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 2024-11-03.

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% 10% 4 8% 5% 5% 5% 4 6% 7% 33%	101211
	Night	16% 10% 4 8% 5% 4 4 3 5% 6% 35%	97738
Transparency	Day	50% 5% 11% 21% 12% 1	101024
	Night	49% 5% 10% 21% 12% 2	97595
Seeing	Day	21% 12% 26% 21% 13% 6%	14888
	Night	20% 10% 26% 28% 14% 2	24950

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	18% 20% 6% 12% 5% 4 4 3 4 6% 18%	2836
	11th to 20th	Day	15% 20% 9% 13% 5% 8% 5% 2 3 4 15%	2840
	21st to end	Day	26% 22% 9% 10% 6% 5% 3 2 3 3 12%	3124
February	1st to 10th	Day	21% 15% 5% 10% 7% 4 3 3 4 4 24%	1710
	11th to 20th	Day	16% 13% 6% 12% 6% 4 4 2 5% 6% 25%	1794
	21st to end	Day	19% 15% 5% 9% 5% 4 3 3 3 5% 29%	1570
March	1st to 10th	Day	21% 15% 6% 9% 6% 4 4 3 5% 5% 24%	3305
	11th to 20th	Day	13% 10% 3 8% 5% 5% 5% 4 5% 6% 37%	3480
	21st to end	Day	20% 10% 3 8% 5% 3 4 3 4 7% 33%	3815
April	1st to 10th	Day	16% 13% 3 8% 5% 4 5% 3 5% 6% 33%	2098
	11th to 20th	Day	18% 10% 3 6% 4 4 4 3 5% 6% 36%	2423
	21st to end	Day	19% 8% 3 7% 6% 5% 4 5% 4 6% 33%	2470
May	1st to 10th	Day	22% 11% 3 7% 5% 5% 4 4 5% 6% 29%	4082
	11th to 20th	Day	22% 8% 3 6% 4 4 4 4 5% 7% 34%	4081
	21st to end	Day	11% 7% 3 7% 6% 5% 6% 5% 7% 9% 34%	4476
June	1st to 10th	Day	11% 7% 3 7% 4 6% 5% 4 7% 9% 36%	2470
	11th to 20th	Day	12% 7% 3 6% 5% 5% 5% 4 8% 10% 36%	2470
	21st to end	Day	12% 7% 2 5% 5% 5% 6% 5% 7% 10% 35%	2470
July	1st to 10th	Day	11% 7% 3 8% 5% 6% 5% 4 6% 9% 37%	4120
	11th to 20th	Day	8% 5% 2 5% 5% 4 5% 5% 7% 11% 42%	4120
	21st to end	Day	12% 6% 3 7% 5% 5% 6% 5% 7% 9% 35%	4466
August	1st to 10th	Day	10% 6% 3 7% 5% 5% 6% 4 7% 10% 37%	4104
	11th to 20th	Day	9% 6% 3 7% 5% 5% 6% 5% 8% 10% 35%	4044
	21st to end	Day	6% 4 2 5% 5% 6% 7% 4 7% 10% 45%	4501
September	1st to 10th	Day	14% 5% 2 5% 3 4 4 4 5% 7% 47%	2090
	11th to 20th	Day	9% 5% 2 6% 4 4 5% 4 5% 9% 48%	2090
	21st to end	Day	19% 7% 3 6% 4 4 4 3 4 6% 41%	2090
October	1st to 10th	Day	14% 7% 2 6% 3 3 4 4 5% 7% 44%	2010
	11th to 20th	Day	15% 8% 2 7% 4 4 5% 3 5% 6% 41%	1900
	21st to end	Day	21% 9% 3 7% 4 3 4 3 5% 5% 35%	2065
November	1st to 10th	Day	11% 8% 3 6% 4 4 4 3 5% 7% 47%	1690
	11th to 20th	Day	17% 13% 4 7% 5% 3 4 3 5% 6% 34%	1710
	21st to end	Day	19% 13% 4 8% 5% 5% 3 4 4 6% 30%	1710
December	1st to 10th	Day	21% 19% 7% 9% 5% 3 4 3 5% 4 20%	1710
	11th to 20th	Day	20% 17% 5% 11% 6% 4 4 3 5% 5% 22%	2153
	21st to end	Day	22% 25% 5% 11% 5% 4 4 3 4 5% 12%	3124
January	1st to 10th	Night	16% 20% 7% 12% 5% 5% 4 3 4 4 19%	4109
	11th to 20th	Night	15% 18% 6% 16% 5% 5% 6% 3 4 4 16%	4120
	21st to end	Night	26% 18% 8% 12% 6% 3 3 2 2 4 16%	4532
February	1st to 10th	Night	20% 15% 3 10% 5% 4 4 3 4 4 28%	2470
	11th to 20th	Night	18% 13% 4 10% 6% 5% 5% 3 4 6% 26%	2270
	21st to end	Night	20% 15% 5% 11% 4 5% 4 3 3 4 26%	1884
March	1st to 10th	Night	21% 14% 4 6% 4 4 4 3 4 5% 32%	3546
	11th to 20th	Night	12% 9% 4 7% 5% 5% 4 3 5% 6% 40%	3480
	21st to end	Night	19% 8% 3 6% 4 3 4 3 4 5% 39%	3817
April	1st to 10th	Night	16% 11% 3 6% 4 3 3 4 6% 7% 37%	2090
	11th to 20th	Night	15% 8% 3 7% 4 5% 4 4 6% 7% 38%	1715
	21st to end	Night	16% 8% 3 6% 4 5% 4 4 5% 7% 38%	1710
May	1st to 10th	Night	27% 10% 3 6% 5% 4 4 3 6% 5% 27%	2813
	11th to 20th	Night	18% 8% 3 6% 4 4 3 3 4 8% 39%	2812
	21st to end	Night	9% 6% 2 6% 4 4 4 4 7% 10% 43%	3079
June	1st to 10th	Night	8% 5% 2 7% 5% 4 4 4 7% 8% 45%	1710
	11th to 20th	Night	10% 5% 2 5% 4 4 4 4 7% 10% 45%	1710
	21st to end	Night	9% 5% 2 6% 4 5% 5% 5% 7% 9% 43%	1710
July	1st to 10th	Night	11% 6% 3 6% 4 4 5% 4 6% 8% 45%	2840
	11th to 20th	Night	8% 5% 2 5% 5% 5% 4 5% 6% 9% 46%	2840
	21st to end	Night	7% 7% 3 7% 5% 6% 6% 5% 6% 8% 39%	3087
August	1st to 10th	Night	8% 7% 3 8% 6% 6% 6% 4 7% 9% 37%	2825
	11th to 20th	Night	10% 8% 4 8% 4 4 3 3 4 7% 45%	2785
	21st to end	Night	5% 3 2 5% 4 5% 5% 5% 8% 9% 49%	3124
September	1st to 10th	Night	12% 5% 1 4 3 4 4 3 4 7% 52%	2083
	11th to 20th	Night	8% 4 1 5% 4 3 3 3 5% 7% 56%	2090
	21st to end	Night	16% 6% 2 5% 4 4 4 4 4 6% 45%	2090
October	1st to 10th	Night	10% 6% 2 6% 4 3 4 3 5% 8% 49%	2168
	11th to 20th	Night	15% 7% 3 7% 4 4 4 3 5% 8% 41%	2280
	21st to end	Night	21% 7% 3 7% 4 4 4 3 4 6% 37%	2532
November	1st to 10th	Night	14% 8% 2 5% 4 3 3 3 4 6% 47%	2433
	11th to 20th	Night	17% 10% 4 7% 4 4 4 3 5% 6% 35%	2470
	21st to end	Night	19% 13% 4 8% 5% 4 4 3 6% 5% 29%	2470
December	1st to 10th	Night	22% 15% 6% 9% 5% 4 4 4 4 4 23%	2470
	11th to 20th	Night	18% 15% 7% 8% 5% 4 3 3 5% 6% 26%	3042
	21st to end	Night	23% 21% 6% 9% 6% 4 4 3 4 5% 16%	4532

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	69% 4 10% 12% 5%	2837
	11th to 20th	Day	75% 4 8% 10% 3	2840
	21st to end	Day	78% 4 7% 8% 3 1	3124
February	1st to 10th	Day	64% 4 9% 14% 9%	1710
	11th to 20th	Day	62% 4 8% 17% 9% 1	1804
	21st to end	Day	60% 4 10% 18% 8% 2	1570
March	1st to 10th	Day	62% 4 8% 19% 5% 1	3305
	11th to 20th	Day	48% 5% 10% 27% 10% 1	3480
	21st to end	Day	52% 4 9% 24% 11%	3815
April	1st to 10th	Day	53% 4 10% 19% 11% 2	2098
	11th to 20th	Day	49% 5% 11% 18% 14% 3	2423
	21st to end	Day	51% 4 9% 21% 12% 2	2470
May	1st to 10th	Day	55% 5% 10% 21% 7% 1	4120
	11th to 20th	Day	50% 5% 12% 20% 13% 1	4085
	21st to end	Day	41% 8% 14% 20% 13% 4	4489
June	1st to 10th	Day	42% 6% 11% 23% 16% 1	2470
	11th to 20th	Day	42% 6% 14% 22% 15% 1	2470
	21st to end	Day	42% 7% 15% 20% 14% 2	2470
July	1st to 10th	Day	43% 6% 11% 22% 16% 2	4055
	11th to 20th	Day	34% 6% 12% 30% 17% 1	4051
	21st to end	Day	42% 7% 12% 17% 18% 3	4324
August	1st to 10th	Day	40% 8% 15% 26% 12%	4091
	11th to 20th	Day	39% 7% 10% 29% 14%	4083
	21st to end	Day	33% 8% 14% 31% 12% 3	4501
September	1st to 10th	Day	37% 5% 11% 22% 22% 3	2090
	11th to 20th	Day	34% 4 12% 26% 21% 3	2090
	21st to end	Day	45% 3 8% 23% 19% 1	2090
October	1st to 10th	Day	39% 5% 10% 25% 20% 1	2010
	11th to 20th	Day	43% 4 13% 23% 16% 2	1900
	21st to end	Day	51% 4 11% 22% 11% 2	2065
November	1st to 10th	Day	37% 5% 10% 27% 18% 3	1690
	11th to 20th	Day	52% 4 9% 21% 12% 3	1710
	21st to end	Day	56% 4 11% 19% 10% 1	1710
December	1st to 10th	Day	68% 4 10% 14% 4	1710
	11th to 20th	Day	65% 4 8% 17% 6%	2150
	21st to end	Day	76% 4 9% 7% 3	3124
January	1st to 10th	Night	69% 4 8% 14% 4	4109
	11th to 20th	Night	72% 3 10% 12% 3	4120
	21st to end	Night	75% 2 7% 12% 4 1	4532
February	1st to 10th	Night	61% 3 9% 17% 8% 1	2470
	11th to 20th	Night	60% 4 9% 17% 9% 1	2271
	21st to end	Night	63% 3 9% 14% 9% 2	1884
March	1st to 10th	Night	54% 4 8% 23% 10% 1	3546
	11th to 20th	Night	45% 5% 9% 30% 10% 1	3480
	21st to end	Night	47% 4 8% 28% 12% 1	3817
April	1st to 10th	Night	46% 4 11% 22% 14% 2	2090
	11th to 20th	Night	44% 4 12% 17% 19% 3	1715
	21st to end	Night	45% 5% 12% 20% 16% 2	1710
May	1st to 10th	Night	57% 6% 8% 19% 8% 2	2840
	11th to 20th	Night	46% 5% 10% 26% 11% 2	2813
	21st to end	Night	34% 8% 15% 27% 13% 3	3087
June	1st to 10th	Night	35% 7% 12% 24% 20% 2	1710
	11th to 20th	Night	34% 7% 15% 24% 18% 3	1710
	21st to end	Night	34% 7% 14% 25% 17% 3	1710
July	1st to 10th	Night	37% 6% 13% 21% 18% 5%	2795
	11th to 20th	Night	34% 6% 13% 30% 16% 1	2786
	21st to end	Night	39% 8% 13% 20% 17% 3	2988
August	1st to 10th	Night	41% 7% 14% 24% 13% 1	2814
	11th to 20th	Night	40% 5% 8% 25% 21% 1	2812
	21st to end	Night	27% 7% 15% 31% 17% 3	3124
September	1st to 10th	Night	33% 4 11% 24% 22% 6%	2083
	11th to 20th	Night	29% 4 11% 27% 26% 3	2090
	21st to end	Night	40% 4 10% 21% 23% 1	2090
October	1st to 10th	Night	35% 5% 9% 28% 22% 2	2168
	11th to 20th	Night	42% 4 10% 26% 16% 2	2280
	21st to end	Night	48% 4 8% 23% 14% 2	2532
November	1st to 10th	Night	39% 4 12% 23% 19% 3	2433
	11th to 20th	Night	50% 3 8% 21% 15% 2	2470
	21st to end	Night	56% 3 11% 21% 8% 1	2470
December	1st to 10th	Night	65% 4 9% 16% 6%	2470
	11th to 20th	Night	59% 5% 11% 20% 6%	3044
	21st to end	Night	71% 4 9% 12% 3	4532

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% 23% 33% 9% 6%	270
	11th to 20th	Day	32% 19% 38% 9% 2	270
	21st to end	Day	34% 21% 30% 11% 3	297
February	1st to 10th	Day	31% 23% 29% 13% 2	270
	11th to 20th	Day	32% 29% 28% 9% 2 1	270
	21st to end	Day	31% 26% 37% 5% 1	225
March	1st to 10th	Day	28% 21% 30% 17% 4	377
	11th to 20th	Day	30% 16% 33% 14% 6%	460
	21st to end	Day	31% 16% 30% 18% 4	506
April	1st to 10th	Day	27% 15% 31% 17% 8% 2	460
	11th to 20th	Day	27% 16% 27% 16% 9% 4	452
	21st to end	Day	27% 15% 34% 16% 6% 2	460
May	1st to 10th	Day	29% 15% 28% 16% 8% 4	463
	11th to 20th	Day	23% 10% 27% 24% 11% 5%	487
	21st to end	Day	12% 10% 26% 26% 19% 8%	529
June	1st to 10th	Day	13% 7% 27% 29% 16% 6%	490
	11th to 20th	Day	15% 9% 23% 29% 17% 7%	490
	21st to end	Day	14% 8% 26% 29% 17% 7%	490
July	1st to 10th	Day	15% 5% 16% 26% 19% 19%	485
	11th to 20th	Day	12% 5% 21% 27% 24% 11%	484
	21st to end	Day	14% 5% 21% 27% 20% 12%	532
August	1st to 10th	Day	12% 4 18% 27% 25% 14%	486
	11th to 20th	Day	13% 5% 23% 28% 20% 10%	479
	21st to end	Day	8% 4 17% 27% 30% 13%	539
September	1st to 10th	Day	14% 5% 18% 25% 25% 12%	490
	11th to 20th	Day	10% 3 17% 25% 31% 13%	490
	21st to end	Day	25% 9% 18% 26% 17% 6%	490
October	1st to 10th	Day	12% 8% 29% 27% 19% 5%	490
	11th to 20th	Day	18% 14% 30% 23% 11% 3	490
	21st to end	Day	28% 13% 29% 19% 10% 1	514
November	1st to 10th	Day	18% 16% 33% 21% 9% 2	276
	11th to 20th	Day	28% 18% 29% 17% 8% 1	270
	21st to end	Day	26% 21% 35% 16% 2	270
December	1st to 10th	Day	30% 20% 30% 14% 4 1	270
	11th to 20th	Day	28% 24% 33% 12% 2 1	270
	21st to end	Day	35% 16% 32% 14% 3	297
January	1st to 10th	Night	26% 19% 34% 17% 4	760
	11th to 20th	Night	30% 15% 34% 18% 3	760
	21st to end	Night	28% 17% 31% 22% 2	836
February	1st to 10th	Night	29% 13% 31% 24% 3	760
	11th to 20th	Night	28% 17% 34% 19% 2	743
	21st to end	Night	28% 14% 38% 18% 2	628
March	1st to 10th	Night	24% 14% 31% 26% 5%	760
	11th to 20th	Night	23% 15% 31% 23% 7%	760
	21st to end	Night	26% 10% 33% 23% 7% 1	836
April	1st to 10th	Night	22% 13% 35% 23% 7%	760
	11th to 20th	Night	18% 11% 34% 24% 11% 1	572
	21st to end	Night	21% 7% 37% 28% 7% 1	570
May	1st to 10th	Night	22% 9% 29% 27% 13% 1	570
	11th to 20th	Night	19% 6% 26% 33% 15% 1	561
	21st to end	Night	10% 4 20% 36% 27% 2	617
June	1st to 10th	Night	10% 3 25% 39% 22% 1	570
	11th to 20th	Night	13% 4 18% 41% 22% 2	570
	21st to end	Night	11% 4 24% 35% 22% 3	570
July	1st to 10th	Night	11% 3 14% 38% 27% 7%	555
	11th to 20th	Night	7% 3 15% 35% 35% 4	552
	21st to end	Night	11% 3 13% 37% 34% 3	624
August	1st to 10th	Night	8% 2 12% 40% 33% 4	567
	11th to 20th	Night	11% 3 12% 40% 30% 4	564
	21st to end	Night	9% 1 15% 33% 34% 7%	627
September	1st to 10th	Night	15% 3 15% 34% 28% 6%	757
	11th to 20th	Night	10% 3 13% 36% 34% 4	760
	21st to end	Night	19% 5% 22% 31% 19% 3	760
October	1st to 10th	Night	14% 4 24% 34% 21% 3	760
	11th to 20th	Night	21% 9% 29% 27% 13% 1	760
	21st to end	Night	25% 10% 28% 27% 10%	836
November	1st to 10th	Night	19% 11% 26% 28% 15% 1	749
	11th to 20th	Night	24% 14% 28% 25% 8% 1	760
	21st to end	Night	26% 13% 27% 26% 6% 1	760
December	1st to 10th	Night	31% 15% 29% 20% 4	760
	11th to 20th	Night	25% 16% 31% 23% 4	760
	21st to end	Night	33% 13% 28% 23% 2	836

Page generated at 2024-10-31 03:39:23. Version ac07

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