Sky Meadows State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Sky Meadows State Park clear sky chart from 2005-11-06 to 2025-09-04.

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% 6% 2 6% 5% 4 5% 4 6% 8% 41%	125971
	Night	14% 6% 2 6% 4 4 4 4 6% 7% 43%	122744
Transparency	Day	39% 6% 12% 23% 16% 4	129570
	Night	38% 6% 12% 24% 17% 4	127214
Seeing	Day	18% 13% 25% 24% 14% 5%	16016
	Night	17% 10% 29% 31% 12% 1	25575

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	14% 5% 2 5% 4 4 4 3 5% 6% 48%	3852
	11th to 20th	Day	13% 8% 3 7% 4 4 4 3 4 5% 47%	4060
	21st to end	Day	13% 8% 3 7% 5% 4 4 3 5% 6% 42%	4466
February	1st to 10th	Day	13% 9% 2 7% 5% 4 6% 4 6% 6% 38%	1800
	11th to 20th	Day	18% 7% 3 6% 4 4 4 3 6% 7% 38%	1762
	21st to end	Day	16% 9% 3 6% 5% 3 3 4 4 5% 41%	1667
March	1st to 10th	Day	17% 8% 2 6% 4 4 4 3 4 6% 42%	4935
	11th to 20th	Day	10% 5% 3 6% 4 4 4 4 5% 7% 50%	4980
	21st to end	Day	15% 7% 2 7% 5% 4 5% 4 5% 7% 39%	5465
April	1st to 10th	Day	13% 6% 3 8% 5% 5% 5% 3 6% 7% 40%	2398
	11th to 20th	Day	13% 7% 2 6% 5% 4 4 4 5% 6% 46%	2374
	21st to end	Day	16% 7% 2 7% 5% 4 4 5% 5% 7% 40%	2418
May	1st to 10th	Day	18% 7% 2 7% 5% 5% 5% 5% 6% 10% 30%	5862
	11th to 20th	Day	22% 7% 2 6% 4 4 4 4 6% 9% 31%	5992
	21st to end	Day	16% 5% 2 6% 4 4 5% 4 7% 9% 38%	6934
June	1st to 10th	Day	11% 5% 2 5% 4 5% 4 4 7% 10% 42%	2800
	11th to 20th	Day	11% 5% 2 7% 5% 4 6% 5% 8% 10% 39%	2800
	21st to end	Day	9% 3 2 5% 5% 4 5% 6% 6% 10% 45%	2800
July	1st to 10th	Day	7% 4 2 6% 5% 5% 5% 4 7% 10% 44%	6360
	11th to 20th	Day	8% 6% 2 7% 6% 7% 7% 5% 9% 12% 31%	5957
	21st to end	Day	9% 5% 2 7% 6% 5% 5% 6% 7% 10% 39%	6424
August	1st to 10th	Day	15% 5% 2 6% 5% 6% 6% 5% 7% 10% 33%	4234
	11th to 20th	Day	9% 4 2 6% 5% 5% 6% 5% 8% 9% 40%	4075
	21st to end	Day	10% 4 2 5% 4 4 4 4 6% 7% 49%	4312
September	1st to 10th	Day	14% 7% 2 5% 5% 4 4 3 4 5% 46%	2316
	11th to 20th	Day	13% 6% 2 6% 3 3 4 3 5% 7% 47%	2254
	21st to end	Day	21% 7% 2 6% 5% 3 5% 3 5% 5% 38%	1995
October	1st to 10th	Day	17% 5% 2 6% 3 3 3 3 5% 6% 46%	1900
	11th to 20th	Day	16% 5% 1 5% 4 4 4 3 4 5% 48%	1900
	21st to end	Day	14% 5% 2 5% 3 3 3 3 4 6% 51%	2090
November	1st to 10th	Day	12% 6% 2 3 3 3 3 3 5% 7% 51%	1915
	11th to 20th	Day	14% 6% 2 5% 4 4 3 3 5% 6% 48%	1724
	21st to end	Day	14% 6% 2 4 5% 4 4 4 4 7% 46%	1600
December	1st to 10th	Day	11% 5% 2 5% 3 4 4 3 5% 8% 50%	2600
	11th to 20th	Day	18% 7% 2 5% 4 4 4 3 5% 6% 41%	2990
	21st to end	Day	16% 7% 3 7% 4 4 5% 4 6% 9% 35%	3960
January	1st to 10th	Night	10% 7% 2 6% 4 3 4 3 5% 7% 49%	6091
	11th to 20th	Night	14% 7% 2 5% 3 3 3 3 4 5% 50%	5900
	21st to end	Night	13% 8% 2 6% 3 3 3 3 4 5% 48%	6490
February	1st to 10th	Night	13% 8% 2 7% 5% 4 4 4 6% 6% 40%	2600
	11th to 20th	Night	17% 9% 2 6% 4 3 3 4 5% 5% 41%	2523
	21st to end	Night	16% 8% 2 6% 5% 4 4 3 5% 6% 41%	1960
March	1st to 10th	Night	16% 6% 2 6% 4 3 4 3 4 6% 46%	4918
	11th to 20th	Night	10% 5% 3 6% 4 4 4 3 5% 7% 50%	4980
	21st to end	Night	11% 7% 2 6% 4 4 5% 4 5% 6% 45%	5467
April	1st to 10th	Night	14% 8% 2 7% 4 4 5% 4 5% 6% 40%	2000
	11th to 20th	Night	12% 5% 2 7% 5% 4 4 4 6% 8% 43%	1975
	21st to end	Night	16% 5% 2 5% 4 5% 4 4 5% 8% 43%	1999
May	1st to 10th	Night	21% 8% 3 8% 6% 5% 5% 4 5% 8% 29%	4033
	11th to 20th	Night	25% 8% 2 6% 4 4 4 4 5% 8% 30%	3900
	21st to end	Night	17% 6% 2 7% 4 5% 5% 4 7% 9% 35%	3920
June	1st to 10th	Night	10% 5% 2 6% 4 4 6% 5% 7% 8% 43%	1600
	11th to 20th	Night	13% 5% 2 6% 5% 4 5% 4 7% 9% 42%	1600
	21st to end	Night	8% 5% 2 5% 5% 4 5% 4 8% 10% 45%	1600
July	1st to 10th	Night	7% 6% 2 6% 5% 5% 5% 5% 8% 10% 41%	3598
	11th to 20th	Night	9% 7% 3 8% 6% 7% 7% 6% 8% 9% 30%	3981
	21st to end	Night	7% 6% 2 6% 5% 5% 5% 5% 7% 10% 41%	4427
August	1st to 10th	Night	15% 6% 3 7% 5% 5% 5% 4 7% 10% 33%	2915
	11th to 20th	Night	10% 6% 3 7% 4 5% 6% 6% 6% 10% 38%	2939
	21st to end	Night	13% 4 1 5% 3 4 4 4 5% 8% 48%	3586
September	1st to 10th	Night	15% 4 2 5% 4 4 4 4 5% 6% 45%	1931
	11th to 20th	Night	12% 6% 2 5% 4 4 3 3 4 6% 52%	1923
	21st to end	Night	21% 7% 2 7% 4 4 3 3 4 6% 41%	2184
October	1st to 10th	Night	19% 5% 2 5% 3 4 3 2 4 7% 45%	2280
	11th to 20th	Night	14% 4 2 5% 3 4 4 3 4 6% 52%	2280
	21st to end	Night	14% 5% 2 5% 3 3 3 3 5% 6% 50%	2508
November	1st to 10th	Night	11% 6% 2 5% 3 3 4 3 5% 6% 53%	2381
	11th to 20th	Night	13% 7% 2 4 3 4 4 3 4 7% 48%	2674
	21st to end	Night	13% 5% 2 5% 4 4 5% 3 5% 8% 47%	2800
December	1st to 10th	Night	10% 5% 2 4 3 4 4 3 5% 6% 53%	4580
	11th to 20th	Night	18% 7% 2 5% 4 4 4 3 5% 6% 40%	5205
	21st to end	Night	15% 7% 3 6% 5% 4 5% 4 7% 9% 35%	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	37% 4 5% 27% 20% 7%	3853
	11th to 20th	Day	40% 3 8% 21% 18% 10%	4060
	21st to end	Day	41% 4 10% 27% 15% 4	4466
February	1st to 10th	Day	44% 6% 12% 24% 12% 2	1800
	11th to 20th	Day	44% 5% 9% 23% 16% 3	1771
	21st to end	Day	45% 5% 10% 20% 16% 4	1667
March	1st to 10th	Day	42% 4 9% 21% 16% 8%	4935
	11th to 20th	Day	32% 6% 9% 26% 21% 6%	4980
	21st to end	Day	43% 5% 10% 18% 17% 6%	5465
April	1st to 10th	Day	41% 6% 11% 19% 18% 5%	2398
	11th to 20th	Day	37% 6% 11% 21% 19% 5%	2374
	21st to end	Day	44% 5% 10% 23% 15% 4	2418
May	1st to 10th	Day	47% 8% 15% 18% 10% 2	5897
	11th to 20th	Day	48% 7% 11% 25% 9% 1	5996
	21st to end	Day	40% 8% 14% 21% 16% 2	6949
June	1st to 10th	Day	36% 7% 15% 24% 17% 1	2800
	11th to 20th	Day	38% 8% 16% 23% 13% 2	2800
	21st to end	Day	32% 9% 16% 25% 17% 2	2800
July	1st to 10th	Day	33% 11% 16% 21% 15% 3	6290
	11th to 20th	Day	40% 11% 17% 24% 7% 1	5886
	21st to end	Day	37% 8% 10% 25% 20% 1	6240
August	1st to 10th	Day	43% 9% 16% 24% 8%	4221
	11th to 20th	Day	36% 9% 14% 27% 14% 1	4114
	21st to end	Day	33% 6% 15% 28% 16% 2	4312
September	1st to 10th	Day	39% 5% 12% 19% 20% 4	2316
	11th to 20th	Day	35% 5% 9% 27% 20% 3	2254
	21st to end	Day	46% 6% 9% 20% 17% 2	1995
October	1st to 10th	Day	36% 4 8% 19% 27% 6%	3160
	11th to 20th	Day	26% 4 8% 29% 22% 12%	3140
	21st to end	Day	22% 3 11% 30% 27% 7%	3428
November	1st to 10th	Day	33% 4 11% 25% 22% 5%	1915
	11th to 20th	Day	37% 4 11% 21% 22% 5%	1724
	21st to end	Day	37% 5% 10% 28% 18% 2	1600
December	1st to 10th	Day	33% 5% 12% 29% 17% 4	2600
	11th to 20th	Day	43% 4 14% 26% 10% 3	2986
	21st to end	Day	43% 7% 15% 21% 14% 1	3960
January	1st to 10th	Night	32% 5% 8% 26% 25% 4	6091
	11th to 20th	Night	36% 3 7% 24% 22% 7%	5900
	21st to end	Night	37% 3 9% 30% 18% 3	6490
February	1st to 10th	Night	43% 6% 12% 23% 14% 2	2600
	11th to 20th	Night	44% 3 10% 23% 16% 5%	2525
	21st to end	Night	43% 4 10% 22% 15% 5%	1960
March	1st to 10th	Night	38% 5% 9% 25% 15% 8%	4918
	11th to 20th	Night	32% 5% 10% 25% 21% 6%	4980
	21st to end	Night	37% 6% 11% 22% 19% 5%	5467
April	1st to 10th	Night	43% 5% 10% 20% 18% 4	2000
	11th to 20th	Night	37% 6% 12% 22% 18% 5%	1975
	21st to end	Night	39% 6% 12% 25% 13% 4	1999
May	1st to 10th	Night	52% 7% 13% 17% 8% 4	4060
	11th to 20th	Night	50% 7% 11% 21% 10% 1	3901
	21st to end	Night	43% 7% 15% 24% 8% 3	3927
June	1st to 10th	Night	35% 9% 12% 25% 16% 3	1600
	11th to 20th	Night	37% 8% 15% 24% 14% 2	1600
	21st to end	Night	32% 9% 15% 23% 18% 2	1600
July	1st to 10th	Night	37% 11% 17% 18% 14% 3	3560
	11th to 20th	Night	46% 14% 16% 16% 8% 1	3932
	21st to end	Night	35% 9% 15% 23% 18%	4297
August	1st to 10th	Night	46% 8% 15% 24% 7% 1	2904
	11th to 20th	Night	39% 9% 12% 25% 15% 1	2966
	21st to end	Night	33% 7% 14% 29% 15% 2	3586
September	1st to 10th	Night	39% 6% 11% 21% 19% 4	1931
	11th to 20th	Night	35% 5% 9% 28% 21% 3	1923
	21st to end	Night	46% 5% 9% 21% 17% 3	2184
October	1st to 10th	Night	40% 5% 9% 21% 21% 4	3800
	11th to 20th	Night	23% 3 11% 23% 31% 8%	3779
	21st to end	Night	23% 4 9% 32% 25% 7%	4120
November	1st to 10th	Night	32% 4 10% 26% 22% 5%	2381
	11th to 20th	Night	36% 4 7% 25% 21% 6%	2674
	21st to end	Night	36% 4 12% 24% 20% 4	2800
December	1st to 10th	Night	31% 4 13% 30% 20% 2	4580
	11th to 20th	Night	44% 4 12% 19% 16% 4	5208
	21st to end	Night	42% 7% 15% 20% 15% 1	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	33% 24% 24% 14% 4	257
	11th to 20th	Day	29% 25% 29% 13% 3	300
	21st to end	Day	22% 27% 34% 13% 4 1	330
February	1st to 10th	Day	25% 24% 33% 13% 4	300
	11th to 20th	Day	36% 25% 32% 6% 1	309
	21st to end	Day	27% 18% 35% 16% 3	414
March	1st to 10th	Day	23% 23% 27% 23% 3	500
	11th to 20th	Day	24% 23% 30% 17% 5% 1	500
	21st to end	Day	22% 20% 33% 19% 5% 1	550
April	1st to 10th	Day	25% 21% 25% 20% 7% 1	500
	11th to 20th	Day	17% 20% 27% 21% 13% 3	492
	21st to end	Day	23% 15% 30% 20% 9% 2	500
May	1st to 10th	Day	22% 16% 29% 17% 12% 3	503
	11th to 20th	Day	23% 10% 28% 21% 13% 4	527
	21st to end	Day	20% 7% 23% 24% 19% 6%	573
June	1st to 10th	Day	14% 9% 25% 25% 20% 6%	530
	11th to 20th	Day	14% 9% 24% 30% 18% 5%	530
	21st to end	Day	11% 5% 26% 30% 22% 6%	530
July	1st to 10th	Day	11% 4 15% 32% 26% 12%	525
	11th to 20th	Day	6% 4 19% 33% 27% 11%	524
	21st to end	Day	11% 3 20% 32% 25% 8%	576
August	1st to 10th	Day	12% 5% 17% 29% 26% 11%	526
	11th to 20th	Day	11% 5% 20% 30% 23% 11%	519
	21st to end	Day	8% 6% 19% 30% 23% 14%	583
September	1st to 10th	Day	16% 7% 18% 26% 21% 12%	502
	11th to 20th	Day	15% 4 18% 30% 22% 12%	490
	21st to end	Day	26% 11% 18% 25% 16% 3	490
October	1st to 10th	Day	18% 9% 19% 27% 22% 6%	490
	11th to 20th	Day	16% 14% 26% 29% 13% 3	490
	21st to end	Day	16% 12% 34% 25% 11% 3	539
November	1st to 10th	Day	16% 12% 30% 26% 13% 3	473
	11th to 20th	Day	20% 16% 31% 22% 10% 1	324
	21st to end	Day	23% 19% 31% 23% 5% 1	200
December	1st to 10th	Day	18% 23% 35% 20% 5% 1	200
	11th to 20th	Day	23% 19% 30% 24% 6%	200
	21st to end	Day	21% 18% 32% 21% 8%	220
January	1st to 10th	Night	19% 18% 39% 21% 3	800
	11th to 20th	Night	22% 14% 34% 27% 4	800
	21st to end	Night	18% 15% 43% 22% 2	880
February	1st to 10th	Night	17% 16% 38% 27% 2	800
	11th to 20th	Night	23% 20% 38% 17% 2	783
	21st to end	Night	23% 16% 39% 20% 3	660
March	1st to 10th	Night	19% 15% 40% 23% 3	800
	11th to 20th	Night	23% 17% 33% 22% 5% 1	800
	21st to end	Night	19% 15% 39% 21% 4 1	880
April	1st to 10th	Night	19% 18% 36% 24% 4	800
	11th to 20th	Night	16% 12% 36% 27% 8% 1	791
	21st to end	Night	19% 10% 33% 31% 6%	799
May	1st to 10th	Night	21% 7% 26% 33% 13%	600
	11th to 20th	Night	20% 5% 26% 36% 12%	537
	21st to end	Night	14% 4 22% 40% 20%	433
June	1st to 10th	Night	11% 3 24% 41% 21%	400
	11th to 20th	Night	13% 6% 19% 40% 22% 1	400
	21st to end	Night	6% 4 23% 46% 20% 2	400
July	1st to 10th	Night	11% 2 17% 41% 26% 4	390
	11th to 20th	Night	5% 2 15% 38% 37% 3	547
	21st to end	Night	8% 1 16% 44% 28% 3	657
August	1st to 10th	Night	11% 2 10% 44% 30% 3	597
	11th to 20th	Night	10% 3 14% 40% 30% 3	632
	21st to end	Night	13% 2 17% 39% 25% 4	880
September	1st to 10th	Night	15% 3 15% 34% 28% 4	773
	11th to 20th	Night	13% 3 17% 33% 30% 4	760
	21st to end	Night	24% 4 22% 29% 21% 1	760
October	1st to 10th	Night	21% 6% 20% 29% 22% 3	760
	11th to 20th	Night	14% 9% 27% 36% 14% 1	760
	21st to end	Night	17% 8% 32% 31% 11%	836
November	1st to 10th	Night	13% 8% 33% 35% 11% 1	780
	11th to 20th	Night	17% 13% 33% 29% 8% 1	800
	21st to end	Night	17% 13% 33% 30% 7%	800
December	1st to 10th	Night	20% 13% 36% 25% 6%	800
	11th to 20th	Night	19% 8% 39% 30% 4	800
	21st to end	Night	17% 12% 35% 33% 3	880

Page generated at 2025-09-01 01:51:02. Version ac07

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