Tuckahoe State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Tuckahoe State Park clear sky chart from 2005-11-06 to 2025-09-04.

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% 6% 2 6% 4 4 4 4 6% 8% 43%	126067
	Night	14% 7% 2 6% 4 4 4 4 5% 7% 44%	122688
Transparency	Day	37% 7% 12% 24% 17% 3	129653
	Night	38% 6% 12% 23% 18% 4	127171
Seeing	Day	17% 11% 27% 25% 15% 5%	16133
	Night	17% 10% 29% 31% 12% 1	25487

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	14% 4 2 5% 3 3 3 3 5% 6% 53%	3597
	11th to 20th	Day	14% 8% 3 7% 4 4 3 3 3 4 47%	3942
	21st to end	Day	16% 6% 2 6% 4 4 4 3 4 5% 45%	4466
February	1st to 10th	Day	15% 7% 3 6% 5% 4 4 4 6% 7% 41%	1800
	11th to 20th	Day	19% 7% 2 4 3 4 5% 3 5% 5% 43%	1886
	21st to end	Day	17% 9% 2 5% 5% 4 4 3 4 6% 41%	1650
March	1st to 10th	Day	19% 5% 1 4 3 3 3 3 4 6% 47%	4632
	11th to 20th	Day	10% 6% 2 5% 4 4 4 3 5% 6% 51%	4980
	21st to end	Day	17% 6% 2 6% 4 4 4 3 4 6% 44%	5708
April	1st to 10th	Day	14% 6% 3 6% 4 3 5% 4 5% 6% 45%	2400
	11th to 20th	Day	12% 6% 2 4 4 3 4 4 6% 8% 47%	2374
	21st to end	Day	15% 6% 2 5% 3 3 4 4 6% 7% 45%	2400
May	1st to 10th	Day	20% 8% 3 6% 4 4 4 4 6% 8% 34%	5611
	11th to 20th	Day	20% 7% 3 7% 4 4 4 4 6% 8% 33%	6318
	21st to end	Day	15% 6% 2 6% 4 4 5% 4 6% 9% 40%	6934
June	1st to 10th	Day	10% 6% 2 6% 5% 4 5% 4 7% 10% 42%	2800
	11th to 20th	Day	11% 5% 2 5% 4 4 5% 5% 7% 10% 44%	2800
	21st to end	Day	9% 4 2 4 4 3 5% 5% 7% 11% 47%	2800
July	1st to 10th	Day	7% 4 2 6% 4 5% 5% 5% 7% 11% 44%	6360
	11th to 20th	Day	10% 6% 2 7% 5% 6% 6% 6% 9% 12% 32%	6360
	21st to end	Day	8% 5% 2 6% 5% 5% 6% 5% 8% 11% 40%	6521
August	1st to 10th	Day	15% 6% 2 6% 4 4 5% 4 7% 11% 36%	4234
	11th to 20th	Day	9% 5% 2 6% 5% 5% 5% 4 6% 9% 42%	3864
	21st to end	Day	7% 5% 2 5% 4 4 5% 4 7% 9% 49%	4312
September	1st to 10th	Day	12% 6% 2 5% 4 5% 4 3 6% 6% 46%	2316
	11th to 20th	Day	10% 6% 3 5% 4 3 4 4 5% 8% 48%	2280
	21st to end	Day	18% 9% 3 6% 4 3 4 4 4 6% 38%	2043
October	1st to 10th	Day	15% 5% 2 6% 4 4 4 3 4 7% 46%	1900
	11th to 20th	Day	15% 5% 2 4 4 3 3 2 5% 6% 52%	1900
	21st to end	Day	14% 5% 2 5% 4 4 3 2 4 5% 51%	2090
November	1st to 10th	Day	12% 5% 1 4 4 4 3 4 5% 6% 52%	1766
	11th to 20th	Day	13% 6% 2 5% 3 3 4 3 6% 7% 48%	1800
	21st to end	Day	14% 6% 2 5% 4 3 4 3 4 6% 49%	1673
December	1st to 10th	Day	12% 5% 1 6% 4 4 4 3 5% 7% 50%	2600
	11th to 20th	Day	19% 8% 3 5% 3 3 3 3 4 6% 44%	2990
	21st to end	Day	13% 7% 2 5% 4 4 4 3 6% 7% 44%	3960
January	1st to 10th	Night	13% 7% 3 5% 4 4 4 4 4 5% 49%	6349
	11th to 20th	Night	14% 6% 2 5% 3 3 3 3 4 5% 52%	6015
	21st to end	Night	15% 8% 2 5% 3 3 4 2 4 5% 47%	6490
February	1st to 10th	Night	16% 7% 2 6% 4 4 5% 4 5% 6% 41%	2600
	11th to 20th	Night	20% 7% 2 5% 4 4 3 3 4 5% 42%	2398
	21st to end	Night	17% 7% 2 5% 4 4 4 3 4 6% 44%	1980
March	1st to 10th	Night	16% 7% 2 5% 4 3 3 3 4 5% 48%	5218
	11th to 20th	Night	11% 6% 2 5% 3 3 4 4 5% 7% 49%	4980
	21st to end	Night	14% 7% 2 6% 4 3 4 3 5% 5% 45%	5222
April	1st to 10th	Night	15% 8% 2 6% 4 5% 4 3 5% 6% 42%	2000
	11th to 20th	Night	12% 6% 2 6% 5% 4 5% 3 5% 6% 46%	1975
	21st to end	Night	16% 5% 2 5% 3 4 5% 4 6% 7% 44%	2000
May	1st to 10th	Night	16% 9% 2 7% 5% 5% 5% 4 7% 8% 31%	4324
	11th to 20th	Night	19% 9% 3 6% 4 5% 5% 4 6% 8% 33%	3575
	21st to end	Night	17% 7% 2 6% 4 4 4 4 6% 8% 38%	3920
June	1st to 10th	Night	11% 7% 2 6% 4 5% 6% 4 6% 9% 43%	1600
	11th to 20th	Night	9% 6% 2 7% 5% 4 5% 4 7% 9% 41%	1600
	21st to end	Night	9% 5% 1 6% 5% 5% 5% 5% 8% 10% 40%	1600
July	1st to 10th	Night	9% 6% 2 7% 5% 5% 6% 5% 7% 10% 39%	3598
	11th to 20th	Night	11% 7% 3 8% 5% 5% 5% 4 8% 11% 32%	3597
	21st to end	Night	10% 7% 2 6% 4 4 6% 4 6% 9% 41%	4326
August	1st to 10th	Night	16% 7% 3 7% 4 5% 5% 4 6% 10% 33%	2915
	11th to 20th	Night	11% 6% 3 7% 5% 5% 4 4 6% 9% 39%	3151
	21st to end	Night	8% 5% 2 6% 4 4 4 4 6% 7% 50%	3586
September	1st to 10th	Night	13% 6% 3 5% 4 3 4 3 5% 8% 46%	1931
	11th to 20th	Night	9% 5% 2 6% 4 3 3 3 5% 9% 51%	1900
	21st to end	Night	17% 7% 3 5% 4 4 5% 3 4 6% 40%	2133
October	1st to 10th	Night	16% 8% 3 6% 4 4 3 3 4 5% 45%	2280
	11th to 20th	Night	15% 5% 2 5% 3 3 3 3 4 5% 53%	2280
	21st to end	Night	15% 6% 2 5% 3 3 3 3 4 7% 49%	2508
November	1st to 10th	Night	11% 5% 3 5% 3 3 4 3 5% 6% 53%	2531
	11th to 20th	Night	15% 7% 3 5% 4 3 4 3 4 5% 48%	2600
	21st to end	Night	12% 6% 2 4 4 4 4 4 6% 6% 48%	2725
December	1st to 10th	Night	11% 6% 2 5% 3 3 4 3 5% 7% 52%	4580
	11th to 20th	Night	20% 6% 2 5% 4 4 4 3 5% 7% 39%	5205
	21st to end	Night	14% 8% 3 7% 4 4 4 4 5% 7% 41%	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	32% 4 8% 27% 25% 4	3598
	11th to 20th	Day	42% 4 8% 22% 18% 6%	3942
	21st to end	Day	41% 4 11% 28% 14% 3	4466
February	1st to 10th	Day	41% 7% 14% 24% 13% 2	1800
	11th to 20th	Day	42% 5% 9% 25% 17% 2	1895
	21st to end	Day	44% 4 11% 21% 15% 4	1650
March	1st to 10th	Day	38% 4 9% 23% 19% 7%	4632
	11th to 20th	Day	32% 6% 10% 26% 19% 6%	4980
	21st to end	Day	42% 5% 8% 18% 21% 6%	5708
April	1st to 10th	Day	39% 6% 12% 21% 17% 6%	2400
	11th to 20th	Day	35% 6% 11% 23% 18% 6%	2374
	21st to end	Day	37% 6% 12% 22% 19% 4	2400
May	1st to 10th	Day	46% 8% 15% 19% 11% 2	5643
	11th to 20th	Day	46% 8% 12% 23% 10% 1	6322
	21st to end	Day	40% 7% 12% 24% 16% 2	6949
June	1st to 10th	Day	35% 9% 14% 24% 16% 2	2800
	11th to 20th	Day	34% 10% 14% 24% 15% 2	2800
	21st to end	Day	29% 9% 16% 25% 19% 1	2800
July	1st to 10th	Day	34% 9% 21% 19% 14% 3	6290
	11th to 20th	Day	40% 11% 19% 22% 7% 1	6285
	21st to end	Day	34% 9% 12% 23% 20% 1	6334
August	1st to 10th	Day	41% 7% 17% 27% 8%	4221
	11th to 20th	Day	37% 8% 12% 30% 12% 1	3900
	21st to end	Day	31% 7% 13% 28% 18% 2	4312
September	1st to 10th	Day	38% 6% 13% 21% 18% 4	2316
	11th to 20th	Day	33% 6% 11% 24% 23% 3	2280
	21st to end	Day	46% 6% 8% 18% 18% 3	2043
October	1st to 10th	Day	35% 5% 8% 20% 27% 5%	3160
	11th to 20th	Day	24% 3 7% 28% 28% 10%	3140
	21st to end	Day	23% 3 8% 32% 26% 8%	3428
November	1st to 10th	Day	32% 4 13% 28% 19% 4	1766
	11th to 20th	Day	35% 5% 11% 23% 23% 3	1800
	21st to end	Day	37% 5% 10% 29% 17% 3	1673
December	1st to 10th	Day	34% 5% 17% 27% 13% 4	2600
	11th to 20th	Day	42% 5% 11% 29% 11% 2	2986
	21st to end	Day	38% 6% 16% 22% 17% 1	3960
January	1st to 10th	Night	37% 4 8% 23% 23% 5%	6349
	11th to 20th	Night	35% 3 9% 26% 20% 7%	6015
	21st to end	Night	40% 3 9% 28% 19% 2	6490
February	1st to 10th	Night	43% 6% 13% 22% 15% 2	2600
	11th to 20th	Night	44% 4 8% 21% 19% 4	2400
	21st to end	Night	42% 4 10% 21% 17% 5%	1980
March	1st to 10th	Night	39% 4 8% 24% 15% 10%	5218
	11th to 20th	Night	32% 6% 13% 25% 18% 6%	4980
	21st to end	Night	40% 4 9% 18% 23% 5%	5222
April	1st to 10th	Night	42% 5% 11% 18% 20% 5%	2000
	11th to 20th	Night	39% 5% 11% 20% 19% 6%	1975
	21st to end	Night	38% 6% 11% 22% 18% 5%	2000
May	1st to 10th	Night	49% 7% 13% 19% 9% 2	4354
	11th to 20th	Night	48% 7% 14% 20% 10% 1	3576
	21st to end	Night	43% 8% 13% 20% 13% 2	3927
June	1st to 10th	Night	37% 7% 13% 22% 19% 1	1600
	11th to 20th	Night	37% 9% 14% 24% 14% 2	1600
	21st to end	Night	35% 9% 16% 22% 16% 3	1600
July	1st to 10th	Night	39% 10% 18% 18% 13% 2	3560
	11th to 20th	Night	44% 9% 21% 19% 6% 1	3552
	21st to end	Night	37% 8% 14% 22% 19%	4199
August	1st to 10th	Night	46% 8% 18% 20% 8%	2904
	11th to 20th	Night	39% 8% 14% 27% 12% 1	3181
	21st to end	Night	32% 7% 12% 27% 21% 2	3586
September	1st to 10th	Night	37% 7% 12% 22% 18% 5%	1931
	11th to 20th	Night	30% 7% 11% 25% 23% 4	1900
	21st to end	Night	45% 6% 9% 20% 17% 3	2133
October	1st to 10th	Night	40% 5% 9% 21% 20% 4	3800
	11th to 20th	Night	23% 3 13% 21% 31% 8%	3779
	21st to end	Night	23% 3 12% 30% 25% 7%	4120
November	1st to 10th	Night	32% 6% 10% 26% 19% 6%	2531
	11th to 20th	Night	39% 5% 10% 21% 21% 5%	2600
	21st to end	Night	34% 6% 13% 24% 20% 3	2725
December	1st to 10th	Night	33% 4 13% 28% 18% 3	4580
	11th to 20th	Night	44% 4 13% 19% 15% 4	5208
	21st to end	Night	42% 6% 12% 21% 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	25% 19% 35% 14% 7% 1	200
	11th to 20th	Day	27% 22% 33% 14% 4	275
	21st to end	Day	24% 18% 41% 12% 5% 1	330
February	1st to 10th	Day	26% 22% 33% 13% 6%	300
	11th to 20th	Day	29% 19% 38% 11% 2	434
	21st to end	Day	26% 18% 36% 16% 4	414
March	1st to 10th	Day	22% 21% 33% 21% 4	500
	11th to 20th	Day	22% 18% 35% 18% 6% 1	500
	21st to end	Day	20% 19% 32% 21% 6% 1	550
April	1st to 10th	Day	24% 17% 33% 18% 5% 2	500
	11th to 20th	Day	18% 17% 29% 22% 11% 2	492
	21st to end	Day	23% 12% 30% 24% 10% 1	500
May	1st to 10th	Day	22% 15% 32% 19% 9% 3	503
	11th to 20th	Day	17% 10% 34% 25% 12% 2	527
	21st to end	Day	16% 7% 24% 26% 19% 8%	573
June	1st to 10th	Day	12% 7% 27% 28% 19% 7%	530
	11th to 20th	Day	13% 7% 23% 30% 19% 8%	530
	21st to end	Day	11% 3 23% 32% 24% 7%	530
July	1st to 10th	Day	8% 4 18% 35% 23% 13%	525
	11th to 20th	Day	5% 1 17% 35% 30% 13%	524
	21st to end	Day	9% 3 18% 31% 30% 9%	576
August	1st to 10th	Day	13% 3 17% 31% 26% 10%	526
	11th to 20th	Day	11% 3 14% 31% 29% 12%	519
	21st to end	Day	8% 5% 17% 33% 22% 15%	583
September	1st to 10th	Day	14% 5% 19% 26% 21% 15%	502
	11th to 20th	Day	11% 4 24% 28% 21% 12%	490
	21st to end	Day	24% 8% 25% 25% 13% 5%	490
October	1st to 10th	Day	19% 9% 23% 24% 17% 8%	490
	11th to 20th	Day	16% 13% 26% 26% 16% 4	490
	21st to end	Day	17% 9% 32% 26% 12% 3	539
November	1st to 10th	Day	17% 10% 30% 27% 14% 3	398
	11th to 20th	Day	15% 17% 33% 23% 11% 1	400
	21st to end	Day	22% 15% 27% 25% 10% 1	273
December	1st to 10th	Day	17% 20% 40% 16% 6% 2	200
	11th to 20th	Day	27% 19% 32% 16% 7%	200
	21st to end	Day	24% 12% 32% 22% 9% 1	220
January	1st to 10th	Night	22% 18% 37% 20% 4	800
	11th to 20th	Night	20% 15% 34% 26% 4	800
	21st to end	Night	18% 15% 39% 25% 2	880
February	1st to 10th	Night	21% 11% 39% 26% 2	800
	11th to 20th	Night	24% 19% 39% 17% 1	783
	21st to end	Night	22% 17% 36% 22% 3	660
March	1st to 10th	Night	18% 16% 39% 22% 5%	800
	11th to 20th	Night	20% 14% 38% 20% 6% 1	800
	21st to end	Night	19% 13% 39% 25% 5%	880
April	1st to 10th	Night	20% 16% 40% 19% 5%	800
	11th to 20th	Night	15% 12% 36% 31% 6%	791
	21st to end	Night	19% 10% 34% 30% 8%	800
May	1st to 10th	Night	18% 9% 31% 32% 9% 1	738
	11th to 20th	Night	15% 7% 34% 33% 10% 1	394
	21st to end	Night	15% 4 22% 41% 17% 1	433
June	1st to 10th	Night	12% 5% 26% 42% 16% 1	400
	11th to 20th	Night	10% 3 24% 47% 16% 1	400
	21st to end	Night	10% 2 20% 51% 17% 1	400
July	1st to 10th	Night	11% 3 18% 43% 25% 2	390
	11th to 20th	Night	8% 3 14% 44% 28% 3	388
	21st to end	Night	8% 1 14% 47% 27% 3	608
August	1st to 10th	Night	10% 1 13% 46% 28% 2	597
	11th to 20th	Night	12% 3 14% 38% 30% 2	756
	21st to end	Night	11% 3 14% 38% 29% 4	880
September	1st to 10th	Night	15% 2 16% 37% 25% 4	773
	11th to 20th	Night	12% 2 17% 36% 28% 4	760
	21st to end	Night	21% 5% 19% 35% 19% 1	760
October	1st to 10th	Night	20% 5% 19% 32% 20% 4	760
	11th to 20th	Night	17% 8% 26% 34% 14% 1	760
	21st to end	Night	17% 8% 32% 28% 14% 1	836
November	1st to 10th	Night	14% 7% 33% 32% 12% 2	780
	11th to 20th	Night	18% 12% 31% 30% 8% 1	800
	21st to end	Night	15% 14% 33% 28% 9% 1	800
December	1st to 10th	Night	21% 14% 33% 22% 8% 1	800
	11th to 20th	Night	20% 11% 36% 27% 6%	800
	21st to end	Night	18% 12% 34% 31% 4	880

Page generated at 2025-09-01 01:51:08. Version ac07

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