Jenny Jump State Forest
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Jenny Jump State Forest clear sky chart from 2005-11-06 to 2025-09-04.

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% 8% 3 7% 4 4 4 4 5% 7% 38%	126282
	Night	17% 8% 3 6% 4 4 4 3 5% 6% 40%	122455
Transparency	Day	44% 6% 11% 22% 15% 2	129796
	Night	43% 5% 11% 22% 16% 3	127028
Seeing	Day	25% 16% 29% 19% 8% 2	15988
	Night	22% 14% 30% 24% 8% 1	25148

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	14% 10% 3 8% 4 4 3 3 4 5% 44%	3597
	11th to 20th	Day	13% 10% 4 10% 6% 5% 4 3 4 5% 34%	3570
	21st to end	Day	18% 9% 3 7% 4 5% 4 3 4 5% 38%	4438
February	1st to 10th	Day	16% 9% 3 8% 6% 4 5% 4 5% 7% 36%	1800
	11th to 20th	Day	15% 9% 4 8% 4 4 4 3 5% 6% 39%	1900
	21st to end	Day	19% 10% 2 8% 5% 4 4 3 4 5% 37%	1650
March	1st to 10th	Day	22% 10% 2 6% 4 3 3 3 3 5% 40%	4476
	11th to 20th	Day	11% 8% 3 7% 5% 4 4 3 5% 7% 42%	4924
	21st to end	Day	18% 7% 2 6% 4 4 4 3 5% 7% 41%	5829
April	1st to 10th	Day	18% 10% 3 7% 5% 4 4 4 5% 6% 36%	2400
	11th to 20th	Day	18% 7% 2 6% 4 4 3 4 5% 7% 39%	2374
	21st to end	Day	17% 7% 2 6% 4 4 4 4 6% 6% 39%	2400
May	1st to 10th	Day	27% 8% 2 6% 4 4 4 3 5% 7% 28%	5959
	11th to 20th	Day	22% 9% 3 7% 4 4 4 3 4 6% 32%	6318
	21st to end	Day	21% 6% 2 5% 4 4 5% 4 6% 9% 34%	6949
June	1st to 10th	Day	16% 6% 2 6% 5% 5% 6% 4 7% 8% 36%	2800
	11th to 20th	Day	17% 6% 2 7% 5% 4 5% 4 7% 9% 34%	2800
	21st to end	Day	13% 6% 2 6% 5% 5% 5% 4 6% 8% 40%	2800
July	1st to 10th	Day	9% 7% 2 8% 6% 6% 5% 4 7% 10% 36%	6360
	11th to 20th	Day	11% 7% 3 7% 5% 6% 6% 6% 8% 10% 32%	6360
	21st to end	Day	13% 7% 2 7% 4 4 5% 4 6% 8% 39%	6926
August	1st to 10th	Day	21% 6% 2 7% 4 4 5% 4 6% 8% 32%	4271
	11th to 20th	Day	12% 7% 2 6% 5% 4 4 4 6% 8% 41%	3859
	21st to end	Day	12% 6% 2 5% 4 4 4 3 5% 8% 46%	4312
September	1st to 10th	Day	16% 4 2 6% 4 4 5% 3 5% 7% 43%	2316
	11th to 20th	Day	13% 5% 2 5% 3 4 4 4 4 7% 50%	2237
	21st to end	Day	20% 6% 3 7% 4 4 5% 3 4 6% 39%	2090
October	1st to 10th	Day	20% 6% 2 6% 4 4 4 3 5% 7% 40%	1920
	11th to 20th	Day	16% 6% 2 6% 4 4 4 2 4 7% 45%	1900
	21st to end	Day	21% 6% 2 5% 4 4 4 3 5% 7% 40%	1986
November	1st to 10th	Day	13% 8% 2 5% 3 3 3 2 4 4 53%	1761
	11th to 20th	Day	17% 6% 2 5% 4 3 4 4 5% 6% 44%	1800
	21st to end	Day	17% 8% 2 5% 3 5% 4 4 5% 6% 41%	1654
December	1st to 10th	Day	16% 9% 3 6% 4 4 4 3 5% 6% 41%	2600
	11th to 20th	Day	22% 9% 3 5% 3 3 4 3 4 5% 38%	2986
	21st to end	Day	18% 9% 3 9% 5% 4 4 4 5% 7% 32%	3960
January	1st to 10th	Night	13% 8% 3 8% 5% 5% 4 4 5% 5% 41%	6349
	11th to 20th	Night	13% 9% 3 9% 5% 5% 5% 3 6% 7% 36%	6315
	21st to end	Night	18% 9% 3 7% 4 4 4 3 5% 6% 39%	6514
February	1st to 10th	Night	17% 9% 3 7% 4 4 4 4 5% 6% 39%	2600
	11th to 20th	Night	16% 9% 3 7% 5% 5% 4 3 5% 5% 38%	2384
	21st to end	Night	18% 8% 2 7% 4 4 4 4 5% 5% 39%	1980
March	1st to 10th	Night	19% 9% 3 6% 4 3 3 3 5% 5% 40%	5364
	11th to 20th	Night	12% 9% 3 6% 4 4 3 3 4 6% 47%	5032
	21st to end	Night	16% 9% 3 7% 4 4 4 3 4 5% 40%	5101
April	1st to 10th	Night	19% 8% 3 7% 4 5% 5% 4 5% 6% 35%	2000
	11th to 20th	Night	18% 7% 2 6% 4 5% 4 3 5% 7% 39%	1975
	21st to end	Night	20% 6% 2 4 4 3 4 4 5% 7% 42%	2000
May	1st to 10th	Night	28% 9% 3 6% 3 4 5% 3 5% 6% 27%	4019
	11th to 20th	Night	23% 10% 4 7% 4 4 4 3 5% 5% 33%	3575
	21st to end	Night	21% 7% 2 6% 4 4 4 4 6% 8% 35%	3926
June	1st to 10th	Night	16% 6% 2 5% 4 5% 5% 4 4 7% 43%	1600
	11th to 20th	Night	14% 7% 2 6% 4 5% 4 3 7% 9% 40%	1600
	21st to end	Night	13% 4 1 5% 4 3 5% 5% 7% 9% 44%	1600
July	1st to 10th	Night	11% 7% 2 7% 4 6% 5% 4 6% 10% 38%	3600
	11th to 20th	Night	13% 8% 3 7% 5% 5% 6% 5% 7% 10% 33%	3600
	21st to end	Night	12% 5% 2 5% 4 4 5% 4 5% 8% 45%	3926
August	1st to 10th	Night	21% 7% 2 7% 4 5% 4 4 6% 8% 32%	2874
	11th to 20th	Night	14% 7% 3 7% 5% 4 4 3 5% 7% 42%	3157
	21st to end	Night	13% 5% 2 4 3 4 4 3 5% 8% 50%	3586
September	1st to 10th	Night	15% 6% 2 6% 3 3 3 3 5% 6% 46%	1931
	11th to 20th	Night	12% 5% 2 5% 3 3 3 2 4 6% 53%	1943
	21st to end	Night	18% 7% 2 6% 3 3 4 4 4 6% 44%	2090
October	1st to 10th	Night	21% 6% 3 6% 4 3 3 3 4 6% 42%	2256
	11th to 20th	Night	18% 5% 2 5% 3 4 3 3 4 6% 48%	2280
	21st to end	Night	21% 7% 2 5% 3 3 2 2 5% 7% 43%	2612
November	1st to 10th	Night	12% 6% 2 5% 3 3 4 4 5% 5% 51%	2537
	11th to 20th	Night	17% 8% 2 5% 3 3 4 3 4 5% 46%	2600
	21st to end	Night	14% 7% 3 6% 4 4 4 3 6% 8% 42%	2745
December	1st to 10th	Night	13% 9% 3 8% 4 4 4 3 4 5% 44%	4580
	11th to 20th	Night	23% 9% 2 5% 3 3 4 3 4 5% 38%	5208
	21st to end	Night	20% 12% 3 7% 4 3 4 2 4 6% 36%	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	43% 4 7% 28% 16% 2	3598
	11th to 20th	Day	52% 3 8% 20% 12% 4	3600
	21st to end	Day	49% 5% 9% 22% 14% 1	4438
February	1st to 10th	Day	48% 5% 12% 21% 12% 1	1800
	11th to 20th	Day	47% 5% 8% 23% 15% 2	1909
	21st to end	Day	50% 5% 9% 21% 12% 3	1650
March	1st to 10th	Day	47% 3 9% 21% 12% 7%	4479
	11th to 20th	Day	40% 6% 13% 27% 10% 4	4924
	21st to end	Day	43% 4 10% 12% 24% 5%	5829
April	1st to 10th	Day	48% 5% 9% 19% 14% 5%	2400
	11th to 20th	Day	45% 5% 11% 20% 16% 3	2374
	21st to end	Day	43% 7% 10% 20% 16% 5%	2400
May	1st to 10th	Day	55% 6% 13% 15% 10% 1	5970
	11th to 20th	Day	53% 6% 8% 21% 12% 1	6322
	21st to end	Day	46% 7% 10% 23% 14% 1	6949
June	1st to 10th	Day	43% 8% 12% 21% 14% 1	2800
	11th to 20th	Day	45% 7% 12% 22% 10% 2	2800
	21st to end	Day	41% 8% 13% 24% 15% 1	2800
July	1st to 10th	Day	43% 8% 12% 21% 15% 1	6290
	11th to 20th	Day	43% 8% 17% 21% 10% 1	6285
	21st to end	Day	42% 5% 10% 20% 21% 1	6728
August	1st to 10th	Day	49% 8% 13% 20% 10%	4257
	11th to 20th	Day	40% 6% 13% 29% 12% 1	3895
	21st to end	Day	36% 5% 10% 31% 17% 2	4312
September	1st to 10th	Day	41% 6% 11% 22% 19% 2	2316
	11th to 20th	Day	34% 5% 10% 23% 25% 3	2237
	21st to end	Day	46% 6% 8% 18% 19% 2	2090
October	1st to 10th	Day	42% 4 8% 19% 23% 4	3193
	11th to 20th	Day	30% 5% 9% 28% 25% 4	3140
	21st to end	Day	28% 3 16% 24% 24% 4	3250
November	1st to 10th	Day	35% 4 12% 24% 20% 3	1761
	11th to 20th	Day	41% 4 9% 24% 19% 3	1800
	21st to end	Day	42% 5% 13% 27% 11% 2	1654
December	1st to 10th	Day	44% 4 15% 25% 10% 1	2600
	11th to 20th	Day	47% 4 14% 22% 12% 1	2986
	21st to end	Day	51% 4 10% 19% 14% 1	3960
January	1st to 10th	Night	43% 4 10% 24% 17% 3	6349
	11th to 20th	Night	46% 5% 13% 20% 12% 4	6360
	21st to end	Night	47% 4 10% 19% 17% 4	6514
February	1st to 10th	Night	46% 5% 13% 23% 11% 2	2600
	11th to 20th	Night	47% 5% 9% 19% 16% 4	2386
	21st to end	Night	45% 4 9% 24% 16% 3	1980
March	1st to 10th	Night	46% 4 10% 21% 12% 7%	5374
	11th to 20th	Night	38% 4 16% 25% 13% 4	5033
	21st to end	Night	46% 4 6% 16% 22% 5%	5101
April	1st to 10th	Night	49% 6% 9% 19% 14% 4	2000
	11th to 20th	Night	46% 6% 9% 19% 20% 1	1975
	21st to end	Night	42% 5% 9% 23% 17% 4	2000
May	1st to 10th	Night	57% 6% 11% 15% 10% 1	4025
	11th to 20th	Night	52% 7% 12% 14% 13% 1	3576
	21st to end	Night	46% 7% 13% 22% 10% 2	3927
June	1st to 10th	Night	41% 6% 10% 23% 19% 1	1600
	11th to 20th	Night	41% 7% 15% 24% 12% 1	1600
	21st to end	Night	34% 9% 14% 26% 15% 1	1600
July	1st to 10th	Night	42% 7% 14% 19% 15% 2	3560
	11th to 20th	Night	45% 8% 15% 21% 10% 1	3552
	21st to end	Night	36% 6% 13% 24% 20% 1	3809
August	1st to 10th	Night	49% 8% 16% 17% 9% 1	2864
	11th to 20th	Night	43% 6% 13% 27% 11% 1	3187
	21st to end	Night	33% 6% 10% 33% 18% 1	3586
September	1st to 10th	Night	39% 6% 10% 25% 20% 1	1931
	11th to 20th	Night	34% 5% 9% 23% 26% 4	1943
	21st to end	Night	41% 6% 9% 22% 21% 1	2090
October	1st to 10th	Night	43% 4 9% 23% 19% 1	3763
	11th to 20th	Night	29% 5% 9% 27% 27% 3	3779
	21st to end	Night	30% 4 13% 31% 20% 2	4298
November	1st to 10th	Night	34% 6% 12% 23% 21% 4	2537
	11th to 20th	Night	41% 4 10% 23% 19% 4	2600
	21st to end	Night	40% 5% 14% 27% 13% 1	2745
December	1st to 10th	Night	43% 4 13% 30% 9% 1	4580
	11th to 20th	Night	48% 3 11% 22% 14% 2	5208
	21st to end	Night	51% 3 9% 19% 15% 2	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	36% 25% 27% 10% 2 1	200
	11th to 20th	Day	40% 27% 24% 8% 2	200
	21st to end	Day	28% 31% 29% 7% 5%	323
February	1st to 10th	Day	35% 28% 30% 7% 1	300
	11th to 20th	Day	38% 24% 30% 7% 1	448
	21st to end	Day	35% 23% 29% 11% 2	414
March	1st to 10th	Day	32% 22% 30% 14% 2	500
	11th to 20th	Day	29% 24% 31% 11% 3 1	500
	21st to end	Day	36% 21% 28% 11% 3 1	550
April	1st to 10th	Day	32% 23% 28% 11% 6%	500
	11th to 20th	Day	30% 22% 30% 11% 5% 1	492
	21st to end	Day	32% 15% 34% 13% 4 1	500
May	1st to 10th	Day	35% 19% 26% 13% 6% 1	503
	11th to 20th	Day	26% 17% 30% 20% 6% 1	527
	21st to end	Day	24% 11% 27% 24% 12% 2	573
June	1st to 10th	Day	20% 15% 30% 24% 10% 2	530
	11th to 20th	Day	22% 14% 27% 25% 11% 1	530
	21st to end	Day	18% 12% 32% 27% 10% 1	530
July	1st to 10th	Day	15% 8% 29% 28% 16% 4	525
	11th to 20th	Day	12% 6% 28% 33% 17% 3	524
	21st to end	Day	15% 11% 31% 30% 10% 3	576
August	1st to 10th	Day	14% 8% 29% 31% 13% 6%	526
	11th to 20th	Day	13% 8% 28% 30% 17% 5%	519
	21st to end	Day	13% 9% 31% 26% 14% 6%	583
September	1st to 10th	Day	20% 10% 25% 25% 15% 6%	502
	11th to 20th	Day	12% 9% 29% 25% 14% 10%	490
	21st to end	Day	24% 14% 27% 21% 10% 3	490
October	1st to 10th	Day	26% 10% 27% 19% 12% 4	490
	11th to 20th	Day	20% 17% 32% 21% 9% 2	490
	21st to end	Day	26% 18% 30% 17% 8% 1	484
November	1st to 10th	Day	21% 17% 30% 21% 9% 2	395
	11th to 20th	Day	28% 19% 31% 17% 5% 1	400
	21st to end	Day	31% 20% 33% 13% 2 1	254
December	1st to 10th	Day	34% 24% 27% 10% 6%	200
	11th to 20th	Day	39% 24% 24% 11% 3	200
	21st to end	Day	31% 20% 32% 13% 4 1	220
January	1st to 10th	Night	25% 23% 37% 13% 3	800
	11th to 20th	Night	28% 20% 31% 19% 2	800
	21st to end	Night	23% 22% 38% 16% 1	880
February	1st to 10th	Night	26% 20% 36% 17% 2	800
	11th to 20th	Night	29% 22% 37% 12% 1	783
	21st to end	Night	30% 19% 33% 16% 2	660
March	1st to 10th	Night	27% 22% 31% 17% 3	800
	11th to 20th	Night	26% 22% 30% 18% 3 1	800
	21st to end	Night	24% 23% 34% 13% 5% 1	880
April	1st to 10th	Night	27% 19% 35% 16% 3	800
	11th to 20th	Night	24% 18% 34% 19% 5%	791
	21st to end	Night	24% 15% 32% 24% 4 1	800
May	1st to 10th	Night	27% 15% 29% 23% 6%	591
	11th to 20th	Night	20% 14% 35% 25% 7%	394
	21st to end	Night	19% 6% 25% 37% 12%	433
June	1st to 10th	Night	16% 9% 28% 35% 12% 1	400
	11th to 20th	Night	15% 5% 34% 36% 11%	400
	21st to end	Night	14% 5% 27% 41% 13%	400
July	1st to 10th	Night	12% 6% 24% 37% 20% 2	390
	11th to 20th	Night	13% 4 20% 42% 19% 2	388
	21st to end	Night	14% 4 24% 41% 16% 1	438
August	1st to 10th	Night	13% 2 20% 40% 23% 3	569
	11th to 20th	Night	14% 5% 20% 36% 23% 2	762
	21st to end	Night	15% 5% 22% 36% 20% 1	880
September	1st to 10th	Night	19% 5% 27% 31% 16% 2	773
	11th to 20th	Night	14% 6% 24% 31% 20% 4	760
	21st to end	Night	21% 6% 27% 30% 15% 2	760
October	1st to 10th	Night	23% 11% 23% 27% 14% 2	760
	11th to 20th	Night	19% 13% 29% 29% 8%	760
	21st to end	Night	26% 15% 31% 21% 7%	836
November	1st to 10th	Night	17% 16% 33% 24% 9% 1	780
	11th to 20th	Night	24% 17% 31% 23% 6% 1	800
	21st to end	Night	21% 18% 35% 20% 5%	800
December	1st to 10th	Night	26% 17% 34% 18% 4	800
	11th to 20th	Night	27% 17% 34% 19% 3	800
	21st to end	Night	27% 18% 34% 19% 2	880

Page generated at 2025-09-01 01:51:07. Version ac07

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