Hamburg (NJ)
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hamburg (NJ) clear sky chart from 2005-11-06 to 2026-09-29.

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	16% 8% 3 7% 5% 4 5% 4 6% 7% 37%	149434
	Night	16% 8% 3 7% 4 4 4 3 5% 7% 39%	141997
Transparency	Day	44% 4 11% 23% 15% 2	152950
	Night	44% 4 11% 24% 15% 2	146570
Seeing	Day	25% 17% 30% 18% 8% 2	17374
	Night	23% 16% 30% 23% 8% 1	26478

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	12% 10% 3 9% 5% 4 4 4 4 6% 37%	4661
	11th to 20th	Day	15% 10% 3 8% 5% 4 4 2 4 5% 39%	4650
	21st to end	Day	15% 6% 3 8% 4 4 4 4 5% 6% 40%	5638
February	1st to 10th	Day	15% 8% 3 8% 5% 5% 5% 4 5% 7% 36%	1890
	11th to 20th	Day	14% 9% 4 8% 5% 4 4 4 4 6% 38%	2014
	21st to end	Day	17% 11% 3 6% 4 4 4 4 5% 6% 38%	1730
March	1st to 10th	Day	21% 8% 3 7% 4 3 3 2 4 6% 39%	4576
	11th to 20th	Day	12% 7% 3 7% 6% 4 4 3 5% 7% 41%	4965
	21st to end	Day	17% 7% 2 6% 5% 4 4 3 5% 6% 40%	6003
April	1st to 10th	Day	18% 9% 3 7% 5% 4 5% 3 5% 6% 37%	2520
	11th to 20th	Day	17% 8% 2 5% 5% 4 4 3 5% 7% 40%	2494
	21st to end	Day	17% 8% 2 6% 5% 5% 5% 4 5% 7% 37%	2520
May	1st to 10th	Day	23% 8% 3 6% 4 4 4 4 5% 7% 32%	7752
	11th to 20th	Day	17% 9% 3 8% 5% 4 5% 3 4 6% 36%	8221
	21st to end	Day	23% 7% 2 6% 5% 4 5% 4 6% 8% 30%	9060
June	1st to 10th	Day	14% 6% 2 6% 5% 6% 5% 5% 6% 8% 36%	2940
	11th to 20th	Day	15% 7% 3 6% 5% 5% 5% 4 7% 9% 35%	2940
	21st to end	Day	12% 6% 3 7% 6% 4 5% 4 6% 9% 38%	2940
July	1st to 10th	Day	12% 7% 3 7% 5% 5% 5% 5% 6% 9% 34%	8280
	11th to 20th	Day	8% 7% 2 7% 5% 5% 6% 5% 8% 11% 35%	8280
	21st to end	Day	13% 7% 2 7% 4 4 5% 4 6% 8% 40%	8993
August	1st to 10th	Day	16% 7% 3 8% 6% 6% 6% 5% 8% 9% 27%	6143
	11th to 20th	Day	11% 6% 2 6% 4 4 5% 4 6% 9% 42%	5488
	21st to end	Day	12% 6% 3 6% 4 4 4 4 6% 9% 41%	6080
September	1st to 10th	Day	14% 5% 2 6% 5% 4 4 3 5% 8% 42%	2520
	11th to 20th	Day	12% 5% 2 5% 4 4 4 3 5% 7% 48%	2456
	21st to end	Day	19% 7% 3 7% 4 4 4 4 5% 6% 37%	2288
October	1st to 10th	Day	18% 7% 2 6% 3 4 4 4 4 7% 41%	2045
	11th to 20th	Day	14% 7% 3 6% 3 5% 4 3 5% 7% 43%	2000
	21st to end	Day	20% 6% 2 7% 4 3 4 4 5% 6% 40%	2064
November	1st to 10th	Day	13% 7% 2 5% 4 3 3 2 5% 5% 51%	1851
	11th to 20th	Day	16% 8% 2 5% 4 4 4 4 5% 8% 42%	1890
	21st to end	Day	16% 8% 2 7% 4 4 5% 4 5% 7% 38%	1748
December	1st to 10th	Day	14% 9% 3 8% 4 4 5% 3 5% 6% 39%	2680
	11th to 20th	Day	19% 10% 3 6% 4 3 3 3 4 5% 40%	3066
	21st to end	Day	16% 10% 4 9% 6% 5% 4 3 5% 7% 31%	4048
January	1st to 10th	Night	12% 11% 3 10% 6% 5% 4 3 6% 6% 33%	8234
	11th to 20th	Night	14% 9% 4 11% 5% 5% 4 3 5% 6% 33%	8235
	21st to end	Night	14% 8% 3 7% 5% 5% 4 3 5% 6% 42%	8539
February	1st to 10th	Night	15% 9% 3 6% 4 4 4 3 5% 6% 40%	2730
	11th to 20th	Night	16% 8% 3 7% 4 5% 5% 4 5% 7% 37%	2490
	21st to end	Night	17% 8% 3 7% 4 5% 3 3 6% 6% 39%	2076
March	1st to 10th	Night	18% 10% 3 6% 3 3 3 2 5% 6% 39%	5484
	11th to 20th	Night	12% 8% 3 6% 4 4 4 3 5% 6% 44%	5211
	21st to end	Night	16% 8% 3 8% 4 4 5% 4 5% 6% 37%	5171
April	1st to 10th	Night	18% 9% 3 7% 5% 4 5% 4 5% 7% 34%	2100
	11th to 20th	Night	17% 7% 2 7% 5% 4 4 4 5% 7% 37%	2075
	21st to end	Night	19% 7% 3 5% 4 3 5% 3 5% 6% 41%	2097
May	1st to 10th	Night	24% 9% 3 7% 4 3 4 4 5% 7% 30%	5201
	11th to 20th	Night	19% 9% 3 6% 4 4 4 3 5% 7% 36%	4639
	21st to end	Night	23% 9% 3 6% 4 4 4 4 5% 7% 32%	5114
June	1st to 10th	Night	15% 6% 2 5% 5% 4 4 3 5% 8% 43%	1680
	11th to 20th	Night	13% 7% 3 6% 5% 4 4 4 7% 8% 39%	1680
	21st to end	Night	12% 4 2 7% 4 4 4 4 6% 9% 44%	1680
July	1st to 10th	Night	14% 6% 2 6% 5% 4 5% 4 6% 9% 38%	4680
	11th to 20th	Night	10% 7% 3 7% 4 5% 5% 5% 7% 10% 37%	4680
	21st to end	Night	13% 7% 2 6% 4 4 4 4 6% 8% 43%	5084
August	1st to 10th	Night	17% 8% 2 8% 5% 5% 5% 5% 6% 7% 32%	3985
	11th to 20th	Night	14% 7% 3 6% 5% 5% 5% 4 5% 7% 40%	4528
	21st to end	Night	12% 6% 2 6% 4 4 4 3 5% 7% 47%	5045
September	1st to 10th	Night	15% 6% 2 6% 4 4 3 3 4 7% 46%	2100
	11th to 20th	Night	12% 6% 2 5% 4 4 3 3 4 6% 52%	2163
	21st to end	Night	18% 7% 2 7% 4 3 4 3 4 5% 43%	2289
October	1st to 10th	Night	19% 7% 2 5% 4 3 3 2 5% 6% 43%	2350
	11th to 20th	Night	16% 6% 2 6% 3 3 4 3 5% 6% 47%	2400
	21st to end	Night	19% 7% 2 5% 3 3 4 3 5% 6% 43%	2775
November	1st to 10th	Night	12% 6% 2 5% 3 3 3 4 5% 7% 49%	2667
	11th to 20th	Night	17% 8% 2 5% 3 3 3 3 5% 6% 44%	2730
	21st to end	Night	14% 8% 3 5% 4 4 5% 4 5% 7% 42%	2867
December	1st to 10th	Night	13% 10% 4 6% 4 4 4 3 4 7% 42%	4720
	11th to 20th	Night	22% 10% 2 5% 3 3 4 3 4 5% 38%	5348
	21st to end	Night	18% 12% 4 7% 4 4 4 3 5% 5% 33%	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	43% 6% 8% 27% 13% 2	4662
	11th to 20th	Day	47% 4 8% 22% 14% 6%	4680
	21st to end	Day	44% 4 11% 24% 17% 1	5638
February	1st to 10th	Day	48% 3 12% 22% 14% 2	1890
	11th to 20th	Day	48% 4 8% 23% 16% 2	2023
	21st to end	Day	48% 3 9% 24% 13% 3	1730
March	1st to 10th	Day	47% 3 9% 21% 13% 7%	4579
	11th to 20th	Day	43% 3 11% 30% 10% 4	4965
	21st to end	Day	46% 3 10% 12% 24% 5%	6003
April	1st to 10th	Day	49% 2 7% 21% 15% 4	2520
	11th to 20th	Day	45% 4 11% 20% 17% 3	2494
	21st to end	Day	47% 3 8% 22% 15% 4	2520
May	1st to 10th	Day	52% 4 12% 18% 12% 1	7764
	11th to 20th	Day	48% 4 10% 23% 13% 1	8225
	21st to end	Day	51% 4 11% 21% 12% 1	9061
June	1st to 10th	Day	45% 5% 11% 22% 16% 1	2940
	11th to 20th	Day	46% 4 12% 24% 12% 2	2940
	21st to end	Day	42% 5% 13% 24% 14% 1	2940
July	1st to 10th	Day	45% 8% 13% 20% 14% 1	8210
	11th to 20th	Day	40% 7% 16% 26% 12%	8205
	21st to end	Day	41% 5% 11% 24% 18% 1	8795
August	1st to 10th	Day	51% 7% 15% 18% 10%	6129
	11th to 20th	Day	38% 5% 18% 31% 9%	5524
	21st to end	Day	38% 4 12% 31% 14% 2	6080
September	1st to 10th	Day	41% 4 11% 24% 18% 2	2520
	11th to 20th	Day	37% 3 9% 24% 25% 3	2456
	21st to end	Day	47% 4 9% 19% 18% 2	2288
October	1st to 10th	Day	41% 3 7% 21% 23% 5%	3331
	11th to 20th	Day	31% 3 9% 29% 24% 4	3240
	21st to end	Day	29% 3 16% 26% 23% 4	3315
November	1st to 10th	Day	37% 3 12% 25% 21% 3	1851
	11th to 20th	Day	42% 3 9% 25% 19% 3	1890
	21st to end	Day	45% 3 12% 28% 11% 2	1748
December	1st to 10th	Day	44% 4 14% 27% 10% 1	2680
	11th to 20th	Day	47% 2 12% 22% 14% 2	3066
	21st to end	Day	51% 4 8% 21% 15% 2	4048
January	1st to 10th	Night	45% 6% 10% 25% 12% 2	8234
	11th to 20th	Night	46% 7% 11% 19% 12% 4	8280
	21st to end	Night	43% 3 9% 23% 20% 3	8539
February	1st to 10th	Night	45% 3 12% 24% 13% 2	2730
	11th to 20th	Night	47% 4 8% 20% 17% 3	2492
	21st to end	Night	46% 3 6% 26% 15% 3	2076
March	1st to 10th	Night	46% 3 10% 21% 14% 5%	5494
	11th to 20th	Night	41% 2 15% 25% 13% 4	5212
	21st to end	Night	46% 4 7% 16% 22% 5%	5171
April	1st to 10th	Night	50% 3 9% 20% 14% 4	2100
	11th to 20th	Night	47% 4 10% 19% 19% 1	2075
	21st to end	Night	45% 3 8% 24% 17% 4	2097
May	1st to 10th	Night	54% 4 11% 19% 11% 1	5207
	11th to 20th	Night	49% 4 12% 22% 12% 1	4640
	21st to end	Night	52% 4 11% 22% 9% 1	5115
June	1st to 10th	Night	41% 4 10% 25% 19% 1	1680
	11th to 20th	Night	42% 5% 13% 28% 11% 1	1680
	21st to end	Night	37% 5% 15% 27% 15% 1	1680
July	1st to 10th	Night	42% 7% 15% 20% 15% 1	4640
	11th to 20th	Night	41% 7% 15% 25% 11% 1	4632
	21st to end	Night	38% 5% 12% 25% 18% 1	4967
August	1st to 10th	Night	50% 7% 15% 19% 9% 1	3975
	11th to 20th	Night	42% 5% 17% 28% 8%	4558
	21st to end	Night	36% 5% 13% 31% 15% 1	5045
September	1st to 10th	Night	40% 4 10% 26% 19% 1	2100
	11th to 20th	Night	35% 3 10% 24% 26% 2	2163
	21st to end	Night	44% 3 8% 22% 21% 1	2289
October	1st to 10th	Night	41% 4 9% 24% 20% 1	3844
	11th to 20th	Night	29% 4 10% 28% 26% 4	3899
	21st to end	Night	31% 3 14% 31% 19% 2	4474
November	1st to 10th	Night	35% 4 12% 25% 22% 3	2667
	11th to 20th	Night	41% 3 9% 24% 20% 4	2730
	21st to end	Night	41% 4 12% 30% 13% 1	2867
December	1st to 10th	Night	42% 4 13% 31% 9% 1	4720
	11th to 20th	Night	48% 3 10% 21% 16% 2	5348
	21st to end	Night	52% 3 8% 19% 15% 3	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	37% 26% 26% 10% 1	220
	11th to 20th	Day	41% 28% 25% 6%	220
	21st to end	Day	33% 28% 29% 6% 3 1	337
February	1st to 10th	Day	36% 27% 28% 6% 2	330
	11th to 20th	Day	40% 26% 27% 6%	502
	21st to end	Day	35% 26% 30% 8% 2	446
March	1st to 10th	Day	32% 24% 30% 12% 2	540
	11th to 20th	Day	31% 25% 30% 10% 4 1	540
	21st to end	Day	35% 25% 27% 9% 4 1	594
April	1st to 10th	Day	36% 20% 29% 10% 4	540
	11th to 20th	Day	30% 23% 29% 12% 5% 1	532
	21st to end	Day	30% 18% 35% 13% 4 1	540
May	1st to 10th	Day	36% 20% 27% 12% 5% 1	543
	11th to 20th	Day	23% 20% 31% 18% 7% 1	567
	21st to end	Day	25% 11% 30% 24% 8% 2	617
June	1st to 10th	Day	19% 16% 31% 23% 10% 2	570
	11th to 20th	Day	22% 14% 29% 24% 10% 1	570
	21st to end	Day	17% 13% 33% 27% 9% 2	570
July	1st to 10th	Day	16% 8% 28% 29% 15% 4	565
	11th to 20th	Day	11% 7% 33% 30% 16% 3	564
	21st to end	Day	13% 12% 32% 30% 11% 2	620
August	1st to 10th	Day	14% 7% 28% 30% 13% 7%	566
	11th to 20th	Day	14% 6% 29% 31% 14% 5%	559
	21st to end	Day	14% 9% 32% 26% 13% 6%	627
September	1st to 10th	Day	18% 12% 31% 20% 13% 6%	570
	11th to 20th	Day	15% 9% 29% 25% 13% 10%	570
	21st to end	Day	26% 12% 28% 20% 10% 4	562
October	1st to 10th	Day	25% 12% 27% 20% 13% 4	530
	11th to 20th	Day	22% 20% 29% 20% 7% 2	530
	21st to end	Day	26% 17% 31% 17% 7% 1	508
November	1st to 10th	Day	24% 19% 30% 18% 8% 1	425
	11th to 20th	Day	28% 23% 28% 16% 4	430
	21st to end	Day	34% 24% 27% 11% 3	288
December	1st to 10th	Day	35% 25% 25% 11% 4	220
	11th to 20th	Day	42% 21% 26% 6% 4	220
	21st to end	Day	31% 26% 31% 7% 5%	242
January	1st to 10th	Night	24% 27% 33% 13% 3	840
	11th to 20th	Night	30% 21% 30% 17% 3	840
	21st to end	Night	25% 26% 33% 15% 2	924
February	1st to 10th	Night	27% 21% 33% 17% 2	840
	11th to 20th	Night	29% 27% 33% 11% 1	823
	21st to end	Night	31% 23% 31% 13% 2	692
March	1st to 10th	Night	29% 22% 31% 14% 3	840
	11th to 20th	Night	28% 25% 30% 15% 3	840
	21st to end	Night	25% 25% 32% 13% 4	924
April	1st to 10th	Night	29% 21% 31% 15% 4	840
	11th to 20th	Night	24% 20% 33% 18% 4	831
	21st to end	Night	25% 16% 32% 21% 5%	837
May	1st to 10th	Night	29% 14% 32% 20% 5%	610
	11th to 20th	Night	21% 14% 37% 22% 6%	414
	21st to end	Night	20% 7% 28% 33% 11% 1	455
June	1st to 10th	Night	17% 6% 31% 34% 10% 1	420
	11th to 20th	Night	14% 9% 32% 35% 10%	420
	21st to end	Night	13% 6% 26% 44% 11%	420
July	1st to 10th	Night	14% 4 25% 39% 17% 1	410
	11th to 20th	Night	12% 4 28% 38% 16% 1	408
	21st to end	Night	12% 5% 25% 42% 15% 1	460
August	1st to 10th	Night	12% 3 24% 37% 22% 2	555
	11th to 20th	Night	14% 5% 22% 36% 21% 2	814
	21st to end	Night	15% 5% 24% 36% 17% 2	924
September	1st to 10th	Night	17% 8% 25% 35% 15% 2	840
	11th to 20th	Night	15% 7% 26% 30% 18% 4	840
	21st to end	Night	23% 8% 25% 29% 14% 2	833
October	1st to 10th	Night	22% 11% 25% 27% 14% 2	800
	11th to 20th	Night	21% 14% 31% 26% 8%	800
	21st to end	Night	25% 16% 32% 20% 6%	880
November	1st to 10th	Night	19% 16% 34% 22% 9% 1	820
	11th to 20th	Night	26% 19% 30% 19% 5% 1	840
	21st to end	Night	22% 22% 33% 18% 5%	840
December	1st to 10th	Night	27% 20% 31% 17% 5%	840
	11th to 20th	Night	27% 22% 32% 16% 3	840
	21st to end	Night	30% 21% 31% 15% 2	924

Page generated at 2026-09-26 04:18:39. Version ac07

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