Newark
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Newark clear sky chart from 2005-11-06 to 2024-07-05.

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	17% 7% 2 6% 4 4 4 4 5% 7% 40%	89578
	Night	18% 7% 2 6% 4 4 4 3 5% 6% 42%	89689
Transparency	Day	42% 7% 12% 22% 15% 2	89297
	Night	42% 6% 11% 22% 15% 3	89524
Seeing	Day	20% 15% 31% 22% 10% 3	14525
	Night	20% 11% 31% 28% 9% 1	23720

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% 8% 2 5% 4 3 4 3 5% 5% 48%	2517
	11th to 20th	Day	15% 9% 3 6% 5% 5% 4 3 6% 7% 36%	2520
	21st to end	Day	22% 12% 4 7% 4 4 4 3 4 4 33%	3030
February	1st to 10th	Day	18% 8% 3 6% 4 3 3 3 6% 6% 39%	1714
	11th to 20th	Day	15% 7% 3 6% 4 5% 4 3 5% 6% 44%	1848
	21st to end	Day	20% 8% 2 5% 4 3 5% 4 5% 6% 37%	1570
March	1st to 10th	Day	27% 8% 2 6% 4 3 3 3 4 5% 35%	3116
	11th to 20th	Day	10% 6% 1 5% 5% 5% 6% 4 6% 7% 44%	3347
	21st to end	Day	21% 6% 2 6% 3 3 3 3 4 6% 43%	4127
April	1st to 10th	Day	19% 8% 2 6% 4 4 4 4 5% 7% 38%	2280
	11th to 20th	Day	17% 6% 2 6% 4 5% 4 3 5% 7% 42%	2254
	21st to end	Day	19% 6% 2 6% 4 4 4 3 6% 7% 40%	2293
May	1st to 10th	Day	28% 8% 2 5% 4 4 3 3 5% 8% 30%	4106
	11th to 20th	Day	24% 8% 3 7% 5% 4 4 4 5% 7% 30%	4382
	21st to end	Day	14% 5% 2 5% 4 4 4 4 6% 9% 44%	4837
June	1st to 10th	Day	15% 6% 2 5% 5% 4 5% 5% 7% 9% 38%	2660
	11th to 20th	Day	15% 7% 2 6% 5% 4 5% 4 7% 8% 37%	2660
	21st to end	Day	11% 6% 2 6% 5% 5% 5% 5% 7% 9% 40%	2660
July	1st to 10th	Day	10% 5% 2 7% 6% 4 6% 5% 7% 9% 38%	2576
	11th to 20th	Day	10% 5% 2 5% 4 4 6% 5% 7% 11% 41%	2520
	21st to end	Day	12% 6% 3 7% 6% 6% 7% 5% 6% 9% 35%	2744
August	1st to 10th	Day	9% 5% 2 7% 5% 6% 5% 5% 8% 9% 38%	2360
	11th to 20th	Day	13% 5% 2 6% 6% 5% 6% 4 6% 9% 39%	2126
	21st to end	Day	13% 6% 2 6% 5% 4 4 4 6% 7% 42%	2376
September	1st to 10th	Day	14% 6% 2 5% 4 5% 5% 4 5% 8% 43%	2160
	11th to 20th	Day	13% 5% 2 5% 3 3 3 3 5% 7% 50%	2088
	21st to end	Day	17% 5% 2 6% 5% 4 4 4 4 6% 42%	1980
October	1st to 10th	Day	21% 6% 2 5% 3 3 4 3 4 7% 41%	1872
	11th to 20th	Day	16% 5% 2 5% 4 4 4 3 5% 6% 47%	1800
	21st to end	Day	22% 5% 1 5% 3 4 5% 3 4 6% 42%	1846
November	1st to 10th	Day	15% 5% 2 5% 3 3 3 3 4 5% 52%	1671
	11th to 20th	Day	18% 5% 2 5% 4 3 3 3 4 6% 48%	1710
	21st to end	Day	15% 7% 1 5% 3 4 4 3 5% 6% 45%	1630
December	1st to 10th	Day	18% 8% 2 6% 4 4 4 2 5% 8% 39%	1520
	11th to 20th	Day	23% 5% 2 4 4 2 3 3 4 6% 45%	1906
	21st to end	Day	18% 9% 3 8% 5% 4 5% 5% 6% 7% 32%	2772
January	1st to 10th	Night	17% 7% 2 5% 3 3 3 3 4 5% 47%	4429
	11th to 20th	Night	17% 9% 3 6% 3 4 4 3 4 4 43%	4440
	21st to end	Night	25% 10% 3 6% 3 3 4 3 4 5% 35%	4624
February	1st to 10th	Night	17% 9% 3 5% 3 4 4 3 5% 6% 42%	2465
	11th to 20th	Night	17% 9% 2 6% 4 4 3 3 5% 6% 41%	2218
	21st to end	Night	20% 7% 2 5% 4 3 3 3 5% 5% 41%	1884
March	1st to 10th	Night	24% 10% 3 6% 4 3 3 2 4 5% 37%	3724
	11th to 20th	Night	12% 6% 2 6% 4 4 4 4 5% 6% 47%	3608
	21st to end	Night	20% 9% 3 5% 3 3 3 3 4 5% 42%	3503
April	1st to 10th	Night	19% 7% 2 6% 4 4 4 4 6% 5% 38%	1900
	11th to 20th	Night	18% 7% 2 6% 4 4 5% 3 4 7% 41%	1875
	21st to end	Night	19% 7% 2 5% 3 3 4 3 5% 6% 42%	1886
May	1st to 10th	Night	26% 10% 3 7% 4 4 3 3 4 6% 30%	2834
	11th to 20th	Night	25% 8% 3 7% 5% 4 3 3 4 5% 33%	2540
	21st to end	Night	16% 7% 3 6% 4 4 4 3 6% 8% 41%	2738
June	1st to 10th	Night	16% 7% 2 4 4 4 4 3 6% 8% 40%	1520
	11th to 20th	Night	13% 7% 2 5% 5% 4 4 4 6% 8% 42%	1520
	21st to end	Night	10% 4 2 5% 5% 4 5% 4 7% 10% 44%	1520
July	1st to 10th	Night	12% 5% 2 6% 5% 5% 4 5% 7% 9% 39%	1478
	11th to 20th	Night	12% 5% 2 5% 5% 5% 6% 5% 7% 8% 40%	1440
	21st to end	Night	10% 5% 2 5% 4 4 5% 5% 7% 10% 42%	1574
August	1st to 10th	Night	9% 5% 3 6% 4 4 6% 5% 6% 9% 43%	1555
	11th to 20th	Night	12% 5% 2 9% 5% 5% 5% 4 6% 8% 37%	1774
	21st to end	Night	14% 5% 2 6% 5% 4 5% 3 5% 8% 42%	1980
September	1st to 10th	Night	15% 5% 2 7% 4 4 5% 3 5% 6% 43%	1800
	11th to 20th	Night	16% 5% 1 4 3 3 3 3 4 7% 51%	1872
	21st to end	Night	17% 7% 2 5% 4 4 3 3 4 6% 45%	1980
October	1st to 10th	Night	20% 6% 3 6% 4 3 4 3 5% 6% 41%	2083
	11th to 20th	Night	15% 5% 2 6% 4 3 3 3 4 7% 48%	2160
	21st to end	Night	21% 7% 2 5% 3 3 3 3 5% 5% 43%	2510
November	1st to 10th	Night	13% 5% 1 5% 4 3 4 4 4 5% 52%	2407
	11th to 20th	Night	19% 6% 2 5% 3 3 3 3 4 5% 47%	2470
	21st to end	Night	14% 6% 2 5% 4 3 4 4 5% 7% 46%	2546
December	1st to 10th	Night	20% 7% 3 6% 4 3 3 4 5% 6% 40%	2660
	11th to 20th	Night	20% 7% 1 5% 4 4 4 3 5% 6% 42%	3288
	21st to end	Night	20% 9% 3 6% 4 4 4 3 4 6% 36%	4884

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	38% 3 11% 31% 14% 3	2518
	11th to 20th	Day	45% 6% 13% 23% 12% 2	2520
	21st to end	Day	55% 4 9% 21% 10% 2	3030
February	1st to 10th	Day	45% 5% 13% 23% 12% 2	1714
	11th to 20th	Day	42% 4 10% 25% 17% 3	1857
	21st to end	Day	46% 5% 11% 22% 13% 3	1570
March	1st to 10th	Day	48% 6% 11% 23% 9% 2	3119
	11th to 20th	Day	32% 9% 14% 30% 14% 2	3347
	21st to end	Day	43% 4 9% 15% 24% 5%	4127
April	1st to 10th	Day	44% 5% 11% 20% 16% 4	2280
	11th to 20th	Day	41% 6% 12% 21% 17% 3	2254
	21st to end	Day	43% 6% 11% 20% 17% 4	2293
May	1st to 10th	Day	53% 6% 14% 14% 12% 1	4120
	11th to 20th	Day	50% 8% 13% 18% 9% 1	4386
	21st to end	Day	34% 8% 12% 25% 18% 2	4837
June	1st to 10th	Day	40% 9% 13% 21% 15% 2	2660
	11th to 20th	Day	42% 8% 13% 23% 12% 2	2660
	21st to end	Day	38% 9% 14% 22% 16% 1	2660
July	1st to 10th	Day	39% 10% 12% 22% 16% 1	2506
	11th to 20th	Day	33% 10% 16% 24% 15% 2	2445
	21st to end	Day	40% 10% 14% 18% 16% 3	2591
August	1st to 10th	Day	37% 11% 16% 22% 14% 1	2346
	11th to 20th	Day	38% 9% 15% 22% 14% 1	2126
	21st to end	Day	39% 7% 11% 21% 18% 3	2376
September	1st to 10th	Day	39% 8% 12% 21% 18% 3	2160
	11th to 20th	Day	33% 6% 12% 23% 24% 3	2088
	21st to end	Day	42% 6% 10% 19% 20% 3	1980
October	1st to 10th	Day	42% 6% 12% 22% 16% 2	1872
	11th to 20th	Day	37% 6% 12% 25% 19% 2	1800
	21st to end	Day	43% 5% 9% 22% 17% 2	1846
November	1st to 10th	Day	36% 4 11% 23% 23% 3	1671
	11th to 20th	Day	39% 5% 9% 23% 21% 4	1710
	21st to end	Day	39% 5% 14% 29% 12% 3	1630
December	1st to 10th	Day	45% 4 15% 21% 14% 1	1520
	11th to 20th	Day	42% 4 14% 24% 14% 2	1906
	21st to end	Day	48% 9% 12% 22% 8%	2772
January	1st to 10th	Night	39% 4 10% 30% 12% 4	4429
	11th to 20th	Night	44% 5% 12% 25% 12% 2	4440
	21st to end	Night	51% 5% 9% 22% 12% 2	4624
February	1st to 10th	Night	44% 5% 12% 24% 13% 2	2465
	11th to 20th	Night	45% 4 9% 19% 18% 5%	2220
	21st to end	Night	44% 5% 8% 25% 16% 4	1884
March	1st to 10th	Night	49% 6% 10% 21% 11% 3	3734
	11th to 20th	Night	35% 8% 13% 25% 17% 3	3609
	21st to end	Night	45% 5% 7% 15% 22% 6%	3503
April	1st to 10th	Night	45% 6% 11% 19% 17% 3	1900
	11th to 20th	Night	44% 5% 9% 20% 19% 2	1875
	21st to end	Night	42% 6% 8% 21% 19% 4	1886
May	1st to 10th	Night	54% 7% 11% 16% 10% 1	2840
	11th to 20th	Night	53% 7% 15% 13% 10% 2	2541
	21st to end	Night	39% 8% 14% 23% 13% 3	2739
June	1st to 10th	Night	41% 7% 10% 21% 20% 2	1520
	11th to 20th	Night	38% 8% 14% 27% 12% 1	1520
	21st to end	Night	35% 9% 15% 24% 16% 1	1520
July	1st to 10th	Night	40% 10% 13% 20% 16% 2	1438
	11th to 20th	Night	37% 10% 14% 25% 12% 2	1392
	21st to end	Night	32% 10% 19% 20% 16% 3	1486
August	1st to 10th	Night	34% 11% 16% 22% 15% 2	1545
	11th to 20th	Night	41% 10% 14% 23% 10% 1	1774
	21st to end	Night	39% 8% 13% 19% 19% 2	1980
September	1st to 10th	Night	41% 7% 10% 23% 17% 1	1800
	11th to 20th	Night	33% 5% 11% 23% 24% 3	1872
	21st to end	Night	40% 6% 8% 22% 23% 2	1980
October	1st to 10th	Night	43% 6% 12% 22% 14% 3	2083
	11th to 20th	Night	36% 5% 13% 27% 17% 2	2160
	21st to end	Night	43% 5% 10% 23% 17% 1	2510
November	1st to 10th	Night	35% 6% 10% 23% 22% 4	2407
	11th to 20th	Night	40% 4 9% 24% 19% 4	2470
	21st to end	Night	38% 4 13% 28% 15% 2	2546
December	1st to 10th	Night	44% 6% 12% 23% 13% 2	2660
	11th to 20th	Night	43% 5% 12% 20% 17% 4	3288
	21st to end	Night	47% 7% 12% 21% 12%	4884

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	21% 28% 30% 18% 3 1	180
	11th to 20th	Day	23% 34% 29% 11% 3	180
	21st to end	Day	20% 27% 32% 13% 6% 1	272
February	1st to 10th	Day	26% 26% 34% 13% 2	274
	11th to 20th	Day	24% 21% 37% 16% 2	456
	21st to end	Day	27% 19% 35% 15% 3	382
March	1st to 10th	Day	22% 23% 30% 20% 4	460
	11th to 20th	Day	23% 20% 36% 15% 5% 1	460
	21st to end	Day	27% 21% 34% 13% 5% 1	506
April	1st to 10th	Day	25% 22% 32% 13% 7% 1	460
	11th to 20th	Day	22% 22% 31% 16% 8% 1	452
	21st to end	Day	26% 17% 34% 17% 4 2	460
May	1st to 10th	Day	31% 19% 27% 16% 5% 3	463
	11th to 20th	Day	22% 14% 36% 21% 7% 1	487
	21st to end	Day	19% 8% 30% 26% 15% 3	529
June	1st to 10th	Day	16% 12% 30% 27% 12% 3	490
	11th to 20th	Day	16% 13% 32% 27% 11% 2	490
	21st to end	Day	14% 13% 30% 27% 15% 2	490
July	1st to 10th	Day	12% 6% 27% 33% 17% 5%	461
	11th to 20th	Day	10% 4 28% 32% 21% 4	444
	21st to end	Day	14% 7% 29% 31% 15% 3	488
August	1st to 10th	Day	10% 7% 26% 33% 17% 7%	446
	11th to 20th	Day	16% 4 24% 33% 20% 5%	439
	21st to end	Day	12% 8% 28% 30% 16% 6%	495
September	1st to 10th	Day	18% 8% 29% 22% 15% 8%	450
	11th to 20th	Day	15% 7% 29% 26% 14% 10%	450
	21st to end	Day	20% 12% 30% 22% 11% 5%	450
October	1st to 10th	Day	26% 8% 27% 21% 14% 4	450
	11th to 20th	Day	19% 16% 28% 25% 11% 1	450
	21st to end	Day	25% 14% 34% 20% 6% 2	428
November	1st to 10th	Day	16% 14% 32% 23% 12% 3	365
	11th to 20th	Day	23% 18% 31% 21% 6%	370
	21st to end	Day	19% 19% 35% 21% 5% 2	290
December	1st to 10th	Day	23% 26% 32% 12% 8%	180
	11th to 20th	Day	29% 25% 34% 9% 2	180
	21st to end	Day	26% 19% 36% 11% 8%	198
January	1st to 10th	Night	19% 16% 40% 22% 3	760
	11th to 20th	Night	26% 17% 31% 23% 3	760
	21st to end	Night	20% 17% 40% 22% 2	836
February	1st to 10th	Night	22% 15% 36% 25% 3	760
	11th to 20th	Night	23% 18% 40% 18% 1	743
	21st to end	Night	22% 20% 34% 21% 3	628
March	1st to 10th	Night	22% 15% 37% 21% 5%	760
	11th to 20th	Night	22% 16% 37% 20% 4 1	760
	21st to end	Night	22% 15% 37% 20% 5%	836
April	1st to 10th	Night	23% 16% 35% 22% 4	760
	11th to 20th	Night	22% 15% 34% 24% 6%	751
	21st to end	Night	22% 12% 35% 25% 5% 1	746
May	1st to 10th	Night	24% 13% 34% 22% 7%	570
	11th to 20th	Night	22% 10% 37% 24% 7%	406
	21st to end	Night	19% 5% 24% 38% 13% 1	411
June	1st to 10th	Night	18% 7% 28% 35% 11%	380
	11th to 20th	Night	15% 7% 26% 39% 14%	380
	21st to end	Night	11% 4 24% 51% 10% 1	380
July	1st to 10th	Night	12% 5% 24% 40% 18% 1	360
	11th to 20th	Night	12% 3 22% 43% 19% 1	348
	21st to end	Night	14% 4 21% 45% 15% 1	394
August	1st to 10th	Night	10% 4 20% 44% 21% 1	481
	11th to 20th	Night	15% 3 18% 38% 24% 1	710
	21st to end	Night	15% 4 18% 41% 20% 2	792
September	1st to 10th	Night	16% 5% 24% 35% 18% 2	720
	11th to 20th	Night	18% 3 24% 32% 18% 4	720
	21st to end	Night	21% 5% 26% 32% 15% 2	720
October	1st to 10th	Night	23% 8% 24% 27% 14% 3	720
	11th to 20th	Night	18% 11% 29% 31% 11% 1	720
	21st to end	Night	24% 9% 36% 23% 8%	792
November	1st to 10th	Night	15% 11% 33% 28% 11% 1	740
	11th to 20th	Night	22% 14% 32% 24% 8% 1	760
	21st to end	Night	17% 16% 35% 24% 7% 1	760
December	1st to 10th	Night	24% 14% 32% 24% 5% 1	760
	11th to 20th	Night	23% 13% 37% 25% 3	760
	21st to end	Night	23% 13% 37% 24% 3	836

Page generated at 2024-07-02 06:41:28. Version ac07

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