Cuyahoga Valley National Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cuyahoga Valley National Park clear sky chart from 2005-11-06 to 2025-01-22.

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% 11% 4 9% 5% 4 4 4 5% 7% 30%	104810
	Night	17% 12% 4 9% 5% 4 4 3 5% 6% 30%	104472
Transparency	Day	54% 2 10% 21% 11% 1	108487
	Night	55% 2 10% 21% 11% 1	108934
Seeing	Day	23% 14% 28% 20% 11% 4	14809
	Night	22% 11% 27% 27% 12% 1	24758

By Month

Percentage Cloud Cover SE (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	18% 23% 9% 16% 5% 4 3 2 3 4 14%	2926
	11th to 20th	Day	15% 25% 7% 12% 7% 6% 4 2 4 4 13%	2930
	21st to end	Day	27% 21% 11% 12% 6% 4 3 3 2 3 8%	3133
February	1st to 10th	Day	17% 20% 6% 11% 8% 4 3 3 4 5% 20%	1710
	11th to 20th	Day	15% 14% 7% 14% 8% 5% 4 3 4 4 21%	1720
	21st to end	Day	18% 15% 4 13% 7% 4 4 3 5% 5% 23%	1570
March	1st to 10th	Day	22% 13% 6% 9% 5% 4 3 2 5% 6% 25%	3361
	11th to 20th	Day	13% 15% 5% 10% 5% 5% 3 3 4 5% 33%	3480
	21st to end	Day	21% 12% 5% 8% 5% 4 4 3 4 5% 29%	3815
April	1st to 10th	Day	15% 15% 4 7% 5% 4 4 3 5% 7% 30%	2125
	11th to 20th	Day	19% 11% 3 7% 5% 4 5% 3 4 6% 32%	2413
	21st to end	Day	20% 11% 3 7% 6% 3 4 3 4 6% 32%	2470
May	1st to 10th	Day	21% 9% 3 8% 5% 4 5% 4 5% 7% 30%	4082
	11th to 20th	Day	20% 9% 2 6% 4 4 4 4 6% 8% 33%	4081
	21st to end	Day	12% 6% 3 7% 4 5% 5% 4 7% 9% 39%	4507
June	1st to 10th	Day	14% 7% 2 7% 5% 5% 4 4 7% 8% 36%	2660
	11th to 20th	Day	14% 6% 2 7% 6% 4 5% 4 7% 8% 38%	2660
	21st to end	Day	12% 5% 2 6% 5% 5% 5% 5% 7% 10% 38%	2634
July	1st to 10th	Day	9% 7% 3 7% 5% 5% 6% 5% 7% 10% 38%	4120
	11th to 20th	Day	9% 5% 2 6% 5% 5% 5% 4 7% 10% 42%	4120
	21st to end	Day	11% 6% 3 7% 5% 5% 6% 5% 6% 8% 38%	4466
August	1st to 10th	Day	13% 8% 3 8% 5% 5% 5% 5% 6% 8% 34%	4104
	11th to 20th	Day	11% 7% 2 7% 4 5% 6% 5% 8% 10% 35%	4044
	21st to end	Day	9% 5% 2 6% 5% 5% 6% 5% 7% 9% 39%	4450
September	1st to 10th	Day	14% 6% 2 6% 4 5% 5% 3 5% 8% 43%	2176
	11th to 20th	Day	11% 6% 2 7% 5% 4 5% 4 5% 8% 43%	2090
	21st to end	Day	21% 8% 3 6% 4 4 4 2 4 6% 38%	2090
October	1st to 10th	Day	16% 6% 2 7% 4 4 5% 3 6% 7% 39%	1966
	11th to 20th	Day	20% 9% 3 8% 4 5% 3 4 4 6% 34%	1900
	21st to end	Day	23% 10% 3 9% 5% 4 5% 3 5% 6% 28%	2085
November	1st to 10th	Day	13% 11% 4 7% 5% 5% 4 4 5% 6% 38%	1762
	11th to 20th	Day	19% 16% 4 7% 5% 4 4 3 5% 5% 28%	1780
	21st to end	Day	19% 18% 6% 10% 5% 5% 5% 3 5% 6% 18%	1600
December	1st to 10th	Day	18% 16% 8% 15% 7% 4 4 3 4 4 18%	2600
	11th to 20th	Day	23% 21% 7% 11% 5% 3 3 2 3 5% 16%	2990
	21st to end	Day	26% 23% 7% 13% 6% 4 3 2 3 4 9%	4190
January	1st to 10th	Night	16% 23% 10% 15% 6% 4 3 2 4 4 14%	4239
	11th to 20th	Night	16% 21% 9% 18% 6% 4 6% 4 3 3 11%	4250
	21st to end	Night	27% 20% 7% 13% 5% 3 3 1 3 3 13%	4546
February	1st to 10th	Night	21% 16% 6% 11% 6% 4 3 3 4 5% 21%	2470
	11th to 20th	Night	16% 15% 6% 12% 6% 6% 5% 4 4 4 22%	2345
	21st to end	Night	20% 14% 4 12% 5% 5% 3 3 4 5% 24%	1884
March	1st to 10th	Night	23% 14% 4 7% 3 3 3 2 3 5% 33%	3492
	11th to 20th	Night	16% 11% 4 7% 4 4 5% 4 5% 5% 34%	3480
	21st to end	Night	18% 12% 4 7% 4 4 4 3 5% 5% 33%	3817
April	1st to 10th	Night	17% 14% 3 6% 6% 5% 4 4 5% 6% 31%	2054
	11th to 20th	Night	16% 10% 3 8% 5% 4 5% 4 5% 6% 34%	1733
	21st to end	Night	15% 9% 2 7% 4 5% 5% 4 5% 6% 36%	1710
May	1st to 10th	Night	24% 9% 3 7% 5% 4 4 3 5% 6% 28%	2813
	11th to 20th	Night	17% 9% 2 6% 4 4 4 3 5% 8% 38%	2812
	21st to end	Night	11% 5% 2 4 3 3 4 4 7% 10% 45%	3030
June	1st to 10th	Night	10% 7% 2 6% 5% 5% 4 5% 6% 7% 42%	1520
	11th to 20th	Night	10% 4 2 6% 6% 6% 5% 4 8% 8% 41%	1520
	21st to end	Night	11% 5% 2 5% 4 4 5% 4 8% 10% 41%	1540
July	1st to 10th	Night	10% 6% 2 6% 4 4 4 4 5% 8% 46%	2840
	11th to 20th	Night	9% 5% 2 5% 4 4 5% 4 6% 9% 47%	2840
	21st to end	Night	8% 6% 2 6% 5% 5% 5% 4 6% 9% 45%	3087
August	1st to 10th	Night	11% 7% 3 8% 6% 5% 5% 4 5% 8% 39%	2825
	11th to 20th	Night	14% 8% 3 8% 4 4 3 3 4 7% 42%	2785
	21st to end	Night	8% 5% 2 8% 5% 5% 6% 5% 6% 8% 43%	3172
September	1st to 10th	Night	12% 5% 2 5% 5% 4 5% 4 5% 6% 47%	2000
	11th to 20th	Night	10% 5% 1 5% 4 4 4 3 4 8% 53%	2090
	21st to end	Night	17% 7% 2 7% 5% 4 3 4 5% 7% 39%	2090
October	1st to 10th	Night	13% 6% 2 6% 4 3 5% 3 6% 8% 44%	2213
	11th to 20th	Night	21% 7% 3 8% 5% 4 5% 3 5% 6% 34%	2280
	21st to end	Night	23% 11% 2 7% 4 4 4 3 6% 6% 30%	2510
November	1st to 10th	Night	15% 9% 3 6% 4 4 4 4 5% 5% 40%	2536
	11th to 20th	Night	17% 16% 4 8% 5% 5% 4 3 5% 6% 28%	2616
	21st to end	Night	21% 16% 4 8% 5% 5% 4 4 5% 6% 23%	2800
December	1st to 10th	Night	16% 16% 7% 12% 6% 5% 4 3 5% 6% 20%	4580
	11th to 20th	Night	20% 21% 8% 12% 5% 4 3 3 4 4 18%	5205
	21st to end	Night	25% 21% 7% 12% 5% 4 4 3 4 4 13%	6748

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	76% 2 9% 10% 3	2927
	11th to 20th	Day	77% 1 8% 9% 4	2930
	21st to end	Day	84% 2 6% 6% 2	3133
February	1st to 10th	Day	68% 2 9% 14% 6% 1	1710
	11th to 20th	Day	68% 3 7% 15% 7% 1	1729
	21st to end	Day	65% 2 10% 15% 7% 1	1570
March	1st to 10th	Day	63% 2 8% 23% 5%	3361
	11th to 20th	Day	56% 2 11% 23% 8% 1	3480
	21st to end	Day	59% 1 8% 18% 12% 1	3815
April	1st to 10th	Day	55% 2 10% 19% 12% 1	2125
	11th to 20th	Day	54% 2 11% 18% 13% 2	2413
	21st to end	Day	55% 2 9% 21% 11% 2	2470
May	1st to 10th	Day	56% 2 9% 23% 10% 1	4120
	11th to 20th	Day	51% 2 11% 24% 10% 1	4085
	21st to end	Day	43% 2 12% 22% 16% 5%	4521
June	1st to 10th	Day	45% 3 10% 26% 14% 1	2660
	11th to 20th	Day	44% 3 13% 23% 15% 1	2660
	21st to end	Day	39% 5% 12% 25% 17% 2	2634
July	1st to 10th	Day	42% 3 11% 25% 16% 3	4055
	11th to 20th	Day	37% 3 11% 28% 19% 2	4051
	21st to end	Day	43% 3 13% 19% 20% 2	4324
August	1st to 10th	Day	48% 3 12% 25% 12%	4091
	11th to 20th	Day	43% 3 11% 31% 11% 1	4083
	21st to end	Day	40% 3 13% 31% 11% 2	4450
September	1st to 10th	Day	41% 4 12% 23% 18% 3	2176
	11th to 20th	Day	40% 3 12% 26% 17% 2	2090
	21st to end	Day	49% 2 8% 24% 16% 1	2090
October	1st to 10th	Day	34% 3 12% 31% 19% 1	3265
	11th to 20th	Day	48% 2 10% 21% 15% 4	3140
	21st to end	Day	44% 2 12% 26% 16%	3411
November	1st to 10th	Day	48% 3 8% 25% 15% 1	1762
	11th to 20th	Day	59% 2 9% 19% 9% 2	1780
	21st to end	Day	68% 2 9% 15% 6%	1600
December	1st to 10th	Day	71% 2 11% 13% 2	2600
	11th to 20th	Day	74% 1 8% 14% 3	2986
	21st to end	Day	82% 1 7% 9% 2	4190
January	1st to 10th	Night	76% 1 7% 12% 4	4239
	11th to 20th	Night	81% 2 6% 9% 2	4250
	21st to end	Night	79% 1 6% 10% 3	4546
February	1st to 10th	Night	67% 2 9% 15% 6%	2470
	11th to 20th	Night	65% 3 7% 17% 7%	2347
	21st to end	Night	65% 2 8% 14% 9% 2	1884
March	1st to 10th	Night	57% 1 9% 23% 9%	3492
	11th to 20th	Night	52% 2 14% 20% 11% 1	3480
	21st to end	Night	54% 1 6% 25% 11% 1	3817
April	1st to 10th	Night	54% 3 9% 18% 14% 1	2054
	11th to 20th	Night	50% 3 11% 17% 15% 3	1733
	21st to end	Night	48% 2 10% 21% 16% 3	1710
May	1st to 10th	Night	58% 2 8% 21% 10% 2	2840
	11th to 20th	Night	47% 2 11% 25% 12% 2	2813
	21st to end	Night	35% 3 14% 28% 17% 3	3037
June	1st to 10th	Night	41% 4 10% 27% 16% 3	1520
	11th to 20th	Night	39% 3 14% 22% 18% 3	1520
	21st to end	Night	37% 5% 12% 26% 17% 2	1540
July	1st to 10th	Night	39% 2 11% 26% 18% 5%	2795
	11th to 20th	Night	35% 3 12% 31% 19% 2	2786
	21st to end	Night	38% 3 13% 20% 25% 2	2988
August	1st to 10th	Night	44% 3 11% 26% 14% 1	2814
	11th to 20th	Night	43% 3 10% 30% 13% 1	2812
	21st to end	Night	39% 3 12% 30% 15% 2	3172
September	1st to 10th	Night	37% 3 10% 28% 18% 4	2000
	11th to 20th	Night	32% 3 12% 28% 23% 2	2090
	21st to end	Night	45% 3 11% 22% 19% 1	2090
October	1st to 10th	Night	33% 3 9% 31% 24% 1	3694
	11th to 20th	Night	47% 1 9% 22% 18% 2	3779
	21st to end	Night	42% 2 9% 29% 16% 1	4134
November	1st to 10th	Night	45% 2 11% 24% 15% 3	2536
	11th to 20th	Night	59% 2 8% 18% 10% 3	2616
	21st to end	Night	63% 2 11% 18% 6%	2800
December	1st to 10th	Night	66% 3 10% 17% 4	4580
	11th to 20th	Night	72% 1 9% 15% 2	5208
	21st to end	Night	77% 2 9% 11% 1	6748

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	32% 23% 31% 9% 3 1	300
	11th to 20th	Day	30% 26% 34% 8% 3	300
	21st to end	Day	32% 29% 27% 10% 2	300
February	1st to 10th	Day	34% 23% 33% 9% 1	270
	11th to 20th	Day	29% 29% 33% 7% 1	270
	21st to end	Day	35% 28% 31% 6%	225
March	1st to 10th	Day	28% 21% 31% 16% 4	408
	11th to 20th	Day	31% 16% 33% 14% 5% 1	460
	21st to end	Day	32% 20% 27% 16% 5%	506
April	1st to 10th	Day	26% 22% 29% 15% 7% 1	460
	11th to 20th	Day	29% 19% 26% 15% 8% 3	452
	21st to end	Day	26% 18% 31% 17% 6% 2	460
May	1st to 10th	Day	29% 15% 30% 17% 8% 2	463
	11th to 20th	Day	24% 12% 32% 20% 8% 4	487
	21st to end	Day	17% 10% 28% 24% 17% 4	529
June	1st to 10th	Day	18% 10% 32% 26% 10% 3	490
	11th to 20th	Day	18% 9% 25% 32% 12% 4	490
	21st to end	Day	16% 9% 33% 26% 11% 5%	490
July	1st to 10th	Day	12% 4 24% 29% 22% 8%	485
	11th to 20th	Day	14% 5% 27% 28% 19% 7%	484
	21st to end	Day	13% 5% 25% 29% 20% 8%	532
August	1st to 10th	Day	16% 5% 21% 29% 21% 9%	486
	11th to 20th	Day	17% 6% 24% 25% 18% 9%	479
	21st to end	Day	11% 5% 22% 30% 21% 11%	539
September	1st to 10th	Day	18% 6% 21% 28% 20% 9%	490
	11th to 20th	Day	12% 3 19% 29% 27% 10%	490
	21st to end	Day	27% 8% 23% 23% 15% 5%	490
October	1st to 10th	Day	16% 8% 30% 25% 17% 4	490
	11th to 20th	Day	24% 16% 33% 17% 8% 2	490
	21st to end	Day	32% 15% 29% 19% 4	534
November	1st to 10th	Day	22% 21% 33% 13% 10% 1	300
	11th to 20th	Day	35% 20% 26% 15% 3 1	290
	21st to end	Day	28% 23% 40% 9% 1	200
December	1st to 10th	Day	30% 21% 35% 11% 3 2	200
	11th to 20th	Day	30% 26% 31% 11% 3	200
	21st to end	Day	35% 21% 31% 11% 1	270
January	1st to 10th	Night	29% 20% 33% 15% 4	800
	11th to 20th	Night	35% 19% 28% 15% 3	800
	21st to end	Night	28% 20% 29% 20% 3	841
February	1st to 10th	Night	30% 17% 31% 19% 3	760
	11th to 20th	Night	26% 21% 31% 19% 3	743
	21st to end	Night	29% 20% 33% 15% 2	628
March	1st to 10th	Night	25% 15% 34% 21% 5%	760
	11th to 20th	Night	24% 17% 30% 23% 6% 1	760
	21st to end	Night	25% 13% 32% 23% 7% 1	836
April	1st to 10th	Night	25% 14% 32% 24% 5% 1	760
	11th to 20th	Night	25% 11% 33% 20% 9% 1	609
	21st to end	Night	20% 11% 35% 28% 7% 1	570
May	1st to 10th	Night	22% 9% 27% 32% 9% 1	570
	11th to 20th	Night	21% 6% 25% 36% 11% 1	561
	21st to end	Night	13% 3 25% 37% 20% 2	593
June	1st to 10th	Night	13% 4 32% 36% 15% 1	380
	11th to 20th	Night	12% 4 26% 44% 13%	380
	21st to end	Night	13% 5% 26% 38% 18% 1	400
July	1st to 10th	Night	11% 1 15% 42% 27% 3	555
	11th to 20th	Night	11% 2 20% 39% 25% 4	552
	21st to end	Night	10% 3 15% 44% 26% 2	624
August	1st to 10th	Night	11% 2 15% 42% 27% 3	567
	11th to 20th	Night	15% 1 13% 39% 29% 3	564
	21st to end	Night	11% 1 18% 35% 31% 3	649
September	1st to 10th	Night	14% 4 18% 32% 26% 4	760
	11th to 20th	Night	11% 2 17% 36% 30% 4	760
	21st to end	Night	20% 7% 22% 29% 18% 4	760
October	1st to 10th	Night	16% 7% 24% 30% 20% 2	760
	11th to 20th	Night	25% 10% 27% 26% 9% 2	760
	21st to end	Night	27% 12% 29% 25% 7%	836
November	1st to 10th	Night	21% 13% 29% 26% 11% 1	780
	11th to 20th	Night	28% 17% 29% 19% 7% 1	800
	21st to end	Night	31% 16% 30% 16% 6%	800
December	1st to 10th	Night	33% 17% 30% 16% 5%	800
	11th to 20th	Night	28% 19% 32% 18% 3	800
	21st to end	Night	32% 16% 30% 20% 2	880

Page generated at 2025-01-19 03:06:43. Version ac07

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