French Creek State Gamelands
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the French Creek State Gamelands 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	16% 7% 2 6% 4 4 4 4 6% 7% 40%	126867
	Night	16% 7% 2 6% 4 4 4 3 5% 7% 42%	123179
Transparency	Day	41% 7% 12% 23% 15% 3	130425
	Night	40% 6% 12% 23% 17% 3	127690
Seeing	Day	23% 16% 28% 20% 10% 3	16242
	Night	20% 15% 29% 26% 10% 1	25519

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	12% 7% 3 7% 5% 4 4 3 5% 6% 46%	3597
	11th to 20th	Day	14% 9% 3 10% 5% 4 4 3 5% 5% 38%	3783
	21st to end	Day	16% 8% 3 8% 4 5% 4 3 4 6% 40%	4466
February	1st to 10th	Day	15% 9% 3 7% 5% 4 4 4 6% 6% 39%	1800
	11th to 20th	Day	16% 8% 3 8% 5% 4 4 4 6% 5% 38%	1865
	21st to end	Day	18% 10% 4 6% 4 4 3 3 4 6% 38%	1650
March	1st to 10th	Day	21% 5% 2 5% 4 4 3 3 4 6% 44%	4571
	11th to 20th	Day	12% 6% 3 6% 5% 5% 4 3 6% 7% 43%	4980
	21st to end	Day	18% 6% 2 6% 4 4 4 3 5% 6% 42%	5733
April	1st to 10th	Day	16% 8% 3 6% 4 5% 4 3 5% 6% 40%	2400
	11th to 20th	Day	15% 7% 3 5% 4 5% 5% 4 5% 6% 42%	2374
	21st to end	Day	16% 6% 2 7% 4 4 4 4 6% 7% 40%	2400
May	1st to 10th	Day	26% 7% 2 6% 4 4 4 4 5% 8% 30%	5843
	11th to 20th	Day	25% 8% 3 7% 4 3 3 3 5% 7% 32%	6318
	21st to end	Day	19% 6% 2 6% 4 4 5% 4 6% 8% 36%	6934
June	1st to 10th	Day	13% 5% 2 6% 5% 4 5% 5% 6% 9% 39%	2800
	11th to 20th	Day	14% 6% 3 6% 5% 4 5% 4 7% 9% 37%	2800
	21st to end	Day	10% 5% 2 5% 5% 5% 5% 5% 6% 9% 42%	2800
July	1st to 10th	Day	8% 5% 2 6% 5% 5% 6% 5% 7% 11% 39%	6360
	11th to 20th	Day	10% 8% 3 7% 5% 5% 6% 5% 8% 10% 32%	6360
	21st to end	Day	10% 7% 3 7% 4 5% 5% 4 6% 9% 40%	6709
August	1st to 10th	Day	19% 6% 2 7% 5% 5% 5% 4 7% 6% 35%	4234
	11th to 20th	Day	13% 6% 2 6% 4 4 5% 4 6% 9% 41%	3912
	21st to end	Day	12% 5% 2 5% 4 3 4 3 5% 7% 49%	4312
September	1st to 10th	Day	15% 6% 2 5% 5% 4 5% 3 5% 7% 45%	2400
	11th to 20th	Day	14% 5% 2 4 4 3 3 3 5% 8% 50%	2395
	21st to end	Day	19% 7% 4 7% 4 4 4 3 4 6% 38%	2156
October	1st to 10th	Day	17% 6% 2 5% 4 4 4 3 5% 6% 45%	2000
	11th to 20th	Day	16% 6% 1 6% 3 3 3 3 5% 7% 47%	2000
	21st to end	Day	17% 6% 2 5% 3 4 3 3 6% 6% 46%	2161
November	1st to 10th	Day	12% 7% 2 5% 3 3 3 3 5% 7% 52%	1779
	11th to 20th	Day	16% 5% 2 5% 4 4 4 3 6% 6% 47%	1800
	21st to end	Day	15% 7% 3 4 4 4 3 4 5% 7% 44%	1625
December	1st to 10th	Day	13% 8% 2 7% 5% 4 3 4 5% 6% 43%	2600
	11th to 20th	Day	21% 9% 2 5% 3 3 3 3 4 6% 42%	2990
	21st to end	Day	16% 6% 2 7% 5% 5% 5% 4 6% 6% 38%	3960
January	1st to 10th	Night	12% 6% 2 6% 4 4 4 4 4 7% 47%	6349
	11th to 20th	Night	14% 7% 2 6% 4 3 3 3 5% 6% 47%	6162
	21st to end	Night	16% 9% 3 7% 4 4 3 3 4 5% 43%	6490
February	1st to 10th	Night	17% 8% 3 6% 5% 4 4 3 5% 6% 40%	2600
	11th to 20th	Night	17% 8% 2 6% 5% 4 4 4 5% 5% 40%	2418
	21st to end	Night	17% 8% 3 6% 4 3 4 4 6% 6% 40%	1980
March	1st to 10th	Night	17% 8% 2 6% 4 4 4 3 4 5% 43%	5264
	11th to 20th	Night	11% 6% 2 6% 4 4 3 3 4 6% 50%	4980
	21st to end	Night	14% 8% 3 7% 4 4 4 3 5% 6% 44%	5198
April	1st to 10th	Night	17% 7% 2 6% 6% 4 5% 4 5% 6% 40%	2000
	11th to 20th	Night	15% 6% 3 6% 4 4 4 4 6% 7% 41%	1975
	21st to end	Night	18% 7% 2 5% 3 4 4 3 5% 6% 44%	2000
May	1st to 10th	Night	24% 8% 2 7% 4 5% 5% 4 6% 8% 28%	4094
	11th to 20th	Night	25% 8% 3 6% 4 3 4 4 5% 7% 31%	3575
	21st to end	Night	21% 6% 2 6% 4 3 4 3 5% 8% 38%	3920
June	1st to 10th	Night	15% 5% 2 6% 5% 4 4 4 5% 9% 41%	1600
	11th to 20th	Night	13% 6% 2 6% 5% 5% 4 4 7% 10% 39%	1600
	21st to end	Night	11% 4 2 6% 3 3 4 5% 7% 10% 43%	1600
July	1st to 10th	Night	8% 7% 3 7% 5% 5% 5% 4 7% 9% 39%	3598
	11th to 20th	Night	12% 9% 3 7% 5% 5% 5% 5% 8% 10% 30%	3597
	21st to end	Night	11% 6% 2 6% 4 4 4 4 6% 9% 44%	4139
August	1st to 10th	Night	20% 6% 2 6% 3 5% 5% 4 6% 8% 36%	2915
	11th to 20th	Night	13% 7% 3 7% 4 4 4 4 6% 7% 40%	3102
	21st to end	Night	11% 6% 2 5% 3 4 4 4 6% 8% 48%	3586
September	1st to 10th	Night	14% 6% 2 6% 4 3 4 3 5% 6% 48%	2000
	11th to 20th	Night	12% 6% 2 4 2 3 3 3 6% 6% 52%	2005
	21st to end	Night	20% 6% 2 5% 4 4 4 4 5% 7% 39%	2240
October	1st to 10th	Night	20% 7% 2 5% 4 3 3 2 3 6% 45%	2400
	11th to 20th	Night	16% 6% 2 4 3 3 3 3 4 5% 50%	2400
	21st to end	Night	17% 6% 2 4 2 3 3 2 5% 6% 49%	2677
November	1st to 10th	Night	10% 6% 2 5% 4 3 4 3 6% 6% 53%	2564
	11th to 20th	Night	16% 7% 2 5% 4 3 4 3 5% 5% 47%	2600
	21st to end	Night	13% 5% 2 5% 5% 4 5% 4 5% 7% 45%	2770
December	1st to 10th	Night	12% 7% 3 7% 4 4 4 3 4 7% 45%	4580
	11th to 20th	Night	22% 7% 2 5% 3 3 3 3 4 6% 41%	5205
	21st to end	Night	18% 7% 3 6% 4 4 4 4 5% 6% 39%	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% 5% 11% 25% 20% 2	3598
	11th to 20th	Day	46% 5% 10% 20% 14% 5%	3783
	21st to end	Day	45% 6% 12% 22% 14% 1	4466
February	1st to 10th	Day	45% 7% 13% 23% 11% 2	1800
	11th to 20th	Day	46% 6% 9% 24% 13% 2	1874
	21st to end	Day	48% 4 10% 23% 12% 3	1650
March	1st to 10th	Day	40% 5% 9% 24% 16% 7%	4571
	11th to 20th	Day	38% 7% 12% 26% 12% 5%	4980
	21st to end	Day	41% 6% 10% 17% 21% 5%	5733
April	1st to 10th	Day	43% 7% 10% 21% 15% 5%	2400
	11th to 20th	Day	41% 7% 11% 22% 16% 4	2374
	21st to end	Day	40% 8% 11% 20% 17% 4	2400
May	1st to 10th	Day	50% 8% 12% 18% 9% 2	5875
	11th to 20th	Day	51% 6% 9% 22% 11% 1	6322
	21st to end	Day	43% 7% 12% 23% 14% 1	6949
June	1st to 10th	Day	39% 8% 14% 23% 15% 1	2800
	11th to 20th	Day	40% 9% 15% 23% 10% 3	2800
	21st to end	Day	36% 9% 14% 25% 15% 1	2800
July	1st to 10th	Day	37% 11% 14% 21% 15% 2	6290
	11th to 20th	Day	41% 10% 18% 20% 9% 1	6285
	21st to end	Day	39% 8% 10% 21% 22% 1	6516
August	1st to 10th	Day	46% 8% 12% 23% 10%	4221
	11th to 20th	Day	37% 8% 12% 29% 13% 1	3950
	21st to end	Day	33% 7% 11% 29% 19% 2	4312
September	1st to 10th	Day	39% 7% 12% 20% 20% 3	2400
	11th to 20th	Day	32% 5% 11% 26% 22% 4	2395
	21st to end	Day	48% 5% 9% 17% 19% 2	2156
October	1st to 10th	Day	36% 5% 9% 18% 27% 5%	3260
	11th to 20th	Day	26% 4 12% 27% 24% 6%	3240
	21st to end	Day	25% 4 13% 26% 28% 4	3475
November	1st to 10th	Day	33% 4 15% 24% 19% 4	1779
	11th to 20th	Day	37% 6% 11% 25% 20% 2	1800
	21st to end	Day	38% 6% 14% 30% 10% 2	1625
December	1st to 10th	Day	41% 5% 16% 24% 11% 2	2600
	11th to 20th	Day	43% 5% 13% 29% 9% 1	2986
	21st to end	Day	43% 7% 14% 20% 14% 2	3960
January	1st to 10th	Night	36% 5% 11% 24% 20% 5%	6349
	11th to 20th	Night	37% 4 13% 23% 16% 6%	6162
	21st to end	Night	44% 4 10% 23% 17% 2	6490
February	1st to 10th	Night	45% 5% 13% 25% 10% 2	2600
	11th to 20th	Night	45% 4 10% 21% 17% 3	2420
	21st to end	Night	44% 5% 10% 22% 16% 4	1980
March	1st to 10th	Night	41% 5% 10% 23% 12% 8%	5264
	11th to 20th	Night	34% 6% 14% 28% 13% 5%	4980
	21st to end	Night	42% 5% 8% 17% 25% 4	5198
April	1st to 10th	Night	44% 6% 11% 20% 16% 4	2000
	11th to 20th	Night	41% 6% 10% 20% 19% 3	1975
	21st to end	Night	40% 6% 10% 22% 18% 5%	2000
May	1st to 10th	Night	53% 8% 11% 15% 11% 2	4124
	11th to 20th	Night	51% 8% 11% 17% 12% 1	3576
	21st to end	Night	44% 8% 11% 22% 14% 2	3927
June	1st to 10th	Night	40% 7% 12% 22% 19% 1	1600
	11th to 20th	Night	38% 9% 15% 23% 14% 1	1600
	21st to end	Night	34% 9% 15% 27% 14% 2	1600
July	1st to 10th	Night	40% 10% 15% 19% 14% 2	3560
	11th to 20th	Night	46% 11% 15% 18% 9% 1	3552
	21st to end	Night	35% 9% 11% 23% 21% 1	4018
August	1st to 10th	Night	45% 8% 19% 18% 9% 1	2904
	11th to 20th	Night	41% 7% 13% 23% 15% 1	3130
	21st to end	Night	32% 7% 12% 28% 19% 1	3586
September	1st to 10th	Night	38% 7% 10% 21% 21% 3	2000
	11th to 20th	Night	32% 6% 10% 22% 26% 4	2005
	21st to end	Night	43% 6% 9% 20% 20% 2	2240
October	1st to 10th	Night	42% 5% 9% 21% 21% 2	3920
	11th to 20th	Night	25% 4 10% 29% 27% 4	3899
	21st to end	Night	26% 4 12% 32% 24% 4	4313
November	1st to 10th	Night	31% 6% 12% 25% 20% 5%	2564
	11th to 20th	Night	39% 5% 9% 23% 19% 4	2600
	21st to end	Night	38% 6% 12% 27% 15% 1	2770
December	1st to 10th	Night	40% 5% 13% 29% 12% 1	4580
	11th to 20th	Night	45% 4 11% 25% 12% 3	5208
	21st to end	Night	45% 7% 11% 20% 17% 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	38% 25% 22% 12% 4	200
	11th to 20th	Day	41% 26% 24% 8%	240
	21st to end	Day	28% 31% 27% 11% 3 1	330
February	1st to 10th	Day	29% 27% 32% 10% 2	300
	11th to 20th	Day	35% 26% 30% 7% 1	413
	21st to end	Day	35% 23% 28% 12% 2	414
March	1st to 10th	Day	34% 19% 30% 14% 3	500
	11th to 20th	Day	31% 25% 29% 12% 3 1	500
	21st to end	Day	31% 25% 30% 10% 4 1	550
April	1st to 10th	Day	30% 24% 29% 12% 4 1	500
	11th to 20th	Day	27% 24% 27% 15% 5% 2	492
	21st to end	Day	28% 19% 31% 16% 4 2	500
May	1st to 10th	Day	34% 17% 28% 15% 6% 1	503
	11th to 20th	Day	24% 16% 32% 19% 8% 2	527
	21st to end	Day	21% 12% 27% 23% 15% 2	573
June	1st to 10th	Day	17% 14% 31% 23% 13% 2	530
	11th to 20th	Day	19% 10% 31% 25% 13% 2	530
	21st to end	Day	14% 10% 31% 28% 13% 4	530
July	1st to 10th	Day	11% 7% 24% 33% 19% 6%	525
	11th to 20th	Day	8% 5% 27% 32% 22% 5%	524
	21st to end	Day	11% 7% 32% 31% 16% 3	576
August	1st to 10th	Day	12% 6% 28% 27% 21% 7%	526
	11th to 20th	Day	13% 6% 22% 34% 18% 7%	519
	21st to end	Day	13% 6% 27% 28% 17% 9%	583
September	1st to 10th	Day	18% 9% 23% 27% 16% 7%	530
	11th to 20th	Day	15% 5% 26% 28% 16% 9%	530
	21st to end	Day	24% 14% 25% 21% 12% 3	530
October	1st to 10th	Day	23% 9% 27% 21% 15% 5%	530
	11th to 20th	Day	21% 17% 28% 22% 11% 2	530
	21st to end	Day	22% 19% 33% 16% 9% 2	561
November	1st to 10th	Day	21% 15% 31% 20% 10% 3	401
	11th to 20th	Day	22% 23% 30% 20% 6%	400
	21st to end	Day	28% 20% 31% 18% 2 1	225
December	1st to 10th	Day	34% 25% 29% 10% 3 1	200
	11th to 20th	Day	37% 23% 26% 12% 3	200
	21st to end	Day	28% 22% 28% 15% 6% 1	220
January	1st to 10th	Night	23% 26% 34% 15% 2	800
	11th to 20th	Night	28% 20% 29% 20% 3	800
	21st to end	Night	20% 23% 38% 18% 2	880
February	1st to 10th	Night	26% 19% 35% 19% 1	800
	11th to 20th	Night	29% 27% 31% 12% 1	783
	21st to end	Night	27% 22% 33% 15% 2	660
March	1st to 10th	Night	24% 24% 29% 20% 3	800
	11th to 20th	Night	24% 23% 30% 17% 5%	800
	21st to end	Night	22% 19% 37% 17% 4 1	880
April	1st to 10th	Night	23% 24% 31% 18% 4	800
	11th to 20th	Night	20% 18% 34% 22% 6%	791
	21st to end	Night	22% 16% 31% 25% 6%	800
May	1st to 10th	Night	24% 12% 32% 25% 6%	638
	11th to 20th	Night	20% 10% 31% 31% 7%	394
	21st to end	Night	18% 10% 24% 36% 11% 1	433
June	1st to 10th	Night	15% 7% 26% 39% 13%	400
	11th to 20th	Night	14% 6% 31% 39% 11%	400
	21st to end	Night	11% 4 29% 43% 13% 1	400
July	1st to 10th	Night	11% 3 22% 42% 21% 1	390
	11th to 20th	Night	8% 4 21% 40% 25% 3	388
	21st to end	Night	10% 5% 21% 40% 23% 2	525
August	1st to 10th	Night	13% 2 17% 42% 24% 2	597
	11th to 20th	Night	15% 5% 17% 38% 24% 2	731
	21st to end	Night	14% 4 20% 38% 22% 2	880
September	1st to 10th	Night	16% 5% 26% 32% 19% 3	800
	11th to 20th	Night	14% 5% 19% 36% 23% 3	800
	21st to end	Night	21% 8% 22% 30% 18% 1	800
October	1st to 10th	Night	24% 9% 24% 24% 17% 3	800
	11th to 20th	Night	20% 13% 29% 28% 12%	800
	21st to end	Night	23% 14% 30% 25% 9%	880
November	1st to 10th	Night	16% 13% 31% 27% 12% 1	789
	11th to 20th	Night	22% 18% 28% 25% 7% 1	800
	21st to end	Night	20% 20% 33% 22% 7%	800
December	1st to 10th	Night	27% 19% 31% 18% 5% 1	800
	11th to 20th	Night	21% 21% 32% 22% 5%	800
	21st to end	Night	23% 20% 31% 23% 3	880

Page generated at 2025-10-31 02:02:39. Version ac07

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