Breezy Point Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Breezy Point Observatory clear sky chart from 2005-11-06 to 2025-10-19.

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	15% 9% 3 8% 5% 5% 5% 4 6% 7% 34%	126623
	Night	16% 10% 3 8% 5% 4 4 3 5% 7% 35%	123095
Transparency	Day	47% 6% 10% 21% 13% 2	130281
	Night	48% 5% 10% 21% 14% 2	127506
Seeing	Day	22% 13% 26% 22% 12% 5%	16290
	Night	21% 10% 25% 28% 15% 2	26339

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	17% 20% 8% 13% 8% 4 3 2 4 4 18%	4056
	11th to 20th	Day	16% 19% 9% 11% 7% 4 3 3 3 3 22%	4060
	21st to end	Day	20% 15% 5% 10% 7% 5% 4 3 5% 4 23%	4466
February	1st to 10th	Day	22% 13% 5% 9% 5% 3 2 3 4 5% 29%	1800
	11th to 20th	Day	21% 14% 4 11% 4 5% 3 3 4 5% 26%	1876
	21st to end	Day	22% 13% 4 8% 4 3 4 3 4 5% 31%	1650
March	1st to 10th	Day	17% 15% 4 8% 5% 4 3 3 4 5% 32%	4847
	11th to 20th	Day	13% 7% 3 6% 4 4 5% 3 6% 8% 42%	4980
	21st to end	Day	18% 10% 3 8% 5% 4 5% 4 5% 7% 32%	5465
April	1st to 10th	Day	16% 11% 3 7% 5% 4 4 4 5% 7% 34%	2202
	11th to 20th	Day	17% 9% 2 7% 4 4 4 3 5% 6% 40%	2501
	21st to end	Day	18% 8% 3 6% 6% 4 4 3 6% 7% 35%	2600
May	1st to 10th	Day	18% 9% 3 9% 5% 6% 5% 5% 7% 7% 25%	5862
	11th to 20th	Day	18% 9% 3 8% 5% 5% 5% 4 6% 7% 31%	5861
	21st to end	Day	15% 7% 3 6% 5% 5% 6% 4 7% 8% 34%	6433
June	1st to 10th	Day	13% 6% 2 6% 5% 4 5% 4 7% 9% 39%	2600
	11th to 20th	Day	10% 6% 3 7% 5% 6% 6% 6% 7% 9% 37%	2600
	21st to end	Day	10% 6% 2 6% 5% 5% 6% 5% 7% 11% 37%	2600
July	1st to 10th	Day	9% 6% 3 7% 5% 5% 5% 4 5% 8% 43%	5900
	11th to 20th	Day	11% 6% 2 7% 5% 6% 6% 5% 8% 10% 33%	5900
	21st to end	Day	13% 8% 3 7% 6% 5% 6% 4 7% 8% 32%	6424
August	1st to 10th	Day	9% 6% 2 8% 6% 6% 6% 5% 8% 10% 34%	4234
	11th to 20th	Day	9% 6% 3 6% 5% 5% 5% 5% 7% 9% 38%	4174
	21st to end	Day	6% 3 1 5% 4 5% 5% 4 6% 8% 51%	4553
September	1st to 10th	Day	14% 5% 2 5% 4 4 4 5% 5% 7% 46%	2236
	11th to 20th	Day	10% 6% 2 6% 4 4 4 3 6% 7% 47%	2200
	21st to end	Day	19% 7% 3 6% 4 5% 4 3 5% 6% 39%	2200
October	1st to 10th	Day	13% 6% 2 5% 3 4 4 3 5% 8% 46%	2090
	11th to 20th	Day	16% 6% 2 6% 4 4 4 3 4 6% 45%	1980
	21st to end	Day	20% 7% 2 6% 3 4 4 3 4 6% 41%	2090
November	1st to 10th	Day	13% 6% 2 6% 3 4 3 3 4 5% 51%	1814
	11th to 20th	Day	16% 12% 3 7% 4 4 4 3 5% 6% 36%	1800
	21st to end	Day	17% 11% 4 8% 5% 4 4 3 5% 5% 35%	1800
December	1st to 10th	Day	21% 14% 3 12% 5% 4 3 3 3 4 28%	2930
	11th to 20th	Day	25% 14% 6% 9% 3 3 3 3 5% 5% 24%	3373
	21st to end	Day	19% 17% 5% 11% 5% 5% 5% 4 5% 5% 19%	4466
January	1st to 10th	Night	16% 17% 6% 17% 6% 4 4 3 4 4 20%	5889
	11th to 20th	Night	18% 16% 6% 13% 6% 5% 4 3 3 4 22%	5900
	21st to end	Night	21% 12% 4 9% 6% 4 3 3 4 4 30%	6490
February	1st to 10th	Night	22% 13% 4 9% 5% 4 3 3 4 5% 29%	2600
	11th to 20th	Night	22% 13% 5% 8% 5% 4 4 2 4 5% 27%	2407
	21st to end	Night	22% 14% 4 7% 3 5% 4 3 4 5% 28%	1980
March	1st to 10th	Night	19% 12% 3 6% 4 3 3 3 4 6% 36%	4994
	11th to 20th	Night	12% 8% 2 7% 4 4 4 3 6% 8% 42%	4980
	21st to end	Night	17% 10% 3 9% 6% 5% 4 3 4 5% 34%	5467
April	1st to 10th	Night	17% 11% 3 7% 4 4 4 3 5% 7% 35%	2197
	11th to 20th	Night	15% 7% 3 7% 4 4 5% 3 5% 8% 40%	1865
	21st to end	Night	15% 8% 2 8% 4 4 4 3 6% 7% 40%	1800
May	1st to 10th	Night	22% 10% 4 9% 5% 4 5% 4 4 7% 26%	4033
	11th to 20th	Night	16% 7% 3 7% 5% 4 5% 4 6% 9% 33%	4032
	21st to end	Night	16% 9% 3 8% 4 5% 4 3 6% 8% 35%	4421
June	1st to 10th	Night	11% 5% 2 5% 5% 4 4 4 7% 9% 45%	1800
	11th to 20th	Night	9% 6% 3 7% 5% 4 5% 4 7% 10% 41%	1800
	21st to end	Night	9% 5% 2 5% 4 4 4 4 7% 10% 44%	1800
July	1st to 10th	Night	9% 7% 3 7% 4 5% 5% 4 6% 8% 43%	4058
	11th to 20th	Night	11% 8% 3 7% 5% 5% 6% 5% 7% 9% 34%	4057
	21st to end	Night	10% 7% 3 8% 5% 5% 6% 5% 7% 8% 36%	4427
August	1st to 10th	Night	10% 7% 3 8% 6% 5% 6% 4 6% 9% 36%	2915
	11th to 20th	Night	11% 7% 2 7% 5% 5% 5% 3 5% 8% 43%	2875
	21st to end	Night	5% 3 2 5% 5% 5% 4 4 7% 10% 49%	3312
September	1st to 10th	Night	11% 4 2 5% 4 4 4 4 5% 6% 51%	2160
	11th to 20th	Night	9% 4 2 5% 4 4 3 4 5% 6% 55%	2200
	21st to end	Night	16% 6% 2 6% 4 4 4 4 5% 6% 42%	2200
October	1st to 10th	Night	12% 4 2 5% 4 4 4 3 5% 7% 50%	2310
	11th to 20th	Night	14% 6% 2 6% 3 3 4 3 4 6% 48%	2377
	21st to end	Night	21% 6% 3 6% 4 4 3 2 4 5% 43%	2508
November	1st to 10th	Night	12% 6% 2 5% 4 4 4 3 4 5% 50%	2479
	11th to 20th	Night	17% 10% 3 6% 5% 4 4 4 4 7% 36%	2600
	21st to end	Night	18% 12% 3 7% 4 4 4 3 4 6% 35%	2600
December	1st to 10th	Night	19% 12% 4 12% 5% 4 4 3 4 5% 29%	4250
	11th to 20th	Night	19% 15% 7% 10% 5% 4 4 3 4 5% 26%	4822
	21st to end	Night	18% 17% 5% 10% 5% 5% 4 4 5% 6% 21%	6490

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	70% 4 10% 12% 4	4057
	11th to 20th	Day	68% 3 7% 13% 8% 1	4060
	21st to end	Day	65% 3 7% 16% 7% 1	4466
February	1st to 10th	Day	59% 3 10% 18% 8% 1	1800
	11th to 20th	Day	61% 4 9% 16% 9% 1	1885
	21st to end	Day	56% 4 9% 19% 10% 1	1650
March	1st to 10th	Day	55% 4 6% 23% 10% 3	4847
	11th to 20th	Day	39% 5% 8% 28% 17% 3	4980
	21st to end	Day	51% 5% 9% 21% 12% 2	5465
April	1st to 10th	Day	49% 6% 10% 19% 13% 3	2202
	11th to 20th	Day	45% 4 10% 20% 17% 4	2501
	21st to end	Day	47% 7% 11% 20% 12% 2	2600
May	1st to 10th	Day	54% 7% 11% 17% 9% 2	5897
	11th to 20th	Day	51% 7% 10% 21% 11% 1	5865
	21st to end	Day	43% 8% 13% 19% 13% 3	6447
June	1st to 10th	Day	40% 8% 13% 22% 17% 2	2600
	11th to 20th	Day	41% 9% 13% 20% 16% 2	2600
	21st to end	Day	39% 9% 14% 23% 14% 2	2600
July	1st to 10th	Day	38% 7% 10% 25% 17% 2	5835
	11th to 20th	Day	42% 9% 13% 25% 11% 1	5831
	21st to end	Day	46% 7% 12% 18% 16% 2	6240
August	1st to 10th	Day	41% 9% 13% 26% 10%	4221
	11th to 20th	Day	38% 9% 9% 29% 16% 1	4213
	21st to end	Day	30% 6% 13% 28% 20% 2	4553
September	1st to 10th	Day	36% 5% 10% 20% 23% 6%	2236
	11th to 20th	Day	35% 6% 10% 26% 21% 3	2200
	21st to end	Day	45% 5% 11% 20% 18% 1	2200
October	1st to 10th	Day	27% 4 8% 26% 33% 2	3402
	11th to 20th	Day	33% 4 12% 26% 21% 5%	3220
	21st to end	Day	32% 3 11% 30% 22% 2	3428
November	1st to 10th	Day	36% 5% 9% 29% 18% 4	1814
	11th to 20th	Day	49% 4 7% 20% 16% 3	1800
	21st to end	Day	51% 5% 10% 21% 13% 1	1800
December	1st to 10th	Day	61% 4 8% 22% 5%	2930
	11th to 20th	Day	63% 3 10% 17% 6%	3370
	21st to end	Day	66% 5% 10% 14% 5%	4466
January	1st to 10th	Night	68% 4 9% 14% 5%	5889
	11th to 20th	Night	66% 4 9% 13% 7% 2	5900
	21st to end	Night	59% 3 9% 19% 8% 1	6490
February	1st to 10th	Night	57% 5% 10% 18% 9% 1	2600
	11th to 20th	Night	60% 4 7% 16% 12% 1	2409
	21st to end	Night	57% 5% 9% 16% 10% 3	1980
March	1st to 10th	Night	50% 3 6% 24% 14% 3	4994
	11th to 20th	Night	39% 4 9% 27% 19% 2	4980
	21st to end	Night	52% 4 7% 21% 13% 2	5467
April	1st to 10th	Night	49% 5% 9% 19% 16% 3	2197
	11th to 20th	Night	42% 5% 12% 20% 15% 6%	1865
	21st to end	Night	44% 5% 10% 21% 18% 2	1800
May	1st to 10th	Night	57% 7% 11% 13% 9% 3	4060
	11th to 20th	Night	46% 8% 13% 21% 11% 1	4033
	21st to end	Night	45% 7% 13% 22% 9% 3	4429
June	1st to 10th	Night	34% 8% 11% 25% 19% 3	1800
	11th to 20th	Night	36% 9% 15% 19% 19% 2	1800
	21st to end	Night	33% 8% 15% 23% 19% 2	1800
July	1st to 10th	Night	38% 7% 9% 24% 19% 3	4015
	11th to 20th	Night	42% 9% 16% 21% 11% 1	4006
	21st to end	Night	41% 9% 11% 21% 15% 4	4297
August	1st to 10th	Night	42% 8% 14% 25% 10% 1	2904
	11th to 20th	Night	39% 7% 9% 22% 23% 1	2902
	21st to end	Night	28% 6% 13% 28% 22% 3	3312
September	1st to 10th	Night	32% 6% 12% 20% 22% 7%	2160
	11th to 20th	Night	30% 5% 11% 25% 26% 3	2200
	21st to end	Night	41% 7% 10% 19% 21% 2	2200
October	1st to 10th	Night	28% 4 8% 26% 29% 5%	3778
	11th to 20th	Night	30% 4 9% 24% 24% 9%	3876
	21st to end	Night	32% 3 6% 27% 26% 5%	4120
November	1st to 10th	Night	37% 4 10% 22% 22% 5%	2479
	11th to 20th	Night	48% 4 8% 19% 17% 3	2600
	21st to end	Night	50% 5% 9% 22% 12% 1	2600
December	1st to 10th	Night	58% 4 11% 21% 5%	4250
	11th to 20th	Night	62% 4 11% 17% 6% 1	4824
	21st to end	Night	63% 5% 10% 15% 7%	6490

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% 22% 33% 10% 3 1	300
	11th to 20th	Day	38% 26% 28% 7% 1	300
	21st to end	Day	32% 27% 28% 10% 3	330
February	1st to 10th	Day	35% 22% 29% 11% 3	300
	11th to 20th	Day	43% 25% 26% 5% 1 1	300
	21st to end	Day	34% 23% 33% 9%	249
March	1st to 10th	Day	30% 20% 30% 15% 4	460
	11th to 20th	Day	28% 21% 30% 14% 6% 1	500
	21st to end	Day	32% 16% 31% 17% 3 1	550
April	1st to 10th	Day	29% 20% 27% 18% 6% 1	500
	11th to 20th	Day	25% 18% 28% 19% 7% 3	492
	21st to end	Day	27% 17% 29% 18% 7% 2	500
May	1st to 10th	Day	25% 16% 32% 16% 7% 3	503
	11th to 20th	Day	21% 13% 32% 20% 11% 4	527
	21st to end	Day	15% 11% 27% 26% 15% 7%	573
June	1st to 10th	Day	15% 10% 26% 27% 17% 6%	530
	11th to 20th	Day	14% 8% 24% 31% 17% 6%	530
	21st to end	Day	11% 8% 28% 28% 18% 7%	530
July	1st to 10th	Day	12% 4 23% 26% 19% 16%	525
	11th to 20th	Day	10% 6% 23% 32% 20% 9%	524
	21st to end	Day	16% 5% 20% 29% 21% 10%	576
August	1st to 10th	Day	12% 3 21% 33% 21% 10%	526
	11th to 20th	Day	14% 5% 22% 27% 22% 10%	519
	21st to end	Day	9% 3 21% 35% 21% 10%	583
September	1st to 10th	Day	15% 5% 18% 28% 25% 10%	530
	11th to 20th	Day	10% 3 15% 30% 29% 13%	530
	21st to end	Day	23% 8% 23% 24% 17% 4	530
October	1st to 10th	Day	14% 7% 25% 26% 22% 5%	530
	11th to 20th	Day	20% 11% 28% 26% 12% 3	522
	21st to end	Day	25% 13% 29% 23% 8% 2	539
November	1st to 10th	Day	19% 14% 33% 22% 9% 2	352
	11th to 20th	Day	29% 17% 29% 18% 6% 1	300
	21st to end	Day	23% 25% 30% 16% 4 1	300
December	1st to 10th	Day	32% 19% 31% 14% 2 1	300
	11th to 20th	Day	29% 21% 31% 13% 4 1	300
	21st to end	Day	34% 21% 27% 14% 4	330
January	1st to 10th	Night	27% 20% 30% 19% 4	800
	11th to 20th	Night	32% 19% 28% 19% 3	800
	21st to end	Night	27% 18% 31% 21% 3	880
February	1st to 10th	Night	29% 12% 30% 27% 1	800
	11th to 20th	Night	33% 18% 29% 18% 1	783
	21st to end	Night	32% 15% 32% 21% 2	660
March	1st to 10th	Night	26% 15% 29% 25% 6%	800
	11th to 20th	Night	27% 16% 27% 22% 8% 1	800
	21st to end	Night	27% 14% 31% 21% 5%	880
April	1st to 10th	Night	26% 15% 30% 22% 6%	800
	11th to 20th	Night	18% 15% 33% 24% 10% 1	681
	21st to end	Night	18% 10% 35% 30% 7%	600
May	1st to 10th	Night	19% 10% 29% 29% 13% 1	600
	11th to 20th	Night	19% 6% 28% 29% 17% 2	591
	21st to end	Night	14% 3 24% 31% 25% 3	650
June	1st to 10th	Night	12% 3 24% 36% 23% 2	600
	11th to 20th	Night	11% 4 20% 38% 26% 2	600
	21st to end	Night	12% 4 19% 38% 25% 3	600
July	1st to 10th	Night	13% 3 14% 35% 30% 5%	585
	11th to 20th	Night	9% 3 19% 34% 32% 4	582
	21st to end	Night	11% 3 14% 33% 33% 5%	657
August	1st to 10th	Night	9% 2 15% 38% 34% 2	597
	11th to 20th	Night	12% 2 13% 37% 30% 6%	594
	21st to end	Night	11% 1 16% 34% 32% 5%	710
September	1st to 10th	Night	13% 3 16% 33% 30% 5%	800
	11th to 20th	Night	10% 3 16% 32% 34% 5%	800
	21st to end	Night	19% 6% 20% 33% 20% 3	800
October	1st to 10th	Night	15% 4 21% 31% 27% 3	800
	11th to 20th	Night	18% 7% 29% 30% 15% 1	793
	21st to end	Night	23% 10% 24% 31% 11% 1	836
November	1st to 10th	Night	16% 10% 27% 31% 15% 1	780
	11th to 20th	Night	24% 14% 24% 28% 9% 1	800
	21st to end	Night	26% 10% 27% 29% 7% 1	800
December	1st to 10th	Night	30% 15% 27% 23% 5%	800
	11th to 20th	Night	26% 14% 30% 25% 5%	800
	21st to end	Night	28% 15% 26% 28% 2	880

Page generated at 2025-10-16 01:50:23. Version ac07

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