Voorheesville
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Voorheesville clear sky chart from 2005-11-06 to 2026-03-18.

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% 8% 3 8% 5% 5% 5% 4 6% 7% 34%	131155
	Night	15% 9% 3 8% 5% 5% 5% 4 5% 7% 34%	130359
Transparency	Day	46% 7% 13% 21% 12% 1	134644
	Night	47% 6% 14% 20% 12% 1	134957
Seeing	Day	21% 17% 30% 20% 9% 3	16469
	Night	20% 16% 31% 25% 7% 1	25665

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	10% 9% 5% 14% 7% 7% 7% 5% 5% 6% 24%	4661
	11th to 20th	Day	13% 12% 3 11% 6% 5% 6% 4 6% 7% 26%	4650
	21st to end	Day	12% 11% 4 8% 5% 5% 5% 4 5% 6% 34%	5341
February	1st to 10th	Day	13% 11% 4 9% 7% 5% 6% 5% 6% 6% 28%	1890
	11th to 20th	Day	12% 10% 3 11% 7% 5% 6% 5% 6% 6% 28%	2012
	21st to end	Day	15% 12% 3 9% 6% 5% 4 3 7% 5% 30%	1730
March	1st to 10th	Day	19% 10% 4 9% 4 5% 4 4 5% 5% 31%	4576
	11th to 20th	Day	14% 10% 4 8% 5% 4 4 3 4 6% 38%	4812
	21st to end	Day	17% 10% 2 7% 5% 5% 5% 3 5% 5% 35%	5956
April	1st to 10th	Day	17% 10% 3 7% 6% 5% 4 4 5% 6% 34%	2400
	11th to 20th	Day	16% 9% 3 7% 5% 5% 5% 4 5% 5% 37%	2374
	21st to end	Day	18% 8% 2 7% 5% 5% 5% 4 5% 7% 34%	2480
May	1st to 10th	Day	29% 8% 3 8% 5% 4 4 3 5% 6% 25%	6018
	11th to 20th	Day	14% 8% 3 8% 5% 5% 6% 4 6% 7% 33%	6318
	21st to end	Day	17% 7% 2 7% 5% 5% 5% 5% 7% 9% 31%	6949
June	1st to 10th	Day	14% 6% 2 7% 6% 6% 6% 5% 6% 9% 34%	2800
	11th to 20th	Day	14% 5% 2 7% 5% 5% 6% 5% 7% 10% 35%	2800
	21st to end	Day	14% 7% 2 7% 5% 5% 5% 4 6% 8% 36%	2800
July	1st to 10th	Day	8% 6% 3 8% 6% 6% 6% 5% 8% 10% 35%	6360
	11th to 20th	Day	7% 5% 2 6% 6% 6% 6% 5% 8% 10% 37%	6360
	21st to end	Day	12% 5% 2 6% 5% 5% 5% 4 6% 8% 42%	6926
August	1st to 10th	Day	14% 6% 3 7% 6% 6% 5% 5% 6% 8% 34%	4533
	11th to 20th	Day	11% 6% 3 8% 5% 6% 6% 5% 7% 9% 34%	3852
	21st to end	Day	9% 4 3 6% 4 5% 6% 5% 8% 10% 41%	4312
September	1st to 10th	Day	11% 5% 2 5% 5% 5% 5% 4 5% 8% 44%	2400
	11th to 20th	Day	11% 4 2 5% 4 4 4 3 6% 9% 49%	2314
	21st to end	Day	16% 5% 2 6% 4 4 4 4 7% 8% 40%	2200
October	1st to 10th	Day	16% 8% 3 7% 5% 4 5% 3 5% 6% 37%	2080
	11th to 20th	Day	14% 8% 3 6% 5% 5% 4 3 5% 8% 39%	2000
	21st to end	Day	21% 7% 3 6% 4 5% 5% 3 6% 6% 33%	1997
November	1st to 10th	Day	13% 8% 2 5% 4 4 4 4 6% 6% 43%	1851
	11th to 20th	Day	13% 8% 3 7% 6% 4 4 5% 6% 6% 39%	1890
	21st to end	Day	17% 9% 3 7% 5% 5% 5% 4 6% 6% 33%	1719
December	1st to 10th	Day	13% 12% 5% 11% 6% 6% 6% 4 6% 7% 24%	2680
	11th to 20th	Day	20% 9% 3 7% 5% 4 5% 4 5% 6% 32%	3066
	21st to end	Day	19% 13% 5% 9% 6% 4 4 4 5% 6% 25%	4048
January	1st to 10th	Night	13% 11% 5% 15% 6% 5% 5% 4 5% 6% 26%	8234
	11th to 20th	Night	12% 15% 4 13% 6% 5% 5% 4 5% 7% 25%	8235
	21st to end	Night	13% 9% 3 9% 6% 6% 6% 4 6% 6% 33%	8835
February	1st to 10th	Night	14% 11% 4 9% 7% 5% 5% 3 6% 6% 29%	2730
	11th to 20th	Night	11% 11% 4 11% 6% 5% 5% 4 6% 7% 29%	2492
	21st to end	Night	15% 10% 3 9% 6% 5% 6% 4 6% 7% 30%	2076
March	1st to 10th	Night	19% 9% 4 8% 6% 5% 5% 4 5% 6% 30%	5484
	11th to 20th	Night	15% 9% 3 7% 4 5% 4 4 5% 6% 37%	5297
	21st to end	Night	19% 10% 3 8% 5% 5% 4 3 5% 5% 33%	4974
April	1st to 10th	Night	19% 9% 3 9% 4 5% 5% 4 6% 6% 31%	2000
	11th to 20th	Night	19% 7% 2 7% 5% 5% 4 3 5% 7% 35%	1975
	21st to end	Night	19% 6% 2 6% 4 4 4 4 5% 7% 39%	1918
May	1st to 10th	Night	28% 8% 3 7% 4 5% 5% 3 5% 5% 27%	3965
	11th to 20th	Night	14% 9% 4 9% 6% 6% 5% 4 6% 7% 31%	3575
	21st to end	Night	18% 7% 3 8% 5% 5% 5% 4 6% 7% 32%	3926
June	1st to 10th	Night	15% 8% 3 6% 5% 4 4 5% 6% 7% 39%	1600
	11th to 20th	Night	13% 6% 2 6% 4 4 6% 5% 6% 9% 40%	1600
	21st to end	Night	11% 5% 2 7% 5% 4 5% 4 6% 9% 43%	1600
July	1st to 10th	Night	8% 5% 2 8% 5% 6% 6% 4 7% 8% 42%	3600
	11th to 20th	Night	9% 6% 3 8% 5% 6% 6% 5% 7% 9% 37%	3600
	21st to end	Night	9% 6% 2 7% 4 4 4 4 5% 7% 47%	3926
August	1st to 10th	Night	17% 6% 2 6% 5% 4 4 5% 7% 8% 35%	2613
	11th to 20th	Night	13% 7% 2 7% 5% 4 5% 5% 6% 7% 39%	3161
	21st to end	Night	11% 5% 2 5% 4 3 4 4 6% 8% 47%	3586
September	1st to 10th	Night	12% 6% 3 6% 4 3 4 3 6% 7% 45%	2000
	11th to 20th	Night	13% 4 2 4 4 3 3 3 4 8% 53%	2085
	21st to end	Night	14% 6% 2 6% 5% 5% 4 4 4 7% 44%	2200
October	1st to 10th	Night	17% 8% 2 7% 4 4 5% 4 5% 5% 39%	2317
	11th to 20th	Night	15% 5% 2 6% 4 5% 5% 4 5% 6% 42%	2400
	21st to end	Night	21% 7% 2 6% 5% 4 4 4 6% 6% 35%	2842
November	1st to 10th	Night	15% 7% 3 6% 4 4 4 3 5% 6% 43%	2667
	11th to 20th	Night	15% 8% 3 7% 5% 4 5% 4 5% 6% 38%	2730
	21st to end	Night	15% 8% 3 7% 5% 5% 5% 4 5% 7% 37%	2898
December	1st to 10th	Night	14% 11% 4 9% 5% 5% 5% 4 6% 7% 29%	4720
	11th to 20th	Night	22% 10% 3 6% 5% 4 4 3 5% 5% 32%	5348
	21st to end	Night	21% 13% 5% 9% 5% 4 4 3 5% 5% 27%	7150

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	54% 7% 14% 18% 7%	4662
	11th to 20th	Day	52% 6% 13% 14% 13% 3	4680
	21st to end	Day	49% 5% 11% 22% 13% 1	5341
February	1st to 10th	Day	53% 8% 12% 16% 9% 1	1890
	11th to 20th	Day	53% 7% 12% 18% 9% 1	2021
	21st to end	Day	52% 6% 12% 17% 12% 1	1730
March	1st to 10th	Day	53% 4 12% 15% 10% 5%	4579
	11th to 20th	Day	45% 6% 17% 21% 7% 4	4812
	21st to end	Day	49% 5% 8% 15% 19% 4	5956
April	1st to 10th	Day	50% 5% 10% 21% 12% 2	2400
	11th to 20th	Day	46% 7% 10% 20% 15% 2	2374
	21st to end	Day	48% 7% 11% 18% 13% 3	2480
May	1st to 10th	Day	58% 8% 10% 14% 9% 1	6029
	11th to 20th	Day	47% 7% 16% 20% 9% 1	6322
	21st to end	Day	46% 9% 13% 22% 10% 1	6949
June	1st to 10th	Day	46% 8% 14% 20% 11% 1	2800
	11th to 20th	Day	42% 10% 15% 20% 12% 1	2800
	21st to end	Day	45% 7% 15% 20% 11% 1	2800
July	1st to 10th	Day	41% 10% 14% 21% 13% 1	6290
	11th to 20th	Day	38% 10% 16% 23% 12% 1	6285
	21st to end	Day	38% 8% 14% 28% 13%	6728
August	1st to 10th	Day	46% 9% 15% 20% 10% 1	4519
	11th to 20th	Day	45% 8% 16% 26% 6%	3888
	21st to end	Day	36% 8% 17% 28% 11% 1	4312
September	1st to 10th	Day	37% 8% 13% 26% 15% 1	2400
	11th to 20th	Day	32% 7% 12% 27% 20% 1	2314
	21st to end	Day	40% 7% 13% 24% 13% 2	2200
October	1st to 10th	Day	41% 6% 11% 21% 20% 1	3392
	11th to 20th	Day	36% 4 13% 28% 17% 1	3240
	21st to end	Day	34% 7% 16% 27% 14% 2	3197
November	1st to 10th	Day	41% 6% 14% 25% 13% 1	1851
	11th to 20th	Day	45% 7% 12% 20% 14% 2	1890
	21st to end	Day	49% 7% 16% 19% 7% 1	1719
December	1st to 10th	Day	56% 6% 14% 18% 5%	2680
	11th to 20th	Day	50% 6% 15% 18% 10% 1	3066
	21st to end	Day	57% 5% 12% 16% 10% 1	4048
January	1st to 10th	Night	55% 6% 15% 14% 9% 1	8234
	11th to 20th	Night	56% 5% 14% 12% 10% 3	8280
	21st to end	Night	49% 5% 13% 15% 15% 3	8835
February	1st to 10th	Night	52% 7% 13% 19% 8% 1	2730
	11th to 20th	Night	51% 8% 13% 18% 9% 1	2494
	21st to end	Night	51% 6% 14% 18% 9% 2	2076
March	1st to 10th	Night	51% 6% 14% 15% 12% 2	5494
	11th to 20th	Night	47% 6% 17% 21% 8% 2	5298
	21st to end	Night	51% 4 8% 16% 17% 3	4974
April	1st to 10th	Night	52% 6% 12% 19% 11% 1	2000
	11th to 20th	Night	47% 7% 11% 18% 16% 1	1975
	21st to end	Night	44% 7% 13% 18% 15% 3	1918
May	1st to 10th	Night	59% 6% 12% 12% 9% 2	3971
	11th to 20th	Night	51% 8% 13% 19% 9% 1	3576
	21st to end	Night	50% 8% 13% 18% 11% 1	3927
June	1st to 10th	Night	43% 7% 13% 24% 13% 2	1600
	11th to 20th	Night	39% 9% 16% 23% 12%	1600
	21st to end	Night	36% 9% 16% 25% 13% 1	1600
July	1st to 10th	Night	38% 7% 16% 22% 16% 1	3560
	11th to 20th	Night	40% 9% 16% 21% 13% 1	3552
	21st to end	Night	35% 6% 13% 31% 14% 1	3809
August	1st to 10th	Night	44% 8% 17% 22% 9% 1	2603
	11th to 20th	Night	41% 7% 17% 26% 9%	3191
	21st to end	Night	32% 7% 14% 35% 12% 1	3586
September	1st to 10th	Night	38% 6% 13% 27% 16% 1	2000
	11th to 20th	Night	31% 5% 14% 26% 23% 1	2085
	21st to end	Night	40% 6% 13% 24% 17% 1	2200
October	1st to 10th	Night	45% 5% 13% 21% 15% 1	3785
	11th to 20th	Night	32% 5% 14% 26% 22% 1	3899
	21st to end	Night	38% 6% 15% 30% 12% 1	4592
November	1st to 10th	Night	41% 6% 12% 22% 17% 2	2667
	11th to 20th	Night	45% 7% 12% 21% 13% 2	2730
	21st to end	Night	46% 7% 17% 22% 8%	2898
December	1st to 10th	Night	50% 7% 15% 22% 6%	4720
	11th to 20th	Night	52% 6% 15% 13% 13% 1	5348
	21st to end	Night	58% 5% 11% 14% 10% 1	7150

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	26% 27% 31% 12% 4	220
	11th to 20th	Day	33% 30% 23% 13% 1	220
	21st to end	Day	24% 29% 33% 10% 4	281
February	1st to 10th	Day	32% 26% 30% 10% 1	330
	11th to 20th	Day	30% 26% 33% 9% 1	500
	21st to end	Day	27% 25% 32% 14% 2	446
March	1st to 10th	Day	28% 23% 32% 15% 2	540
	11th to 20th	Day	28% 26% 29% 13% 3 1	528
	21st to end	Day	31% 25% 26% 13% 4 1	550
April	1st to 10th	Day	32% 25% 25% 13% 5% 1	500
	11th to 20th	Day	28% 27% 25% 13% 6% 1	492
	21st to end	Day	29% 21% 31% 13% 5% 1	500
May	1st to 10th	Day	31% 18% 29% 14% 5% 2	503
	11th to 20th	Day	17% 19% 33% 22% 7% 2	527
	21st to end	Day	17% 13% 31% 26% 11% 3	573
June	1st to 10th	Day	16% 17% 31% 23% 11% 2	530
	11th to 20th	Day	16% 14% 31% 25% 12% 2	530
	21st to end	Day	15% 15% 33% 25% 9% 2	530
July	1st to 10th	Day	11% 10% 30% 32% 14% 4	525
	11th to 20th	Day	11% 8% 31% 32% 15% 3	524
	21st to end	Day	12% 8% 35% 28% 14% 3	576
August	1st to 10th	Day	10% 7% 28% 32% 18% 5%	526
	11th to 20th	Day	13% 6% 27% 30% 17% 5%	519
	21st to end	Day	11% 12% 27% 28% 16% 5%	583
September	1st to 10th	Day	15% 9% 29% 22% 18% 7%	530
	11th to 20th	Day	12% 9% 25% 22% 20% 12%	530
	21st to end	Day	18% 12% 25% 27% 13% 6%	530
October	1st to 10th	Day	22% 12% 25% 22% 14% 5%	530
	11th to 20th	Day	18% 19% 30% 22% 9% 2	530
	21st to end	Day	26% 14% 33% 19% 7%	470
November	1st to 10th	Day	26% 17% 25% 21% 9% 1	425
	11th to 20th	Day	24% 22% 30% 18% 5% 1	430
	21st to end	Day	28% 25% 25% 20% 2	259
December	1st to 10th	Day	26% 22% 31% 16% 5%	220
	11th to 20th	Day	33% 21% 35% 9% 2	220
	21st to end	Day	23% 25% 37% 12% 3	242
January	1st to 10th	Night	22% 21% 36% 19% 2	840
	11th to 20th	Night	25% 20% 33% 19% 3	840
	21st to end	Night	18% 21% 40% 18% 2	924
February	1st to 10th	Night	22% 21% 38% 18% 2	840
	11th to 20th	Night	22% 22% 38% 17%	823
	21st to end	Night	25% 22% 34% 18% 2	692
March	1st to 10th	Night	24% 22% 35% 17% 2	840
	11th to 20th	Night	24% 24% 33% 17% 2	829
	21st to end	Night	22% 24% 33% 17% 4	880
April	1st to 10th	Night	25% 23% 32% 17% 3	800
	11th to 20th	Night	23% 21% 32% 18% 5%	791
	21st to end	Night	21% 21% 32% 21% 4	718
May	1st to 10th	Night	25% 17% 30% 22% 5% 1	563
	11th to 20th	Night	17% 16% 37% 24% 6% 1	394
	21st to end	Night	15% 9% 30% 36% 9% 1	433
June	1st to 10th	Night	17% 9% 35% 29% 10% 1	400
	11th to 20th	Night	17% 8% 33% 33% 10%	400
	21st to end	Night	11% 7% 33% 38% 10% 1	400
July	1st to 10th	Night	11% 5% 29% 39% 16% 1	390
	11th to 20th	Night	12% 7% 22% 42% 16% 1	388
	21st to end	Night	11% 5% 29% 42% 13%	438
August	1st to 10th	Night	13% 3 25% 39% 20% 1	412
	11th to 20th	Night	12% 5% 24% 36% 18% 4	766
	21st to end	Night	15% 7% 24% 35% 19% 1	880
September	1st to 10th	Night	14% 7% 27% 34% 17% 1	800
	11th to 20th	Night	14% 7% 24% 30% 19% 5%	800
	21st to end	Night	17% 7% 28% 34% 13% 1	800
October	1st to 10th	Night	21% 11% 26% 27% 15% 2	800
	11th to 20th	Night	19% 13% 30% 30% 8%	800
	21st to end	Night	25% 14% 31% 26% 4	880
November	1st to 10th	Night	20% 16% 30% 26% 7%	820
	11th to 20th	Night	20% 19% 33% 21% 6% 1	840
	21st to end	Night	21% 19% 31% 24% 5%	840
December	1st to 10th	Night	25% 19% 35% 18% 3	840
	11th to 20th	Night	27% 17% 33% 20% 3	840
	21st to end	Night	29% 20% 31% 19% 2	924

Page generated at 2026-03-15 02:23:54. Version ac07

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