Sinnemahoning State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Sinnemahoning State Park 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	17% 11% 4 9% 5% 5% 4 4 5% 6% 29%	120319
	Night	17% 12% 4 10% 5% 4 4 3 5% 6% 29%	118758
Transparency	Day	52% 7% 11% 19% 10% 1	123955
	Night	53% 6% 12% 18% 10% 1	123282
Seeing	Day	26% 17% 26% 18% 10% 4	15574
	Night	24% 15% 24% 25% 11% 1	24992

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	13% 19% 9% 17% 6% 4 4 3 3 4 19%	3597
	11th to 20th	Day	10% 19% 10% 24% 7% 6% 3 3 3 3 13%	3962
	21st to end	Day	19% 16% 9% 11% 6% 4 4 3 4 5% 21%	4466
February	1st to 10th	Day	16% 16% 6% 12% 7% 5% 5% 4 4 4 22%	1800
	11th to 20th	Day	15% 14% 7% 13% 6% 4 4 3 5% 6% 24%	1753
	21st to end	Day	20% 13% 4 11% 6% 3 3 2 5% 5% 27%	1612
March	1st to 10th	Day	18% 14% 5% 8% 5% 3 2 2 4 5% 32%	4903
	11th to 20th	Day	13% 12% 5% 9% 6% 4 3 3 4 6% 35%	4980
	21st to end	Day	14% 11% 4 10% 6% 5% 5% 4 4 5% 32%	5500
April	1st to 10th	Day	18% 15% 3 9% 4 4 4 3 4 6% 30%	2400
	11th to 20th	Day	18% 12% 3 8% 4 4 4 4 5% 5% 33%	2374
	21st to end	Day	20% 9% 3 7% 5% 4 4 3 4 6% 35%	2508
May	1st to 10th	Day	26% 8% 3 9% 5% 5% 5% 4 5% 5% 26%	5888
	11th to 20th	Day	25% 10% 3 8% 5% 4 4 4 5% 7% 26%	6269
	21st to end	Day	19% 7% 2 7% 5% 5% 5% 5% 6% 7% 30%	6949
June	1st to 10th	Day	15% 8% 3 7% 5% 5% 5% 4 6% 8% 34%	2800
	11th to 20th	Day	16% 7% 3 8% 6% 5% 5% 4 5% 8% 33%	2800
	21st to end	Day	14% 6% 2 6% 5% 6% 5% 4 7% 9% 36%	2800
July	1st to 10th	Day	9% 7% 3 7% 6% 5% 6% 5% 7% 10% 36%	4580
	11th to 20th	Day	9% 7% 3 8% 6% 6% 6% 6% 6% 9% 35%	4580
	21st to end	Day	10% 7% 3 6% 5% 6% 6% 5% 7% 8% 35%	4468
August	1st to 10th	Day	20% 8% 3 7% 5% 5% 5% 5% 6% 8% 30%	4104
	11th to 20th	Day	14% 7% 3 8% 6% 7% 6% 5% 8% 8% 28%	4028
	21st to end	Day	15% 7% 2 6% 4 5% 6% 4 7% 10% 35%	4180
September	1st to 10th	Day	18% 7% 3 6% 4 4 4 3 5% 6% 40%	2280
	11th to 20th	Day	14% 7% 2 7% 4 3 4 3 6% 6% 44%	2257
	21st to end	Day	23% 8% 2 6% 4 5% 4 3 4 7% 34%	1995
October	1st to 10th	Day	17% 10% 3 6% 4 4 4 3 6% 8% 34%	1900
	11th to 20th	Day	21% 9% 3 7% 5% 4 4 3 6% 5% 33%	1900
	21st to end	Day	21% 11% 3 7% 4 5% 4 4 5% 6% 30%	2090
November	1st to 10th	Day	13% 8% 3 7% 5% 4 4 3 6% 6% 39%	1828
	11th to 20th	Day	17% 16% 4 9% 5% 4 4 4 6% 6% 27%	1622
	21st to end	Day	19% 18% 4 9% 5% 4 4 3 5% 6% 23%	1600
December	1st to 10th	Day	17% 20% 9% 17% 6% 4 4 2 3 4 14%	2600
	11th to 20th	Day	22% 18% 5% 8% 4 4 3 2 4 5% 24%	2986
	21st to end	Day	23% 20% 6% 12% 5% 4 3 3 4 5% 15%	3960
January	1st to 10th	Night	13% 16% 6% 20% 8% 5% 4 3 4 5% 16%	6349
	11th to 20th	Night	12% 16% 7% 20% 8% 5% 5% 4 5% 6% 13%	5905
	21st to end	Night	18% 15% 6% 15% 6% 7% 5% 3 3 4 18%	6490
February	1st to 10th	Night	15% 16% 6% 11% 6% 5% 4 3 5% 5% 24%	2600
	11th to 20th	Night	16% 13% 5% 12% 6% 5% 4 4 5% 7% 23%	2533
	21st to end	Night	18% 13% 4 12% 6% 4 4 4 3 6% 26%	2016
March	1st to 10th	Night	18% 13% 5% 9% 7% 5% 4 3 4 5% 28%	4922
	11th to 20th	Night	14% 13% 5% 8% 4 4 3 3 5% 6% 36%	4979
	21st to end	Night	15% 11% 4 9% 5% 4 4 3 4 5% 35%	5430
April	1st to 10th	Night	20% 14% 3 8% 5% 4 4 3 4 6% 29%	2000
	11th to 20th	Night	18% 11% 3 6% 5% 4 4 3 5% 7% 35%	1975
	21st to end	Night	18% 9% 4 7% 4 4 3 4 5% 7% 36%	1910
May	1st to 10th	Night	30% 10% 3 7% 4 4 4 3 4 5% 27%	4053
	11th to 20th	Night	25% 10% 3 8% 4 4 4 3 5% 5% 30%	3621
	21st to end	Night	20% 8% 3 8% 5% 5% 4 4 5% 7% 30%	3926
June	1st to 10th	Night	14% 7% 2 6% 5% 4 4 3 7% 7% 41%	1600
	11th to 20th	Night	13% 7% 3 6% 5% 4 5% 5% 6% 9% 39%	1600
	21st to end	Night	13% 5% 3 6% 4 4 5% 4 6% 10% 40%	1600
July	1st to 10th	Night	12% 6% 4 7% 5% 5% 5% 4 6% 7% 39%	2600
	11th to 20th	Night	8% 6% 3 6% 5% 4 5% 4 7% 9% 42%	2600
	21st to end	Night	12% 6% 3 7% 5% 4 5% 3 6% 7% 41%	3080
August	1st to 10th	Night	19% 6% 2 7% 4 5% 4 4 5% 7% 36%	2825
	11th to 20th	Night	18% 7% 2 6% 4 4 4 4 5% 6% 39%	2785
	21st to end	Night	14% 5% 2 5% 4 4 4 4 6% 7% 44%	3459
September	1st to 10th	Night	16% 6% 2 5% 4 5% 4 2 4 6% 45%	1900
	11th to 20th	Night	13% 6% 2 6% 3 4 3 3 4 7% 50%	1919
	21st to end	Night	21% 7% 3 7% 4 4 4 3 4 6% 36%	2185
October	1st to 10th	Night	18% 7% 2 7% 4 3 3 3 5% 7% 40%	2280
	11th to 20th	Night	19% 9% 2 6% 4 4 4 3 5% 7% 36%	2280
	21st to end	Night	23% 11% 3 7% 3 4 3 3 5% 7% 32%	2508
November	1st to 10th	Night	12% 9% 2 6% 5% 4 4 3 5% 6% 43%	2469
	11th to 20th	Night	17% 14% 4 8% 6% 5% 4 4 4 7% 28%	2775
	21st to end	Night	17% 15% 5% 10% 5% 4 4 4 6% 6% 24%	2800
December	1st to 10th	Night	15% 16% 8% 16% 7% 5% 4 4 6% 5% 15%	4580
	11th to 20th	Night	21% 14% 6% 11% 4 4 4 3 4 5% 24%	5208
	21st to end	Night	22% 17% 6% 12% 5% 4 4 4 4 5% 16%	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	67% 5% 10% 11% 6% 1	3598
	11th to 20th	Day	76% 4 6% 9% 4 1	3996
	21st to end	Day	65% 5% 9% 14% 6% 1	4466
February	1st to 10th	Day	65% 4 10% 13% 7%	1800
	11th to 20th	Day	60% 4 9% 18% 8%	1762
	21st to end	Day	60% 4 9% 18% 7% 2	1612
March	1st to 10th	Day	53% 4 12% 20% 9% 2	4906
	11th to 20th	Day	50% 5% 16% 18% 8% 3	4980
	21st to end	Day	51% 6% 9% 17% 14% 2	5500
April	1st to 10th	Day	55% 5% 9% 18% 11% 2	2400
	11th to 20th	Day	51% 7% 10% 17% 14% 2	2374
	21st to end	Day	50% 6% 8% 20% 13% 3	2508
May	1st to 10th	Day	58% 7% 9% 16% 9% 2	5897
	11th to 20th	Day	56% 7% 9% 18% 8% 1	6273
	21st to end	Day	48% 9% 12% 20% 10% 1	6949
June	1st to 10th	Day	46% 9% 11% 20% 13% 1	2800
	11th to 20th	Day	47% 8% 14% 19% 12% 1	2800
	21st to end	Day	41% 8% 14% 24% 12%	2800
July	1st to 10th	Day	40% 9% 14% 24% 11% 1	4510
	11th to 20th	Day	41% 9% 14% 22% 13%	4505
	21st to end	Day	41% 9% 13% 25% 12% 1	4325
August	1st to 10th	Day	50% 9% 13% 20% 9%	4091
	11th to 20th	Day	47% 9% 14% 23% 7%	4067
	21st to end	Day	40% 8% 14% 27% 11% 1	4180
September	1st to 10th	Day	44% 5% 10% 24% 15% 2	2280
	11th to 20th	Day	39% 7% 11% 25% 18% 1	2257
	21st to end	Day	50% 5% 12% 19% 14% 1	1995
October	1st to 10th	Day	42% 7% 12% 21% 16% 3	3160
	11th to 20th	Day	43% 6% 11% 22% 16% 2	3140
	21st to end	Day	37% 6% 16% 27% 13% 1	3428
November	1st to 10th	Day	44% 6% 12% 20% 15% 3	1828
	11th to 20th	Day	56% 6% 11% 18% 7% 2	1622
	21st to end	Day	61% 6% 11% 16% 6% 1	1600
December	1st to 10th	Day	74% 4 8% 10% 3	2600
	11th to 20th	Day	64% 4 11% 15% 6%	2986
	21st to end	Day	71% 5% 10% 9% 4 1	3960
January	1st to 10th	Night	67% 7% 9% 13% 5%	6349
	11th to 20th	Night	67% 7% 12% 9% 4 1	5946
	21st to end	Night	68% 5% 8% 11% 7% 1	6490
February	1st to 10th	Night	60% 5% 12% 16% 7%	2600
	11th to 20th	Night	58% 5% 12% 17% 8%	2535
	21st to end	Night	59% 4 10% 16% 10% 1	2016
March	1st to 10th	Night	56% 5% 12% 17% 8% 1	4932
	11th to 20th	Night	47% 6% 17% 20% 7% 4	4980
	21st to end	Night	49% 5% 9% 18% 17% 2	5430
April	1st to 10th	Night	56% 5% 8% 18% 12% 1	2000
	11th to 20th	Night	49% 6% 12% 19% 13% 2	1975
	21st to end	Night	47% 6% 10% 21% 14% 2	1910
May	1st to 10th	Night	60% 5% 8% 15% 8% 3	4060
	11th to 20th	Night	54% 8% 11% 16% 11% 1	3622
	21st to end	Night	48% 9% 12% 17% 11% 3	3927
June	1st to 10th	Night	41% 7% 12% 24% 15% 1	1600
	11th to 20th	Night	40% 9% 13% 24% 13% 2	1600
	21st to end	Night	38% 8% 13% 26% 14%	1600
July	1st to 10th	Night	41% 8% 13% 22% 16% 1	2560
	11th to 20th	Night	35% 9% 17% 23% 15% 1	2552
	21st to end	Night	40% 8% 13% 21% 18% 1	2982
August	1st to 10th	Night	45% 9% 14% 23% 9%	2814
	11th to 20th	Night	43% 7% 12% 27% 10%	2812
	21st to end	Night	36% 8% 12% 32% 10% 2	3459
September	1st to 10th	Night	40% 6% 9% 25% 16% 3	1900
	11th to 20th	Night	34% 5% 13% 27% 19% 2	1919
	21st to end	Night	47% 6% 12% 20% 14% 1	2185
October	1st to 10th	Night	42% 6% 11% 21% 19% 1	3800
	11th to 20th	Night	38% 6% 13% 22% 17% 5%	3779
	21st to end	Night	38% 4 17% 24% 15% 1	4120
November	1st to 10th	Night	40% 6% 13% 23% 15% 2	2469
	11th to 20th	Night	55% 4 12% 17% 9% 2	2775
	21st to end	Night	56% 6% 13% 18% 5% 1	2800
December	1st to 10th	Night	65% 8% 12% 11% 3	4580
	11th to 20th	Night	63% 5% 12% 16% 4	5208
	21st to end	Night	68% 6% 9% 12% 4	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	35% 25% 30% 6% 5%	200
	11th to 20th	Day	41% 25% 25% 7% 1	287
	21st to end	Day	35% 25% 29% 9% 2	330
February	1st to 10th	Day	35% 30% 26% 8% 1	300
	11th to 20th	Day	44% 25% 26% 4 1	300
	21st to end	Day	41% 22% 26% 9% 2	376
March	1st to 10th	Day	34% 21% 28% 13% 4	500
	11th to 20th	Day	33% 24% 26% 13% 3 1	500
	21st to end	Day	34% 24% 25% 12% 4 1	550
April	1st to 10th	Day	34% 24% 23% 13% 4 1	500
	11th to 20th	Day	32% 23% 22% 14% 6% 3	492
	21st to end	Day	29% 19% 30% 13% 7% 2	500
May	1st to 10th	Day	31% 19% 26% 13% 8% 3	503
	11th to 20th	Day	28% 16% 28% 17% 8% 4	527
	21st to end	Day	23% 12% 26% 21% 14% 4	573
June	1st to 10th	Day	19% 18% 27% 22% 12% 2	530
	11th to 20th	Day	21% 14% 25% 23% 12% 3	530
	21st to end	Day	18% 13% 30% 26% 11% 2	530
July	1st to 10th	Day	14% 10% 26% 26% 17% 7%	525
	11th to 20th	Day	11% 10% 29% 25% 19% 6%	524
	21st to end	Day	14% 10% 28% 27% 16% 5%	532
August	1st to 10th	Day	13% 8% 24% 27% 20% 7%	486
	11th to 20th	Day	15% 10% 24% 25% 15% 10%	479
	21st to end	Day	16% 9% 27% 22% 16% 10%	539
September	1st to 10th	Day	21% 13% 19% 23% 16% 9%	490
	11th to 20th	Day	15% 6% 24% 22% 22% 10%	490
	21st to end	Day	29% 12% 22% 18% 14% 5%	490
October	1st to 10th	Day	23% 13% 22% 19% 17% 5%	490
	11th to 20th	Day	28% 16% 27% 18% 8% 3	490
	21st to end	Day	30% 19% 26% 18% 7% 1	539
November	1st to 10th	Day	24% 18% 25% 19% 13% 2	430
	11th to 20th	Day	32% 25% 25% 13% 5%	222
	21st to end	Day	38% 21% 33% 6% 3	200
December	1st to 10th	Day	37% 29% 24% 7% 4 1	200
	11th to 20th	Day	43% 16% 28% 13% 2	200
	21st to end	Day	41% 18% 28% 10% 3	220
January	1st to 10th	Night	30% 25% 28% 14% 3	800
	11th to 20th	Night	30% 23% 28% 17% 3	800
	21st to end	Night	28% 24% 28% 17% 2	880
February	1st to 10th	Night	31% 20% 29% 19% 2	800
	11th to 20th	Night	32% 24% 29% 13% 1	783
	21st to end	Night	31% 21% 28% 18% 2	660
March	1st to 10th	Night	27% 22% 29% 20% 2	800
	11th to 20th	Night	30% 20% 25% 20% 5% 1	800
	21st to end	Night	23% 22% 31% 19% 5% 1	880
April	1st to 10th	Night	30% 18% 26% 21% 4	800
	11th to 20th	Night	27% 16% 27% 23% 7% 1	791
	21st to end	Night	24% 15% 24% 30% 7%	710
May	1st to 10th	Night	25% 10% 21% 30% 14% 1	600
	11th to 20th	Night	20% 11% 25% 36% 8%	414
	21st to end	Night	14% 9% 22% 31% 21% 1	433
June	1st to 10th	Night	15% 7% 22% 39% 16% 1	400
	11th to 20th	Night	15% 10% 18% 42% 15% 1	400
	21st to end	Night	14% 4 25% 41% 17%	400
July	1st to 10th	Night	14% 6% 16% 37% 24% 4	390
	11th to 20th	Night	8% 3 17% 41% 28% 1	388
	21st to end	Night	11% 4 18% 41% 24% 2	617
August	1st to 10th	Night	12% 3 16% 40% 27% 2	567
	11th to 20th	Night	16% 5% 11% 36% 28% 4	564
	21st to end	Night	13% 5% 19% 31% 29% 3	819
September	1st to 10th	Night	18% 6% 18% 32% 23% 3	760
	11th to 20th	Night	16% 6% 18% 27% 29% 6%	760
	21st to end	Night	23% 11% 18% 26% 18% 4	760
October	1st to 10th	Night	22% 9% 19% 26% 20% 3	760
	11th to 20th	Night	24% 14% 25% 26% 11% 1	760
	21st to end	Night	28% 14% 23% 28% 6%	836
November	1st to 10th	Night	20% 14% 26% 30% 10%	780
	11th to 20th	Night	28% 17% 26% 21% 7% 1	800
	21st to end	Night	28% 18% 28% 21% 5% 1	800
December	1st to 10th	Night	32% 22% 28% 14% 5%	800
	11th to 20th	Night	29% 20% 27% 21% 3	800
	21st to end	Night	30% 20% 27% 21% 2	880

Page generated at 2025-07-18 01:10:04. Version ac07

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