Cherry Springs State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cherry Springs State Park clear sky chart from 2005-11-06 to 2025-11-03.

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% 5% 4 5% 6% 29%	126955
	Night	17% 12% 4 10% 6% 4 4 3 5% 6% 29%	123049
Transparency	Day	53% 5% 11% 20% 11% 1	130548
	Night	54% 5% 11% 19% 10% 1	127543
Seeing	Day	26% 18% 28% 17% 8% 3	15981
	Night	24% 17% 27% 22% 9% 1	25333

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% 8% 19% 8% 3 3 3 3 3 18%	3597
	11th to 20th	Day	9% 19% 10% 23% 8% 7% 3 2 3 3 13%	3908
	21st to end	Day	18% 14% 8% 13% 6% 4 4 3 4 5% 20%	4466
February	1st to 10th	Day	14% 18% 6% 13% 7% 5% 5% 3 4 4 21%	1800
	11th to 20th	Day	13% 14% 6% 14% 7% 5% 5% 3 4 6% 23%	1753
	21st to end	Day	18% 14% 3 12% 6% 4 3 3 4 6% 27%	1618
March	1st to 10th	Day	17% 13% 7% 9% 4 4 3 2 4 5% 32%	4860
	11th to 20th	Day	13% 13% 6% 9% 5% 4 4 2 4 5% 35%	4980
	21st to end	Day	14% 12% 4 11% 7% 5% 4 4 5% 5% 29%	5526
April	1st to 10th	Day	18% 16% 4 7% 5% 4 4 3 5% 6% 28%	2400
	11th to 20th	Day	18% 13% 4 7% 5% 4 5% 4 5% 5% 32%	2374
	21st to end	Day	21% 10% 3 6% 5% 4 3 3 5% 5% 34%	2501
May	1st to 10th	Day	28% 9% 3 7% 4 5% 4 3 5% 5% 26%	5906
	11th to 20th	Day	25% 10% 3 8% 5% 4 5% 4 5% 6% 26%	6318
	21st to end	Day	21% 7% 2 7% 5% 5% 5% 4 6% 7% 30%	6949
June	1st to 10th	Day	16% 8% 3 7% 5% 5% 5% 4 6% 8% 33%	2800
	11th to 20th	Day	17% 7% 3 7% 5% 6% 6% 5% 6% 8% 31%	2800
	21st to end	Day	15% 7% 2 6% 5% 5% 5% 5% 6% 9% 35%	2800
July	1st to 10th	Day	9% 7% 2 7% 6% 5% 5% 5% 7% 9% 38%	6360
	11th to 20th	Day	10% 7% 3 8% 5% 6% 6% 5% 7% 9% 32%	6360
	21st to end	Day	11% 6% 2 6% 5% 5% 5% 4 6% 8% 41%	6498
August	1st to 10th	Day	21% 7% 3 7% 4 5% 5% 4 6% 8% 30%	4234
	11th to 20th	Day	16% 7% 3 8% 5% 6% 6% 5% 8% 8% 28%	4152
	21st to end	Day	16% 6% 2 6% 4 4 5% 5% 7% 8% 38%	4312
September	1st to 10th	Day	19% 7% 2 6% 3 4 4 4 5% 7% 39%	2400
	11th to 20th	Day	14% 5% 3 7% 4 4 4 4 5% 6% 44%	2393
	21st to end	Day	26% 7% 2 7% 4 5% 4 3 5% 6% 31%	2090
October	1st to 10th	Day	17% 8% 3 8% 4 4 5% 4 5% 8% 35%	2000
	11th to 20th	Day	21% 10% 4 7% 5% 4 4 4 5% 5% 32%	2000
	21st to end	Day	22% 13% 3 8% 5% 4 4 4 5% 6% 27%	2200
November	1st to 10th	Day	12% 12% 4 7% 5% 4 4 3 5% 7% 37%	1829
	11th to 20th	Day	17% 16% 4 10% 4 4 4 4 5% 6% 26%	1625
	21st to end	Day	18% 19% 6% 9% 6% 4 4 3 4 6% 22%	1600
December	1st to 10th	Day	18% 19% 9% 20% 5% 4 3 2 3 4 12%	2600
	11th to 20th	Day	21% 17% 6% 10% 5% 4 3 3 4 5% 21%	2986
	21st to end	Day	21% 22% 7% 11% 5% 4 4 3 4 4 16%	3960
January	1st to 10th	Night	13% 15% 8% 20% 8% 5% 4 3 4 5% 16%	6349
	11th to 20th	Night	11% 15% 7% 23% 8% 5% 5% 4 5% 5% 12%	5974
	21st to end	Night	16% 15% 7% 14% 8% 6% 6% 3 4 4 18%	6490
February	1st to 10th	Night	13% 16% 6% 11% 8% 6% 3 4 4 5% 23%	2600
	11th to 20th	Night	14% 13% 5% 13% 7% 5% 5% 4 5% 7% 22%	2533
	21st to end	Night	17% 12% 5% 12% 7% 5% 4 4 5% 6% 24%	2010
March	1st to 10th	Night	17% 15% 5% 9% 7% 5% 4 3 4 5% 27%	4962
	11th to 20th	Night	14% 12% 6% 9% 4 3 3 3 4 6% 34%	4979
	21st to end	Night	14% 13% 4 9% 5% 4 4 3 4 6% 34%	5405
April	1st to 10th	Night	20% 13% 4 8% 5% 5% 4 4 4 6% 28%	2000
	11th to 20th	Night	18% 12% 2 8% 5% 4 3 3 4 6% 34%	1975
	21st to end	Night	17% 12% 3 7% 4 5% 4 3 5% 7% 35%	1915
May	1st to 10th	Night	31% 12% 3 5% 4 3 3 3 4 5% 27%	4035
	11th to 20th	Night	25% 12% 3 6% 4 4 4 2 4 6% 30%	3575
	21st to end	Night	19% 10% 3 7% 5% 5% 4 3 5% 6% 31%	3926
June	1st to 10th	Night	14% 7% 2 7% 6% 5% 4 3 6% 8% 38%	1600
	11th to 20th	Night	14% 7% 3 6% 4 5% 4 5% 7% 8% 38%	1600
	21st to end	Night	13% 6% 2 7% 4 4 5% 4 7% 8% 42%	1600
July	1st to 10th	Night	13% 7% 3 7% 5% 5% 4 4 5% 8% 39%	3600
	11th to 20th	Night	13% 8% 2 7% 4 4 5% 4 6% 10% 37%	3600
	21st to end	Night	12% 5% 2 6% 4 4 3 3 5% 8% 47%	4336
August	1st to 10th	Night	19% 7% 2 7% 4 4 5% 4 5% 7% 36%	2915
	11th to 20th	Night	19% 7% 3 5% 4 3 4 3 5% 7% 40%	2875
	21st to end	Night	14% 6% 2 5% 4 3 5% 3 6% 8% 45%	3573
September	1st to 10th	Night	15% 7% 2 7% 4 3 3 3 5% 6% 46%	2000
	11th to 20th	Night	13% 5% 2 6% 3 4 3 3 5% 6% 49%	2004
	21st to end	Night	22% 8% 3 6% 4 4 4 3 5% 6% 35%	2310
October	1st to 10th	Night	18% 8% 2 6% 4 4 3 3 5% 6% 40%	2400
	11th to 20th	Night	20% 11% 3 6% 4 4 4 3 5% 6% 35%	2400
	21st to end	Night	22% 14% 3 7% 4 3 4 3 5% 6% 30%	2640
November	1st to 10th	Night	12% 9% 3 7% 5% 5% 4 4 5% 6% 39%	2514
	11th to 20th	Night	18% 14% 4 9% 6% 4 4 3 5% 6% 27%	2770
	21st to end	Night	16% 16% 6% 11% 6% 5% 4 3 6% 6% 22%	2800
December	1st to 10th	Night	15% 16% 8% 18% 7% 6% 5% 4 5% 4 13%	4580
	11th to 20th	Night	21% 15% 6% 12% 5% 4 4 2 4 4 23%	5208
	21st to end	Night	19% 18% 8% 12% 6% 4 4 3 4 5% 17%	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	71% 3 7% 13% 6% 1	3598
	11th to 20th	Day	77% 3 6% 9% 4 1	3942
	21st to end	Day	66% 2 9% 16% 6% 1	4466
February	1st to 10th	Day	65% 4 10% 13% 7%	1800
	11th to 20th	Day	61% 5% 7% 19% 8% 1	1762
	21st to end	Day	59% 3 8% 19% 8% 2	1618
March	1st to 10th	Day	54% 4 10% 20% 10% 2	4863
	11th to 20th	Day	51% 4 16% 18% 7% 3	4980
	21st to end	Day	55% 6% 6% 17% 14% 2	5526
April	1st to 10th	Day	56% 5% 9% 18% 11% 2	2400
	11th to 20th	Day	52% 6% 10% 16% 14% 1	2374
	21st to end	Day	50% 6% 8% 20% 14% 3	2501
May	1st to 10th	Day	59% 4 9% 16% 9% 2	5915
	11th to 20th	Day	58% 6% 9% 18% 9% 1	6322
	21st to end	Day	51% 6% 11% 20% 11% 1	6949
June	1st to 10th	Day	47% 7% 11% 20% 14% 1	2800
	11th to 20th	Day	48% 7% 14% 18% 12% 1	2800
	21st to end	Day	44% 7% 13% 23% 12% 1	2800
July	1st to 10th	Day	42% 4 14% 26% 13% 1	6290
	11th to 20th	Day	47% 4 14% 23% 12%	6285
	21st to end	Day	41% 4 11% 28% 17% 1	6312
August	1st to 10th	Day	51% 5% 13% 20% 10%	4221
	11th to 20th	Day	50% 6% 14% 24% 6%	4191
	21st to end	Day	43% 4 11% 31% 10% 1	4312
September	1st to 10th	Day	44% 5% 9% 25% 14% 2	2400
	11th to 20th	Day	39% 5% 11% 25% 18% 1	2393
	21st to end	Day	52% 5% 10% 18% 14% 1	2090
October	1st to 10th	Day	44% 4 8% 23% 18% 2	3260
	11th to 20th	Day	46% 3 10% 20% 17% 3	3240
	21st to end	Day	41% 4 16% 27% 11% 1	3538
November	1st to 10th	Day	45% 6% 11% 21% 14% 3	1829
	11th to 20th	Day	57% 4 11% 19% 7% 2	1625
	21st to end	Day	62% 5% 10% 16% 6% 1	1600
December	1st to 10th	Day	76% 3 7% 10% 3	2600
	11th to 20th	Day	65% 4 10% 15% 7%	2986
	21st to end	Day	71% 4 9% 9% 5% 1	3960
January	1st to 10th	Night	69% 5% 8% 12% 6%	6349
	11th to 20th	Night	71% 4 10% 9% 6% 1	6015
	21st to end	Night	68% 4 7% 11% 8% 1	6490
February	1st to 10th	Night	60% 5% 12% 15% 7%	2600
	11th to 20th	Night	58% 6% 10% 18% 7% 1	2535
	21st to end	Night	59% 4 10% 15% 9% 2	2010
March	1st to 10th	Night	59% 4 11% 16% 9% 1	4972
	11th to 20th	Night	49% 6% 17% 19% 6% 4	4980
	21st to end	Night	51% 4 8% 17% 17% 2	5405
April	1st to 10th	Night	57% 5% 8% 17% 12% 1	2000
	11th to 20th	Night	50% 6% 11% 19% 12% 2	1975
	21st to end	Night	48% 5% 10% 22% 13% 2	1915
May	1st to 10th	Night	61% 4 7% 18% 8% 2	4042
	11th to 20th	Night	56% 6% 11% 17% 10%	3576
	21st to end	Night	51% 8% 10% 18% 11% 3	3927
June	1st to 10th	Night	41% 8% 13% 23% 15% 1	1600
	11th to 20th	Night	40% 8% 14% 25% 11% 2	1600
	21st to end	Night	39% 7% 13% 26% 14%	1600
July	1st to 10th	Night	44% 4 13% 25% 14% 1	3560
	11th to 20th	Night	43% 4 16% 25% 12%	3552
	21st to end	Night	36% 4 12% 26% 21%	4208
August	1st to 10th	Night	47% 7% 13% 24% 8% 1	2904
	11th to 20th	Night	44% 5% 13% 28% 10%	2902
	21st to end	Night	38% 5% 12% 34% 11% 1	3573
September	1st to 10th	Night	40% 5% 11% 26% 16% 3	2000
	11th to 20th	Night	35% 5% 13% 28% 18% 2	2004
	21st to end	Night	48% 5% 13% 20% 13% 1	2310
October	1st to 10th	Night	47% 4 8% 22% 18% 1	3920
	11th to 20th	Night	42% 4 11% 22% 15% 6%	3899
	21st to end	Night	42% 3 15% 25% 14% 2	4252
November	1st to 10th	Night	41% 6% 14% 22% 15% 2	2514
	11th to 20th	Night	56% 5% 12% 16% 9% 2	2770
	21st to end	Night	58% 5% 13% 18% 5% 1	2800
December	1st to 10th	Night	70% 5% 10% 12% 3	4580
	11th to 20th	Night	65% 3 10% 16% 6%	5208
	21st to end	Night	69% 5% 8% 12% 6%	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	36% 27% 27% 8% 4	200
	11th to 20th	Day	39% 29% 24% 6% 1	275
	21st to end	Day	35% 26% 30% 7% 1	330
February	1st to 10th	Day	40% 29% 27% 4	300
	11th to 20th	Day	43% 27% 28% 2	300
	21st to end	Day	41% 24% 27% 7% 1	382
March	1st to 10th	Day	33% 25% 28% 11% 2	500
	11th to 20th	Day	32% 26% 27% 12% 3 1	500
	21st to end	Day	35% 24% 26% 11% 3 1	550
April	1st to 10th	Day	34% 24% 26% 11% 3 1	500
	11th to 20th	Day	31% 25% 25% 12% 5% 2	492
	21st to end	Day	31% 20% 31% 12% 5% 1	500
May	1st to 10th	Day	33% 19% 28% 11% 7% 2	503
	11th to 20th	Day	29% 17% 30% 14% 6% 3	527
	21st to end	Day	24% 13% 27% 21% 10% 5%	573
June	1st to 10th	Day	20% 16% 31% 23% 8% 2	530
	11th to 20th	Day	22% 16% 25% 22% 13% 1	530
	21st to end	Day	19% 13% 34% 24% 8% 2	530
July	1st to 10th	Day	14% 10% 30% 26% 14% 6%	525
	11th to 20th	Day	12% 8% 32% 29% 13% 5%	524
	21st to end	Day	14% 11% 32% 26% 13% 4	576
August	1st to 10th	Day	14% 8% 27% 28% 17% 7%	526
	11th to 20th	Day	18% 8% 27% 26% 15% 7%	519
	21st to end	Day	15% 12% 29% 24% 13% 8%	583
September	1st to 10th	Day	22% 12% 19% 24% 15% 8%	530
	11th to 20th	Day	13% 8% 24% 23% 22% 9%	530
	21st to end	Day	28% 13% 23% 20% 12% 3	530
October	1st to 10th	Day	24% 12% 25% 21% 13% 5%	530
	11th to 20th	Day	25% 21% 31% 15% 6% 2	530
	21st to end	Day	32% 20% 28% 15% 4	583
November	1st to 10th	Day	25% 21% 28% 16% 9% 1	428
	11th to 20th	Day	34% 24% 28% 12% 3	225
	21st to end	Day	35% 27% 30% 8% 1 1	200
December	1st to 10th	Day	39% 28% 25% 5% 3 1	200
	11th to 20th	Day	40% 24% 27% 9% 1	200
	21st to end	Day	38% 25% 30% 5% 1	220
January	1st to 10th	Night	28% 28% 31% 11% 2	800
	11th to 20th	Night	29% 26% 29% 14% 2	800
	21st to end	Night	27% 29% 29% 14% 1	880
February	1st to 10th	Night	27% 25% 34% 13% 1	800
	11th to 20th	Night	31% 28% 30% 10% 1	783
	21st to end	Night	32% 25% 29% 12% 2	660
March	1st to 10th	Night	26% 27% 31% 14% 2	800
	11th to 20th	Night	30% 24% 25% 17% 3	800
	21st to end	Night	24% 24% 32% 15% 4 1	880
April	1st to 10th	Night	29% 22% 29% 18% 3	800
	11th to 20th	Night	27% 18% 30% 19% 5% 1	791
	21st to end	Night	24% 15% 30% 26% 5%	715
May	1st to 10th	Night	27% 13% 24% 27% 10%	595
	11th to 20th	Night	21% 12% 27% 31% 9%	394
	21st to end	Night	16% 9% 26% 31% 16% 1	433
June	1st to 10th	Night	17% 7% 29% 34% 13% 1	400
	11th to 20th	Night	18% 9% 22% 41% 11%	400
	21st to end	Night	13% 7% 31% 36% 13% 1	400
July	1st to 10th	Night	12% 5% 22% 38% 21% 2	390
	11th to 20th	Night	11% 4 21% 40% 23% 1	388
	21st to end	Night	13% 5% 19% 43% 18% 2	617
August	1st to 10th	Night	13% 4 19% 38% 25% 1	597
	11th to 20th	Night	17% 5% 17% 33% 26% 3	594
	21st to end	Night	15% 6% 19% 35% 22% 2	867
September	1st to 10th	Night	18% 8% 22% 30% 19% 2	800
	11th to 20th	Night	14% 7% 19% 29% 27% 4	800
	21st to end	Night	24% 11% 21% 24% 17% 3	800
October	1st to 10th	Night	22% 11% 24% 22% 18% 2	800
	11th to 20th	Night	25% 17% 28% 23% 7% 1	800
	21st to end	Night	31% 16% 28% 22% 4	880
November	1st to 10th	Night	18% 18% 33% 24% 7%	789
	11th to 20th	Night	29% 19% 29% 18% 5% 1	800
	21st to end	Night	27% 21% 32% 17% 3 1	800
December	1st to 10th	Night	32% 25% 28% 12% 3	800
	11th to 20th	Night	30% 24% 29% 15% 3	800
	21st to end	Night	30% 24% 29% 15% 2	880

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