Wyalusing
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Wyalusing clear sky chart from 2005-11-06 to 2025-12-03.

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	13% 9% 3 8% 5% 4 4 4 5% 7% 38%	127516
	Night	13% 9% 4 8% 5% 4 4 3 5% 6% 39%	123450
Transparency	Day	44% 6% 12% 24% 12% 1	131043
	Night	45% 5% 12% 23% 14% 2	127998
Seeing	Day	17% 12% 29% 25% 12% 4	17385
	Night	17% 10% 31% 30% 11% 1	27238

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	6% 11% 7% 19% 8% 8% 5% 4 4 4 25%	3617
	11th to 20th	Day	7% 9% 7% 11% 8% 5% 6% 8% 7% 6% 25%	3620
	21st to end	Day	12% 17% 6% 9% 4 2 4 3 4 6% 33%	4424
February	1st to 10th	Day	11% 12% 5% 9% 6% 5% 5% 4 6% 7% 30%	1800
	11th to 20th	Day	14% 11% 4 7% 4 4 5% 3 6% 6% 35%	1789
	21st to end	Day	12% 12% 4 11% 5% 4 3 3 4 6% 36%	1650
March	1st to 10th	Day	16% 7% 3 5% 3 3 3 2 4 5% 48%	4572
	11th to 20th	Day	12% 6% 2 6% 4 4 4 3 6% 7% 45%	4980
	21st to end	Day	23% 13% 3 10% 4 3 3 3 4 5% 28%	5725
April	1st to 10th	Day	20% 12% 3 6% 5% 4 4 3 5% 6% 32%	2400
	11th to 20th	Day	17% 12% 4 7% 5% 5% 4 3 5% 6% 33%	2374
	21st to end	Day	20% 10% 3 7% 4 4 5% 3 5% 6% 33%	2405
May	1st to 10th	Day	14% 8% 2 7% 5% 4 5% 4 6% 7% 40%	6244
	11th to 20th	Day	15% 6% 2 6% 4 4 4 3 5% 7% 43%	6319
	21st to end	Day	17% 7% 2 6% 5% 4 5% 4 5% 7% 38%	6935
June	1st to 10th	Day	11% 5% 2 6% 4 5% 5% 4 6% 9% 45%	2800
	11th to 20th	Day	12% 6% 3 6% 5% 4 4 4 6% 8% 42%	2800
	21st to end	Day	12% 7% 3 7% 5% 5% 5% 4 6% 8% 39%	2800
July	1st to 10th	Day	8% 6% 3 7% 5% 5% 6% 5% 8% 9% 39%	6360
	11th to 20th	Day	9% 5% 3 6% 3 4 4 4 6% 8% 48%	6360
	21st to end	Day	9% 7% 3 7% 5% 5% 5% 5% 7% 8% 38%	6924
August	1st to 10th	Day	8% 7% 3 7% 5% 5% 5% 5% 7% 9% 40%	4272
	11th to 20th	Day	12% 5% 2 6% 4 4 5% 4 6% 8% 45%	4082
	21st to end	Day	8% 5% 2 6% 4 4 5% 4 6% 9% 47%	4312
September	1st to 10th	Day	14% 5% 2 5% 4 4 4 3 5% 8% 46%	2400
	11th to 20th	Day	11% 6% 2 6% 4 3 4 4 6% 9% 46%	2400
	21st to end	Day	13% 6% 2 5% 4 4 4 4 6% 6% 46%	2130
October	1st to 10th	Day	14% 6% 2 6% 4 3 3 2 5% 7% 48%	2000
	11th to 20th	Day	18% 9% 2 7% 4 4 4 4 4 6% 39%	2000
	21st to end	Day	16% 12% 3 6% 4 4 3 3 4 6% 40%	2110
November	1st to 10th	Day	11% 9% 2 8% 5% 4 4 4 6% 6% 43%	1852
	11th to 20th	Day	14% 13% 4 9% 4 4 4 4 5% 6% 34%	1764
	21st to end	Day	13% 14% 4 7% 5% 3 3 2 6% 7% 36%	1680
December	1st to 10th	Day	8% 10% 4 10% 6% 4 5% 4 6% 7% 36%	2626
	11th to 20th	Day	15% 15% 4 11% 7% 5% 5% 4 6% 6% 22%	3008
	21st to end	Day	19% 23% 9% 13% 4 4 3 2 3 4 15%	3982
January	1st to 10th	Night	7% 10% 7% 17% 8% 6% 4 3 4 5% 28%	6348
	11th to 20th	Night	10% 14% 5% 13% 6% 5% 5% 5% 7% 6% 23%	6360
	21st to end	Night	12% 14% 6% 9% 6% 4 4 3 4 5% 32%	6536
February	1st to 10th	Night	10% 14% 6% 10% 6% 4 6% 4 4 5% 33%	2600
	11th to 20th	Night	11% 10% 3 9% 5% 4 4 3 4 6% 41%	2496
	21st to end	Night	14% 10% 4 8% 4 4 4 3 4 5% 38%	1980
March	1st to 10th	Night	15% 9% 4 7% 4 3 3 3 4 4 45%	5312
	11th to 20th	Night	10% 7% 2 6% 4 4 4 3 6% 7% 48%	4980
	21st to end	Night	24% 12% 4 10% 5% 4 4 3 4 4 27%	5203
April	1st to 10th	Night	15% 11% 3 7% 5% 3 3 3 6% 6% 39%	2000
	11th to 20th	Night	18% 9% 3 5% 4 4 4 4 5% 6% 39%	1975
	21st to end	Night	19% 8% 3 7% 4 4 4 4 5% 7% 37%	1990
May	1st to 10th	Night	16% 7% 2 6% 4 3 4 3 6% 7% 42%	3670
	11th to 20th	Night	11% 6% 2 5% 4 4 4 4 5% 7% 48%	3596
	21st to end	Night	15% 7% 2 5% 4 4 4 3 6% 7% 43%	3942
June	1st to 10th	Night	10% 6% 2 6% 5% 4 4 4 6% 7% 47%	1600
	11th to 20th	Night	10% 6% 2 7% 4 4 4 4 7% 9% 44%	1600
	21st to end	Night	11% 5% 1 5% 5% 4 5% 3 6% 7% 48%	1600
July	1st to 10th	Night	9% 7% 2 6% 4 4 4 4 7% 10% 44%	3618
	11th to 20th	Night	6% 4 2 5% 3 4 4 4 6% 9% 53%	3617
	21st to end	Night	7% 6% 2 6% 4 4 5% 4 6% 7% 48%	3947
August	1st to 10th	Night	9% 5% 1 5% 4 4 5% 4 5% 8% 50%	2884
	11th to 20th	Night	9% 4 2 6% 4 4 4 3 4 8% 52%	2973
	21st to end	Night	10% 6% 2 5% 3 3 4 3 5% 7% 51%	3586
September	1st to 10th	Night	10% 5% 2 5% 3 4 4 3 5% 7% 54%	2000
	11th to 20th	Night	13% 4 1 4 4 4 4 3 6% 6% 52%	2000
	21st to end	Night	10% 4 2 4 4 3 4 3 4 7% 54%	2246
October	1st to 10th	Night	11% 7% 2 4 3 3 3 3 4 6% 52%	2400
	11th to 20th	Night	16% 7% 3 6% 3 4 4 3 5% 7% 44%	2400
	21st to end	Night	17% 10% 3 6% 4 3 4 3 5% 6% 39%	2730
November	1st to 10th	Night	13% 8% 3 6% 4 4 4 3 5% 5% 46%	2666
	11th to 20th	Night	14% 12% 5% 8% 6% 4 4 3 5% 5% 35%	2851
	21st to end	Night	15% 11% 4 8% 5% 4 3 3 4 5% 36%	2940
December	1st to 10th	Night	7% 8% 3 8% 6% 6% 4 4 6% 7% 40%	4609
	11th to 20th	Night	15% 16% 5% 11% 5% 4 4 3 5% 5% 27%	5199
	21st to end	Night	21% 18% 7% 14% 6% 5% 4 3 4 4 15%	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	63% 5% 10% 16% 6%	3618
	11th to 20th	Day	53% 7% 12% 12% 16%	3620
	21st to end	Day	53% 5% 14% 17% 10%	4424
February	1st to 10th	Day	53% 6% 13% 18% 10% 1	1800
	11th to 20th	Day	47% 6% 10% 25% 9% 1	1798
	21st to end	Day	51% 6% 10% 21% 10% 2	1650
March	1st to 10th	Day	39% 5% 12% 29% 12% 4	4572
	11th to 20th	Day	37% 5% 13% 33% 12% 1	4980
	21st to end	Day	58% 6% 11% 16% 8% 1	5727
April	1st to 10th	Day	52% 6% 11% 22% 9%	2400
	11th to 20th	Day	52% 5% 10% 21% 10% 2	2374
	21st to end	Day	51% 7% 11% 19% 11% 1	2405
May	1st to 10th	Day	43% 6% 9% 23% 18% 2	6284
	11th to 20th	Day	39% 7% 11% 29% 12% 2	6323
	21st to end	Day	43% 7% 10% 28% 12% 1	6949
June	1st to 10th	Day	35% 8% 14% 27% 15% 1	2800
	11th to 20th	Day	40% 7% 13% 23% 17% 1	2800
	21st to end	Day	41% 8% 13% 24% 13% 2	2800
July	1st to 10th	Day	38% 7% 15% 31% 8% 1	6291
	11th to 20th	Day	33% 7% 13% 31% 15% 1	6285
	21st to end	Day	41% 9% 13% 20% 16% 1	6728
August	1st to 10th	Day	38% 8% 14% 25% 13% 1	4257
	11th to 20th	Day	36% 7% 12% 31% 13% 1	4121
	21st to end	Day	32% 6% 15% 31% 14% 1	4311
September	1st to 10th	Day	35% 7% 13% 25% 17% 2	2400
	11th to 20th	Day	35% 7% 12% 30% 15% 1	2400
	21st to end	Day	38% 6% 11% 29% 16% 1	2130
October	1st to 10th	Day	24% 3 7% 40% 24% 1	3260
	11th to 20th	Day	35% 5% 10% 27% 20% 3	3240
	21st to end	Day	42% 3 11% 29% 13% 2	3387
November	1st to 10th	Day	41% 5% 14% 25% 13% 2	1852
	11th to 20th	Day	52% 5% 12% 21% 9% 1	1764
	21st to end	Day	49% 5% 16% 23% 6%	1680
December	1st to 10th	Day	47% 6% 18% 22% 6% 1	2626
	11th to 20th	Day	62% 6% 14% 13% 6% 1	3005
	21st to end	Day	74% 4 8% 10% 3	3982
January	1st to 10th	Night	57% 5% 11% 19% 7% 1	6348
	11th to 20th	Night	58% 5% 11% 12% 13%	6360
	21st to end	Night	55% 4 12% 18% 10% 1	6536
February	1st to 10th	Night	53% 5% 11% 18% 11% 1	2600
	11th to 20th	Night	46% 5% 12% 23% 12% 1	2497
	21st to end	Night	46% 6% 13% 21% 12% 2	1980
March	1st to 10th	Night	44% 4 11% 24% 13% 5%	5312
	11th to 20th	Night	34% 5% 11% 31% 16% 2	4980
	21st to end	Night	61% 5% 10% 14% 9% 1	5203
April	1st to 10th	Night	45% 6% 11% 22% 15% 1	2000
	11th to 20th	Night	46% 6% 9% 22% 14% 3	1975
	21st to end	Night	47% 6% 11% 20% 13% 3	1990
May	1st to 10th	Night	40% 6% 10% 22% 21% 1	3694
	11th to 20th	Night	34% 7% 12% 24% 18% 4	3597
	21st to end	Night	38% 8% 10% 29% 13% 1	3950
June	1st to 10th	Night	35% 7% 13% 27% 17% 2	1600
	11th to 20th	Night	36% 6% 13% 23% 20% 3	1600
	21st to end	Night	34% 8% 14% 24% 17% 4	1600
July	1st to 10th	Night	35% 6% 17% 27% 13% 2	3580
	11th to 20th	Night	28% 7% 14% 33% 17% 1	3572
	21st to end	Night	33% 7% 19% 20% 19% 2	3832
August	1st to 10th	Night	32% 7% 14% 28% 18% 1	2875
	11th to 20th	Night	32% 6% 14% 31% 15% 1	3000
	21st to end	Night	32% 6% 13% 27% 18% 3	3586
September	1st to 10th	Night	30% 7% 10% 28% 25% 1	2000
	11th to 20th	Night	32% 6% 12% 32% 17% 2	2000
	21st to end	Night	30% 6% 11% 29% 23% 1	2246
October	1st to 10th	Night	24% 4 6% 35% 29% 2	3920
	11th to 20th	Night	31% 5% 10% 23% 29% 2	3899
	21st to end	Night	45% 4 9% 24% 16% 1	4403
November	1st to 10th	Night	39% 5% 14% 23% 17% 2	2666
	11th to 20th	Night	52% 5% 12% 19% 10% 1	2851
	21st to end	Night	50% 5% 13% 24% 8% 1	2940
December	1st to 10th	Night	43% 5% 19% 25% 7% 1	4609
	11th to 20th	Night	59% 6% 13% 16% 6%	5201
	21st to end	Night	73% 5% 8% 11% 3	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	17% 15% 34% 23% 9% 2	300
	11th to 20th	Day	18% 19% 41% 17% 5%	300
	21st to end	Day	21% 18% 36% 22% 3	330
February	1st to 10th	Day	18% 19% 44% 15% 4 1	300
	11th to 20th	Day	21% 24% 32% 18% 5% 1	300
	21st to end	Day	23% 19% 39% 16% 3	249
March	1st to 10th	Day	16% 22% 42% 16% 5%	300
	11th to 20th	Day	21% 16% 38% 19% 5% 1	300
	21st to end	Day	29% 16% 31% 18% 5% 1	438
April	1st to 10th	Day	31% 14% 33% 16% 5%	500
	11th to 20th	Day	24% 21% 24% 22% 8% 1	492
	21st to end	Day	24% 16% 30% 19% 10% 2	505
May	1st to 10th	Day	20% 14% 32% 23% 9% 2	703
	11th to 20th	Day	22% 15% 26% 25% 9% 3	725
	21st to end	Day	20% 10% 26% 25% 14% 5%	789
June	1st to 10th	Day	11% 8% 28% 33% 16% 4	730
	11th to 20th	Day	16% 9% 29% 30% 12% 3	730
	21st to end	Day	15% 9% 32% 28% 13% 4	730
July	1st to 10th	Day	9% 5% 21% 30% 22% 13%	721
	11th to 20th	Day	10% 6% 27% 31% 19% 7%	718
	21st to end	Day	7% 5% 26% 36% 20% 6%	794
August	1st to 10th	Day	8% 3 24% 33% 22% 10%	726
	11th to 20th	Day	15% 7% 18% 28% 22% 10%	665
	21st to end	Day	9% 6% 26% 31% 20% 8%	583
September	1st to 10th	Day	15% 9% 22% 29% 20% 5%	530
	11th to 20th	Day	12% 4 21% 36% 20% 6%	530
	21st to end	Day	18% 10% 28% 26% 15% 4	448
October	1st to 10th	Day	18% 9% 31% 27% 13% 2	330
	11th to 20th	Day	27% 17% 33% 17% 6%	330
	21st to end	Day	27% 16% 31% 18% 6% 2	363
November	1st to 10th	Day	18% 18% 37% 18% 7% 2	330
	11th to 20th	Day	21% 24% 30% 18% 7% 1	330
	21st to end	Day	24% 17% 37% 18% 5%	330
December	1st to 10th	Day	17% 19% 39% 18% 6% 1	306
	11th to 20th	Day	21% 15% 36% 19% 8% 1	300
	21st to end	Day	28% 12% 41% 15% 4	330
January	1st to 10th	Night	13% 16% 38% 26% 8%	1000
	11th to 20th	Night	19% 12% 36% 27% 5%	1000
	21st to end	Night	20% 12% 37% 27% 5%	1100
February	1st to 10th	Night	18% 14% 38% 25% 6%	1000
	11th to 20th	Night	15% 16% 39% 24% 6%	942
	21st to end	Night	21% 13% 39% 23% 3	660
March	1st to 10th	Night	22% 13% 35% 24% 6%	778
	11th to 20th	Night	17% 12% 35% 29% 7% 1	600
	21st to end	Night	24% 11% 32% 27% 5% 1	660
April	1st to 10th	Night	20% 14% 36% 26% 5%	600
	11th to 20th	Night	22% 12% 32% 29% 5%	593
	21st to end	Night	22% 10% 33% 28% 7% 1	600
May	1st to 10th	Night	19% 8% 33% 31% 7% 1	600
	11th to 20th	Night	17% 8% 30% 34% 9% 1	591
	21st to end	Night	16% 5% 29% 35% 15% 1	650
June	1st to 10th	Night	11% 4 29% 44% 11% 1	600
	11th to 20th	Night	12% 5% 30% 41% 12% 1	600
	21st to end	Night	13% 5% 27% 40% 14% 1	600
July	1st to 10th	Night	7% 2 17% 41% 31% 3	585
	11th to 20th	Night	8% 3 20% 44% 21% 4	582
	21st to end	Night	8% 2 17% 47% 24% 2	657
August	1st to 10th	Night	8% 3 16% 46% 27% 1	597
	11th to 20th	Night	10% 2 15% 42% 25% 6%	594
	21st to end	Night	11% 2 18% 43% 23% 3	660
September	1st to 10th	Night	13% 5% 21% 36% 21% 5%	600
	11th to 20th	Night	14% 3 20% 35% 25% 3	600
	21st to end	Night	12% 8% 26% 34% 19% 1	767
October	1st to 10th	Night	15% 7% 28% 33% 16% 2	800
	11th to 20th	Night	19% 11% 34% 27% 9%	800
	21st to end	Night	22% 12% 30% 30% 6%	880
November	1st to 10th	Night	18% 10% 36% 26% 9% 1	820
	11th to 20th	Night	20% 15% 40% 21% 5%	961
	21st to end	Night	22% 14% 34% 23% 7%	1050
December	1st to 10th	Night	17% 14% 39% 24% 5% 1	1011
	11th to 20th	Night	23% 12% 34% 25% 6%	1000
	21st to end	Night	27% 13% 32% 24% 3	1100

Page generated at 2025-11-30 00:00:54. Version ac07

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