Good Earth State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Good Earth State Park clear sky chart from 2005-11-06 to 2025-12-03.

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	12% 7% 3 7% 5% 4 4 4 6% 7% 41%	127093
	Night	10% 7% 3 7% 5% 4 4 4 5% 7% 44%	123822
Transparency	Day	41% 5% 13% 25% 14% 2	130669
	Night	39% 5% 13% 26% 15% 2	128313
Seeing	Day	16% 8% 31% 29% 13% 3	17415
	Night	14% 8% 34% 34% 10% 1	27303

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	10% 13% 4 16% 10% 8% 6% 4 4 5% 19%	3470
	11th to 20th	Day	5% 12% 4 10% 7% 7% 8% 4 9% 9% 26%	3883
	21st to end	Day	5% 10% 6% 12% 8% 7% 5% 4 4 5% 34%	4488
February	1st to 10th	Day	9% 13% 4 12% 7% 7% 7% 4 5% 6% 27%	1800
	11th to 20th	Day	8% 11% 5% 9% 7% 5% 6% 4 5% 6% 33%	1764
	21st to end	Day	11% 10% 4 9% 5% 5% 4 5% 5% 7% 36%	1650
March	1st to 10th	Day	12% 8% 3 8% 4 3 3 3 4 6% 46%	4778
	11th to 20th	Day	8% 8% 2 6% 3 3 3 3 5% 8% 50%	4980
	21st to end	Day	23% 11% 4 10% 5% 4 4 4 4 6% 25%	5462
April	1st to 10th	Day	16% 9% 2 7% 4 4 4 4 6% 7% 37%	2264
	11th to 20th	Day	18% 9% 2 6% 5% 4 4 3 4 6% 37%	2568
	21st to end	Day	21% 8% 2 6% 4 4 4 3 5% 6% 37%	2600
May	1st to 10th	Day	12% 4 2 5% 4 4 4 4 7% 7% 47%	5862
	11th to 20th	Day	17% 7% 2 5% 3 3 3 3 4 6% 48%	5862
	21st to end	Day	19% 8% 3 6% 4 4 4 4 5% 7% 36%	6935
June	1st to 10th	Day	12% 5% 2 5% 3 4 3 3 6% 9% 47%	2879
	11th to 20th	Day	13% 6% 2 6% 5% 4 4 4 6% 7% 43%	3000
	21st to end	Day	10% 4 2 5% 4 4 4 4 6% 9% 48%	3000
July	1st to 10th	Day	8% 5% 2 6% 5% 4 6% 5% 7% 10% 43%	6800
	11th to 20th	Day	8% 4 2 5% 3 4 4 3 5% 8% 53%	6221
	21st to end	Day	6% 5% 2 5% 4 4 5% 5% 8% 10% 47%	6422
August	1st to 10th	Day	9% 6% 2 6% 5% 4 6% 4 7% 10% 43%	4234
	11th to 20th	Day	15% 8% 3 7% 4 4 4 4 7% 8% 36%	4171
	21st to end	Day	9% 4 2 6% 4 4 4 3 5% 7% 52%	4675
September	1st to 10th	Day	12% 5% 2 5% 4 3 3 3 5% 6% 52%	2333
	11th to 20th	Day	11% 5% 2 5% 3 3 4 2 4 8% 53%	2200
	21st to end	Day	10% 5% 2 4 4 3 3 3 5% 7% 54%	2200
October	1st to 10th	Day	14% 7% 1 6% 3 3 3 3 6% 6% 48%	2054
	11th to 20th	Day	14% 7% 2 5% 3 3 3 3 4 5% 51%	2000
	21st to end	Day	15% 8% 2 6% 4 3 3 3 5% 5% 46%	2126
November	1st to 10th	Day	11% 7% 3 6% 4 3 4 3 6% 7% 44%	1853
	11th to 20th	Day	9% 9% 4 10% 5% 5% 4 4 4 6% 39%	1725
	21st to end	Day	11% 9% 3 9% 4 4 4 4 5% 7% 38%	1680
December	1st to 10th	Day	4 8% 4 11% 7% 6% 4 4 7% 6% 40%	2626
	11th to 20th	Day	9% 12% 5% 11% 8% 6% 6% 4 5% 6% 26%	3008
	21st to end	Day	17% 9% 4 16% 5% 4 4 4 5% 8% 23%	3520
January	1st to 10th	Night	8% 11% 4 14% 10% 7% 6% 4 5% 7% 25%	6493
	11th to 20th	Night	4 8% 4 11% 7% 6% 7% 5% 8% 8% 33%	6080
	21st to end	Night	5% 9% 5% 11% 4 5% 5% 4 5% 6% 39%	6490
February	1st to 10th	Night	9% 11% 3 10% 7% 5% 4 4 5% 6% 37%	2600
	11th to 20th	Night	8% 10% 3 9% 5% 4 5% 4 5% 6% 40%	2533
	21st to end	Night	8% 8% 3 8% 5% 4 4 4 6% 7% 42%	1987
March	1st to 10th	Night	11% 7% 2 5% 3 3 3 3 4 6% 53%	5082
	11th to 20th	Night	10% 6% 2 5% 3 3 4 4 6% 8% 48%	4980
	21st to end	Night	20% 10% 3 7% 5% 4 4 3 5% 7% 32%	5467
April	1st to 10th	Night	14% 8% 3 6% 5% 4 4 4 6% 7% 39%	2135
	11th to 20th	Night	16% 9% 3 6% 3 3 4 2 4 6% 44%	1779
	21st to end	Night	17% 9% 3 6% 3 4 4 4 5% 6% 40%	1800
May	1st to 10th	Night	13% 4 2 4 3 2 3 3 5% 7% 55%	4053
	11th to 20th	Night	13% 6% 2 4 3 4 3 3 5% 6% 51%	4037
	21st to end	Night	18% 7% 2 5% 4 4 3 4 5% 7% 42%	3942
June	1st to 10th	Night	8% 5% 2 4 3 3 4 4 6% 8% 54%	1516
	11th to 20th	Night	7% 4 1 4 4 4 4 4 6% 9% 51%	1400
	21st to end	Night	8% 3 2 4 4 3 4 4 4 9% 56%	1400
July	1st to 10th	Night	8% 5% 2 5% 3 3 4 4 6% 9% 51%	3178
	11th to 20th	Night	8% 4 1 4 3 3 4 3 5% 6% 58%	3734
	21st to end	Night	7% 4 2 5% 3 3 4 3 6% 10% 54%	4449
August	1st to 10th	Night	7% 5% 3 6% 4 4 6% 4 6% 8% 47%	2926
	11th to 20th	Night	11% 4 2 5% 3 4 4 4 5% 8% 50%	2888
	21st to end	Night	8% 4 2 5% 3 3 4 3 5% 8% 56%	3234
September	1st to 10th	Night	8% 3 2 4 3 3 3 3 5% 7% 59%	2062
	11th to 20th	Night	9% 4 2 5% 3 3 4 3 6% 6% 56%	2200
	21st to end	Night	9% 5% 2 4 3 2 3 3 5% 6% 58%	2200
October	1st to 10th	Night	14% 5% 2 4 3 2 3 3 4 6% 54%	2325
	11th to 20th	Night	13% 7% 3 4 3 3 3 3 4 6% 52%	2400
	21st to end	Night	14% 8% 2 5% 4 3 3 3 4 6% 48%	2710
November	1st to 10th	Night	9% 5% 2 5% 5% 4 4 3 5% 6% 51%	2665
	11th to 20th	Night	9% 7% 3 7% 5% 4 4 4 6% 6% 46%	2893
	21st to end	Night	9% 8% 3 7% 4 4 3 3 5% 7% 46%	2940
December	1st to 10th	Night	5% 7% 4 11% 6% 4 4 4 6% 7% 42%	4609
	11th to 20th	Night	10% 9% 4 9% 7% 6% 5% 4 5% 8% 32%	5199
	21st to end	Night	15% 13% 4 13% 5% 4 4 3 5% 6% 26%	7436

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	65% 6% 12% 12% 5%	3471
	11th to 20th	Day	53% 3 10% 19% 15%	3883
	21st to end	Day	52% 5% 13% 19% 10% 1	4488
February	1st to 10th	Day	58% 5% 12% 16% 9% 1	1800
	11th to 20th	Day	51% 5% 12% 20% 10% 2	1773
	21st to end	Day	48% 6% 13% 21% 11% 1	1650
March	1st to 10th	Day	40% 3 11% 32% 11% 2	4778
	11th to 20th	Day	33% 4 9% 34% 17% 2	4980
	21st to end	Day	61% 5% 12% 16% 4 1	5464
April	1st to 10th	Day	46% 4 13% 23% 12% 1	2264
	11th to 20th	Day	48% 5% 10% 23% 12% 2	2568
	21st to end	Day	48% 6% 11% 24% 11%	2600
May	1st to 10th	Day	34% 5% 10% 27% 23%	5900
	11th to 20th	Day	38% 4 10% 23% 16% 9%	5866
	21st to end	Day	48% 6% 9% 22% 14% 1	6949
June	1st to 10th	Day	34% 7% 15% 28% 14% 2	2879
	11th to 20th	Day	39% 6% 14% 24% 14% 3	3000
	21st to end	Day	32% 6% 15% 29% 15% 3	3000
July	1st to 10th	Day	34% 7% 19% 29% 11% 1	6726
	11th to 20th	Day	30% 5% 13% 32% 17% 2	6145
	21st to end	Day	30% 6% 19% 26% 16% 1	6240
August	1st to 10th	Day	35% 7% 14% 28% 13% 2	4220
	11th to 20th	Day	44% 7% 14% 25% 9% 1	4210
	21st to end	Day	32% 5% 16% 28% 16% 3	4674
September	1st to 10th	Day	33% 5% 12% 31% 18% 2	2333
	11th to 20th	Day	31% 6% 16% 32% 15% 1	2200
	21st to end	Day	30% 5% 11% 30% 22% 2	2200
October	1st to 10th	Day	26% 3 8% 29% 30% 4	3340
	11th to 20th	Day	32% 3 14% 25% 22% 4	3240
	21st to end	Day	40% 3 13% 24% 17% 2	3419
November	1st to 10th	Day	39% 4 15% 25% 14% 3	1853
	11th to 20th	Day	45% 4 14% 23% 13% 1	1725
	21st to end	Day	45% 4 14% 24% 12% 1	1680
December	1st to 10th	Day	43% 4 15% 28% 9% 1	2626
	11th to 20th	Day	57% 5% 16% 16% 5%	3005
	21st to end	Day	60% 5% 12% 17% 6% 1	3520
January	1st to 10th	Night	58% 5% 11% 18% 8%	6493
	11th to 20th	Night	46% 4 16% 16% 17% 1	6080
	21st to end	Night	45% 6% 12% 23% 14%	6490
February	1st to 10th	Night	48% 5% 11% 23% 11% 1	2600
	11th to 20th	Night	45% 5% 11% 24% 13% 3	2534
	21st to end	Night	41% 5% 13% 24% 14% 3	1987
March	1st to 10th	Night	34% 4 9% 34% 18% 1	5082
	11th to 20th	Night	33% 4 9% 32% 19% 2	4980
	21st to end	Night	53% 6% 13% 21% 6% 1	5467
April	1st to 10th	Night	43% 6% 13% 23% 14% 1	2135
	11th to 20th	Night	42% 4 10% 24% 18% 2	1779
	21st to end	Night	44% 5% 12% 23% 14% 2	1800
May	1st to 10th	Night	30% 5% 11% 29% 23% 2	4080
	11th to 20th	Night	34% 5% 10% 22% 20% 9%	4038
	21st to end	Night	42% 5% 9% 30% 14% 1	3950
June	1st to 10th	Night	27% 7% 16% 28% 19% 3	1516
	11th to 20th	Night	29% 5% 17% 26% 20% 4	1400
	21st to end	Night	26% 6% 16% 29% 21% 2	1400
July	1st to 10th	Night	30% 5% 18% 31% 15% 2	3145
	11th to 20th	Night	27% 6% 12% 36% 16% 3	3690
	21st to end	Night	26% 6% 20% 29% 16% 2	4320
August	1st to 10th	Night	33% 7% 14% 29% 15% 3	2916
	11th to 20th	Night	32% 7% 17% 29% 13% 1	2915
	21st to end	Night	27% 5% 17% 26% 21% 3	3234
September	1st to 10th	Night	26% 5% 15% 29% 22% 4	2062
	11th to 20th	Night	28% 5% 14% 34% 17% 2	2200
	21st to end	Night	26% 5% 10% 32% 24% 3	2200
October	1st to 10th	Night	21% 2 7% 26% 41% 3	3806
	11th to 20th	Night	27% 3 13% 30% 24% 3	3899
	21st to end	Night	39% 4 11% 30% 15% 1	4371
November	1st to 10th	Night	34% 4 14% 25% 20% 4	2665
	11th to 20th	Night	38% 5% 14% 25% 16% 2	2893
	21st to end	Night	38% 4 15% 28% 14% 1	2940
December	1st to 10th	Night	42% 4 15% 31% 8%	4609
	11th to 20th	Night	50% 5% 17% 21% 6%	5201
	21st to end	Night	60% 4 10% 19% 7% 1	7436

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	18% 8% 34% 26% 12% 3	300
	11th to 20th	Day	18% 8% 36% 30% 6% 2	300
	21st to end	Day	15% 10% 37% 25% 12% 1	330
February	1st to 10th	Day	13% 16% 38% 29% 4	300
	11th to 20th	Day	11% 11% 46% 24% 7% 1	300
	21st to end	Day	19% 10% 43% 24% 3	249
March	1st to 10th	Day	22% 10% 40% 22% 5% 1	300
	11th to 20th	Day	21% 10% 36% 22% 10% 1	300
	21st to end	Day	32% 10% 34% 17% 6% 2	330
April	1st to 10th	Day	26% 14% 36% 19% 5%	364
	11th to 20th	Day	26% 14% 32% 22% 5% 1	686
	21st to end	Day	26% 11% 31% 20% 10% 2	700
May	1st to 10th	Day	20% 10% 29% 29% 10% 2	703
	11th to 20th	Day	21% 9% 29% 26% 13% 2	725
	21st to end	Day	20% 8% 27% 31% 13% 2	789
June	1st to 10th	Day	11% 7% 24% 33% 21% 5%	730
	11th to 20th	Day	13% 8% 35% 29% 12% 3	730
	21st to end	Day	13% 6% 35% 29% 15% 2	730
July	1st to 10th	Day	7% 3 21% 37% 26% 5%	721
	11th to 20th	Day	7% 4 30% 35% 18% 5%	718
	21st to end	Day	6% 4 24% 40% 23% 4	794
August	1st to 10th	Day	11% 4 22% 37% 23% 4	726
	11th to 20th	Day	12% 3 25% 35% 22% 5%	715
	21st to end	Day	8% 4 28% 34% 21% 4	803
September	1st to 10th	Day	14% 6% 25% 35% 16% 4	463
	11th to 20th	Day	10% 6% 33% 33% 15% 4	330
	21st to end	Day	14% 10% 30% 26% 15% 5%	330
October	1st to 10th	Day	18% 8% 29% 26% 13% 6%	330
	11th to 20th	Day	16% 15% 38% 21% 9% 1	330
	21st to end	Day	23% 16% 35% 21% 5% 1	363
November	1st to 10th	Day	21% 10% 35% 24% 7% 2	330
	11th to 20th	Day	16% 14% 43% 20% 7%	330
	21st to end	Day	18% 18% 33% 22% 9% 1	330
December	1st to 10th	Day	11% 11% 39% 26% 10% 2	306
	11th to 20th	Day	20% 9% 38% 26% 7%	300
	21st to end	Day	24% 13% 35% 24% 5% 1	330
January	1st to 10th	Night	12% 10% 36% 32% 9% 1	1000
	11th to 20th	Night	13% 10% 37% 32% 6% 2	1000
	21st to end	Night	15% 11% 37% 29% 9%	1100
February	1st to 10th	Night	14% 9% 41% 29% 6% 1	1000
	11th to 20th	Night	13% 8% 42% 30% 6% 1	979
	21st to end	Night	13% 8% 39% 31% 8% 1	667
March	1st to 10th	Night	14% 8% 40% 30% 7%	677
	11th to 20th	Night	15% 10% 38% 32% 5%	600
	21st to end	Night	20% 8% 37% 26% 7% 1	660
April	1st to 10th	Night	19% 12% 39% 28% 3	600
	11th to 20th	Night	21% 14% 32% 27% 5% 1	593
	21st to end	Night	20% 11% 34% 27% 7% 1	600
May	1st to 10th	Night	18% 6% 35% 32% 10%	600
	11th to 20th	Night	19% 7% 30% 34% 9% 1	591
	21st to end	Night	18% 6% 30% 34% 12%	650
June	1st to 10th	Night	9% 7% 24% 42% 17% 1	600
	11th to 20th	Night	11% 5% 32% 39% 13% 1	600
	21st to end	Night	10% 4 26% 47% 14%	600
July	1st to 10th	Night	6% 2 21% 44% 26% 1	585
	11th to 20th	Night	5% 1 25% 49% 19%	582
	21st to end	Night	5% 2 23% 51% 19%	657
August	1st to 10th	Night	9% 2 22% 47% 20% 1	597
	11th to 20th	Night	9% 2 23% 43% 23% 1	594
	21st to end	Night	6% 3 26% 45% 19% 1	660
September	1st to 10th	Night	9% 4 25% 45% 15% 2	600
	11th to 20th	Night	10% 3 32% 39% 14% 2	600
	21st to end	Night	11% 6% 34% 34% 15% 1	600
October	1st to 10th	Night	17% 8% 34% 29% 12% 1	725
	11th to 20th	Night	17% 12% 35% 31% 5%	800
	21st to end	Night	18% 10% 36% 27% 9%	950
November	1st to 10th	Night	11% 10% 37% 32% 9% 1	1025
	11th to 20th	Night	14% 11% 39% 29% 7%	1050
	21st to end	Night	13% 9% 37% 33% 8%	1050
December	1st to 10th	Night	13% 9% 38% 32% 7%	1011
	11th to 20th	Night	18% 7% 37% 30% 7%	1000
	21st to end	Night	21% 10% 35% 27% 6% 1	1100

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