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 2025-04-26.

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% 7% 2 6% 5% 4 4 4 5% 7% 38%	113569
	Night	16% 8% 3 6% 4 4 4 3 5% 6% 41%	115041
Transparency	Day	43% 5% 11% 22% 16% 3	117131
	Night	41% 5% 11% 23% 16% 3	119643
Seeing	Day	24% 18% 30% 19% 8% 2	15480
	Night	21% 16% 32% 23% 8% 1	24810

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 6% 5% 4 4 3 5% 5% 46%	3597
	11th to 20th	Day	14% 9% 3 9% 7% 5% 4 3 5% 6% 36%	3570
	21st to end	Day	18% 8% 3 7% 5% 4 4 3 4 5% 39%	4395
February	1st to 10th	Day	16% 8% 3 7% 6% 3 4 4 4 6% 37%	1800
	11th to 20th	Day	14% 10% 3 7% 5% 4 4 4 4 6% 40%	1916
	21st to end	Day	18% 10% 2 7% 6% 3 4 3 5% 6% 36%	1650
March	1st to 10th	Day	21% 7% 2 6% 4 4 3 3 4 4 41%	4476
	11th to 20th	Day	10% 7% 2 7% 5% 5% 5% 4 6% 7% 42%	4878
	21st to end	Day	18% 7% 2 6% 4 4 4 3 5% 7% 41%	5868
April	1st to 10th	Day	17% 8% 3 7% 5% 4 4 3 5% 6% 36%	2400
	11th to 20th	Day	16% 8% 3 7% 4 4 5% 4 6% 6% 38%	2374
	21st to end	Day	16% 8% 2 6% 5% 4 4 4 6% 6% 38%	2340
May	1st to 10th	Day	28% 8% 2 6% 4 4 4 3 4 7% 29%	4149
	11th to 20th	Day	23% 9% 3 8% 5% 4 4 4 5% 6% 28%	4398
	21st to end	Day	13% 6% 2 5% 4 4 5% 4 7% 9% 42%	4837
June	1st to 10th	Day	15% 6% 2 6% 4 5% 5% 5% 7% 9% 35%	2660
	11th to 20th	Day	14% 7% 2 6% 6% 5% 5% 5% 6% 9% 34%	2660
	21st to end	Day	13% 7% 2 6% 6% 4 5% 3 7% 8% 39%	2660
July	1st to 10th	Day	9% 6% 2 8% 6% 6% 6% 5% 7% 11% 32%	4440
	11th to 20th	Day	11% 6% 2 6% 5% 5% 5% 4 8% 10% 38%	4440
	21st to end	Day	15% 9% 3 8% 5% 5% 5% 5% 7% 7% 31%	4814
August	1st to 10th	Day	21% 6% 2 6% 5% 4 5% 5% 6% 7% 31%	4156
	11th to 20th	Day	12% 7% 2 6% 4 4 4 4 6% 8% 41%	3730
	21st to end	Day	12% 6% 2 5% 4 4 4 4 5% 9% 46%	4180
September	1st to 10th	Day	15% 6% 2 6% 5% 4 4 4 5% 7% 43%	2280
	11th to 20th	Day	12% 6% 2 5% 4 4 3 3 4 7% 50%	2225
	21st to end	Day	19% 7% 3 7% 4 4 4 4 4 5% 39%	2090
October	1st to 10th	Day	19% 7% 2 6% 4 4 4 4 5% 7% 39%	1938
	11th to 20th	Day	16% 5% 2 6% 4 4 4 3 5% 7% 46%	1900
	21st to end	Day	20% 6% 2 5% 4 4 4 3 5% 6% 41%	1971
November	1st to 10th	Day	14% 8% 2 4 3 3 3 3 4 6% 52%	1761
	11th to 20th	Day	17% 6% 2 5% 4 4 4 4 5% 6% 45%	1800
	21st to end	Day	16% 7% 2 6% 4 4 4 4 5% 7% 40%	1670
December	1st to 10th	Day	14% 10% 3 6% 4 3 5% 3 5% 6% 41%	2600
	11th to 20th	Day	21% 9% 2 5% 3 4 4 3 4 6% 39%	2986
	21st to end	Day	16% 9% 3 8% 5% 5% 5% 4 6% 7% 32%	3960
January	1st to 10th	Night	12% 7% 2 6% 5% 4 5% 3 6% 7% 42%	6349
	11th to 20th	Night	12% 9% 3 7% 4 4 5% 4 6% 7% 38%	6315
	21st to end	Night	17% 9% 2 6% 4 4 4 3 5% 5% 40%	6559
February	1st to 10th	Night	17% 9% 3 6% 4 3 4 4 4 6% 40%	2600
	11th to 20th	Night	16% 8% 3 6% 5% 4 5% 4 5% 5% 39%	2368
	21st to end	Night	18% 7% 3 6% 4 4 4 3 5% 6% 40%	1980
March	1st to 10th	Night	19% 9% 2 5% 4 3 4 3 4 5% 41%	5364
	11th to 20th	Night	11% 7% 3 7% 4 4 4 3 4 6% 47%	5076
	21st to end	Night	15% 9% 3 7% 4 4 4 3 5% 5% 41%	5064
April	1st to 10th	Night	17% 8% 3 7% 5% 5% 4 4 5% 7% 34%	2000
	11th to 20th	Night	17% 7% 3 6% 5% 4 4 4 5% 7% 38%	1975
	21st to end	Night	19% 6% 3 4 4 3 4 4 5% 7% 41%	1957
May	1st to 10th	Night	26% 9% 3 6% 4 3 4 4 5% 7% 29%	2817
	11th to 20th	Night	24% 10% 3 7% 4 3 4 3 5% 6% 31%	2495
	21st to end	Night	14% 6% 2 5% 4 4 4 5% 6% 9% 41%	2738
June	1st to 10th	Night	15% 6% 2 6% 4 3 5% 4 5% 8% 43%	1520
	11th to 20th	Night	12% 7% 2 6% 4 4 5% 4 6% 8% 41%	1520
	21st to end	Night	12% 3 2 5% 4 4 5% 4 7% 9% 44%	1520
July	1st to 10th	Night	9% 6% 2 7% 5% 5% 4 5% 8% 9% 39%	2520
	11th to 20th	Night	11% 7% 2 6% 4 4 5% 4 8% 11% 37%	2520
	21st to end	Night	16% 7% 3 5% 4 5% 5% 4 6% 7% 36%	2739
August	1st to 10th	Night	22% 7% 3 7% 4 4 5% 4 6% 8% 31%	2751
	11th to 20th	Night	14% 7% 3 7% 4 4 5% 3 5% 6% 40%	3084
	21st to end	Night	11% 5% 1 5% 3 3 4 3 6% 8% 50%	3476
September	1st to 10th	Night	15% 7% 3 6% 3 4 4 2 5% 6% 45%	1900
	11th to 20th	Night	12% 6% 2 6% 3 3 3 2 4 8% 52%	1954
	21st to end	Night	17% 7% 2 6% 3 4 4 2 5% 6% 44%	2090
October	1st to 10th	Night	19% 8% 2 6% 4 3 3 2 5% 6% 41%	2237
	11th to 20th	Night	16% 5% 2 6% 3 3 4 3 4 6% 48%	2280
	21st to end	Night	19% 7% 2 4 3 3 3 3 5% 6% 44%	2627
November	1st to 10th	Night	12% 6% 2 4 3 3 4 3 5% 6% 51%	2537
	11th to 20th	Night	18% 7% 2 5% 3 3 3 3 4 5% 47%	2600
	21st to end	Night	14% 6% 2 6% 4 4 4 4 5% 7% 43%	2725
December	1st to 10th	Night	12% 8% 3 7% 5% 4 4 3 4 6% 44%	4580
	11th to 20th	Night	22% 9% 2 5% 3 3 4 3 4 6% 39%	5208
	21st to end	Night	19% 12% 3 7% 4 3 3 3 4 5% 37%	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	38% 3 9% 30% 18% 2	3598
	11th to 20th	Day	47% 6% 8% 21% 13% 5%	3600
	21st to end	Day	47% 5% 10% 21% 16% 1	4395
February	1st to 10th	Day	47% 5% 13% 22% 12% 2	1800
	11th to 20th	Day	45% 6% 9% 23% 15% 3	1925
	21st to end	Day	49% 5% 9% 21% 13% 3	1650
March	1st to 10th	Day	45% 3 10% 21% 13% 8%	4479
	11th to 20th	Day	39% 6% 12% 28% 10% 4	4878
	21st to end	Day	43% 4 11% 12% 24% 5%	5868
April	1st to 10th	Day	48% 5% 9% 20% 15% 5%	2400
	11th to 20th	Day	44% 5% 11% 21% 16% 3	2374
	21st to end	Day	44% 6% 9% 21% 16% 4	2340
May	1st to 10th	Day	55% 5% 11% 16% 11% 1	4163
	11th to 20th	Day	56% 5% 11% 18% 8% 1	4402
	21st to end	Day	36% 7% 12% 26% 17% 2	4837
June	1st to 10th	Day	43% 7% 14% 21% 14% 1	2660
	11th to 20th	Day	45% 7% 13% 23% 10% 2	2660
	21st to end	Day	41% 6% 14% 23% 15% 1	2660
July	1st to 10th	Day	44% 7% 13% 22% 13% 2	4370
	11th to 20th	Day	39% 7% 17% 24% 13% 1	4365
	21st to end	Day	49% 7% 10% 17% 15% 1	4661
August	1st to 10th	Day	49% 7% 13% 21% 9%	4142
	11th to 20th	Day	39% 6% 13% 29% 13% 1	3766
	21st to end	Day	35% 5% 11% 30% 18% 2	4180
September	1st to 10th	Day	39% 6% 11% 21% 19% 2	2280
	11th to 20th	Day	35% 4 10% 24% 25% 3	2225
	21st to end	Day	47% 5% 9% 18% 19% 2	2090
October	1st to 10th	Day	40% 5% 9% 18% 23% 5%	3224
	11th to 20th	Day	28% 4 10% 26% 27% 5%	3140
	21st to end	Day	28% 4 15% 24% 26% 4	3222
November	1st to 10th	Day	35% 4 12% 25% 21% 3	1761
	11th to 20th	Day	39% 5% 10% 24% 19% 3	1800
	21st to end	Day	42% 5% 12% 28% 11% 2	1670
December	1st to 10th	Day	42% 4 15% 28% 11% 2	2600
	11th to 20th	Day	45% 5% 13% 23% 13% 1	2986
	21st to end	Day	46% 6% 9% 21% 15% 2	3960
January	1st to 10th	Night	36% 4 10% 25% 21% 3	6349
	11th to 20th	Night	41% 5% 15% 20% 14% 5%	6360
	21st to end	Night	46% 4 10% 19% 17% 4	6559
February	1st to 10th	Night	45% 5% 13% 24% 12% 2	2600
	11th to 20th	Night	45% 6% 9% 20% 17% 4	2370
	21st to end	Night	45% 4 7% 24% 17% 3	1980
March	1st to 10th	Night	44% 3 10% 22% 13% 9%	5374
	11th to 20th	Night	39% 4 15% 25% 13% 4	5077
	21st to end	Night	45% 4 7% 17% 22% 5%	5064
April	1st to 10th	Night	47% 6% 10% 20% 13% 3	2000
	11th to 20th	Night	45% 6% 9% 20% 19% 1	1975
	21st to end	Night	42% 6% 10% 23% 17% 4	1957
May	1st to 10th	Night	54% 5% 11% 18% 10% 1	2823
	11th to 20th	Night	53% 6% 14% 15% 10% 1	2496
	21st to end	Night	39% 7% 14% 25% 12% 2	2739
June	1st to 10th	Night	41% 5% 11% 24% 18% 2	1520
	11th to 20th	Night	40% 7% 15% 25% 12% 1	1520
	21st to end	Night	34% 9% 15% 26% 15% 1	1520
July	1st to 10th	Night	39% 9% 17% 19% 15% 2	2480
	11th to 20th	Night	40% 7% 15% 25% 12% 1	2472
	21st to end	Night	44% 6% 14% 16% 18% 2	2651
August	1st to 10th	Night	50% 8% 16% 17% 9% 1	2741
	11th to 20th	Night	43% 6% 12% 28% 10% 1	3114
	21st to end	Night	33% 5% 11% 32% 19% 1	3476
September	1st to 10th	Night	40% 5% 10% 24% 19% 1	1900
	11th to 20th	Night	34% 4 11% 23% 25% 3	1954
	21st to end	Night	41% 5% 8% 23% 21% 1	2090
October	1st to 10th	Night	42% 4 9% 23% 20% 2	3731
	11th to 20th	Night	26% 5% 10% 28% 27% 5%	3779
	21st to end	Night	30% 3 12% 32% 19% 3	4326
November	1st to 10th	Night	33% 5% 11% 24% 22% 4	2537
	11th to 20th	Night	40% 4 9% 24% 20% 4	2600
	21st to end	Night	39% 5% 13% 28% 14% 1	2725
December	1st to 10th	Night	40% 4 13% 31% 10% 2	4580
	11th to 20th	Night	46% 4 11% 22% 15% 3	5208
	21st to end	Night	48% 5% 10% 18% 16% 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	32% 31% 27% 9% 1 1	200
	11th to 20th	Day	37% 31% 25% 7% 1	200
	21st to end	Day	25% 33% 30% 7% 4	315
February	1st to 10th	Day	31% 32% 29% 7% 1	300
	11th to 20th	Day	34% 29% 31% 6%	464
	21st to end	Day	33% 25% 30% 9% 2	414
March	1st to 10th	Day	31% 24% 28% 14% 2	500
	11th to 20th	Day	28% 24% 32% 11% 3 1	500
	21st to end	Day	33% 23% 29% 10% 3 1	550
April	1st to 10th	Day	31% 25% 27% 12% 5%	500
	11th to 20th	Day	28% 23% 31% 11% 6% 1	492
	21st to end	Day	30% 18% 36% 13% 3 1	480
May	1st to 10th	Day	35% 19% 28% 13% 5% 1	463
	11th to 20th	Day	24% 18% 33% 17% 7% 1	487
	21st to end	Day	20% 11% 28% 29% 11% 2	529
June	1st to 10th	Day	19% 16% 31% 23% 9% 1	490
	11th to 20th	Day	19% 14% 29% 26% 11% 1	490
	21st to end	Day	15% 15% 33% 26% 9% 1	490
July	1st to 10th	Day	15% 8% 29% 27% 16% 5%	485
	11th to 20th	Day	12% 5% 30% 36% 15% 3	484
	21st to end	Day	16% 11% 32% 28% 11% 2	532
August	1st to 10th	Day	16% 7% 29% 29% 14% 5%	486
	11th to 20th	Day	15% 8% 29% 29% 15% 4	479
	21st to end	Day	13% 9% 31% 27% 15% 5%	539
September	1st to 10th	Day	21% 12% 25% 23% 13% 5%	490
	11th to 20th	Day	13% 9% 29% 24% 15% 9%	490
	21st to end	Day	24% 14% 28% 21% 9% 3	490
October	1st to 10th	Day	24% 12% 29% 19% 12% 4	490
	11th to 20th	Day	18% 20% 31% 21% 9% 1	490
	21st to end	Day	24% 20% 32% 17% 7% 1	476
November	1st to 10th	Day	20% 18% 32% 20% 9% 2	395
	11th to 20th	Day	26% 24% 30% 17% 4	400
	21st to end	Day	27% 24% 33% 12% 3	270
December	1st to 10th	Day	30% 28% 29% 10% 5%	200
	11th to 20th	Day	37% 27% 25% 9% 3	200
	21st to end	Day	29% 23% 31% 13% 4 1	220
January	1st to 10th	Night	23% 26% 36% 13% 2	800
	11th to 20th	Night	28% 22% 31% 17% 2	800
	21st to end	Night	21% 26% 37% 15% 2	880
February	1st to 10th	Night	25% 23% 35% 16% 2	800
	11th to 20th	Night	26% 27% 36% 10% 1	783
	21st to end	Night	28% 23% 33% 14% 2	660
March	1st to 10th	Night	24% 25% 33% 15% 3	800
	11th to 20th	Night	23% 25% 32% 16% 3 1	800
	21st to end	Night	23% 22% 37% 14% 5%	880
April	1st to 10th	Night	24% 22% 34% 16% 3	800
	11th to 20th	Night	24% 19% 36% 18% 4	791
	21st to end	Night	23% 16% 36% 21% 4 1	783
May	1st to 10th	Night	26% 16% 33% 20% 6%	566
	11th to 20th	Night	20% 14% 37% 22% 6% 1	374
	21st to end	Night	17% 8% 29% 34% 12%	411
June	1st to 10th	Night	18% 10% 28% 33% 11% 1	380
	11th to 20th	Night	14% 7% 34% 35% 10%	380
	21st to end	Night	12% 7% 28% 42% 11%	380
July	1st to 10th	Night	11% 6% 28% 35% 18% 2	370
	11th to 20th	Night	12% 5% 25% 40% 17% 1	368
	21st to end	Night	15% 4 25% 41% 13% 1	416
August	1st to 10th	Night	13% 3 24% 38% 19% 3	519
	11th to 20th	Night	14% 5% 22% 36% 21% 2	737
	21st to end	Night	15% 5% 23% 37% 18% 1	836
September	1st to 10th	Night	18% 6% 27% 32% 16% 1	760
	11th to 20th	Night	15% 5% 27% 30% 19% 3	760
	21st to end	Night	21% 7% 27% 31% 13% 2	760
October	1st to 10th	Night	22% 11% 28% 25% 13% 2	760
	11th to 20th	Night	19% 15% 31% 27% 9%	760
	21st to end	Night	24% 17% 32% 21% 7%	836
November	1st to 10th	Night	17% 16% 33% 25% 8% 1	780
	11th to 20th	Night	25% 18% 31% 21% 5% 1	800
	21st to end	Night	20% 21% 36% 18% 5% 1	800
December	1st to 10th	Night	25% 20% 33% 18% 4	800
	11th to 20th	Night	24% 21% 35% 18% 3	800
	21st to end	Night	24% 22% 33% 18% 2	880

Page generated at 2025-04-23 09:25:04. Version ac07

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