Hobuck Beach
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hobuck Beach clear sky chart from 2005-11-06 to 2025-07-21.

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	25% 13% 4 8% 5% 4 4 3 5% 6% 24%	123937
	Night	28% 14% 4 8% 4 4 3 3 4 5% 23%	123927
Transparency	Day	59% 8% 13% 13% 6% 1	123683
	Night	63% 7% 11% 13% 6% 1	123824
Seeing	Day	28% 4 11% 21% 24% 12%	16534
	Night	36% 5% 13% 20% 18% 8%	24601

By Month

Percentage Cloud Cover NW (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	41% 14% 3 7% 4 4 3 4 3 4 13%	3179
	11th to 20th	Day	22% 10% 2 5% 4 3 4 3 5% 7% 35%	3159
	21st to end	Day	43% 11% 3 6% 3 3 2 2 2 3 22%	4140
February	1st to 10th	Day	35% 14% 3 6% 4 4 5% 4 5% 5% 15%	1800
	11th to 20th	Day	34% 12% 3 9% 4 3 3 3 3 4 23%	1755
	21st to end	Day	29% 14% 4 8% 5% 4 4 3 5% 5% 20%	1485
March	1st to 10th	Day	28% 14% 4 11% 7% 5% 5% 3 4 4 15%	4790
	11th to 20th	Day	25% 13% 4 9% 5% 4 4 3 4 5% 23%	5000
	21st to end	Day	31% 14% 4 10% 6% 5% 5% 3 5% 5% 13%	5486
April	1st to 10th	Day	31% 13% 3 8% 5% 5% 4 4 4 5% 17%	2390
	11th to 20th	Day	23% 12% 4 8% 6% 4 4 4 5% 6% 25%	2543
	21st to end	Day	26% 12% 4 7% 5% 4 5% 3 4 7% 23%	2600
May	1st to 10th	Day	18% 10% 3 7% 4 4 4 3 5% 5% 37%	6223
	11th to 20th	Day	19% 15% 5% 9% 5% 5% 5% 4 7% 7% 21%	6277
	21st to end	Day	22% 10% 4 8% 6% 5% 5% 4 6% 8% 23%	7172
June	1st to 10th	Day	26% 13% 3 7% 6% 4 4 4 5% 6% 22%	3000
	11th to 20th	Day	21% 15% 4 9% 7% 5% 5% 4 5% 7% 18%	3000
	21st to end	Day	20% 14% 5% 9% 6% 5% 5% 4 5% 5% 23%	3000
July	1st to 10th	Day	11% 13% 3 7% 5% 3 3 3 4 7% 41%	4890
	11th to 20th	Day	10% 13% 3 8% 6% 4 4 3 5% 8% 36%	4890
	21st to end	Day	19% 18% 4 9% 5% 5% 4 3 5% 6% 22%	4964
August	1st to 10th	Day	9% 17% 5% 11% 6% 5% 4 3 6% 10% 23%	4154
	11th to 20th	Day	16% 14% 4 10% 6% 6% 6% 4 7% 7% 21%	4026
	21st to end	Day	21% 11% 3 8% 4 4 3 3 4 5% 33%	4500
September	1st to 10th	Day	16% 13% 4 7% 5% 4 4 4 5% 5% 32%	2280
	11th to 20th	Day	21% 12% 4 10% 5% 4 4 2 5% 5% 29%	2185
	21st to end	Day	23% 7% 3 7% 5% 4 4 3 5% 6% 31%	2062
October	1st to 10th	Day	20% 11% 4 10% 6% 5% 5% 3 5% 6% 24%	3180
	11th to 20th	Day	33% 10% 3 7% 4 4 4 3 3 5% 23%	3161
	21st to end	Day	26% 10% 3 8% 5% 4 4 3 5% 6% 25%	3242
November	1st to 10th	Day	40% 9% 3 7% 5% 4 4 3 4 4 17%	1568
	11th to 20th	Day	37% 11% 4 8% 4 3 3 3 4 5% 19%	1600
	21st to end	Day	36% 12% 4 8% 5% 3 4 4 4 4 17%	1600
December	1st to 10th	Day	28% 10% 3 6% 4 4 3 3 4 6% 30%	2493
	11th to 20th	Day	45% 12% 3 7% 5% 5% 4 3 3 4 10%	2645
	21st to end	Day	39% 14% 5% 9% 5% 4 4 3 3 4 9%	3498
January	1st to 10th	Night	38% 15% 4 10% 5% 3 3 2 3 3 14%	6766
	11th to 20th	Night	25% 7% 2 6% 4 4 3 3 5% 6% 35%	6739
	21st to end	Night	40% 12% 3 6% 3 2 2 2 3 4 24%	6829
February	1st to 10th	Night	35% 13% 4 7% 4 4 3 3 3 5% 19%	2600
	11th to 20th	Night	33% 12% 3 8% 4 4 3 2 3 4 25%	2532
	21st to end	Night	32% 14% 4 7% 4 3 3 3 4 5% 21%	2145
March	1st to 10th	Night	26% 15% 4 9% 5% 5% 5% 3 4 4 18%	5096
	11th to 20th	Night	25% 15% 4 8% 5% 4 4 3 5% 6% 21%	4999
	21st to end	Night	37% 16% 5% 9% 5% 4 3 3 4 4 12%	5489
April	1st to 10th	Night	29% 14% 3 9% 5% 4 4 3 5% 5% 19%	2009
	11th to 20th	Night	25% 12% 3 8% 5% 4 5% 3 5% 6% 24%	1804
	21st to end	Night	25% 12% 3 8% 4 5% 4 3 4 7% 24%	1800
May	1st to 10th	Night	18% 10% 3 6% 4 3 3 3 4 6% 41%	3740
	11th to 20th	Night	20% 19% 4 8% 5% 5% 4 4 5% 5% 22%	3616
	21st to end	Night	23% 14% 4 8% 5% 5% 4 3 5% 6% 22%	3700
June	1st to 10th	Night	24% 15% 4 7% 5% 3 4 3 5% 6% 26%	1400
	11th to 20th	Night	27% 16% 3 7% 3 4 4 3 5% 6% 23%	1400
	21st to end	Night	20% 14% 3 9% 5% 4 4 5% 5% 6% 27%	1400
July	1st to 10th	Night	13% 14% 1 3 3 2 3 3 6% 6% 46%	2290
	11th to 20th	Night	11% 19% 3 7% 4 3 2 2 4 5% 40%	2290
	21st to end	Night	19% 23% 4 7% 3 2 3 3 4 5% 28%	2587
August	1st to 10th	Night	10% 26% 5% 13% 5% 4 2 3 3 6% 22%	2781
	11th to 20th	Night	18% 23% 3 8% 4 4 3 2 4 6% 23%	2812
	21st to end	Night	20% 14% 3 6% 3 3 3 2 5% 6% 34%	3168
September	1st to 10th	Night	14% 14% 3 6% 4 4 3 3 5% 6% 37%	1900
	11th to 20th	Night	21% 12% 4 8% 4 3 3 3 4 5% 32%	1993
	21st to end	Night	24% 9% 3 6% 3 3 3 3 4 6% 35%	2118
October	1st to 10th	Night	20% 8% 4 9% 6% 6% 5% 3 6% 6% 26%	3800
	11th to 20th	Night	33% 10% 3 6% 4 3 4 2 5% 6% 23%	3777
	21st to end	Night	29% 8% 3 7% 4 4 4 3 5% 5% 28%	4315
November	1st to 10th	Night	37% 10% 4 9% 4 4 3 2 3 5% 19%	2730
	11th to 20th	Night	37% 12% 3 7% 4 4 4 3 3 4 19%	2800
	21st to end	Night	35% 10% 4 8% 6% 4 3 3 4 5% 20%	2800
December	1st to 10th	Night	29% 11% 3 7% 4 4 3 3 5% 6% 25%	4684
	11th to 20th	Night	44% 15% 5% 7% 4 4 3 2 3 3 10%	5560
	21st to end	Night	38% 14% 5% 9% 5% 5% 4 3 4 4 10%	7458

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	76% 6% 8% 7% 3	3179
	11th to 20th	Day	51% 6% 18% 22% 3 1	3180
	21st to end	Day	71% 4 6% 14% 6%	4140
February	1st to 10th	Day	70% 7% 9% 9% 5% 1	1800
	11th to 20th	Day	68% 4 7% 13% 7% 1	1764
	21st to end	Day	67% 6% 10% 9% 5% 2	1485
March	1st to 10th	Day	71% 7% 9% 11% 3	4790
	11th to 20th	Day	63% 5% 12% 16% 4	5000
	21st to end	Day	72% 9% 11% 7% 1	5486
April	1st to 10th	Day	71% 7% 11% 9% 2	2390
	11th to 20th	Day	62% 7% 10% 12% 8% 1	2543
	21st to end	Day	63% 7% 13% 13% 4 1	2600
May	1st to 10th	Day	49% 7% 16% 19% 10%	6223
	11th to 20th	Day	56% 13% 18% 11% 2	6280
	21st to end	Day	58% 11% 18% 9% 4	7173
June	1st to 10th	Day	61% 9% 15% 11% 4 1	3000
	11th to 20th	Day	65% 9% 11% 11% 3	3000
	21st to end	Day	58% 11% 14% 10% 6% 1	3000
July	1st to 10th	Day	39% 8% 11% 14% 19% 9%	4816
	11th to 20th	Day	35% 10% 16% 26% 13%	4809
	21st to end	Day	54% 11% 17% 13% 4 1	4807
August	1st to 10th	Day	40% 11% 14% 25% 9% 1	4137
	11th to 20th	Day	56% 13% 15% 9% 5% 1	4065
	21st to end	Day	50% 9% 13% 19% 8%	4499
September	1st to 10th	Day	48% 10% 13% 18% 8% 3	2280
	11th to 20th	Day	54% 10% 10% 14% 11% 1	2185
	21st to end	Day	51% 11% 15% 14% 8% 1	2062
October	1st to 10th	Day	59% 8% 15% 12% 5%	3180
	11th to 20th	Day	65% 5% 12% 14% 4	3161
	21st to end	Day	60% 7% 13% 11% 8% 1	3242
November	1st to 10th	Day	72% 5% 11% 9% 3 1	1568
	11th to 20th	Day	69% 4 9% 10% 6% 1	1600
	21st to end	Day	69% 7% 8% 11% 6%	1600
December	1st to 10th	Day	57% 5% 10% 20% 9%	2493
	11th to 20th	Day	76% 7% 8% 7% 2	2648
	21st to end	Day	77% 7% 9% 5% 2	3498
January	1st to 10th	Night	76% 5% 7% 8% 3	6766
	11th to 20th	Night	49% 6% 17% 21% 6% 1	6780
	21st to end	Night	67% 3 7% 15% 7%	6829
February	1st to 10th	Night	69% 6% 8% 11% 6%	2600
	11th to 20th	Night	65% 5% 9% 13% 8% 1	2534
	21st to end	Night	66% 5% 9% 13% 5% 1	2145
March	1st to 10th	Night	66% 7% 11% 12% 5%	5096
	11th to 20th	Night	61% 7% 10% 16% 5% 1	5000
	21st to end	Night	77% 6% 10% 7% 1	5489
April	1st to 10th	Night	67% 7% 13% 10% 3	2009
	11th to 20th	Night	62% 7% 10% 13% 6% 2	1804
	21st to end	Night	62% 6% 11% 13% 6% 1	1800
May	1st to 10th	Night	44% 6% 16% 25% 8%	3737
	11th to 20th	Night	62% 11% 12% 10% 5%	3616
	21st to end	Night	62% 10% 11% 15% 2	3700
June	1st to 10th	Night	61% 7% 14% 11% 6% 1	1400
	11th to 20th	Night	62% 9% 12% 14% 4	1400
	21st to end	Night	55% 10% 15% 12% 6% 2	1400
July	1st to 10th	Night	41% 5% 10% 13% 18% 12%	2255
	11th to 20th	Night	44% 7% 12% 21% 15% 1	2248
	21st to end	Night	58% 8% 14% 14% 5% 1	2505
August	1st to 10th	Night	49% 11% 14% 15% 10% 1	2773
	11th to 20th	Night	59% 10% 11% 13% 5% 2	2839
	21st to end	Night	51% 7% 14% 20% 9%	3168
September	1st to 10th	Night	43% 10% 12% 21% 10% 4	1900
	11th to 20th	Night	53% 8% 12% 11% 12% 3	1993
	21st to end	Night	49% 8% 12% 18% 10% 3	2118
October	1st to 10th	Night	55% 8% 14% 17% 6% 1	3800
	11th to 20th	Night	62% 5% 11% 16% 6%	3777
	21st to end	Night	58% 6% 13% 13% 9% 1	4315
November	1st to 10th	Night	70% 6% 9% 11% 4	2730
	11th to 20th	Night	70% 6% 10% 7% 6% 2	2800
	21st to end	Night	68% 5% 10% 9% 7% 1	2800
December	1st to 10th	Night	61% 5% 8% 19% 6%	4684
	11th to 20th	Night	80% 5% 7% 6% 2 1	5556
	21st to end	Night	77% 7% 9% 5% 2	7458

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	51% 9% 19% 13% 8% 1	200
	11th to 20th	Day	38% 8% 19% 21% 15%	200
	21st to end	Day	41% 4 12% 25% 12% 5%	364
February	1st to 10th	Day	39% 7% 17% 23% 12% 2	400
	11th to 20th	Day	39% 5% 14% 26% 14% 2	395
	21st to end	Day	35% 11% 15% 21% 15% 3	331
March	1st to 10th	Day	31% 6% 16% 24% 18% 5%	480
	11th to 20th	Day	32% 6% 15% 25% 16% 6%	500
	21st to end	Day	37% 5% 14% 22% 17% 5%	550
April	1st to 10th	Day	33% 4 16% 25% 15% 6%	500
	11th to 20th	Day	23% 3 14% 29% 20% 10%	492
	21st to end	Day	27% 5% 13% 25% 22% 9%	500
May	1st to 10th	Day	21% 2 12% 28% 27% 10%	503
	11th to 20th	Day	25% 2 10% 23% 25% 14%	528
	21st to end	Day	22% 3 11% 22% 28% 14%	686
June	1st to 10th	Day	27% 2 10% 20% 28% 13%	730
	11th to 20th	Day	23% 3 10% 25% 28% 11%	730
	21st to end	Day	23% 2 8% 19% 32% 16%	730
July	1st to 10th	Day	21% 2 8% 14% 35% 20%	721
	11th to 20th	Day	17% 2 6% 18% 37% 20%	718
	21st to end	Day	17% 1 7% 15% 31% 29%	640
August	1st to 10th	Day	22% 1 7% 15% 24% 30%	487
	11th to 20th	Day	17% 1 5% 15% 33% 29%	477
	21st to end	Day	23% 1 9% 18% 31% 18%	539
September	1st to 10th	Day	23% 2 8% 18% 33% 16%	490
	11th to 20th	Day	27% 1 10% 17% 27% 17%	490
	21st to end	Day	27% 2 10% 22% 28% 11%	490
October	1st to 10th	Day	27% 3 13% 21% 23% 13%	490
	11th to 20th	Day	36% 3 11% 21% 21% 7%	490
	21st to end	Day	32% 5% 18% 26% 15% 5%	463
November	1st to 10th	Day	42% 7% 10% 26% 15% 1	200
	11th to 20th	Day	38% 5% 14% 25% 17% 3	200
	21st to end	Day	44% 10% 12% 17% 12% 7%	200
December	1st to 10th	Day	40% 6% 17% 20% 13% 5%	200
	11th to 20th	Day	42% 8% 21% 22% 7% 1	200
	21st to end	Day	44% 8% 17% 21% 9% 1	220
January	1st to 10th	Night	46% 10% 19% 16% 8% 1	900
	11th to 20th	Night	43% 7% 12% 24% 14%	900
	21st to end	Night	44% 6% 15% 18% 15% 3	923
February	1st to 10th	Night	41% 6% 19% 23% 10% 1	800
	11th to 20th	Night	40% 4 17% 23% 15% 1	784
	21st to end	Night	38% 10% 18% 22% 10% 2	660
March	1st to 10th	Night	34% 8% 17% 22% 16% 4	800
	11th to 20th	Night	40% 6% 16% 19% 15% 4	800
	21st to end	Night	39% 7% 15% 19% 17% 4	880
April	1st to 10th	Night	34% 6% 13% 22% 19% 6%	800
	11th to 20th	Night	32% 5% 14% 25% 18% 6%	616
	21st to end	Night	32% 5% 12% 24% 21% 7%	600
May	1st to 10th	Night	27% 2 8% 27% 26% 9%	448
	11th to 20th	Night	29% 6% 8% 19% 27% 11%	394
	21st to end	Night	28% 4 11% 21% 27% 9%	433
June	1st to 10th	Night	29% 4 11% 22% 25% 10%	400
	11th to 20th	Night	34% 3 11% 20% 23% 10%	400
	21st to end	Night	26% 2 9% 17% 30% 16%	400
July	1st to 10th	Night	24% 2 11% 11% 34% 19%	390
	11th to 20th	Night	22% 3 6% 18% 30% 20%	388
	21st to end	Night	21% 2 7% 17% 27% 24%	416
August	1st to 10th	Night	32% 3 5% 11% 21% 28%	526
	11th to 20th	Night	21% 2 5% 11% 30% 31%	564
	21st to end	Night	28% 2 9% 16% 29% 16%	636
September	1st to 10th	Night	24% 1 6% 18% 30% 21%	760
	11th to 20th	Night	28% 3 8% 18% 24% 20%	760
	21st to end	Night	30% 2 12% 22% 24% 11%	760
October	1st to 10th	Night	26% 3 11% 23% 25% 12%	760
	11th to 20th	Night	36% 3 10% 20% 21% 9%	760
	21st to end	Night	36% 4 16% 23% 17% 4	836
November	1st to 10th	Night	44% 5% 15% 23% 12% 1	780
	11th to 20th	Night	43% 7% 18% 20% 11% 2	800
	21st to end	Night	40% 5% 18% 21% 14% 2	800
December	1st to 10th	Night	39% 6% 16% 21% 16% 2	837
	11th to 20th	Night	48% 6% 17% 20% 8% 1	900
	21st to end	Night	48% 9% 19% 18% 6% 1	990

Page generated at 2025-07-17 22:09:59. Version ac07

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