Camp Opemikon
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Camp Opemikon clear sky chart from 2005-11-06 to 2025-11-18.

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	16% 10% 3 8% 5% 5% 4 4 5% 7% 32%	127317
	Night	16% 11% 4 9% 5% 5% 4 3 5% 6% 32%	123047
Transparency	Day	50% 7% 11% 21% 11% 1	130821
	Night	51% 6% 11% 19% 10% 1	127630
Seeing	Day	23% 17% 31% 18% 8% 2	15793
	Night	22% 15% 31% 23% 8% 1	24921

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	12% 15% 6% 12% 7% 5% 5% 3 5% 5% 24%	3597
	11th to 20th	Day	11% 18% 8% 13% 6% 5% 5% 3 4 5% 21%	3570
	21st to end	Day	14% 18% 7% 15% 6% 5% 4 4 4 4 20%	4279
February	1st to 10th	Day	15% 15% 4 12% 6% 5% 5% 4 5% 5% 23%	1800
	11th to 20th	Day	12% 15% 6% 10% 7% 5% 5% 3 4 5% 28%	1753
	21st to end	Day	20% 14% 5% 10% 7% 5% 5% 3 5% 4 23%	1634
March	1st to 10th	Day	19% 14% 4 10% 6% 4 4 3 4 6% 27%	4583
	11th to 20th	Day	10% 13% 4 8% 6% 6% 5% 4 5% 7% 32%	4980
	21st to end	Day	17% 12% 4 8% 4 4 3 2 3 4 38%	5694
April	1st to 10th	Day	21% 13% 3 8% 4 4 3 3 4 6% 32%	2400
	11th to 20th	Day	22% 10% 3 7% 4 3 4 2 4 5% 37%	2374
	21st to end	Day	22% 11% 3 7% 5% 4 4 3 5% 5% 32%	2511
May	1st to 10th	Day	24% 10% 3 8% 5% 4 4 3 5% 6% 28%	6346
	11th to 20th	Day	16% 9% 3 8% 5% 5% 4 3 5% 8% 34%	6318
	21st to end	Day	18% 9% 3 6% 4 4 4 4 6% 8% 34%	6949
June	1st to 10th	Day	19% 9% 3 8% 4 5% 5% 5% 6% 6% 31%	2800
	11th to 20th	Day	14% 6% 3 6% 4 6% 5% 4 7% 9% 37%	2800
	21st to end	Day	17% 8% 2 7% 6% 5% 5% 4 6% 8% 33%	2800
July	1st to 10th	Day	12% 7% 3 7% 6% 5% 5% 5% 7% 10% 34%	6360
	11th to 20th	Day	10% 5% 2 6% 5% 5% 5% 4 7% 8% 42%	6360
	21st to end	Day	9% 5% 2 6% 4 4 6% 4 7% 9% 44%	6926
August	1st to 10th	Day	16% 8% 3 7% 4 4 4 3 5% 8% 36%	4374
	11th to 20th	Day	16% 7% 3 6% 4 4 4 4 7% 9% 36%	4151
	21st to end	Day	14% 6% 2 6% 4 4 4 4 7% 10% 39%	4312
September	1st to 10th	Day	13% 6% 3 6% 4 4 5% 4 5% 8% 42%	2400
	11th to 20th	Day	11% 5% 2 5% 4 4 4 3 5% 7% 49%	2400
	21st to end	Day	18% 6% 2 7% 5% 4 4 4 4 7% 39%	2119
October	1st to 10th	Day	20% 9% 2 7% 4 3 3 3 5% 6% 38%	2000
	11th to 20th	Day	19% 9% 3 7% 6% 5% 5% 3 6% 7% 30%	2000
	21st to end	Day	25% 9% 3 9% 5% 5% 4 3 5% 6% 26%	2085
November	1st to 10th	Day	15% 10% 3 8% 4 5% 5% 4 5% 6% 34%	1840
	11th to 20th	Day	17% 14% 4 9% 5% 5% 4 3 4 6% 29%	1656
	21st to end	Day	20% 15% 5% 10% 6% 5% 5% 4 5% 4 22%	1600
December	1st to 10th	Day	21% 17% 4 13% 6% 5% 4 4 4 5% 16%	2600
	11th to 20th	Day	18% 18% 5% 11% 7% 4 3 3 4 4 24%	2986
	21st to end	Day	23% 17% 5% 12% 5% 3 3 2 3 4 23%	3960
January	1st to 10th	Night	15% 15% 8% 13% 7% 5% 4 3 4 4 22%	6349
	11th to 20th	Night	11% 16% 6% 15% 8% 6% 5% 4 4 6% 19%	6315
	21st to end	Night	15% 17% 6% 13% 6% 6% 4 3 4 4 21%	6674
February	1st to 10th	Night	13% 16% 5% 10% 7% 5% 4 4 7% 6% 24%	2600
	11th to 20th	Night	12% 15% 5% 10% 5% 5% 4 3 5% 5% 29%	2533
	21st to end	Night	14% 15% 4 8% 6% 4 5% 3 5% 6% 28%	1995
March	1st to 10th	Night	20% 14% 4 10% 5% 5% 3 2 3 4 30%	5254
	11th to 20th	Night	13% 12% 3 7% 4 5% 5% 4 7% 9% 30%	4979
	21st to end	Night	18% 10% 4 8% 4 4 4 3 4 5% 35%	5238
April	1st to 10th	Night	21% 10% 3 9% 4 4 4 3 4 6% 33%	2000
	11th to 20th	Night	20% 9% 2 7% 4 5% 4 3 5% 4 37%	1975
	21st to end	Night	19% 11% 3 8% 4 4 4 3 5% 6% 33%	1905
May	1st to 10th	Night	24% 11% 3 7% 4 5% 4 4 5% 6% 26%	3594
	11th to 20th	Night	15% 8% 2 6% 3 3 4 3 5% 7% 42%	3575
	21st to end	Night	18% 8% 3 7% 5% 4 4 4 6% 6% 35%	3926
June	1st to 10th	Night	15% 8% 2 7% 6% 4 5% 5% 6% 8% 34%	1600
	11th to 20th	Night	13% 7% 2 6% 4 4 4 3 6% 8% 41%	1600
	21st to end	Night	17% 7% 2 7% 5% 5% 5% 4 6% 8% 35%	1600
July	1st to 10th	Night	12% 5% 3 7% 5% 5% 5% 4 7% 9% 36%	3600
	11th to 20th	Night	11% 5% 2 7% 4 4 4 3 5% 8% 46%	3600
	21st to end	Night	8% 6% 2 6% 4 4 4 4 5% 7% 49%	3926
August	1st to 10th	Night	11% 7% 2 7% 4 5% 4 3 6% 7% 43%	2772
	11th to 20th	Night	12% 7% 3 7% 4 4 4 3 6% 8% 43%	2875
	21st to end	Night	10% 5% 2 6% 5% 4 5% 5% 7% 9% 42%	3576
September	1st to 10th	Night	11% 6% 2 6% 5% 4 4 4 5% 7% 47%	2000
	11th to 20th	Night	12% 4 2 4 3 3 4 4 5% 7% 52%	2000
	21st to end	Night	17% 7% 2 6% 4 4 4 3 5% 6% 43%	2275
October	1st to 10th	Night	17% 7% 3 6% 4 4 4 3 5% 7% 40%	2400
	11th to 20th	Night	20% 9% 2 8% 5% 4 5% 3 5% 6% 32%	2400
	21st to end	Night	22% 10% 3 8% 5% 4 4 4 5% 5% 31%	2755
November	1st to 10th	Night	17% 11% 3 7% 5% 4 4 4 5% 6% 35%	2673
	11th to 20th	Night	17% 12% 3 8% 5% 4 5% 3 5% 6% 32%	2899
	21st to end	Night	20% 13% 4 9% 5% 5% 5% 3 5% 6% 24%	2800
December	1st to 10th	Night	19% 16% 5% 12% 7% 5% 5% 3 5% 6% 17%	4580
	11th to 20th	Night	22% 15% 4 9% 5% 4 4 3 4 4 25%	5208
	21st to end	Night	26% 17% 4 11% 5% 4 4 2 4 4 20%	6996

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	59% 8% 11% 15% 6% 1	3598
	11th to 20th	Day	65% 7% 9% 11% 8%	3600
	21st to end	Day	67% 6% 7% 10% 9% 1	4279
February	1st to 10th	Day	61% 7% 10% 16% 6% 1	1800
	11th to 20th	Day	59% 6% 10% 15% 9% 1	1762
	21st to end	Day	63% 5% 9% 12% 9% 1	1634
March	1st to 10th	Day	58% 5% 9% 13% 12% 3	4586
	11th to 20th	Day	50% 7% 17% 15% 10% 2	4980
	21st to end	Day	49% 5% 6% 19% 18% 3	5694
April	1st to 10th	Day	54% 5% 8% 17% 13% 3	2400
	11th to 20th	Day	49% 6% 7% 20% 16% 2	2374
	21st to end	Day	54% 6% 8% 15% 14% 3	2511
May	1st to 10th	Day	56% 7% 8% 17% 10% 2	6357
	11th to 20th	Day	48% 8% 12% 19% 13% 1	6322
	21st to end	Day	47% 7% 12% 21% 11% 1	6949
June	1st to 10th	Day	50% 8% 10% 18% 12% 1	2800
	11th to 20th	Day	41% 8% 11% 25% 13% 2	2800
	21st to end	Day	48% 8% 12% 20% 11% 1	2800
July	1st to 10th	Day	43% 6% 14% 26% 11% 1	6290
	11th to 20th	Day	36% 7% 14% 27% 15%	6285
	21st to end	Day	34% 7% 13% 36% 10%	6728
August	1st to 10th	Day	45% 6% 14% 24% 10% 1	4360
	11th to 20th	Day	42% 8% 14% 27% 9% 1	4190
	21st to end	Day	39% 6% 14% 30% 10%	4312
September	1st to 10th	Day	38% 8% 15% 28% 12% 1	2400
	11th to 20th	Day	34% 8% 12% 31% 15%	2400
	21st to end	Day	44% 7% 13% 25% 11%	2119
October	1st to 10th	Day	43% 5% 11% 32% 9%	3260
	11th to 20th	Day	44% 6% 14% 24% 11% 1	3240
	21st to end	Day	50% 6% 15% 23% 7%	3349
November	1st to 10th	Day	48% 8% 15% 20% 8% 1	1840
	11th to 20th	Day	56% 7% 11% 16% 10% 1	1656
	21st to end	Day	63% 9% 11% 9% 7%	1600
December	1st to 10th	Day	69% 6% 13% 9% 3	2600
	11th to 20th	Day	65% 5% 10% 14% 6%	2986
	21st to end	Day	67% 5% 7% 15% 6%	3960
January	1st to 10th	Night	64% 7% 11% 13% 5%	6349
	11th to 20th	Night	65% 8% 11% 10% 6%	6360
	21st to end	Night	66% 6% 7% 8% 11% 1	6674
February	1st to 10th	Night	58% 7% 11% 16% 6% 1	2600
	11th to 20th	Night	56% 6% 11% 19% 8% 1	2535
	21st to end	Night	55% 6% 11% 17% 9% 1	1995
March	1st to 10th	Night	58% 5% 7% 16% 10% 4	5264
	11th to 20th	Night	47% 8% 19% 16% 8% 3	4980
	21st to end	Night	49% 5% 8% 22% 13% 2	5238
April	1st to 10th	Night	52% 5% 7% 20% 13% 2	2000
	11th to 20th	Night	49% 6% 7% 20% 17% 1	1975
	21st to end	Night	52% 5% 9% 16% 15% 3	1905
May	1st to 10th	Night	56% 7% 10% 16% 8% 3	3600
	11th to 20th	Night	41% 7% 15% 22% 14% 2	3576
	21st to end	Night	46% 7% 14% 17% 14% 1	3927
June	1st to 10th	Night	46% 9% 13% 20% 12% 1	1600
	11th to 20th	Night	39% 7% 13% 22% 18% 2	1600
	21st to end	Night	45% 10% 13% 19% 12% 1	1600
July	1st to 10th	Night	42% 6% 16% 19% 15% 1	3560
	11th to 20th	Night	35% 6% 13% 32% 12%	3552
	21st to end	Night	33% 7% 12% 32% 14% 1	3809
August	1st to 10th	Night	39% 7% 15% 25% 13% 1	2762
	11th to 20th	Night	39% 6% 14% 31% 10% 1	2902
	21st to end	Night	36% 8% 16% 28% 11% 1	3576
September	1st to 10th	Night	35% 9% 13% 29% 14% 1	2000
	11th to 20th	Night	30% 8% 14% 33% 13% 1	2000
	21st to end	Night	41% 7% 11% 29% 12% 1	2275
October	1st to 10th	Night	40% 5% 11% 28% 15%	3920
	11th to 20th	Night	43% 5% 16% 26% 10%	3899
	21st to end	Night	49% 6% 12% 24% 8%	4441
November	1st to 10th	Night	48% 6% 14% 21% 10% 1	2673
	11th to 20th	Night	52% 7% 11% 19% 10% 1	2899
	21st to end	Night	60% 7% 12% 16% 5%	2800
December	1st to 10th	Night	67% 6% 13% 12% 2	4580
	11th to 20th	Night	62% 6% 8% 14% 9% 1	5208
	21st to end	Night	68% 6% 6% 11% 9%	6996

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	24% 22% 39% 12% 3 1	200
	11th to 20th	Day	32% 18% 31% 16% 3 1	200
	21st to end	Day	26% 24% 33% 14% 3	289
February	1st to 10th	Day	32% 27% 32% 8% 1	300
	11th to 20th	Day	30% 29% 36% 5%	300
	21st to end	Day	33% 23% 32% 11% 2	398
March	1st to 10th	Day	27% 23% 32% 14% 4	500
	11th to 20th	Day	29% 22% 31% 13% 4	500
	21st to end	Day	33% 21% 27% 12% 5% 1	550
April	1st to 10th	Day	31% 25% 28% 11% 5%	500
	11th to 20th	Day	33% 23% 22% 14% 7% 2	492
	21st to end	Day	29% 24% 29% 11% 5% 2	500
May	1st to 10th	Day	26% 17% 32% 17% 6% 2	503
	11th to 20th	Day	19% 16% 37% 19% 8% 2	527
	21st to end	Day	21% 15% 32% 21% 8% 3	573
June	1st to 10th	Day	22% 14% 37% 21% 5% 2	530
	11th to 20th	Day	15% 17% 36% 20% 10% 2	530
	21st to end	Day	19% 17% 31% 22% 9% 2	530
July	1st to 10th	Day	14% 10% 31% 29% 14% 3	525
	11th to 20th	Day	15% 13% 32% 23% 15% 3	524
	21st to end	Day	13% 10% 35% 27% 10% 4	576
August	1st to 10th	Day	13% 9% 32% 30% 13% 3	526
	11th to 20th	Day	15% 9% 28% 27% 15% 6%	519
	21st to end	Day	15% 11% 32% 25% 11% 6%	583
September	1st to 10th	Day	14% 15% 30% 22% 11% 7%	530
	11th to 20th	Day	11% 9% 25% 25% 19% 11%	530
	21st to end	Day	19% 11% 30% 23% 13% 4	530
October	1st to 10th	Day	25% 16% 26% 18% 12% 3	530
	11th to 20th	Day	27% 20% 32% 15% 5% 1	530
	21st to end	Day	28% 21% 29% 19% 4	520
November	1st to 10th	Day	29% 19% 28% 18% 7%	414
	11th to 20th	Day	29% 20% 34% 11% 5% 1	214
	21st to end	Day	33% 23% 28% 15% 3	200
December	1st to 10th	Day	32% 20% 33% 12% 3	200
	11th to 20th	Day	36% 25% 29% 9% 3 1	200
	21st to end	Day	33% 18% 31% 13% 4	220
January	1st to 10th	Night	28% 20% 32% 17% 3	800
	11th to 20th	Night	29% 18% 30% 19% 4 1	800
	21st to end	Night	20% 17% 37% 21% 4	880
February	1st to 10th	Night	23% 22% 34% 19% 2	800
	11th to 20th	Night	23% 22% 36% 16% 3	783
	21st to end	Night	25% 20% 36% 17% 3	660
March	1st to 10th	Night	26% 17% 35% 20% 3	800
	11th to 20th	Night	27% 21% 28% 21% 4 1	800
	21st to end	Night	23% 17% 34% 19% 7%	880
April	1st to 10th	Night	28% 17% 33% 20% 3	800
	11th to 20th	Night	25% 20% 29% 18% 6% 1	791
	21st to end	Night	25% 15% 29% 22% 8% 1	705
May	1st to 10th	Night	24% 13% 27% 26% 9% 2	400
	11th to 20th	Night	15% 11% 38% 28% 7%	394
	21st to end	Night	14% 9% 38% 28% 10%	433
June	1st to 10th	Night	16% 6% 36% 35% 7% 1	400
	11th to 20th	Night	15% 11% 34% 27% 13% 1	400
	21st to end	Night	18% 8% 30% 33% 11% 1	400
July	1st to 10th	Night	11% 6% 33% 36% 13% 1	390
	11th to 20th	Night	12% 4 32% 37% 14% 1	388
	21st to end	Night	11% 4 32% 42% 11%	438
August	1st to 10th	Night	12% 5% 28% 36% 19%	506
	11th to 20th	Night	12% 5% 25% 34% 23% 2	594
	21st to end	Night	12% 7% 31% 33% 15% 2	870
September	1st to 10th	Night	13% 7% 34% 28% 17% 2	800
	11th to 20th	Night	13% 8% 23% 28% 24% 5%	800
	21st to end	Night	20% 10% 24% 27% 17% 2	800
October	1st to 10th	Night	21% 13% 28% 23% 14% 2	800
	11th to 20th	Night	26% 14% 32% 21% 7%	800
	21st to end	Night	28% 15% 29% 23% 5%	880
November	1st to 10th	Night	27% 15% 30% 21% 7%	820
	11th to 20th	Night	25% 17% 34% 16% 7% 1	829
	21st to end	Night	29% 19% 29% 18% 5%	800
December	1st to 10th	Night	29% 20% 31% 16% 4	800
	11th to 20th	Night	27% 19% 34% 17% 3 1	800
	21st to end	Night	33% 17% 30% 18% 2	880

Page generated at 2025-11-15 00:56:01. Version ac07

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