Queens
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Queens clear sky chart from 2005-11-06 to 2025-11-18.

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	19% 10% 3 8% 5% 4 4 3 5% 7% 30%	127732
	Night	19% 10% 3 8% 5% 4 4 4 5% 6% 31%	122754
Transparency	Day	52% 7% 12% 18% 10% 1	131323
	Night	53% 7% 11% 18% 10% 1	127250
Seeing	Day	23% 10% 26% 29% 11% 1	18645
	Night	24% 10% 27% 28% 10% 1	26169

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	15% 12% 5% 15% 8% 6% 4 3 4 5% 23%	3616
	11th to 20th	Day	14% 10% 5% 15% 8% 8% 7% 5% 6% 6% 16%	3917
	21st to end	Day	16% 11% 4 10% 6% 5% 5% 4 6% 6% 27%	4466
February	1st to 10th	Day	20% 13% 5% 8% 6% 5% 5% 5% 6% 5% 23%	1800
	11th to 20th	Day	17% 10% 4 10% 6% 6% 6% 5% 6% 6% 26%	1753
	21st to end	Day	14% 11% 4 8% 5% 6% 5% 4 6% 6% 31%	1537
March	1st to 10th	Day	23% 13% 4 10% 6% 5% 4 3 4 4 23%	4930
	11th to 20th	Day	16% 14% 4 8% 4 5% 4 4 6% 6% 30%	4980
	21st to end	Day	26% 11% 4 10% 5% 5% 4 3 4 5% 23%	5466
April	1st to 10th	Day	23% 14% 4 7% 5% 4 3 3 4 5% 27%	2351
	11th to 20th	Day	20% 10% 3 7% 4 4 3 3 6% 7% 34%	2474
	21st to end	Day	22% 7% 3 7% 4 4 4 3 5% 6% 35%	2600
May	1st to 10th	Day	26% 12% 4 9% 5% 5% 4 3 5% 7% 22%	5886
	11th to 20th	Day	25% 11% 3 6% 4 4 4 3 5% 6% 29%	6267
	21st to end	Day	18% 11% 3 8% 4 4 4 3 5% 7% 33%	6948
June	1st to 10th	Day	23% 11% 3 6% 5% 4 4 3 4 7% 29%	2800
	11th to 20th	Day	19% 9% 3 8% 4 4 3 3 5% 6% 37%	2894
	21st to end	Day	24% 9% 3 7% 5% 4 5% 4 6% 7% 28%	3000
July	1st to 10th	Day	19% 9% 3 9% 5% 4 4 4 6% 10% 28%	6641
	11th to 20th	Day	12% 10% 4 11% 6% 5% 5% 3 5% 8% 31%	6360
	21st to end	Day	15% 6% 3 5% 4 4 4 4 6% 11% 39%	6476
August	1st to 10th	Day	20% 9% 4 8% 5% 4 5% 4 6% 8% 29%	4235
	11th to 20th	Day	15% 9% 3 7% 4 4 5% 4 6% 8% 36%	4175
	21st to end	Day	9% 5% 3 5% 4 4 4 4 5% 8% 49%	4520
September	1st to 10th	Day	14% 7% 2 5% 5% 3 4 3 5% 7% 44%	2400
	11th to 20th	Day	18% 6% 2 5% 3 3 4 3 5% 6% 45%	2266
	21st to end	Day	18% 7% 2 5% 5% 4 3 3 4 6% 42%	2170
October	1st to 10th	Day	19% 5% 2 6% 4 4 4 4 5% 8% 40%	2000
	11th to 20th	Day	19% 7% 2 7% 4 4 5% 4 6% 7% 36%	2000
	21st to end	Day	21% 8% 3 7% 4 5% 5% 4 6% 6% 32%	2200
November	1st to 10th	Day	19% 10% 3 8% 5% 4 4 3 5% 6% 34%	1760
	11th to 20th	Day	21% 9% 3 8% 5% 5% 5% 4 6% 7% 28%	1656
	21st to end	Day	21% 10% 4 9% 6% 5% 4 3 5% 6% 27%	1600
December	1st to 10th	Day	25% 9% 3 8% 5% 5% 5% 4 6% 6% 25%	2610
	11th to 20th	Day	30% 9% 2 7% 4 4 4 4 5% 5% 25%	2996
	21st to end	Day	21% 12% 4 8% 5% 3 4 3 4 6% 30%	3982
January	1st to 10th	Night	13% 13% 5% 15% 8% 7% 6% 4 5% 6% 19%	6349
	11th to 20th	Night	16% 11% 5% 13% 8% 7% 6% 5% 6% 7% 18%	5968
	21st to end	Night	14% 11% 4 10% 5% 6% 6% 5% 6% 7% 26%	6490
February	1st to 10th	Night	20% 11% 4 8% 6% 5% 5% 4 5% 6% 25%	2600
	11th to 20th	Night	17% 10% 3 9% 7% 5% 6% 5% 7% 7% 25%	2533
	21st to end	Night	13% 9% 4 8% 6% 5% 5% 5% 5% 7% 33%	2090
March	1st to 10th	Night	24% 13% 4 9% 7% 5% 4 3 4 5% 24%	4910
	11th to 20th	Night	17% 12% 5% 8% 5% 4 4 4 6% 7% 27%	4979
	21st to end	Night	30% 10% 4 8% 4 3 3 3 4 5% 28%	5466
April	1st to 10th	Night	25% 11% 3 6% 4 4 3 3 4 6% 31%	2048
	11th to 20th	Night	25% 8% 3 6% 4 4 4 3 4 6% 34%	1873
	21st to end	Night	23% 9% 3 7% 4 4 3 3 5% 5% 34%	1800
May	1st to 10th	Night	26% 13% 3 9% 5% 4 3 3 4 5% 24%	4054
	11th to 20th	Night	26% 11% 3 7% 4 3 4 3 5% 6% 30%	3642
	21st to end	Night	17% 13% 3 8% 5% 4 4 3 5% 5% 33%	3948
June	1st to 10th	Night	26% 9% 3 5% 4 3 4 4 5% 6% 32%	1600
	11th to 20th	Night	21% 9% 3 6% 6% 5% 3 3 4 5% 36%	1517
	21st to end	Night	25% 10% 3 7% 5% 4 4 3 5% 6% 27%	1400
July	1st to 10th	Night	18% 11% 3 8% 5% 4 5% 3 6% 8% 27%	3288
	11th to 20th	Night	16% 12% 3 8% 5% 5% 5% 3 6% 7% 30%	3620
	21st to end	Night	16% 8% 2 6% 4 4 3 3 5% 8% 40%	4374
August	1st to 10th	Night	18% 9% 4 8% 5% 4 4 2 5% 7% 35%	2915
	11th to 20th	Night	16% 9% 3 7% 4 4 4 3 5% 7% 36%	2872
	21st to end	Night	9% 6% 2 5% 4 4 3 3 5% 7% 52%	3377
September	1st to 10th	Night	14% 6% 3 6% 4 4 4 3 5% 8% 43%	2000
	11th to 20th	Night	17% 6% 2 5% 2 3 4 3 5% 6% 46%	2130
	21st to end	Night	21% 7% 3 6% 5% 3 3 3 4 7% 39%	2230
October	1st to 10th	Night	20% 6% 2 4 3 4 4 3 5% 6% 43%	2400
	11th to 20th	Night	18% 8% 2 6% 3 3 4 3 5% 7% 41%	2400
	21st to end	Night	23% 7% 2 6% 3 4 4 4 4 7% 36%	2640
November	1st to 10th	Night	19% 8% 3 6% 4 4 4 3 6% 7% 37%	2753
	11th to 20th	Night	20% 9% 3 8% 5% 5% 5% 4 7% 7% 28%	2899
	21st to end	Night	21% 9% 3 7% 5% 5% 5% 4 6% 7% 30%	2800
December	1st to 10th	Night	16% 9% 4 11% 5% 5% 6% 4 6% 7% 27%	4580
	11th to 20th	Night	25% 10% 3 6% 4 4 3 3 5% 6% 31%	5213
	21st to end	Night	24% 10% 3 7% 6% 4 4 3 5% 5% 31%	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	61% 7% 13% 14% 5%	3617
	11th to 20th	Day	60% 10% 13% 13% 4	3950
	21st to end	Day	53% 7% 10% 15% 13% 3	4466
February	1st to 10th	Day	60% 8% 12% 12% 7% 1	1800
	11th to 20th	Day	58% 8% 12% 16% 6% 1	1761
	21st to end	Day	49% 8% 12% 19% 10% 2	1537
March	1st to 10th	Day	59% 6% 10% 13% 9% 3	4934
	11th to 20th	Day	49% 9% 16% 17% 8% 1	4980
	21st to end	Day	60% 4 7% 17% 12% 1	5466
April	1st to 10th	Day	55% 5% 9% 16% 13% 2	2351
	11th to 20th	Day	48% 5% 13% 20% 13% 1	2474
	21st to end	Day	48% 6% 12% 19% 13% 2	2600
May	1st to 10th	Day	61% 8% 12% 13% 5%	5897
	11th to 20th	Day	55% 7% 10% 19% 8% 1	6271
	21st to end	Day	49% 11% 12% 17% 11% 1	6948
June	1st to 10th	Day	54% 7% 10% 18% 10%	2800
	11th to 20th	Day	49% 7% 11% 19% 12% 2	2894
	21st to end	Day	59% 7% 9% 13% 10% 1	3000
July	1st to 10th	Day	58% 8% 11% 12% 10% 1	6569
	11th to 20th	Day	54% 9% 11% 18% 7%	6284
	21st to end	Day	44% 9% 13% 23% 11% 1	6291
August	1st to 10th	Day	57% 8% 9% 15% 10% 1	4222
	11th to 20th	Day	47% 8% 16% 21% 7% 1	4214
	21st to end	Day	32% 7% 12% 28% 20% 1	4520
September	1st to 10th	Day	40% 6% 11% 24% 16% 2	2400
	11th to 20th	Day	41% 6% 10% 24% 17% 2	2266
	21st to end	Day	43% 7% 9% 22% 17% 1	2170
October	1st to 10th	Day	41% 6% 12% 26% 12% 1	3260
	11th to 20th	Day	36% 6% 10% 23% 24% 1	3240
	21st to end	Day	42% 6% 14% 24% 11% 4	3538
November	1st to 10th	Day	50% 6% 12% 22% 9% 1	1760
	11th to 20th	Day	54% 9% 12% 16% 8% 1	1656
	21st to end	Day	56% 7% 14% 17% 5% 1	1600
December	1st to 10th	Day	57% 7% 13% 19% 4	2610
	11th to 20th	Day	60% 7% 10% 14% 9%	2995
	21st to end	Day	56% 7% 13% 16% 7% 1	3982
January	1st to 10th	Night	63% 8% 11% 14% 4	6349
	11th to 20th	Night	60% 9% 12% 14% 4	6010
	21st to end	Night	55% 8% 12% 14% 10% 1	6490
February	1st to 10th	Night	59% 9% 10% 13% 8% 1	2600
	11th to 20th	Night	56% 9% 12% 14% 8% 1	2536
	21st to end	Night	50% 8% 14% 17% 10% 1	2090
March	1st to 10th	Night	63% 4 7% 11% 13% 1	4919
	11th to 20th	Night	55% 7% 14% 17% 7% 1	4980
	21st to end	Night	58% 4 7% 19% 11% 1	5466
April	1st to 10th	Night	55% 5% 9% 15% 12% 3	2048
	11th to 20th	Night	50% 5% 11% 20% 13% 2	1873
	21st to end	Night	51% 4 10% 20% 12% 3	1800
May	1st to 10th	Night	63% 6% 8% 14% 8% 1	4060
	11th to 20th	Night	54% 7% 8% 21% 7% 3	3643
	21st to end	Night	54% 7% 10% 18% 9% 1	3949
June	1st to 10th	Night	55% 5% 10% 21% 9%	1600
	11th to 20th	Night	51% 5% 12% 18% 13% 1	1517
	21st to end	Night	61% 6% 10% 12% 12% 1	1400
July	1st to 10th	Night	60% 6% 9% 14% 9% 1	3251
	11th to 20th	Night	59% 7% 6% 15% 11% 2	3572
	21st to end	Night	47% 7% 10% 21% 14% 1	4245
August	1st to 10th	Night	54% 6% 9% 21% 10% 1	2903
	11th to 20th	Night	47% 8% 16% 21% 7%	2899
	21st to end	Night	32% 6% 13% 28% 21%	3376
September	1st to 10th	Night	41% 6% 10% 25% 15% 2	2000
	11th to 20th	Night	41% 5% 8% 26% 18% 2	2130
	21st to end	Night	47% 5% 8% 23% 15% 1	2230
October	1st to 10th	Night	44% 5% 12% 25% 12% 2	3920
	11th to 20th	Night	33% 5% 12% 27% 22%	3899
	21st to end	Night	41% 5% 9% 26% 17% 1	4252
November	1st to 10th	Night	48% 7% 13% 20% 11% 1	2753
	11th to 20th	Night	54% 8% 12% 17% 8%	2899
	21st to end	Night	55% 9% 14% 15% 5%	2800
December	1st to 10th	Night	55% 7% 11% 22% 5%	4580
	11th to 20th	Night	56% 6% 12% 15% 11% 1	5215
	21st to end	Night	58% 6% 12% 16% 8% 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	27% 18% 33% 19% 4	400
	11th to 20th	Day	26% 16% 34% 19% 6% 1	400
	21st to end	Day	20% 15% 36% 25% 4	440
February	1st to 10th	Day	26% 14% 35% 22% 3	400
	11th to 20th	Day	23% 21% 34% 20% 1	396
	21st to end	Day	17% 15% 37% 25% 5%	357
March	1st to 10th	Day	23% 16% 37% 20% 4	500
	11th to 20th	Day	20% 17% 31% 25% 6% 1	500
	21st to end	Day	25% 13% 33% 23% 7% 1	550
April	1st to 10th	Day	31% 13% 31% 21% 4	500
	11th to 20th	Day	22% 10% 36% 27% 5%	492
	21st to end	Day	21% 8% 29% 30% 10% 1	500
May	1st to 10th	Day	26% 8% 31% 28% 7% 1	503
	11th to 20th	Day	22% 6% 27% 32% 11% 1	699
	21st to end	Day	25% 7% 26% 32% 9% 2	790
June	1st to 10th	Day	26% 6% 22% 35% 10% 1	730
	11th to 20th	Day	22% 5% 21% 38% 13% 1	730
	21st to end	Day	30% 5% 18% 34% 12% 2	730
July	1st to 10th	Day	23% 5% 20% 36% 15% 1	720
	11th to 20th	Day	23% 5% 14% 39% 17% 2	718
	21st to end	Day	21% 4 16% 39% 18% 1	601
August	1st to 10th	Day	17% 6% 16% 37% 21% 2	526
	11th to 20th	Day	20% 6% 18% 29% 22% 4	519
	21st to end	Day	15% 4 21% 35% 20% 4	583
September	1st to 10th	Day	19% 3 19% 39% 19% 2	530
	11th to 20th	Day	21% 6% 21% 28% 19% 5%	530
	21st to end	Day	20% 6% 23% 31% 17% 3	513
October	1st to 10th	Day	19% 5% 26% 30% 18% 2	420
	11th to 20th	Day	18% 13% 27% 26% 14% 2	420
	21st to end	Day	24% 10% 29% 26% 9% 1	462
November	1st to 10th	Day	20% 13% 30% 27% 10%	425
	11th to 20th	Day	25% 19% 28% 22% 6% 1	421
	21st to end	Day	26% 15% 32% 23% 5%	400
December	1st to 10th	Day	32% 12% 31% 21% 4	400
	11th to 20th	Day	31% 22% 28% 16% 3 1	400
	21st to end	Day	24% 18% 33% 20% 5% 1	440
January	1st to 10th	Night	25% 17% 34% 21% 4	900
	11th to 20th	Night	25% 15% 32% 23% 5%	823
	21st to end	Night	20% 16% 39% 20% 5%	880
February	1st to 10th	Night	28% 16% 32% 21% 3	800
	11th to 20th	Night	22% 19% 38% 20% 2	783
	21st to end	Night	18% 12% 39% 24% 6%	660
March	1st to 10th	Night	25% 13% 37% 22% 3	800
	11th to 20th	Night	22% 11% 31% 29% 8%	800
	21st to end	Night	24% 12% 32% 25% 7%	880
April	1st to 10th	Night	33% 7% 29% 24% 6%	648
	11th to 20th	Night	28% 6% 33% 27% 7% 1	594
	21st to end	Night	26% 6% 25% 31% 10% 2	600
May	1st to 10th	Night	29% 5% 25% 31% 8% 2	600
	11th to 20th	Night	27% 4 25% 32% 11% 2	592
	21st to end	Night	24% 4 22% 36% 12% 1	649
June	1st to 10th	Night	29% 5% 19% 32% 14% 1	600
	11th to 20th	Night	26% 4 19% 39% 13%	517
	21st to end	Night	30% 4 16% 34% 16% 1	400
July	1st to 10th	Night	24% 3 14% 41% 16% 1	438
	11th to 20th	Night	20% 5% 15% 43% 15% 1	582
	21st to end	Night	23% 5% 12% 41% 18% 1	656
August	1st to 10th	Night	17% 3 15% 39% 23% 3	598
	11th to 20th	Night	19% 3 18% 36% 23% 2	592
	21st to end	Night	17% 3 19% 36% 20% 4	660
September	1st to 10th	Night	18% 5% 19% 37% 19% 2	600
	11th to 20th	Night	21% 4 21% 31% 19% 4	730
	21st to end	Night	23% 6% 23% 31% 14% 4	800
October	1st to 10th	Night	23% 5% 25% 32% 13% 2	800
	11th to 20th	Night	21% 10% 29% 26% 13% 2	800
	21st to end	Night	27% 11% 28% 27% 7%	880
November	1st to 10th	Night	22% 11% 30% 28% 8% 1	881
	11th to 20th	Night	25% 17% 28% 24% 7%	936
	21st to end	Night	25% 17% 31% 20% 7% 1	900
December	1st to 10th	Night	29% 13% 32% 20% 5% 1	900
	11th to 20th	Night	27% 20% 32% 17% 4	900
	21st to end	Night	27% 16% 33% 20% 5%	990

Page generated at 2025-11-15 01:56:01. Version ac07

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