Lake Hopatcong State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lake Hopatcong State Park clear sky chart from 2005-11-06 to 2026-08-30.

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% 7% 2 6% 4 4 5% 4 5% 7% 38%	144262
	Night	16% 8% 3 6% 4 4 4 3 5% 7% 40%	137977
Transparency	Day	43% 5% 12% 23% 16% 2	147778
	Night	42% 5% 11% 23% 16% 3	142550
Seeing	Day	24% 18% 30% 19% 8% 2	17275
	Night	21% 16% 31% 23% 7% 1	26397

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	13% 7% 2 7% 6% 5% 4 3 5% 5% 43%	4661
	11th to 20th	Day	14% 9% 3 8% 6% 5% 4 3 4 5% 40%	4650
	21st to end	Day	16% 6% 3 6% 5% 5% 5% 4 5% 6% 39%	5695
February	1st to 10th	Day	16% 8% 3 7% 6% 3 4 4 4 6% 38%	1890
	11th to 20th	Day	15% 10% 3 8% 5% 4 4 4 4 6% 39%	2015
	21st to end	Day	18% 10% 2 7% 6% 3 3 3 4 5% 37%	1730
March	1st to 10th	Day	21% 7% 2 6% 4 4 3 3 4 5% 41%	4576
	11th to 20th	Day	10% 6% 2 7% 5% 5% 5% 4 6% 7% 41%	4985
	21st to end	Day	17% 7% 2 6% 4 4 4 3 5% 7% 41%	5997
April	1st to 10th	Day	17% 8% 3 7% 5% 4 4 3 5% 6% 37%	2520
	11th to 20th	Day	16% 7% 2 7% 4 4 5% 3 6% 7% 39%	2494
	21st to end	Day	16% 9% 2 7% 4 4 5% 4 5% 6% 38%	2520
May	1st to 10th	Day	24% 8% 2 6% 4 4 5% 4 5% 7% 32%	7722
	11th to 20th	Day	18% 8% 3 7% 4 4 4 3 5% 6% 37%	8221
	21st to end	Day	23% 7% 2 5% 4 4 4 4 6% 8% 31%	9060
June	1st to 10th	Day	14% 6% 2 6% 4 5% 5% 5% 6% 9% 36%	2940
	11th to 20th	Day	15% 7% 2 6% 5% 5% 5% 5% 6% 8% 35%	2940
	21st to end	Day	13% 7% 2 6% 5% 4 5% 4 6% 9% 38%	2940
July	1st to 10th	Day	13% 7% 3 8% 5% 5% 5% 4 6% 10% 35%	8280
	11th to 20th	Day	9% 7% 3 6% 5% 6% 6% 5% 8% 10% 35%	8280
	21st to end	Day	13% 7% 2 7% 4 4 5% 4 6% 8% 39%	8993
August	1st to 10th	Day	21% 6% 2 6% 5% 5% 5% 5% 6% 7% 32%	4419
	11th to 20th	Day	12% 7% 2 7% 4 4 5% 4 6% 8% 41%	3970
	21st to end	Day	12% 6% 2 5% 4 4 4 4 5% 9% 46%	4420
September	1st to 10th	Day	15% 5% 2 6% 5% 4 4 4 5% 7% 43%	2400
	11th to 20th	Day	12% 6% 2 5% 4 4 3 3 4 7% 50%	2342
	21st to end	Day	18% 7% 3 8% 4 4 4 4 4 5% 38%	2200
October	1st to 10th	Day	18% 6% 2 5% 4 3 4 4 5% 7% 41%	2040
	11th to 20th	Day	16% 6% 2 6% 4 4 4 2 5% 7% 45%	2000
	21st to end	Day	19% 6% 2 5% 4 4 4 3 5% 6% 42%	2074
November	1st to 10th	Day	13% 7% 2 4 3 3 3 3 4 6% 51%	1851
	11th to 20th	Day	17% 6% 2 4 4 4 5% 4 5% 6% 44%	1890
	21st to end	Day	16% 8% 3 6% 4 4 4 4 5% 7% 40%	1753
December	1st to 10th	Day	14% 9% 3 6% 4 4 5% 3 5% 6% 41%	2680
	11th to 20th	Day	20% 9% 2 5% 3 4 4 3 4 6% 40%	3066
	21st to end	Day	16% 9% 3 8% 5% 5% 5% 4 6% 7% 32%	4048
January	1st to 10th	Night	12% 8% 3 7% 5% 4 5% 4 6% 7% 39%	8234
	11th to 20th	Night	14% 10% 3 7% 4 4 5% 4 6% 7% 37%	8235
	21st to end	Night	14% 9% 2 5% 4 4 4 3 5% 6% 43%	8484
February	1st to 10th	Night	16% 9% 3 6% 4 3 4 4 4 6% 40%	2730
	11th to 20th	Night	16% 9% 4 6% 5% 4 5% 4 5% 5% 38%	2489
	21st to end	Night	17% 7% 3 6% 4 4 4 3 5% 6% 39%	2076
March	1st to 10th	Night	19% 9% 2 5% 4 3 4 3 4 5% 41%	5484
	11th to 20th	Night	12% 7% 3 7% 4 4 4 3 4 6% 47%	5188
	21st to end	Night	15% 9% 3 7% 4 4 4 3 5% 5% 40%	5177
April	1st to 10th	Night	18% 8% 3 7% 5% 5% 4 4 5% 7% 34%	2100
	11th to 20th	Night	17% 7% 3 6% 5% 4 4 4 5% 7% 38%	2075
	21st to end	Night	19% 7% 3 5% 4 3 4 4 5% 7% 41%	2100
May	1st to 10th	Night	23% 9% 3 7% 4 4 5% 4 6% 7% 29%	5229
	11th to 20th	Night	19% 8% 3 7% 4 4 4 3 5% 7% 36%	4639
	21st to end	Night	24% 8% 2 6% 4 4 4 4 5% 7% 33%	5114
June	1st to 10th	Night	15% 6% 2 6% 4 3 5% 4 5% 7% 44%	1680
	11th to 20th	Night	13% 8% 3 6% 4 4 5% 4 6% 8% 39%	1680
	21st to end	Night	12% 4 2 5% 4 5% 5% 4 7% 9% 43%	1680
July	1st to 10th	Night	14% 7% 2 6% 5% 5% 4 4 7% 8% 39%	4680
	11th to 20th	Night	11% 8% 3 7% 5% 5% 6% 4 8% 10% 34%	4680
	21st to end	Night	13% 6% 2 6% 4 4 4 4 6% 7% 43%	5084
August	1st to 10th	Night	21% 7% 3 7% 4 4 5% 4 6% 8% 32%	2927
	11th to 20th	Night	13% 7% 3 7% 4 4 5% 3 5% 7% 40%	3282
	21st to end	Night	11% 5% 1 5% 3 3 4 3 6% 8% 50%	3677
September	1st to 10th	Night	15% 7% 3 6% 3 4 4 2 5% 6% 45%	2000
	11th to 20th	Night	11% 6% 2 6% 3 3 3 2 4 8% 51%	2057
	21st to end	Night	17% 8% 2 6% 3 4 4 2 5% 7% 44%	2200
October	1st to 10th	Night	18% 8% 2 5% 4 3 3 2 5% 6% 42%	2355
	11th to 20th	Night	17% 5% 2 5% 3 3 4 3 4 6% 48%	2400
	21st to end	Night	19% 8% 2 4 3 3 3 3 5% 6% 44%	2765
November	1st to 10th	Night	12% 6% 2 5% 3 4 4 3 6% 6% 50%	2667
	11th to 20th	Night	17% 7% 2 5% 4 3 4 3 4 5% 46%	2730
	21st to end	Night	14% 7% 2 6% 4 4 4 4 5% 7% 42%	2861
December	1st to 10th	Night	12% 8% 3 7% 5% 4 4 3 4 6% 44%	4720
	11th to 20th	Night	21% 9% 2 5% 3 3 4 3 4 6% 39%	5348
	21st to end	Night	18% 12% 3 7% 4 3 3 3 4 5% 37%	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	40% 3 10% 29% 17% 2	4662
	11th to 20th	Day	44% 5% 8% 21% 15% 6%	4680
	21st to end	Day	43% 5% 12% 22% 17% 1	5695
February	1st to 10th	Day	46% 4 13% 22% 13% 2	1890
	11th to 20th	Day	46% 5% 9% 23% 15% 3	2024
	21st to end	Day	48% 5% 9% 22% 13% 3	1730
March	1st to 10th	Day	45% 3 10% 21% 13% 8%	4579
	11th to 20th	Day	39% 6% 13% 28% 10% 4	4985
	21st to end	Day	43% 4 12% 12% 24% 5%	5997
April	1st to 10th	Day	48% 5% 9% 20% 15% 5%	2520
	11th to 20th	Day	43% 5% 12% 21% 16% 3	2494
	21st to end	Day	44% 6% 9% 21% 16% 4	2520
May	1st to 10th	Day	51% 5% 12% 18% 13% 1	7734
	11th to 20th	Day	47% 4 10% 24% 13% 1	8225
	21st to end	Day	49% 6% 11% 21% 13% 1	9061
June	1st to 10th	Day	42% 7% 13% 21% 15% 1	2940
	11th to 20th	Day	45% 7% 12% 23% 11% 2	2940
	21st to end	Day	41% 6% 14% 23% 15% 1	2940
July	1st to 10th	Day	44% 7% 13% 20% 15% 1	8210
	11th to 20th	Day	39% 7% 16% 25% 11% 1	8205
	21st to end	Day	41% 6% 10% 23% 20% 1	8795
August	1st to 10th	Day	48% 7% 13% 21% 9% 1	4405
	11th to 20th	Day	38% 6% 13% 29% 12% 1	4006
	21st to end	Day	35% 5% 10% 30% 18% 2	4420
September	1st to 10th	Day	39% 6% 11% 21% 19% 2	2400
	11th to 20th	Day	35% 4 9% 24% 25% 3	2342
	21st to end	Day	47% 5% 9% 17% 18% 2	2200
October	1st to 10th	Day	39% 5% 9% 19% 24% 5%	3326
	11th to 20th	Day	29% 4 10% 26% 26% 5%	3240
	21st to end	Day	27% 4 15% 24% 26% 4	3325
November	1st to 10th	Day	35% 4 12% 24% 22% 3	1851
	11th to 20th	Day	39% 5% 10% 23% 19% 4	1890
	21st to end	Day	43% 5% 12% 28% 11% 2	1753
December	1st to 10th	Day	42% 3 15% 28% 11% 2	2680
	11th to 20th	Day	44% 5% 13% 23% 13% 1	3066
	21st to end	Day	47% 6% 9% 21% 15% 2	4048
January	1st to 10th	Night	40% 4 12% 24% 17% 3	8234
	11th to 20th	Night	42% 4 13% 20% 15% 5%	8280
	21st to end	Night	41% 3 9% 21% 21% 4	8484
February	1st to 10th	Night	44% 5% 12% 24% 13% 2	2730
	11th to 20th	Night	46% 6% 9% 19% 16% 4	2491
	21st to end	Night	45% 4 7% 25% 16% 3	2076
March	1st to 10th	Night	44% 3 10% 22% 13% 8%	5494
	11th to 20th	Night	39% 4 15% 25% 13% 4	5189
	21st to end	Night	45% 4 7% 16% 22% 5%	5177
April	1st to 10th	Night	47% 6% 11% 19% 14% 4	2100
	11th to 20th	Night	45% 6% 10% 20% 19% 2	2075
	21st to end	Night	42% 5% 10% 22% 17% 4	2100
May	1st to 10th	Night	52% 5% 13% 18% 12% 1	5235
	11th to 20th	Night	46% 6% 13% 21% 12% 1	4640
	21st to end	Night	50% 5% 11% 22% 10% 1	5115
June	1st to 10th	Night	40% 4 11% 24% 19% 1	1680
	11th to 20th	Night	42% 7% 14% 24% 12% 1	1680
	21st to end	Night	35% 9% 15% 25% 15% 1	1680
July	1st to 10th	Night	42% 7% 14% 21% 15% 2	4640
	11th to 20th	Night	43% 7% 14% 24% 12% 1	4632
	21st to end	Night	38% 5% 13% 24% 18% 1	4967
August	1st to 10th	Night	49% 7% 16% 18% 9% 1	2917
	11th to 20th	Night	43% 6% 12% 28% 10% 1	3312
	21st to end	Night	33% 5% 10% 32% 19% 1	3677
September	1st to 10th	Night	40% 5% 10% 25% 19% 1	2000
	11th to 20th	Night	34% 4 10% 23% 25% 3	2057
	21st to end	Night	42% 5% 9% 23% 21% 1	2200
October	1st to 10th	Night	41% 4 9% 23% 21% 2	3849
	11th to 20th	Night	27% 5% 10% 28% 26% 5%	3899
	21st to end	Night	30% 3 12% 32% 19% 3	4464
November	1st to 10th	Night	33% 5% 12% 24% 22% 4	2667
	11th to 20th	Night	40% 4 9% 24% 20% 4	2730
	21st to end	Night	40% 5% 13% 28% 14% 1	2861
December	1st to 10th	Night	40% 4 13% 31% 11% 2	4720
	11th to 20th	Night	45% 4 10% 22% 15% 3	5348
	21st to end	Night	48% 5% 10% 18% 16% 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	31% 32% 27% 9% 1	220
	11th to 20th	Day	39% 31% 23% 6% 1	220
	21st to end	Day	28% 33% 29% 6% 4	347
February	1st to 10th	Day	29% 33% 29% 7% 2	330
	11th to 20th	Day	33% 29% 31% 6%	503
	21st to end	Day	31% 27% 30% 9% 2	446
March	1st to 10th	Day	32% 24% 29% 13% 2	540
	11th to 20th	Day	30% 23% 32% 11% 3 1	540
	21st to end	Day	34% 25% 28% 10% 3 1	594
April	1st to 10th	Day	32% 24% 27% 12% 5%	540
	11th to 20th	Day	27% 24% 32% 11% 6% 1	532
	21st to end	Day	30% 18% 35% 13% 2 1	540
May	1st to 10th	Day	35% 20% 28% 12% 5% 1	543
	11th to 20th	Day	25% 18% 34% 16% 7% 1	567
	21st to end	Day	24% 13% 28% 25% 9% 1	617
June	1st to 10th	Day	19% 16% 30% 25% 8% 1	570
	11th to 20th	Day	23% 15% 29% 23% 9% 1	570
	21st to end	Day	16% 15% 32% 27% 9% 1	570
July	1st to 10th	Day	15% 8% 30% 28% 16% 4	565
	11th to 20th	Day	12% 7% 30% 34% 14% 3	564
	21st to end	Day	15% 11% 32% 29% 10% 2	620
August	1st to 10th	Day	15% 7% 29% 29% 15% 5%	566
	11th to 20th	Day	14% 8% 31% 30% 14% 4	559
	21st to end	Day	12% 10% 33% 26% 14% 5%	619
September	1st to 10th	Day	20% 12% 27% 24% 13% 5%	530
	11th to 20th	Day	13% 9% 29% 25% 15% 8%	530
	21st to end	Day	24% 13% 28% 22% 9% 3	530
October	1st to 10th	Day	23% 12% 28% 20% 12% 5%	530
	11th to 20th	Day	21% 20% 30% 20% 9% 1	530
	21st to end	Day	24% 20% 33% 17% 6% 1	513
November	1st to 10th	Day	21% 19% 31% 19% 8% 1	425
	11th to 20th	Day	26% 25% 28% 17% 4	430
	21st to end	Day	29% 26% 31% 12% 3	293
December	1st to 10th	Day	30% 29% 28% 10% 4	220
	11th to 20th	Day	38% 26% 25% 8% 3	220
	21st to end	Day	32% 21% 30% 12% 4 1	242
January	1st to 10th	Night	23% 25% 36% 14% 2	840
	11th to 20th	Night	29% 22% 31% 17% 2	840
	21st to end	Night	21% 27% 36% 14% 2	924
February	1st to 10th	Night	25% 22% 35% 16% 2	840
	11th to 20th	Night	26% 26% 36% 10% 1	823
	21st to end	Night	28% 23% 34% 14% 2	692
March	1st to 10th	Night	24% 25% 33% 15% 3	840
	11th to 20th	Night	24% 25% 32% 16% 3	840
	21st to end	Night	23% 23% 36% 13% 4	924
April	1st to 10th	Night	25% 22% 33% 16% 3	840
	11th to 20th	Night	23% 19% 36% 17% 4	831
	21st to end	Night	23% 17% 35% 21% 4	840
May	1st to 10th	Night	26% 17% 33% 19% 5%	625
	11th to 20th	Night	20% 15% 36% 22% 6%	414
	21st to end	Night	19% 8% 29% 32% 11%	455
June	1st to 10th	Night	17% 10% 30% 32% 11%	420
	11th to 20th	Night	16% 8% 35% 32% 9%	420
	21st to end	Night	13% 7% 28% 42% 10%	420
July	1st to 10th	Night	12% 6% 27% 36% 17% 2	410
	11th to 20th	Night	12% 5% 25% 40% 16% 1	408
	21st to end	Night	14% 4 26% 40% 14% 1	460
August	1st to 10th	Night	13% 3 23% 39% 19% 2	575
	11th to 20th	Night	14% 5% 23% 37% 20% 1	815
	21st to end	Night	16% 5% 25% 36% 17% 1	917
September	1st to 10th	Night	18% 6% 27% 32% 16% 2	800
	11th to 20th	Night	15% 5% 26% 32% 19% 3	800
	21st to end	Night	21% 7% 26% 31% 13% 2	800
October	1st to 10th	Night	21% 11% 28% 25% 14% 2	800
	11th to 20th	Night	20% 15% 30% 27% 9%	800
	21st to end	Night	24% 17% 32% 20% 7%	880
November	1st to 10th	Night	19% 16% 33% 25% 7% 1	820
	11th to 20th	Night	25% 20% 30% 20% 5%	840
	21st to end	Night	20% 21% 35% 19% 5% 1	840
December	1st to 10th	Night	25% 20% 33% 18% 4	840
	11th to 20th	Night	25% 21% 35% 17% 3	840
	21st to end	Night	25% 23% 32% 18% 2	924

Page generated at 2026-08-27 04:07:12. Version ac07

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