Cooney Reservoir State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cooney Reservoir State Park clear sky chart from 2005-11-06 to 2026-01-02.

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	7% 7% 2 6% 4 4 5% 4 6% 8% 47%	137031
	Night	6% 8% 3 7% 4 4 4 4 6% 7% 46%	131737
Transparency	Day	33% 7% 12% 25% 18% 5%	131771
	Night	34% 6% 13% 26% 16% 4	128001
Seeing	Day	12% 10% 32% 30% 14% 2	17323
	Night	11% 6% 33% 38% 12% 1	26942

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	4 12% 4 10% 6% 7% 5% 4 7% 7% 34%	3320
	11th to 20th	Day	2 7% 3 15% 10% 7% 6% 4 6% 6% 33%	3755
	21st to end	Day	2 6% 3 7% 4 5% 4 4 5% 7% 55%	4510
February	1st to 10th	Day	5% 13% 5% 10% 6% 5% 4 4 6% 7% 34%	1800
	11th to 20th	Day	3 13% 5% 10% 8% 5% 5% 4 5% 7% 35%	1755
	21st to end	Day	2 9% 4 10% 7% 5% 5% 5% 6% 6% 39%	1495
March	1st to 10th	Day	5% 8% 3 7% 5% 4 4 4 5% 8% 46%	4910
	11th to 20th	Day	5% 10% 3 9% 4 5% 4 4 7% 8% 41%	5000
	21st to end	Day	9% 17% 5% 10% 5% 5% 5% 3 6% 7% 26%	5486
April	1st to 10th	Day	9% 13% 3 7% 5% 5% 5% 4 6% 8% 35%	2387
	11th to 20th	Day	11% 9% 5% 8% 6% 5% 5% 4 7% 7% 35%	2453
	21st to end	Day	13% 11% 3 8% 5% 5% 5% 5% 6% 7% 32%	2600
May	1st to 10th	Day	15% 12% 2 6% 4 4 4 3 5% 6% 39%	6054
	11th to 20th	Day	12% 7% 2 7% 4 5% 6% 5% 8% 9% 35%	6298
	21st to end	Day	11% 6% 2 6% 4 5% 5% 4 6% 8% 42%	6925
June	1st to 10th	Day	12% 6% 2 5% 4 4 5% 4 8% 9% 41%	2810
	11th to 20th	Day	9% 6% 2 6% 5% 5% 6% 5% 7% 8% 42%	3000
	21st to end	Day	4 3 1 4 3 4 5% 4 7% 8% 57%	3000
July	1st to 10th	Day	4 2 1 3 3 5% 5% 5% 7% 9% 56%	6779
	11th to 20th	Day	6% 2 1 3 2 3 4 4 7% 8% 59%	6459
	21st to end	Day	6% 3 1 4 4 4 5% 5% 7% 8% 52%	6725
August	1st to 10th	Day	4 3 2 4 4 4 5% 5% 8% 9% 51%	5779
	11th to 20th	Day	3 3 1 4 3 4 5% 5% 6% 8% 58%	5798
	21st to end	Day	8% 4 2 5% 3 3 4 3 6% 7% 57%	6302
September	1st to 10th	Day	6% 4 1 4 3 3 3 3 5% 6% 62%	2400
	11th to 20th	Day	10% 5% 2 4 3 3 4 4 6% 8% 52%	2308
	21st to end	Day	10% 4 1 3 3 3 3 3 5% 6% 58%	2161
October	1st to 10th	Day	7% 5% 2 4 2 2 3 3 3 5% 63%	3270
	11th to 20th	Day	8% 7% 2 4 3 3 3 2 4 5% 61%	3250
	21st to end	Day	6% 9% 3 5% 4 4 4 3 7% 8% 48%	3548
November	1st to 10th	Day	7% 10% 3 7% 4 5% 4 4 5% 7% 44%	1671
	11th to 20th	Day	4 9% 3 5% 5% 5% 5% 4 6% 8% 46%	1680
	21st to end	Day	5% 9% 3 7% 4 4 5% 3 6% 8% 46%	1680
December	1st to 10th	Day	2 6% 4 7% 5% 4 4 4 5% 7% 53%	2700
	11th to 20th	Day	3 6% 3 6% 6% 5% 6% 5% 8% 11% 41%	3106
	21st to end	Day	4 9% 4 10% 6% 5% 5% 4 5% 5% 42%	3857
January	1st to 10th	Night	3 12% 4 10% 5% 5% 5% 3 6% 7% 39%	6632
	11th to 20th	Night	3 8% 3 15% 8% 6% 5% 4 5% 6% 36%	6266
	21st to end	Night	2 7% 3 7% 5% 4 4 4 6% 7% 50%	6468
February	1st to 10th	Night	5% 14% 6% 12% 6% 5% 5% 4 5% 7% 33%	2600
	11th to 20th	Night	3 16% 5% 11% 6% 4 4 4 6% 7% 34%	2532
	21st to end	Night	3 10% 4 10% 6% 5% 4 4 6% 6% 41%	2135
March	1st to 10th	Night	3 9% 4 9% 5% 5% 5% 4 5% 6% 46%	4968
	11th to 20th	Night	6% 10% 3 6% 4 4 4 3 6% 10% 42%	5000
	21st to end	Night	9% 14% 5% 11% 5% 4 5% 4 6% 8% 29%	5489
April	1st to 10th	Night	9% 11% 3 6% 5% 4 4 5% 7% 7% 40%	2012
	11th to 20th	Night	11% 13% 4 9% 6% 5% 4 3 7% 6% 33%	1890
	21st to end	Night	14% 11% 3 6% 5% 5% 5% 4 4 7% 36%	1800
May	1st to 10th	Night	14% 11% 3 6% 3 3 4 3 4 6% 42%	3926
	11th to 20th	Night	12% 7% 2 8% 5% 5% 6% 5% 6% 8% 35%	3617
	21st to end	Night	11% 6% 3 6% 4 4 5% 4 7% 10% 40%	3972
June	1st to 10th	Night	11% 7% 2 5% 4 4 7% 5% 8% 8% 39%	1584
	11th to 20th	Night	10% 7% 2 5% 5% 4 4 5% 7% 8% 44%	1400
	21st to end	Night	6% 3 1 5% 2 4 4 4 7% 8% 56%	1400
July	1st to 10th	Night	4 3 1 5% 4 4 5% 5% 7% 9% 52%	3180
	11th to 20th	Night	7% 3 1 4 4 4 5% 4 7% 7% 55%	3500
	21st to end	Night	6% 3 1 3 3 3 4 4 7% 10% 56%	4145
August	1st to 10th	Night	5% 3 1 4 3 4 5% 5% 7% 10% 52%	4033
	11th to 20th	Night	2 3 1 3 3 4 6% 4 7% 8% 58%	4051
	21st to end	Night	8% 4 2 4 3 3 3 3 5% 6% 59%	4675
September	1st to 10th	Night	7% 4 1 4 3 2 4 3 6% 6% 61%	2000
	11th to 20th	Night	9% 5% 2 5% 3 3 3 3 5% 7% 55%	2090
	21st to end	Night	12% 4 2 3 2 2 3 3 5% 6% 58%	2237
October	1st to 10th	Night	9% 5% 2 3 3 3 2 2 4 6% 62%	3920
	11th to 20th	Night	10% 8% 2 4 3 3 3 3 3 5% 56%	3898
	21st to end	Night	8% 8% 2 5% 3 3 3 3 4 6% 54%	4252
November	1st to 10th	Night	8% 9% 3 7% 4 4 4 4 5% 7% 46%	2825
	11th to 20th	Night	6% 8% 3 6% 4 3 5% 4 6% 7% 47%	2940
	21st to end	Night	4 9% 2 7% 4 4 5% 4 7% 8% 47%	2940
December	1st to 10th	Night	2 6% 3 8% 5% 5% 4 3 5% 7% 54%	4710
	11th to 20th	Night	3 6% 3 8% 6% 6% 5% 5% 6% 8% 45%	5321
	21st to end	Night	3 9% 3 8% 5% 5% 5% 4 6% 8% 44%	7329

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	44% 9% 12% 28% 7% 1	3320
	11th to 20th	Day	46% 8% 15% 16% 13% 2	3755
	21st to end	Day	28% 6% 16% 27% 21% 2	4510
February	1st to 10th	Day	47% 7% 15% 19% 10% 1	1800
	11th to 20th	Day	46% 7% 15% 19% 11% 2	1764
	21st to end	Day	41% 7% 13% 22% 15% 3	1495
March	1st to 10th	Day	33% 6% 12% 27% 18% 5%	4910
	11th to 20th	Day	36% 7% 15% 29% 12% 1	5000
	21st to end	Day	53% 11% 12% 20% 3 1	5486
April	1st to 10th	Day	44% 8% 14% 22% 11% 2	2387
	11th to 20th	Day	45% 7% 15% 24% 8% 1	2456
	21st to end	Day	48% 8% 13% 21% 9% 1	2600
May	1st to 10th	Day	43% 6% 9% 28% 13% 1	6054
	11th to 20th	Day	39% 9% 15% 25% 10% 1	6302
	21st to end	Day	36% 9% 14% 31% 10%	6926
June	1st to 10th	Day	36% 10% 18% 24% 11% 1	2810
	11th to 20th	Day	35% 11% 17% 20% 15% 3	3000
	21st to end	Day	22% 7% 14% 27% 22% 7%	3000
July	1st to 10th	Day	21% 6% 10% 27% 26% 10%	6706
	11th to 20th	Day	20% 5% 8% 23% 32% 14%	6381
	21st to end	Day	25% 7% 9% 19% 25% 14%	6530
August	1st to 10th	Day	30% 7% 10% 23% 19% 12%	4208
	11th to 20th	Day	23% 6% 8% 29% 28% 6%	4197
	21st to end	Day	21% 5% 8% 27% 29% 10%	4545
September	1st to 10th	Day	22% 5% 8% 21% 32% 11%	2400
	11th to 20th	Day	29% 6% 11% 25% 25% 5%	2308
	21st to end	Day	26% 4 10% 27% 25% 7%	2161
October	1st to 10th	Day	25% 4 7% 18% 32% 13%	3270
	11th to 20th	Day	28% 4 11% 30% 23% 5%	3250
	21st to end	Day	32% 5% 13% 32% 16% 2	3548
November	1st to 10th	Day	38% 6% 14% 24% 15% 4	1671
	11th to 20th	Day	33% 6% 18% 26% 14% 2	1680
	21st to end	Day	35% 5% 16% 26% 17% 2	1680
December	1st to 10th	Day	30% 5% 18% 27% 16% 4	2700
	11th to 20th	Day	31% 9% 24% 26% 9%	3104
	21st to end	Day	41% 5% 9% 24% 17% 5%	3857
January	1st to 10th	Night	42% 7% 13% 28% 10% 1	6632
	11th to 20th	Night	46% 6% 14% 21% 11% 2	6266
	21st to end	Night	30% 8% 15% 28% 16% 4	6468
February	1st to 10th	Night	48% 7% 14% 21% 9% 1	2600
	11th to 20th	Night	48% 7% 14% 18% 12% 1	2533
	21st to end	Night	40% 6% 14% 23% 13% 2	2135
March	1st to 10th	Night	36% 5% 11% 25% 18% 6%	4968
	11th to 20th	Night	33% 8% 16% 30% 12% 1	5000
	21st to end	Night	49% 10% 13% 19% 8% 1	5489
April	1st to 10th	Night	41% 7% 16% 22% 12% 2	2012
	11th to 20th	Night	47% 8% 13% 25% 7% 1	1890
	21st to end	Night	46% 9% 13% 23% 10%	1800
May	1st to 10th	Night	41% 6% 12% 24% 14% 2	3923
	11th to 20th	Night	41% 8% 15% 27% 7% 2	3618
	21st to end	Night	35% 8% 16% 33% 8%	3972
June	1st to 10th	Night	37% 10% 18% 23% 10% 2	1584
	11th to 20th	Night	34% 9% 16% 23% 15% 4	1400
	21st to end	Night	23% 7% 16% 27% 21% 6%	1400
July	1st to 10th	Night	25% 5% 11% 32% 23% 5%	3145
	11th to 20th	Night	24% 5% 7% 22% 30% 11%	3456
	21st to end	Night	22% 5% 13% 25% 25% 10%	4028
August	1st to 10th	Night	27% 6% 14% 23% 20% 10%	2928
	11th to 20th	Night	26% 5% 9% 30% 22% 8%	2928
	21st to end	Night	21% 4 7% 26% 31% 12%	3363
September	1st to 10th	Night	22% 5% 9% 23% 27% 14%	2000
	11th to 20th	Night	29% 6% 10% 27% 22% 7%	2090
	21st to end	Night	26% 5% 9% 27% 26% 7%	2237
October	1st to 10th	Night	25% 5% 7% 22% 30% 12%	3920
	11th to 20th	Night	32% 4 10% 28% 20% 6%	3898
	21st to end	Night	31% 4 9% 32% 17% 6%	4252
November	1st to 10th	Night	35% 6% 14% 26% 15% 4	2825
	11th to 20th	Night	32% 7% 16% 29% 14% 2	2940
	21st to end	Night	32% 6% 16% 28% 14% 3	2940
December	1st to 10th	Night	29% 6% 16% 32% 16% 2	4710
	11th to 20th	Night	34% 6% 18% 31% 9% 1	5322
	21st to end	Night	35% 6% 11% 29% 14% 4	7329

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	10% 14% 38% 29% 8%	230
	11th to 20th	Day	9% 15% 44% 23% 9%	300
	21st to end	Day	10% 14% 45% 24% 6% 2	330
February	1st to 10th	Day	14% 17% 51% 15% 3	300
	11th to 20th	Day	11% 18% 47% 20% 5% 1	300
	21st to end	Day	8% 17% 45% 24% 5%	249
March	1st to 10th	Day	11% 16% 42% 26% 4 1	480
	11th to 20th	Day	9% 17% 40% 28% 6% 1	500
	21st to end	Day	18% 19% 31% 24% 7% 1	550
April	1st to 10th	Day	17% 18% 34% 27% 3 1	500
	11th to 20th	Day	14% 22% 38% 22% 3 1	492
	21st to end	Day	22% 14% 31% 23% 8% 2	500
May	1st to 10th	Day	20% 12% 24% 27% 16% 2	573
	11th to 20th	Day	20% 7% 27% 26% 17% 3	725
	21st to end	Day	21% 7% 21% 26% 19% 5%	789
June	1st to 10th	Day	12% 5% 26% 32% 19% 6%	730
	11th to 20th	Day	11% 11% 32% 32% 13% 2	730
	21st to end	Day	7% 6% 27% 36% 22% 2	730
July	1st to 10th	Day	5% 5% 23% 39% 25% 3	721
	11th to 20th	Day	3 4 27% 41% 23% 3	718
	21st to end	Day	4 3 23% 41% 25% 5%	717
August	1st to 10th	Day	6% 5% 26% 38% 21% 4	527
	11th to 20th	Day	7% 3 27% 36% 23% 3	517
	21st to end	Day	5% 6% 25% 40% 20% 4	583
September	1st to 10th	Day	6% 7% 27% 36% 20% 4	530
	11th to 20th	Day	15% 5% 22% 38% 16% 5%	530
	21st to end	Day	13% 10% 25% 32% 17% 3	491
October	1st to 10th	Day	14% 7% 28% 32% 15% 4	330
	11th to 20th	Day	15% 10% 35% 25% 12% 2	330
	21st to end	Day	13% 16% 38% 21% 9% 2	363
November	1st to 10th	Day	15% 12% 39% 24% 8% 1	330
	11th to 20th	Day	10% 15% 44% 23% 7% 2	330
	21st to end	Day	10% 14% 42% 29% 6%	330
December	1st to 10th	Day	8% 14% 51% 22% 5%	330
	11th to 20th	Day	11% 12% 51% 22% 4	330
	21st to end	Day	12% 12% 45% 23% 7% 1	308
January	1st to 10th	Night	8% 7% 48% 32% 4	1006
	11th to 20th	Night	10% 12% 46% 27% 6%	965
	21st to end	Night	10% 8% 49% 28% 6%	880
February	1st to 10th	Night	10% 10% 45% 28% 7% 1	800
	11th to 20th	Night	10% 7% 45% 31% 6% 1	784
	21st to end	Night	8% 7% 45% 32% 7% 1	660
March	1st to 10th	Night	7% 6% 43% 34% 10% 1	800
	11th to 20th	Night	11% 4 35% 39% 10% 1	800
	21st to end	Night	16% 8% 28% 37% 10% 1	880
April	1st to 10th	Night	13% 8% 32% 39% 7%	612
	11th to 20th	Night	17% 8% 34% 33% 8%	593
	21st to end	Night	20% 7% 24% 36% 13% 1	600
May	1st to 10th	Night	20% 8% 22% 37% 14% 1	600
	11th to 20th	Night	19% 5% 21% 36% 19% 1	591
	21st to end	Night	20% 3 18% 39% 18% 2	650
June	1st to 10th	Night	13% 4 20% 41% 20% 2	584
	11th to 20th	Night	11% 4 24% 46% 15% 1	400
	21st to end	Night	7% 3 18% 51% 21% 1	400
July	1st to 10th	Night	7% 1 9% 51% 32% 1	390
	11th to 20th	Night	5% 3 15% 57% 19%	524
	21st to end	Night	4 1 15% 56% 22% 1	657
August	1st to 10th	Night	6% 2 14% 56% 22% 1	597
	11th to 20th	Night	5% 2 14% 56% 22% 2	594
	21st to end	Night	9% 2 15% 52% 20% 2	660
September	1st to 10th	Night	7% 3 19% 47% 22% 2	600
	11th to 20th	Night	11% 1 18% 49% 19% 2	690
	21st to end	Night	15% 4 18% 43% 19% 2	800
October	1st to 10th	Night	19% 4 21% 38% 15% 2	800
	11th to 20th	Night	17% 7% 30% 33% 12% 2	800
	21st to end	Night	11% 7% 35% 35% 10% 2	880
November	1st to 10th	Night	12% 7% 37% 36% 7% 1	990
	11th to 20th	Night	10% 8% 46% 31% 5%	1050
	21st to end	Night	9% 7% 46% 34% 4	1050
December	1st to 10th	Night	8% 8% 46% 32% 6%	1050
	11th to 20th	Night	8% 6% 50% 29% 5% 1	1050
	21st to end	Night	9% 8% 47% 30% 6%	1155

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