Fishkill
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Fishkill clear sky chart from 2005-11-06 to 2025-09-19.

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% 3 7% 5% 4 5% 4 5% 7% 38%	126316
	Night	17% 8% 3 7% 4 4 4 3 5% 6% 40%	122725
Transparency	Day	43% 7% 12% 22% 14% 2	129817
	Night	42% 7% 13% 22% 15% 2	127311
Seeing	Day	22% 16% 29% 21% 9% 3	16053
	Night	20% 13% 31% 26% 8% 1	25107

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% 8% 3 8% 4 4 4 4 5% 6% 41%	3597
	11th to 20th	Day	14% 9% 3 9% 5% 4 5% 3 5% 5% 38%	3570
	21st to end	Day	17% 10% 3 8% 4 4 4 3 5% 5% 37%	4215
February	1st to 10th	Day	16% 8% 3 8% 6% 5% 4 4 5% 7% 34%	1800
	11th to 20th	Day	15% 8% 3 7% 6% 4 5% 3 5% 7% 38%	1948
	21st to end	Day	18% 9% 3 6% 4 3 5% 3 4 7% 38%	1650
March	1st to 10th	Day	21% 8% 3 7% 4 3 4 3 4 4 38%	4476
	11th to 20th	Day	12% 7% 2 7% 5% 4 4 4 5% 6% 43%	4742
	21st to end	Day	18% 7% 2 7% 4 4 5% 4 5% 6% 37%	5957
April	1st to 10th	Day	18% 9% 3 6% 5% 4 5% 3 5% 6% 36%	2400
	11th to 20th	Day	18% 7% 2 6% 4 4 4 3 5% 7% 40%	2374
	21st to end	Day	20% 5% 2 6% 5% 4 6% 4 5% 6% 39%	2453
May	1st to 10th	Day	27% 8% 3 6% 4 4 4 4 5% 8% 28%	5886
	11th to 20th	Day	19% 8% 3 7% 5% 4 5% 3 5% 6% 35%	6318
	21st to end	Day	20% 7% 2 5% 4 4 5% 4 6% 8% 35%	6949
June	1st to 10th	Day	17% 6% 2 5% 5% 5% 5% 4 7% 9% 37%	2800
	11th to 20th	Day	15% 7% 3 6% 5% 4 5% 4 6% 10% 36%	2800
	21st to end	Day	13% 5% 3 6% 5% 5% 5% 4 6% 9% 38%	2800
July	1st to 10th	Day	11% 6% 3 8% 6% 5% 6% 5% 6% 9% 36%	6360
	11th to 20th	Day	10% 6% 2 8% 6% 5% 6% 5% 7% 10% 35%	6360
	21st to end	Day	13% 6% 2 7% 4 5% 5% 4 5% 8% 41%	6926
August	1st to 10th	Day	20% 6% 3 6% 5% 4 4 5% 6% 7% 34%	4389
	11th to 20th	Day	11% 6% 3 6% 5% 5% 5% 4 6% 8% 42%	3850
	21st to end	Day	11% 5% 2 6% 4 4 4 4 6% 8% 45%	4312
September	1st to 10th	Day	14% 6% 2 5% 5% 5% 5% 3 5% 7% 44%	2400
	11th to 20th	Day	13% 4 2 5% 4 4 4 4 5% 7% 49%	2287
	21st to end	Day	18% 6% 2 6% 4 4 4 4 5% 6% 42%	2090
October	1st to 10th	Day	19% 6% 2 6% 4 4 4 3 4 6% 41%	1989
	11th to 20th	Day	14% 5% 2 5% 4 5% 5% 3 5% 7% 44%	1900
	21st to end	Day	21% 7% 2 6% 4 4 4 4 5% 6% 37%	1916
November	1st to 10th	Day	13% 6% 2 5% 4 3 4 2 4 6% 50%	1761
	11th to 20th	Day	16% 7% 2 5% 4 3 3 4 5% 7% 44%	1800
	21st to end	Day	17% 7% 2 7% 4 4 4 3 5% 7% 41%	1695
December	1st to 10th	Day	16% 7% 3 7% 4 4 4 4 5% 7% 40%	2600
	11th to 20th	Day	19% 9% 2 5% 4 3 3 3 4 6% 42%	2986
	21st to end	Day	17% 9% 4 8% 5% 4 3 4 5% 7% 34%	3960
January	1st to 10th	Night	14% 7% 3 7% 5% 5% 5% 4 5% 6% 41%	6349
	11th to 20th	Night	13% 8% 3 9% 4 4 5% 4 5% 6% 39%	6315
	21st to end	Night	17% 9% 3 7% 5% 4 4 3 4 6% 37%	6738
February	1st to 10th	Night	14% 11% 3 7% 4 5% 4 3 5% 6% 38%	2599
	11th to 20th	Night	16% 7% 3 8% 5% 4 5% 4 6% 5% 38%	2338
	21st to end	Night	17% 7% 2 8% 5% 3 5% 4 4 5% 39%	1980
March	1st to 10th	Night	19% 9% 3 5% 4 3 3 3 5% 6% 40%	5364
	11th to 20th	Night	12% 9% 3 7% 4 5% 4 4 5% 6% 41%	5214
	21st to end	Night	19% 9% 3 7% 3 4 3 3 4 5% 38%	4973
April	1st to 10th	Night	19% 8% 3 8% 5% 5% 4 4 4 6% 34%	2000
	11th to 20th	Night	19% 8% 2 6% 4 5% 4 3 5% 6% 38%	1975
	21st to end	Night	20% 7% 2 7% 4 3 3 3 5% 5% 41%	1945
May	1st to 10th	Night	31% 8% 2 6% 4 3 4 3 5% 7% 27%	4054
	11th to 20th	Night	21% 8% 3 7% 4 4 4 3 5% 6% 34%	3604
	21st to end	Night	20% 7% 3 6% 4 4 4 4 5% 7% 37%	3926
June	1st to 10th	Night	16% 5% 3 6% 4 4 5% 3 5% 9% 40%	1600
	11th to 20th	Night	14% 7% 2 6% 5% 4 4 4 7% 9% 39%	1600
	21st to end	Night	12% 5% 2 5% 4 4 5% 4 8% 10% 42%	1600
July	1st to 10th	Night	11% 6% 2 7% 5% 4 5% 4 7% 9% 39%	3600
	11th to 20th	Night	13% 6% 3 9% 5% 5% 5% 5% 7% 8% 35%	3600
	21st to end	Night	11% 7% 2 6% 3 4 4 4 5% 6% 47%	3926
August	1st to 10th	Night	20% 6% 2 8% 4 5% 5% 4 5% 8% 33%	2710
	11th to 20th	Night	14% 7% 2 7% 5% 5% 5% 4 5% 6% 41%	3197
	21st to end	Night	12% 5% 1 5% 3 3 4 3 5% 6% 53%	3586
September	1st to 10th	Night	15% 6% 2 6% 4 4 3 3 5% 6% 46%	2000
	11th to 20th	Night	12% 5% 2 5% 3 3 3 3 4 7% 53%	2069
	21st to end	Night	17% 5% 3 5% 4 3 4 3 5% 6% 45%	2090
October	1st to 10th	Night	19% 7% 3 7% 5% 3 4 3 4 5% 41%	2189
	11th to 20th	Night	15% 5% 2 6% 3 4 4 3 5% 7% 47%	2280
	21st to end	Night	21% 6% 2 6% 4 4 4 3 4 6% 39%	2680
November	1st to 10th	Night	12% 6% 3 6% 4 4 4 3 5% 7% 47%	2537
	11th to 20th	Night	17% 8% 2 5% 4 3 3 4 4 5% 44%	2600
	21st to end	Night	16% 7% 2 6% 5% 4 3 4 5% 7% 42%	2703
December	1st to 10th	Night	16% 10% 3 6% 4 4 4 3 4 6% 43%	4580
	11th to 20th	Night	22% 9% 3 6% 4 3 3 3 5% 5% 37%	5208
	21st to end	Night	19% 10% 3 7% 4 4 3 3 5% 5% 36%	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	40% 6% 11% 28% 12% 3	3598
	11th to 20th	Day	46% 6% 10% 22% 12% 5%	3600
	21st to end	Day	47% 6% 9% 23% 14% 1	4215
February	1st to 10th	Day	48% 5% 14% 20% 12% 1	1800
	11th to 20th	Day	45% 6% 11% 22% 14% 2	1957
	21st to end	Day	47% 5% 12% 22% 12% 2	1650
March	1st to 10th	Day	47% 5% 12% 17% 11% 8%	4479
	11th to 20th	Day	36% 8% 15% 28% 9% 4	4742
	21st to end	Day	45% 6% 10% 13% 21% 5%	5957
April	1st to 10th	Day	48% 6% 10% 20% 12% 4	2400
	11th to 20th	Day	43% 6% 12% 20% 16% 2	2374
	21st to end	Day	43% 7% 10% 21% 15% 3	2453
May	1st to 10th	Day	54% 8% 13% 14% 10% 1	5897
	11th to 20th	Day	48% 8% 11% 20% 12% 1	6322
	21st to end	Day	44% 9% 13% 21% 12% 1	6949
June	1st to 10th	Day	42% 8% 14% 21% 13% 1	2800
	11th to 20th	Day	43% 9% 15% 22% 10% 1	2800
	21st to end	Day	41% 9% 12% 24% 12% 1	2800
July	1st to 10th	Day	44% 10% 12% 20% 14% 1	6290
	11th to 20th	Day	40% 10% 17% 22% 11%	6285
	21st to end	Day	41% 6% 12% 22% 18% 1	6728
August	1st to 10th	Day	48% 8% 14% 21% 9% 1	4375
	11th to 20th	Day	37% 8% 17% 29% 9%	3886
	21st to end	Day	34% 7% 13% 31% 15% 1	4312
September	1st to 10th	Day	39% 8% 11% 23% 17% 2	2400
	11th to 20th	Day	34% 7% 10% 25% 23% 2	2287
	21st to end	Day	43% 7% 11% 21% 16% 3	2090
October	1st to 10th	Day	39% 6% 9% 19% 23% 4	3301
	11th to 20th	Day	29% 6% 10% 28% 24% 3	3140
	21st to end	Day	30% 5% 17% 26% 19% 4	3128
November	1st to 10th	Day	36% 5% 13% 26% 18% 2	1761
	11th to 20th	Day	39% 6% 12% 23% 18% 3	1800
	21st to end	Day	42% 6% 14% 26% 10% 2	1695
December	1st to 10th	Day	44% 4 17% 26% 8% 1	2600
	11th to 20th	Day	43% 4 16% 22% 14% 2	2986
	21st to end	Day	48% 7% 9% 20% 14% 2	3960
January	1st to 10th	Night	41% 6% 11% 25% 16% 2	6349
	11th to 20th	Night	42% 6% 16% 19% 12% 5%	6360
	21st to end	Night	46% 5% 11% 18% 16% 4	6738
February	1st to 10th	Night	47% 6% 14% 21% 11% 2	2599
	11th to 20th	Night	45% 6% 11% 19% 15% 3	2340
	21st to end	Night	45% 5% 10% 22% 14% 3	1980
March	1st to 10th	Night	44% 6% 13% 18% 13% 6%	5374
	11th to 20th	Night	40% 8% 16% 23% 10% 3	5215
	21st to end	Night	47% 6% 7% 14% 22% 4	4973
April	1st to 10th	Night	48% 8% 10% 19% 13% 3	2000
	11th to 20th	Night	45% 8% 10% 18% 18% 1	1975
	21st to end	Night	45% 6% 9% 21% 16% 3	1945
May	1st to 10th	Night	56% 8% 13% 12% 9% 1	4060
	11th to 20th	Night	49% 9% 12% 16% 13% 2	3605
	21st to end	Night	45% 8% 14% 22% 9% 1	3927
June	1st to 10th	Night	41% 9% 11% 21% 17% 2	1600
	11th to 20th	Night	39% 9% 18% 23% 10% 1	1600
	21st to end	Night	35% 10% 16% 24% 14% 2	1600
July	1st to 10th	Night	40% 9% 14% 21% 14% 2	3560
	11th to 20th	Night	44% 9% 16% 20% 11% 1	3552
	21st to end	Night	36% 7% 13% 24% 18% 1	3809
August	1st to 10th	Night	49% 9% 15% 18% 9% 1	2700
	11th to 20th	Night	42% 8% 16% 26% 9%	3227
	21st to end	Night	31% 7% 12% 36% 14% 1	3586
September	1st to 10th	Night	38% 7% 10% 27% 17% 1	2000
	11th to 20th	Night	31% 6% 13% 24% 25% 2	2069
	21st to end	Night	39% 7% 11% 21% 21% 1	2090
October	1st to 10th	Night	41% 8% 10% 21% 18% 2	3657
	11th to 20th	Night	28% 5% 10% 29% 26% 3	3779
	21st to end	Night	34% 5% 13% 29% 17% 1	4418
November	1st to 10th	Night	36% 6% 12% 23% 20% 3	2537
	11th to 20th	Night	41% 4 10% 22% 19% 3	2600
	21st to end	Night	40% 6% 15% 28% 10% 1	2703
December	1st to 10th	Night	43% 5% 13% 31% 8%	4580
	11th to 20th	Night	48% 5% 14% 18% 14% 2	5208
	21st to end	Night	48% 6% 12% 17% 15% 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	30% 25% 26% 16% 4	200
	11th to 20th	Day	33% 27% 27% 11% 3	200
	21st to end	Day	22% 27% 35% 12% 2 2	277
February	1st to 10th	Day	33% 26% 29% 10% 1	300
	11th to 20th	Day	30% 24% 33% 12%	496
	21st to end	Day	29% 23% 33% 12% 3	414
March	1st to 10th	Day	30% 19% 32% 15% 3	500
	11th to 20th	Day	26% 25% 31% 14% 4 1	500
	21st to end	Day	30% 22% 31% 12% 3 2	550
April	1st to 10th	Day	33% 21% 27% 12% 6% 1	500
	11th to 20th	Day	27% 25% 27% 13% 7% 1	492
	21st to end	Day	30% 18% 29% 18% 5% 1	500
May	1st to 10th	Day	33% 18% 28% 13% 7% 1	503
	11th to 20th	Day	22% 17% 34% 18% 9% 1	527
	21st to end	Day	19% 14% 28% 24% 12% 3	573
June	1st to 10th	Day	20% 12% 31% 24% 12% 2	530
	11th to 20th	Day	16% 14% 31% 25% 13% 1	530
	21st to end	Day	15% 13% 29% 27% 13% 3	530
July	1st to 10th	Day	13% 8% 31% 28% 15% 5%	525
	11th to 20th	Day	11% 8% 28% 33% 18% 4	524
	21st to end	Day	13% 9% 30% 33% 14% 2	576
August	1st to 10th	Day	14% 9% 25% 31% 16% 5%	526
	11th to 20th	Day	12% 8% 27% 30% 17% 5%	519
	21st to end	Day	11% 9% 30% 28% 15% 7%	583
September	1st to 10th	Day	18% 12% 23% 25% 15% 7%	530
	11th to 20th	Day	13% 8% 29% 24% 15% 11%	522
	21st to end	Day	22% 11% 28% 24% 10% 6%	490
October	1st to 10th	Day	27% 9% 26% 20% 13% 4	490
	11th to 20th	Day	17% 17% 30% 24% 10% 2	490
	21st to end	Day	26% 13% 30% 19% 10% 1	446
November	1st to 10th	Day	18% 17% 28% 24% 10% 2	395
	11th to 20th	Day	25% 19% 30% 20% 6% 1	400
	21st to end	Day	24% 22% 29% 20% 4 1	295
December	1st to 10th	Day	23% 26% 33% 15% 5%	200
	11th to 20th	Day	34% 21% 31% 13% 2	200
	21st to end	Day	23% 23% 32% 16% 6%	220
January	1st to 10th	Night	21% 18% 40% 18% 3	800
	11th to 20th	Night	24% 19% 32% 24% 2	800
	21st to end	Night	18% 19% 38% 22% 3	880
February	1st to 10th	Night	22% 19% 38% 21% 1	800
	11th to 20th	Night	25% 19% 40% 16% 1	783
	21st to end	Night	24% 18% 38% 18% 2	660
March	1st to 10th	Night	24% 21% 33% 20% 3	800
	11th to 20th	Night	22% 22% 34% 19% 4	800
	21st to end	Night	23% 19% 36% 17% 5%	880
April	1st to 10th	Night	24% 21% 33% 19% 4	800
	11th to 20th	Night	24% 17% 31% 24% 4	791
	21st to end	Night	23% 16% 34% 21% 6%	745
May	1st to 10th	Night	25% 16% 31% 22% 5%	600
	11th to 20th	Night	21% 12% 36% 25% 5%	410
	21st to end	Night	18% 7% 27% 39% 9% 1	433
June	1st to 10th	Night	16% 6% 32% 34% 12%	400
	11th to 20th	Night	16% 7% 30% 33% 14% 1	400
	21st to end	Night	12% 6% 26% 42% 14%	400
July	1st to 10th	Night	14% 4 22% 42% 18% 1	390
	11th to 20th	Night	11% 6% 24% 43% 16% 1	388
	21st to end	Night	13% 4 21% 45% 17%	438
August	1st to 10th	Night	12% 3 21% 44% 18% 1	470
	11th to 20th	Night	15% 3 21% 37% 22% 2	790
	21st to end	Night	16% 6% 19% 37% 21% 2	880
September	1st to 10th	Night	17% 5% 26% 35% 15% 2	800
	11th to 20th	Night	15% 6% 24% 32% 20% 4	793
	21st to end	Night	19% 7% 26% 31% 15% 2	760
October	1st to 10th	Night	22% 10% 27% 25% 14% 1	760
	11th to 20th	Night	18% 11% 32% 31% 9% 1	760
	21st to end	Night	26% 11% 31% 25% 7%	836
November	1st to 10th	Night	16% 11% 34% 27% 10% 1	780
	11th to 20th	Night	22% 16% 33% 23% 7% 1	800
	21st to end	Night	20% 16% 33% 24% 7%	800
December	1st to 10th	Night	26% 18% 31% 20% 5%	800
	11th to 20th	Night	25% 15% 32% 24% 4	800
	21st to end	Night	25% 16% 36% 21% 2	880

Page generated at 2025-09-16 01:49:15. Version ac07

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