	11th to 20th	Night	13% 12% 4 12% 7% 6% 6% 4 7% 7% 23%	2356
	21st to end	Night	16% 16% 5% 12% 7% 7% 7% 5% 7% 5% 12%	2832
September	1st to 10th	Night	19% 16% 4 9% 5% 6% 6% 5% 7% 5% 19%	1778
	11th to 20th	Night	13% 16% 5% 9% 6% 5% 6% 5% 7% 6% 22%	1947
	21st to end	Night	13% 21% 5% 9% 6% 4 5% 5% 5% 7% 20%	2095
October	1st to 10th	Night	12% 19% 6% 12% 6% 6% 5% 5% 5% 5% 18%	2356
	11th to 20th	Night	5% 17% 6% 15% 8% 6% 4 4 5% 6% 23%	2470
	21st to end	Night	5% 15% 7% 14% 8% 6% 6% 4 7% 7% 23%	2997
November	1st to 10th	Night	3 14% 7% 17% 11% 8% 7% 4 5% 5% 19%	2803
	11th to 20th	Night	2 11% 5% 17% 11% 10% 7% 5% 5% 7% 20%	3087
	21st to end	Night	1 10% 5% 16% 11% 9% 7% 6% 6% 7% 21%	3230
December	1st to 10th	Night	3 11% 6% 15% 9% 8% 8% 6% 8% 7% 19%	3318
	11th to 20th	Night	1 8% 6% 17% 12% 10% 9% 5% 7% 7% 18%	4240
	21st to end	Night	1 6% 4 14% 9% 9% 9% 7% 9% 12% 20%	6270

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	30% 17% 22% 19% 9% 3	1269
	11th to 20th	Day	33% 17% 14% 19% 14% 2	1580
	21st to end	Day	32% 16% 16% 12% 16% 8%	2090
February	1st to 10th	Day	36% 14% 16% 14% 13% 8%	1265
	11th to 20th	Day	40% 19% 18% 13% 8% 3	1486
	21st to end	Day	40% 15% 14% 15% 13% 3	1306
March	1st to 10th	Day	43% 17% 16% 11% 9% 4	3114
	11th to 20th	Day	33% 19% 17% 15% 14% 3	3242
	21st to end	Day	39% 26% 19% 9% 5% 2	4155
April	1st to 10th	Day	48% 17% 15% 14% 5% 1	2368
	11th to 20th	Day	44% 14% 15% 17% 9%	2587
	21st to end	Day	44% 14% 16% 16% 8% 1	2764
May	1st to 10th	Day	50% 20% 14% 12% 4	4937
	11th to 20th	Day	41% 15% 15% 23% 6%	5165
	21st to end	Day	52% 16% 16% 13% 3	5954
June	1st to 10th	Day	57% 17% 15% 9% 2	3420
	11th to 20th	Day	61% 13% 13% 11% 1	3420
	21st to end	Day	61% 17% 15% 7% 1	3420
July	1st to 10th	Day	57% 19% 17% 7% 1	5611
	11th to 20th	Day	58% 19% 16% 6% 1	5547
	21st to end	Day	59% 17% 17% 7%	5370
August	1st to 10th	Day	59% 16% 14% 8% 3	5027
	11th to 20th	Day	49% 15% 18% 15% 2	4523
	21st to end	Day	62% 15% 11% 10% 1	4834
September	1st to 10th	Day	61% 16% 13% 8% 2	2399
	11th to 20th	Day	55% 18% 13% 11% 2	2233
	21st to end	Day	57% 17% 12% 11% 4	2085
October	1st to 10th	Day	56% 15% 13% 11% 5%	1824
	11th to 20th	Day	51% 19% 15% 10% 4	1710
	21st to end	Day	46% 20% 16% 13% 5% 2	1598
November	1st to 10th	Day	52% 17% 14% 10% 6% 1	1309
	11th to 20th	Day	48% 16% 14% 14% 8%	1093
	21st to end	Day	43% 20% 16% 12% 9%	950
December	1st to 10th	Day	45% 20% 19% 10% 7%	860
	11th to 20th	Day	41% 20% 14% 14% 11% 1	970
	21st to end	Day	29% 15% 18% 14% 14% 9%	1397
January	1st to 10th	Night	38% 15% 20% 15% 8% 4	5686
	11th to 20th	Night	34% 16% 17% 15% 14% 4	5387
	21st to end	Night	29% 18% 13% 14% 17% 9%	5577
February	1st to 10th	Night	35% 13% 14% 16% 14% 8%	2913
	11th to 20th	Night	40% 17% 18% 13% 9% 3	2592
	21st to end	Night	39% 16% 17% 14% 11% 3	2146
March	1st to 10th	Night	41% 16% 13% 13% 13% 3	3740
	11th to 20th	Night	33% 18% 18% 14% 14% 3	3718
	21st to end	Night	33% 24% 20% 14% 6% 2	3473
April	1st to 10th	Night	46% 15% 18% 14% 6%	1812
	11th to 20th	Night	39% 16% 17% 17% 10%	1541
	21st to end	Night	43% 14% 18% 14% 9% 1	1416
May	1st to 10th	Night	50% 21% 13% 12% 4	2033
	11th to 20th	Night	50% 14% 12% 18% 6%	1738
	21st to end	Night	45% 19% 16% 17% 3	1611
June	1st to 10th	Night	56% 19% 13% 11% 1	760
	11th to 20th	Night	55% 17% 17% 10% 1	760
	21st to end	Night	61% 19% 11% 8% 1	760
July	1st to 10th	Night	62% 17% 14% 6% 1	1250
	11th to 20th	Night	60% 17% 13% 9%	1298
	21st to end	Night	63% 15% 15% 7%	1939
August	1st to 10th	Night	59% 16% 17% 7% 1	1888
	11th to 20th	Night	54% 15% 15% 13% 3	2377
	21st to end	Night	66% 16% 12% 7%	2832
September	1st to 10th	Night	58% 20% 13% 7% 1	1778
	11th to 20th	Night	56% 18% 14% 10% 3	1947
	21st to end	Night	58% 16% 14% 10% 2	2095
October	1st to 10th	Night	59% 16% 13% 8% 4	2356
	11th to 20th	Night	51% 18% 16% 11% 5%	2470
	21st to end	Night	51% 16% 14% 12% 7% 1	2997
November	1st to 10th	Night	51% 19% 14% 10% 6% 1	2803
	11th to 20th	Night	49% 15% 17% 14% 6%	3087
	21st to end	Night	43% 19% 17% 12% 9% 1	3230
December	1st to 10th	Night	45% 18% 17% 11% 8%	3318
	11th to 20th	Night	43% 18% 15% 12% 11% 1	4236
	21st to end	Night	34% 17% 14% 14% 14% 7%	6270

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	1 24% 34% 28% 12%	90
	11th to 20th	Day	4 4 15% 45% 19% 13%	166
	21st to end	Day	2 3 20% 38% 24% 13%	308
February	1st to 10th	Day	3 2 19% 35% 26% 14%	302
	11th to 20th	Day	3 2 26% 37% 21% 11%	365
	21st to end	Day	2 3 31% 37% 17% 10%	307
March	1st to 10th	Day	2 4 24% 33% 27% 10%	370
	11th to 20th	Day	2 4 25% 32% 25% 12%	370
	21st to end	Day	2 5% 25% 30% 25% 13%	606
April	1st to 10th	Day	3 6% 26% 29% 26% 10%	603
	11th to 20th	Day	3 5% 17% 33% 30% 12%	640
	21st to end	Day	5% 6% 17% 27% 32% 13%	650
May	1st to 10th	Day	10% 7% 25% 26% 23% 9%	653
	11th to 20th	Day	10% 8% 20% 29% 24% 9%	675
	21st to end	Day	14% 9% 23% 28% 19% 6%	792
June	1st to 10th	Day	19% 8% 21% 27% 18% 7%	870
	11th to 20th	Day	25% 6% 20% 24% 17% 7%	870
	21st to end	Day	23% 7% 17% 23% 21% 8%	870
July	1st to 10th	Day	21% 7% 20% 27% 19% 7%	856
	11th to 20th	Day	22% 10% 19% 23% 21% 6%	824
	21st to end	Day	25% 7% 22% 21% 17% 8%	739
August	1st to 10th	Day	22% 13% 23% 20% 15% 7%	676
	11th to 20th	Day	25% 14% 25% 20% 13% 4	665
	21st to end	Day	26% 12% 21% 23% 15% 4	748
September	1st to 10th	Day	23% 14% 24% 18% 16% 6%	643
	11th to 20th	Day	21% 9% 23% 27% 16% 5%	533
	21st to end	Day	18% 11% 19% 24% 18% 10%	390
October	1st to 10th	Day	17% 9% 24% 21% 18% 11%	390
	11th to 20th	Day	10% 5% 17% 26% 30% 11%	390
	21st to end	Day	8% 5% 21% 30% 24% 12%	429
November	1st to 10th	Day	8% 3 21% 30% 27% 11%	369
	11th to 20th	Day	5% 2 18% 38% 25% 13%	213
	21st to end	Day	4 1 24% 29% 27% 14%	90
December	1st to 10th	Day	7% 2 23% 32% 23% 12%	90
	11th to 20th	Day	2 2 19% 44% 24% 8%	90
	21st to end	Day	3 3 24% 41% 20% 8%	99
January	1st to 10th	Night	2 1 19% 37% 30% 10%	940
	11th to 20th	Night	3 2 19% 47% 22% 8%	887
	21st to end	Night	4 1 21% 43% 23% 8%	935
February	1st to 10th	Night	2 2 20% 40% 27% 9%	850
	11th to 20th	Night	2 1 26% 45% 22% 4	834
	21st to end	Night	3 3 25% 41% 21% 7%	670
March	1st to 10th	Night	1 2 21% 41% 28% 7%	660
	11th to 20th	Night	2 1 18% 39% 28% 10%	639
	21st to end	Night	1 2 19% 32% 33% 13%	627
April	1st to 10th	Night	2 3 19% 36% 31% 9%	570
	11th to 20th	Night	2 2 19% 32% 35% 10%	563
	21st to end	Night	6% 2 15% 32% 38% 7%	570
May	1st to 10th	Night	11% 3 21% 30% 29% 7%	461
	11th to 20th	Night	13% 4 19% 32% 26% 6%	295
	21st to end	Night	7% 3 23% 31% 35%	206
June	1st to 10th	Night	19% 4 14% 32% 29% 2	190
	11th to 20th	Night	21% 3 12% 31% 32% 3	190
	21st to end	Night	20% 5% 17% 28% 26% 4	190
July	1st to 10th	Night	21% 4 16% 25% 30% 4	185
	11th to 20th	Night	21% 5% 15% 27% 29% 3	184
	21st to end	Night	22% 4 13% 28% 26% 6%	379
August	1st to 10th	Night	19% 5% 23% 27% 21% 4	378
	11th to 20th	Night	21% 9% 19% 29% 17% 4	556
	21st to end	Night	24% 6% 17% 27% 21% 4	627
September	1st to 10th	Night	23% 5% 18% 32% 18% 4	570
	11th to 20th	Night	18% 8% 18% 33% 18% 5%	570
	21st to end	Night	20% 6% 17% 26% 21% 9%	573
October	1st to 10th	Night	18% 7% 21% 28% 20% 7%	746
	11th to 20th	Night	10% 4 15% 33% 29% 9%	860
	21st to end	Night	9% 4 16% 36% 27% 8%	946
November	1st to 10th	Night	7% 5% 18% 38% 26% 7%	839
	11th to 20th	Night	5% 3 19% 40% 24% 9%	850
	21st to end	Night	4 3 24% 36% 25% 9%	850
December	1st to 10th	Night	5% 4 20% 35% 25% 11%	892
	11th to 20th	Night	3 2 20% 41% 24% 10%	940
	21st to end	Night	4 4 22% 36% 24% 11%	1034

Page generated at 2024-10-30 09:19:25. Version ac07

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