Torch Lake Township
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Torch Lake Township clear sky chart from 2005-11-06 to 2025-07-21.

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	14% 12% 5% 10% 5% 4 4 3 5% 6% 32%	119454
	Night	15% 15% 6% 12% 6% 4 4 3 4 5% 26%	119846
Transparency	Day	33% 40% 6% 13% 7% 1	122979
	Night	39% 39% 7% 10% 5%	124468
Seeing	Day	18% 10% 25% 27% 16% 5%	16644
	Night	21% 9% 26% 30% 12% 1	26368

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	11% 23% 14% 26% 6% 4 2 2 2 2 7%	3617
	11th to 20th	Day	12% 18% 9% 28% 14% 8% 3 2 2 2 3	3589
	21st to end	Day	13% 20% 9% 21% 8% 5% 6% 2 2 3 10%	3982
February	1st to 10th	Day	10% 18% 8% 18% 15% 5% 3 3 4 5% 12%	1707
	11th to 20th	Day	13% 16% 8% 15% 11% 5% 5% 3 3 5% 15%	1933
	21st to end	Day	12% 18% 7% 14% 7% 5% 5% 3 4 5% 20%	1650
March	1st to 10th	Day	14% 10% 3 12% 6% 4 3 4 5% 6% 32%	4478
	11th to 20th	Day	11% 13% 5% 12% 5% 5% 5% 5% 5% 7% 27%	4857
	21st to end	Day	22% 10% 8% 13% 5% 5% 4 3 4 4 22%	5663
April	1st to 10th	Day	19% 14% 4 8% 5% 4 4 3 5% 6% 30%	2400
	11th to 20th	Day	19% 12% 3 6% 4 3 3 3 5% 5% 35%	2482
	21st to end	Day	15% 10% 4 8% 5% 4 4 4 5% 8% 33%	2600
May	1st to 10th	Day	15% 9% 2 7% 4 3 3 3 4 6% 43%	5888
	11th to 20th	Day	12% 8% 3 7% 4 4 4 3 5% 6% 45%	6084
	21st to end	Day	13% 8% 2 6% 5% 3 4 4 5% 7% 43%	6949
June	1st to 10th	Day	13% 5% 2 6% 4 4 4 3 6% 8% 44%	2925
	11th to 20th	Day	13% 6% 2 6% 4 4 4 5% 7% 8% 41%	3000
	21st to end	Day	15% 6% 2 5% 4 4 5% 4 5% 8% 42%	2911
July	1st to 10th	Day	18% 6% 2 5% 3 3 3 3 5% 9% 42%	4580
	11th to 20th	Day	9% 4 1 4 3 3 4 4 6% 9% 53%	4580
	21st to end	Day	9% 5% 2 5% 4 4 4 3 6% 10% 50%	4815
August	1st to 10th	Day	8% 6% 3 7% 5% 5% 5% 5% 7% 9% 42%	4245
	11th to 20th	Day	13% 6% 2 5% 4 4 4 3 4 7% 47%	4044
	21st to end	Day	14% 6% 3 6% 4 4 4 4 5% 6% 45%	4354
September	1st to 10th	Day	15% 5% 2 5% 4 4 4 4 6% 8% 44%	2252
	11th to 20th	Day	14% 5% 2 5% 4 4 4 4 5% 7% 46%	2090
	21st to end	Day	18% 5% 2 6% 4 4 5% 4 6% 8% 37%	2090
October	1st to 10th	Day	21% 8% 3 8% 5% 3 3 3 5% 8% 35%	2090
	11th to 20th	Day	24% 16% 4 10% 5% 5% 4 3 4 5% 19%	1795
	21st to end	Day	26% 18% 4 9% 5% 5% 4 3 5% 5% 16%	1881
November	1st to 10th	Day	18% 20% 4 8% 4 3 3 3 4 6% 26%	1762
	11th to 20th	Day	14% 28% 7% 12% 5% 4 4 3 4 5% 15%	1800
	21st to end	Day	18% 26% 11% 12% 3 4 3 3 4 3 13%	1642
December	1st to 10th	Day	16% 34% 12% 15% 5% 4 3 2 2 2 6%	2280
	11th to 20th	Day	13% 29% 8% 21% 7% 5% 4 2 3 2 5%	2621
	21st to end	Day	20% 24% 9% 14% 6% 5% 3 3 4 4 8%	3818
January	1st to 10th	Night	11% 22% 11% 28% 7% 5% 3 2 2 3 7%	6348
	11th to 20th	Night	12% 19% 9% 24% 17% 6% 3 2 2 2 5%	6316
	21st to end	Night	12% 22% 10% 19% 9% 8% 4 2 3 3 9%	6996
February	1st to 10th	Night	11% 21% 6% 19% 13% 6% 3 3 2 4 12%	2691
	11th to 20th	Night	12% 16% 7% 18% 11% 5% 3 2 4 4 17%	2348
	21st to end	Night	15% 19% 5% 13% 7% 5% 4 2 4 5% 21%	1980
March	1st to 10th	Night	16% 12% 3 9% 5% 4 3 3 4 6% 35%	5362
	11th to 20th	Night	11% 16% 4 8% 5% 4 4 3 6% 7% 32%	5101
	21st to end	Night	21% 12% 5% 10% 4 3 4 3 5% 5% 27%	5312
April	1st to 10th	Night	20% 12% 4 9% 5% 4 4 3 5% 6% 28%	2000
	11th to 20th	Night	19% 12% 3 7% 5% 4 3 4 3 5% 34%	1865
	21st to end	Night	17% 11% 3 7% 5% 4 4 4 5% 6% 35%	1800
May	1st to 10th	Night	15% 8% 3 6% 4 4 4 3 5% 7% 41%	4053
	11th to 20th	Night	15% 8% 3 7% 4 4 4 4 5% 7% 40%	3817
	21st to end	Night	18% 8% 2 6% 4 3 3 3 5% 6% 42%	3949
June	1st to 10th	Night	14% 6% 2 6% 5% 5% 4 4 4 8% 42%	1470
	11th to 20th	Night	12% 6% 2 6% 5% 4 5% 4 6% 7% 42%	1400
	21st to end	Night	14% 8% 2 6% 5% 4 4 4 5% 6% 43%	1482
July	1st to 10th	Night	14% 6% 3 6% 4 4 4 4 6% 8% 41%	2610
	11th to 20th	Night	9% 5% 2 6% 5% 3 5% 3 5% 7% 51%	2610
	21st to end	Night	9% 5% 2 6% 4 3 4 3 5% 8% 48%	2750
August	1st to 10th	Night	13% 5% 3 6% 5% 5% 4 3 5% 8% 41%	2686
	11th to 20th	Night	14% 4 2 5% 3 4 4 3 5% 8% 48%	2785
	21st to end	Night	13% 6% 2 6% 4 4 4 4 5% 7% 46%	3299
September	1st to 10th	Night	13% 6% 2 6% 4 3 3 4 4 8% 47%	1908
	11th to 20th	Night	15% 6% 2 6% 3 3 4 3 6% 7% 46%	2090
	21st to end	Night	18% 7% 3 6% 5% 4 4 3 5% 7% 36%	2090
October	1st to 10th	Night	20% 8% 3 7% 5% 4 3 3 5% 5% 37%	2090
	11th to 20th	Night	24% 14% 4 8% 4 5% 4 3 5% 5% 23%	2383
	21st to end	Night	27% 17% 3 8% 5% 4 4 3 3 4 21%	2717
November	1st to 10th	Night	19% 17% 4 9% 4 4 3 2 4 6% 27%	2536
	11th to 20th	Night	18% 26% 7% 11% 5% 4 3 3 3 4 17%	2600
	21st to end	Night	18% 29% 9% 11% 5% 3 4 3 3 3 13%	2753
December	1st to 10th	Night	13% 31% 14% 15% 6% 4 2 2 2 3 8%	4910
	11th to 20th	Night	14% 26% 9% 23% 6% 4 2 2 3 2 9%	5586
	21st to end	Night	23% 22% 9% 13% 6% 5% 4 3 3 3 9%	7153

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	67% 26% 4 2	3618
	11th to 20th	Day	69% 27% 2 2	3620
	21st to end	Day	58% 28% 9% 4 1	3982
February	1st to 10th	Day	31% 62% 3 3 1	1707
	11th to 20th	Day	28% 61% 4 5% 2	1943
	21st to end	Day	24% 63% 4 7% 2	1650
March	1st to 10th	Day	37% 29% 12% 13% 8% 1	4480
	11th to 20th	Day	41% 29% 11% 12% 6% 1	4857
	21st to end	Day	51% 29% 5% 9% 5%	5663
April	1st to 10th	Day	24% 62% 3 9% 3	2400
	11th to 20th	Day	19% 63% 3 9% 6% 1	2482
	21st to end	Day	18% 62% 5% 8% 7% 1	2600
May	1st to 10th	Day	30% 29% 6% 17% 15% 3	5897
	11th to 20th	Day	30% 29% 6% 21% 13% 1	6088
	21st to end	Day	31% 29% 6% 17% 16% 2	6949
June	1st to 10th	Day	15% 62% 4 11% 6% 1	2925
	11th to 20th	Day	18% 63% 4 8% 5% 1	3000
	21st to end	Day	16% 61% 5% 13% 6%	2911
July	1st to 10th	Day	30% 36% 10% 16% 8% 1	4511
	11th to 20th	Day	16% 36% 10% 28% 9% 1	4505
	21st to end	Day	19% 38% 7% 22% 14%	4663
August	1st to 10th	Day	22% 40% 9% 21% 9%	4230
	11th to 20th	Day	26% 38% 8% 21% 7%	4083
	21st to end	Day	26% 40% 8% 20% 5%	4353
September	1st to 10th	Day	17% 61% 5% 11% 5%	2252
	11th to 20th	Day	13% 60% 4 14% 7% 1	2090
	21st to end	Day	16% 61% 6% 12% 5%	2090
October	1st to 10th	Day	19% 38% 5% 23% 14%	3480
	11th to 20th	Day	34% 38% 6% 14% 8%	2946
	21st to end	Day	41% 39% 8% 11% 2	3081
November	1st to 10th	Day	32% 55% 3 7% 3	1762
	11th to 20th	Day	33% 57% 4 5% 2	1800
	21st to end	Day	37% 57% 3 2 1	1642
December	1st to 10th	Day	59% 36% 3 2	2280
	11th to 20th	Day	63% 31% 3 2 1	2621
	21st to end	Day	59% 28% 7% 4 2	3818
January	1st to 10th	Night	67% 26% 4 3	6348
	11th to 20th	Night	69% 26% 3 1	6360
	21st to end	Night	59% 29% 5% 6% 1	6996
February	1st to 10th	Night	31% 62% 2 4 1	2691
	11th to 20th	Night	26% 61% 4 7% 1	2349
	21st to end	Night	23% 62% 4 7% 3	1980
March	1st to 10th	Night	38% 29% 14% 14% 6%	5373
	11th to 20th	Night	37% 29% 16% 14% 4	5102
	21st to end	Night	46% 29% 8% 11% 6%	5312
April	1st to 10th	Night	23% 62% 3 7% 4 1	2000
	11th to 20th	Night	22% 62% 2 8% 4 2	1865
	21st to end	Night	21% 61% 4 8% 6% 1	1800
May	1st to 10th	Night	29% 30% 7% 16% 15% 3	4060
	11th to 20th	Night	31% 30% 5% 20% 13%	3818
	21st to end	Night	34% 28% 9% 16% 10% 4	3950
June	1st to 10th	Night	16% 63% 4 10% 7%	1470
	11th to 20th	Night	17% 63% 4 9% 5% 1	1400
	21st to end	Night	17% 61% 4 9% 7% 1	1482
July	1st to 10th	Night	30% 36% 9% 14% 8% 3	2570
	11th to 20th	Night	21% 37% 9% 22% 11%	2562
	21st to end	Night	22% 37% 9% 16% 15% 1	2662
August	1st to 10th	Night	28% 39% 9% 15% 9% 1	2677
	11th to 20th	Night	25% 39% 9% 19% 8%	2812
	21st to end	Night	24% 39% 9% 16% 11%	3299
September	1st to 10th	Night	15% 61% 6% 11% 7%	1908
	11th to 20th	Night	15% 60% 5% 12% 8%	2090
	21st to end	Night	19% 60% 6% 10% 5%	2090
October	1st to 10th	Night	27% 39% 6% 20% 7%	3480
	11th to 20th	Night	30% 37% 7% 16% 9%	3958
	21st to end	Night	35% 38% 10% 14% 3	4467
November	1st to 10th	Night	32% 56% 4 6% 2	2536
	11th to 20th	Night	32% 56% 4 5% 3	2600
	21st to end	Night	36% 57% 4 2 1	2753
December	1st to 10th	Night	55% 37% 3 4	4910
	11th to 20th	Night	60% 32% 4 3 1	5585
	21st to end	Night	60% 28% 7% 4 2	7153

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	18% 15% 33% 24% 8% 2	300
	11th to 20th	Day	21% 16% 36% 22% 4 2	300
	21st to end	Day	22% 12% 30% 28% 7% 1	330
February	1st to 10th	Day	19% 19% 35% 19% 5% 2	300
	11th to 20th	Day	17% 17% 39% 21% 6%	300
	21st to end	Day	16% 22% 38% 20% 4	249
March	1st to 10th	Day	19% 15% 36% 23% 7%	300
	11th to 20th	Day	17% 14% 29% 29% 10% 2	442
	21st to end	Day	27% 10% 26% 25% 12% 1	550
April	1st to 10th	Day	23% 13% 28% 26% 9% 2	500
	11th to 20th	Day	25% 15% 24% 23% 9% 4	492
	21st to end	Day	18% 10% 27% 29% 14% 2	500
May	1st to 10th	Day	20% 11% 25% 26% 15% 3	503
	11th to 20th	Day	16% 6% 27% 29% 17% 5%	620
	21st to end	Day	13% 8% 25% 30% 19% 6%	789
June	1st to 10th	Day	13% 7% 27% 31% 18% 4	730
	11th to 20th	Day	15% 6% 25% 33% 17% 4	730
	21st to end	Day	16% 5% 24% 31% 21% 3	730
July	1st to 10th	Day	9% 3 21% 35% 24% 9%	721
	11th to 20th	Day	11% 5% 19% 35% 22% 8%	718
	21st to end	Day	9% 4 20% 35% 25% 7%	740
August	1st to 10th	Day	10% 3 17% 32% 27% 11%	576
	11th to 20th	Day	13% 3 16% 29% 26% 13%	479
	21st to end	Day	17% 5% 17% 30% 22% 9%	539
September	1st to 10th	Day	17% 7% 19% 24% 23% 10%	490
	11th to 20th	Day	14% 6% 15% 28% 27% 11%	490
	21st to end	Day	19% 9% 16% 26% 23% 7%	490
October	1st to 10th	Day	22% 9% 23% 27% 13% 6%	490
	11th to 20th	Day	29% 13% 26% 23% 8% 1	375
	21st to end	Day	29% 14% 29% 21% 5% 2	330
November	1st to 10th	Day	28% 16% 26% 19% 10% 1	300
	11th to 20th	Day	24% 19% 34% 18% 5%	300
	21st to end	Day	27% 18% 33% 17% 4	246
December	1st to 10th	Day	34% 18% 24% 18% 6% 1	200
	11th to 20th	Day	25% 21% 30% 20% 4 1	200
	21st to end	Day	29% 16% 32% 19% 2 1	295
January	1st to 10th	Night	22% 15% 33% 23% 6% 1	1000
	11th to 20th	Night	24% 15% 31% 23% 6% 1	1000
	21st to end	Night	22% 10% 33% 27% 7% 1	1100
February	1st to 10th	Night	18% 14% 32% 29% 6% 1	891
	11th to 20th	Night	19% 14% 34% 26% 7%	783
	21st to end	Night	23% 13% 31% 27% 5%	660
March	1st to 10th	Night	17% 11% 31% 29% 11% 1	800
	11th to 20th	Night	16% 11% 35% 30% 7% 1	800
	21st to end	Night	22% 7% 28% 33% 10% 1	815
April	1st to 10th	Night	25% 10% 28% 30% 7% 1	600
	11th to 20th	Night	23% 12% 22% 30% 11% 1	593
	21st to end	Night	20% 7% 25% 36% 11% 1	600
May	1st to 10th	Night	17% 5% 24% 38% 15% 1	600
	11th to 20th	Night	18% 4 22% 37% 18% 1	591
	21st to end	Night	18% 3 19% 38% 20% 3	650
June	1st to 10th	Night	14% 4 21% 41% 18% 1	470
	11th to 20th	Night	12% 5% 20% 43% 20% 1	400
	21st to end	Night	13% 4 21% 38% 22% 2	482
July	1st to 10th	Night	11% 2 12% 44% 28% 3	585
	11th to 20th	Night	11% 2 16% 40% 28% 3	582
	21st to end	Night	10% 2 18% 40% 28% 3	624
August	1st to 10th	Night	11% 2 13% 43% 29% 2	567
	11th to 20th	Night	12% 4 13% 36% 31% 5%	564
	21st to end	Night	16% 4 15% 39% 23% 2	627
September	1st to 10th	Night	16% 3 18% 35% 24% 4	578
	11th to 20th	Night	17% 4 17% 33% 25% 4	760
	21st to end	Night	21% 8% 17% 31% 19% 4	760
October	1st to 10th	Night	24% 7% 21% 31% 16% 1	760
	11th to 20th	Night	31% 12% 23% 27% 7% 1	760
	21st to end	Night	37% 11% 22% 23% 6%	836
November	1st to 10th	Night	29% 11% 26% 28% 6% 1	780
	11th to 20th	Night	30% 15% 31% 20% 4	800
	21st to end	Night	31% 15% 30% 20% 4	850
December	1st to 10th	Night	28% 19% 30% 20% 3	1000
	11th to 20th	Night	27% 13% 35% 20% 4 1	1000
	21st to end	Night	30% 12% 33% 22% 3 1	1100

Page generated at 2025-07-18 01:10:00. Version ac07

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