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 2025-05-26.

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 4 4 5% 7% 38%	113947
	Night	16% 8% 3 7% 4 4 4 3 5% 6% 40%	115321
Transparency	Day	45% 4 11% 23% 15% 3	117509
	Night	43% 4 11% 24% 16% 2	119923
Seeing	Day	25% 17% 29% 18% 8% 2	15580
	Night	23% 16% 30% 23% 8% 1	24852

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% 39%	3597
	11th to 20th	Day	15% 10% 4 9% 5% 4 5% 3 4 5% 35%	3570
	21st to end	Day	18% 8% 3 8% 4 4 4 3 4 5% 38%	4352
February	1st to 10th	Day	16% 9% 3 8% 5% 5% 5% 4 5% 7% 35%	1800
	11th to 20th	Day	14% 9% 3 8% 5% 4 4 4 4 6% 39%	1915
	21st to end	Day	17% 11% 3 6% 5% 4 4 4 5% 5% 37%	1650
March	1st to 10th	Day	21% 8% 3 7% 4 3 3 2 4 6% 39%	4476
	11th to 20th	Day	12% 7% 3 7% 6% 5% 4 3 5% 7% 41%	4858
	21st to end	Day	18% 7% 2 6% 5% 4 4 3 5% 6% 40%	5873
April	1st to 10th	Day	18% 9% 3 7% 5% 4 5% 3 5% 6% 36%	2400
	11th to 20th	Day	17% 8% 2 6% 5% 4 4 3 5% 7% 39%	2374
	21st to end	Day	17% 7% 2 6% 5% 5% 5% 4 5% 7% 37%	2400
May	1st to 10th	Day	27% 8% 3 6% 4 4 3 3 5% 6% 31%	4297
	11th to 20th	Day	21% 9% 3 8% 6% 4 5% 4 4 6% 29%	4538
	21st to end	Day	13% 5% 2 5% 4 4 4 4 7% 10% 41%	4907
June	1st to 10th	Day	14% 6% 2 6% 5% 6% 5% 5% 6% 8% 36%	2660
	11th to 20th	Day	15% 7% 3 6% 5% 5% 5% 5% 7% 9% 34%	2660
	21st to end	Day	12% 7% 3 7% 6% 4 5% 4 6% 9% 38%	2660
July	1st to 10th	Day	8% 7% 3 8% 7% 6% 6% 5% 7% 10% 33%	4440
	11th to 20th	Day	10% 7% 2 7% 5% 5% 5% 5% 7% 10% 37%	4440
	21st to end	Day	13% 9% 3 9% 6% 5% 5% 4 6% 7% 33%	4814
August	1st to 10th	Day	21% 6% 3 7% 5% 5% 5% 5% 7% 7% 29%	4188
	11th to 20th	Day	12% 6% 3 7% 4 5% 5% 4 6% 8% 40%	3730
	21st to end	Day	12% 6% 3 5% 3 4 4 3 6% 9% 45%	4180
September	1st to 10th	Day	15% 5% 2 6% 5% 4 4 3 5% 8% 42%	2280
	11th to 20th	Day	12% 5% 2 5% 4 4 4 3 5% 7% 49%	2222
	21st to end	Day	18% 7% 3 7% 4 4 4 4 5% 6% 39%	2090
October	1st to 10th	Day	18% 7% 2 7% 3 4 4 4 4 6% 39%	1943
	11th to 20th	Day	13% 7% 3 6% 3 5% 4 3 5% 7% 44%	1900
	21st to end	Day	21% 6% 2 6% 4 3 4 4 5% 6% 39%	1961
November	1st to 10th	Day	14% 7% 2 5% 4 2 3 2 4 5% 52%	1761
	11th to 20th	Day	17% 8% 2 5% 3 3 3 3 5% 8% 43%	1800
	21st to end	Day	16% 8% 2 6% 4 4 5% 4 5% 7% 38%	1665
December	1st to 10th	Day	14% 9% 3 8% 4 3 5% 3 5% 6% 39%	2600
	11th to 20th	Day	20% 10% 3 6% 4 4 3 3 4 5% 39%	2986
	21st to end	Day	16% 10% 3 9% 6% 5% 4 3 5% 7% 31%	3960
January	1st to 10th	Night	13% 8% 3 9% 5% 5% 4 3 6% 6% 37%	6349
	11th to 20th	Night	12% 9% 4 11% 5% 5% 4 3 5% 6% 35%	6315
	21st to end	Night	16% 9% 3 7% 5% 4 4 3 5% 6% 38%	6600
February	1st to 10th	Night	16% 9% 4 6% 4 4 4 3 5% 6% 39%	2600
	11th to 20th	Night	16% 7% 3 7% 4 5% 5% 4 5% 7% 38%	2369
	21st to end	Night	17% 8% 3 7% 4 5% 3 3 6% 5% 39%	1980
March	1st to 10th	Night	18% 10% 3 6% 3 3 3 3 5% 6% 39%	5364
	11th to 20th	Night	12% 8% 3 6% 4 4 4 3 5% 6% 44%	5098
	21st to end	Night	16% 9% 3 8% 4 4 4 4 5% 6% 38%	5059
April	1st to 10th	Night	17% 9% 3 7% 5% 4 5% 4 5% 7% 34%	2000
	11th to 20th	Night	17% 7% 2 7% 5% 4 4 4 5% 7% 37%	1975
	21st to end	Night	18% 7% 3 5% 4 3 5% 3 5% 6% 41%	1997
May	1st to 10th	Night	26% 9% 3 7% 3 3 3 4 5% 7% 30%	2892
	11th to 20th	Night	23% 9% 4 7% 3 4 4 3 5% 6% 32%	2575
	21st to end	Night	13% 8% 3 6% 4 4 4 4 6% 9% 40%	2784
June	1st to 10th	Night	16% 6% 2 5% 5% 4 4 3 5% 8% 43%	1520
	11th to 20th	Night	13% 6% 2 6% 5% 4 4 4 7% 8% 41%	1520
	21st to end	Night	12% 3 2 7% 4 4 4 4 7% 8% 45%	1520
July	1st to 10th	Night	9% 6% 2 7% 6% 5% 6% 4 7% 9% 39%	2520
	11th to 20th	Night	10% 7% 2 6% 4 5% 4 5% 8% 11% 38%	2520
	21st to end	Night	15% 8% 2 6% 4 4 5% 5% 6% 8% 36%	2739
August	1st to 10th	Night	20% 7% 2 8% 4 5% 5% 4 6% 7% 33%	2720
	11th to 20th	Night	14% 8% 3 6% 4 5% 4 4 5% 7% 40%	3083
	21st to end	Night	11% 5% 2 5% 4 4 4 4 5% 8% 50%	3476
September	1st to 10th	Night	14% 6% 2 6% 4 4 3 3 4 7% 47%	1900
	11th to 20th	Night	12% 6% 2 4 3 3 3 3 4 6% 53%	1957
	21st to end	Night	17% 6% 2 7% 4 3 4 3 5% 5% 45%	2090
October	1st to 10th	Night	19% 7% 2 6% 4 3 3 3 5% 6% 41%	2232
	11th to 20th	Night	16% 6% 2 6% 3 3 4 3 5% 5% 48%	2280
	21st to end	Night	19% 8% 2 5% 3 3 4 3 5% 6% 43%	2636
November	1st to 10th	Night	12% 6% 2 5% 3 3 4 4 5% 6% 50%	2537
	11th to 20th	Night	17% 8% 2 4 3 3 3 3 5% 6% 45%	2600
	21st to end	Night	14% 8% 3 5% 4 4 5% 4 5% 7% 42%	2730
December	1st to 10th	Night	13% 10% 4 6% 4 4 4 3 4 7% 42%	4580
	11th to 20th	Night	22% 10% 2 5% 3 3 4 3 4 5% 38%	5208
	21st to end	Night	18% 12% 4 7% 4 4 4 3 5% 5% 33%	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	41% 6% 7% 30% 14% 2	3598
	11th to 20th	Day	49% 4 7% 22% 12% 5%	3600
	21st to end	Day	48% 3 10% 23% 16% 1	4352
February	1st to 10th	Day	49% 3 13% 21% 13% 1	1800
	11th to 20th	Day	47% 4 7% 23% 17% 3	1924
	21st to end	Day	49% 2 9% 23% 13% 3	1650
March	1st to 10th	Day	47% 3 9% 21% 13% 8%	4479
	11th to 20th	Day	43% 2 11% 30% 10% 4	4858
	21st to end	Day	46% 3 10% 12% 24% 5%	5873
April	1st to 10th	Day	50% 3 7% 21% 15% 4	2400
	11th to 20th	Day	47% 3 9% 20% 18% 3	2374
	21st to end	Day	47% 3 8% 22% 16% 4	2400
May	1st to 10th	Day	56% 2 11% 17% 12% 2	4311
	11th to 20th	Day	57% 2 10% 20% 9% 1	4542
	21st to end	Day	39% 2 11% 27% 18% 2	4907
June	1st to 10th	Day	46% 5% 12% 22% 15% 1	2660
	11th to 20th	Day	46% 4 12% 25% 11% 2	2660
	21st to end	Day	42% 5% 13% 25% 15%	2660
July	1st to 10th	Day	44% 7% 12% 22% 13% 1	4370
	11th to 20th	Day	40% 5% 16% 24% 13% 1	4365
	21st to end	Day	49% 5% 11% 18% 15% 2	4661
August	1st to 10th	Day	52% 5% 13% 21% 9%	4174
	11th to 20th	Day	40% 4 14% 29% 11% 1	3766
	21st to end	Day	36% 4 10% 33% 16% 1	4180
September	1st to 10th	Day	41% 4 10% 24% 18% 2	2280
	11th to 20th	Day	37% 3 8% 24% 26% 3	2222
	21st to end	Day	46% 4 9% 20% 19% 3	2090
October	1st to 10th	Day	42% 3 7% 21% 23% 5%	3229
	11th to 20th	Day	31% 3 9% 29% 25% 4	3140
	21st to end	Day	29% 3 16% 25% 23% 4	3212
November	1st to 10th	Day	36% 3 12% 25% 21% 3	1761
	11th to 20th	Day	41% 3 9% 25% 19% 3	1800
	21st to end	Day	44% 3 13% 28% 11% 2	1665
December	1st to 10th	Day	44% 4 15% 27% 10% 1	2600
	11th to 20th	Day	47% 2 12% 22% 14% 2	2986
	21st to end	Day	51% 4 8% 21% 15% 2	3960
January	1st to 10th	Night	40% 7% 9% 27% 15% 3	6349
	11th to 20th	Night	44% 7% 14% 20% 11% 4	6360
	21st to end	Night	47% 2 9% 20% 18% 4	6600
February	1st to 10th	Night	46% 3 12% 24% 13% 2	2600
	11th to 20th	Night	46% 4 8% 21% 18% 4	2371
	21st to end	Night	47% 2 6% 25% 16% 3	1980
March	1st to 10th	Night	46% 3 10% 21% 14% 5%	5374
	11th to 20th	Night	41% 2 15% 25% 13% 4	5099
	21st to end	Night	46% 4 7% 17% 22% 5%	5059
April	1st to 10th	Night	50% 3 8% 20% 15% 3	2000
	11th to 20th	Night	47% 4 9% 19% 19% 1	1975
	21st to end	Night	45% 3 8% 24% 17% 4	1997
May	1st to 10th	Night	56% 3 9% 21% 10% 1	2898
	11th to 20th	Night	55% 4 12% 17% 10% 1	2576
	21st to end	Night	42% 3 14% 26% 13% 2	2785
June	1st to 10th	Night	41% 4 11% 25% 18% 1	1520
	11th to 20th	Night	40% 5% 14% 29% 10% 1	1520
	21st to end	Night	36% 5% 15% 28% 15% 1	1520
July	1st to 10th	Night	40% 7% 16% 21% 14% 2	2480
	11th to 20th	Night	40% 6% 16% 26% 12% 1	2472
	21st to end	Night	45% 5% 14% 17% 18% 2	2651
August	1st to 10th	Night	51% 6% 15% 19% 9% 1	2710
	11th to 20th	Night	43% 4 14% 28% 10%	3113
	21st to end	Night	32% 4 12% 34% 17% 1	3476
September	1st to 10th	Night	40% 4 9% 26% 19% 1	1900
	11th to 20th	Night	34% 3 10% 25% 26% 2	1957
	21st to end	Night	42% 3 8% 23% 22% 1	2090
October	1st to 10th	Night	42% 4 10% 24% 20% 1	3726
	11th to 20th	Night	28% 4 9% 28% 27% 4	3779
	21st to end	Night	32% 3 14% 31% 19% 2	4335
November	1st to 10th	Night	35% 4 11% 25% 22% 3	2537
	11th to 20th	Night	42% 2 9% 24% 20% 4	2600
	21st to end	Night	40% 4 12% 30% 12% 1	2730
December	1st to 10th	Night	42% 4 13% 31% 9% 1	4580
	11th to 20th	Night	48% 2 10% 21% 15% 2	5208
	21st to end	Night	52% 3 8% 19% 15% 3	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	37% 25% 28% 10% 2	200
	11th to 20th	Day	40% 28% 26% 7% 1	200
	21st to end	Day	30% 29% 30% 7% 4 1	306
February	1st to 10th	Day	38% 26% 29% 6% 1	300
	11th to 20th	Day	40% 26% 27% 6%	463
	21st to end	Day	36% 23% 30% 8% 2	414
March	1st to 10th	Day	32% 24% 29% 12% 3	500
	11th to 20th	Day	29% 25% 31% 11% 4 1	500
	21st to end	Day	34% 23% 28% 9% 4 1	550
April	1st to 10th	Day	35% 20% 30% 10% 4	500
	11th to 20th	Day	31% 22% 28% 12% 5% 1	492
	21st to end	Day	29% 19% 34% 13% 4 1	500
May	1st to 10th	Day	36% 18% 27% 13% 5% 2	503
	11th to 20th	Day	24% 19% 30% 18% 7% 2	527
	21st to end	Day	22% 10% 31% 27% 9% 2	549
June	1st to 10th	Day	20% 15% 32% 21% 10% 2	490
	11th to 20th	Day	19% 14% 28% 26% 12% 1	490
	21st to end	Day	16% 13% 32% 27% 9% 2	490
July	1st to 10th	Day	16% 7% 29% 27% 16% 5%	485
	11th to 20th	Day	11% 5% 33% 31% 17% 2	484
	21st to end	Day	13% 12% 33% 28% 12% 2	532
August	1st to 10th	Day	15% 7% 29% 30% 13% 6%	486
	11th to 20th	Day	14% 6% 29% 30% 15% 6%	479
	21st to end	Day	15% 8% 29% 27% 14% 6%	539
September	1st to 10th	Day	20% 11% 28% 21% 14% 6%	490
	11th to 20th	Day	15% 9% 29% 23% 13% 11%	490
	21st to end	Day	25% 12% 28% 21% 11% 4	490
October	1st to 10th	Day	26% 12% 27% 20% 12% 4	490
	11th to 20th	Day	20% 20% 30% 21% 8% 2	490
	21st to end	Day	26% 18% 31% 17% 8% 1	471
November	1st to 10th	Day	23% 19% 29% 19% 9% 2	395
	11th to 20th	Day	28% 23% 29% 16% 4 1	400
	21st to end	Day	32% 23% 29% 12% 3	265
December	1st to 10th	Day	36% 24% 25% 11% 5%	200
	11th to 20th	Day	41% 22% 27% 7% 4	200
	21st to end	Day	28% 25% 33% 8% 6%	220
January	1st to 10th	Night	25% 27% 33% 13% 2	800
	11th to 20th	Night	29% 20% 30% 18% 3	800
	21st to end	Night	24% 26% 34% 15% 2	880
February	1st to 10th	Night	27% 22% 33% 16% 2	800
	11th to 20th	Night	29% 27% 33% 10% 1	783
	21st to end	Night	32% 22% 30% 13% 3	660
March	1st to 10th	Night	29% 22% 31% 14% 3	800
	11th to 20th	Night	27% 25% 30% 15% 3 1	800
	21st to end	Night	24% 24% 33% 14% 4	880
April	1st to 10th	Night	28% 21% 32% 16% 4	800
	11th to 20th	Night	25% 20% 32% 19% 4	791
	21st to end	Night	25% 16% 32% 21% 5%	797
May	1st to 10th	Night	30% 14% 30% 21% 6%	581
	11th to 20th	Night	22% 14% 36% 22% 7%	394
	21st to end	Night	18% 7% 27% 35% 12% 1	423
June	1st to 10th	Night	19% 6% 30% 35% 10% 1	380
	11th to 20th	Night	13% 7% 31% 37% 11% 1	380
	21st to end	Night	13% 6% 26% 44% 11%	380
July	1st to 10th	Night	13% 5% 25% 38% 18% 2	370
	11th to 20th	Night	12% 4 27% 38% 18% 1	368
	21st to end	Night	13% 5% 24% 42% 15% 1	416
August	1st to 10th	Night	12% 2 24% 38% 21% 2	501
	11th to 20th	Night	15% 5% 21% 36% 21% 2	736
	21st to end	Night	15% 6% 22% 37% 18% 2	836
September	1st to 10th	Night	16% 7% 25% 34% 15% 2	760
	11th to 20th	Night	16% 7% 26% 28% 19% 4	760
	21st to end	Night	21% 8% 26% 29% 14% 2	760
October	1st to 10th	Night	22% 11% 25% 26% 13% 2	760
	11th to 20th	Night	20% 13% 32% 26% 8%	760
	21st to end	Night	26% 16% 32% 20% 7%	836
November	1st to 10th	Night	17% 16% 34% 23% 9% 1	780
	11th to 20th	Night	25% 18% 31% 19% 6% 1	800
	21st to end	Night	22% 21% 33% 18% 5% 1	800
December	1st to 10th	Night	28% 20% 31% 17% 5%	800
	11th to 20th	Night	27% 22% 32% 17% 3	800
	21st to end	Night	28% 21% 32% 16% 3	880

Page generated at 2025-05-23 09:20:59. Version ac07

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