Discovery Park of America
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Discovery Park of America clear sky chart from 2005-11-06 to 2025-12-18.

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% 2 6% 4 4 4 4 6% 8% 43%	126781
	Night	13% 6% 2 6% 4 4 4 3 5% 7% 46%	124427
Transparency	Day	38% 5% 11% 24% 18% 4	130430
	Night	37% 5% 10% 24% 20% 5%	128857
Seeing	Day	15% 7% 22% 25% 21% 10%	16904
	Night	16% 7% 24% 32% 18% 2	26690

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	15% 9% 3 10% 4 4 3 3 4 6% 38%	3617
	11th to 20th	Day	14% 8% 3 6% 4 3 3 2 4 6% 48%	3919
	21st to end	Day	19% 9% 2 6% 3 3 3 3 4 6% 41%	4488
February	1st to 10th	Day	20% 10% 3 6% 4 3 4 2 4 5% 39%	1968
	11th to 20th	Day	20% 10% 3 6% 5% 4 3 2 4 5% 37%	1948
	21st to end	Day	19% 9% 3 7% 5% 4 4 2 4 5% 36%	1650
March	1st to 10th	Day	16% 13% 4 8% 4 3 3 3 5% 5% 38%	4480
	11th to 20th	Day	12% 7% 2 7% 4 3 4 3 5% 6% 48%	4828
	21st to end	Day	11% 7% 3 7% 5% 4 4 3 5% 7% 43%	5916
April	1st to 10th	Day	13% 6% 2 6% 4 4 3 4 5% 7% 46%	2400
	11th to 20th	Day	15% 7% 2 7% 5% 4 4 3 5% 6% 42%	2374
	21st to end	Day	16% 7% 3 6% 4 4 4 3 6% 8% 40%	2400
May	1st to 10th	Day	15% 9% 3 9% 6% 5% 6% 5% 6% 8% 28%	5584
	11th to 20th	Day	15% 8% 3 8% 6% 6% 6% 4 6% 8% 31%	5861
	21st to end	Day	14% 7% 2 7% 5% 4 5% 4 6% 8% 38%	6743
June	1st to 10th	Day	9% 5% 2 5% 5% 5% 5% 4 7% 9% 45%	2800
	11th to 20th	Day	4 4 2 5% 5% 4 6% 5% 7% 11% 46%	2800
	21st to end	Day	4 5% 1 5% 5% 5% 6% 5% 8% 11% 46%	2800
July	1st to 10th	Day	6% 5% 2 7% 5% 5% 5% 5% 7% 9% 43%	6360
	11th to 20th	Day	5% 4 2 5% 5% 5% 7% 5% 9% 12% 40%	6360
	21st to end	Day	7% 7% 3 8% 5% 5% 6% 5% 8% 11% 36%	6588
August	1st to 10th	Day	3 2 2 4 3 3 5% 4 7% 10% 58%	3905
	11th to 20th	Day	8% 5% 2 6% 4 4 5% 4 6% 10% 46%	3849
	21st to end	Day	5% 4 1 4 3 3 3 4 6% 8% 58%	4312
September	1st to 10th	Day	10% 5% 2 6% 4 4 4 4 6% 8% 47%	2400
	11th to 20th	Day	12% 5% 2 5% 4 3 4 3 5% 8% 48%	2296
	21st to end	Day	13% 5% 2 4 3 4 4 3 4 7% 51%	2200
October	1st to 10th	Day	8% 4 2 5% 2 3 3 3 4 5% 60%	2142
	11th to 20th	Day	12% 5% 2 4 3 3 3 3 5% 5% 55%	2000
	21st to end	Day	19% 6% 2 4 2 3 3 3 4 5% 48%	2145
November	1st to 10th	Day	11% 6% 2 5% 3 3 3 3 4 6% 54%	1852
	11th to 20th	Day	14% 7% 2 5% 3 3 3 3 4 5% 51%	1890
	21st to end	Day	16% 7% 3 7% 3 4 4 3 4 6% 43%	1890
December	1st to 10th	Day	13% 9% 3 6% 4 3 4 3 4 5% 46%	2970
	11th to 20th	Day	16% 8% 2 7% 4 4 3 3 5% 6% 42%	3064
	21st to end	Day	17% 11% 3 9% 6% 5% 5% 4 5% 5% 30%	3982
January	1st to 10th	Night	17% 7% 3 9% 4 3 4 3 5% 7% 38%	6348
	11th to 20th	Night	14% 7% 3 6% 4 4 4 3 4 5% 47%	6056
	21st to end	Night	21% 8% 2 6% 3 3 3 3 4 5% 43%	6490
February	1st to 10th	Night	21% 9% 3 6% 5% 3 3 3 4 5% 37%	2429
	11th to 20th	Night	19% 6% 3 7% 4 4 4 3 4 5% 41%	2338
	21st to end	Night	18% 7% 3 6% 4 4 4 3 5% 5% 40%	1980
March	1st to 10th	Night	17% 10% 3 7% 4 4 4 3 4 5% 39%	5373
	11th to 20th	Night	11% 7% 2 5% 3 4 4 3 5% 6% 49%	5174
	21st to end	Night	12% 7% 3 7% 4 4 4 4 6% 7% 41%	5013
April	1st to 10th	Night	12% 5% 2 6% 4 3 3 3 6% 7% 48%	2000
	11th to 20th	Night	15% 6% 2 5% 4 4 4 2 4 7% 48%	1975
	21st to end	Night	13% 5% 2 7% 5% 4 4 4 6% 8% 42%	2000
May	1st to 10th	Night	16% 9% 3 8% 4 4 5% 4 6% 7% 35%	4307
	11th to 20th	Night	13% 9% 3 8% 5% 5% 5% 4 5% 7% 36%	4032
	21st to end	Night	12% 7% 3 7% 4 5% 5% 4 7% 8% 38%	4122
June	1st to 10th	Night	7% 6% 2 6% 4 5% 4 4 7% 8% 47%	1600
	11th to 20th	Night	5% 3 2 4 4 4 4 4 6% 10% 55%	1600
	21st to end	Night	2 2 2 3 4 4 5% 5% 8% 11% 54%	1600
July	1st to 10th	Night	6% 5% 2 7% 4 5% 6% 5% 7% 9% 45%	3618
	11th to 20th	Night	4 4 2 5% 4 5% 5% 5% 7% 12% 47%	3617
	21st to end	Night	5% 7% 3 7% 4 4 5% 4 7% 13% 41%	4265
August	1st to 10th	Night	2 2 1 4 3 4 4 4 6% 7% 63%	3240
	11th to 20th	Night	4 3 1 5% 4 5% 5% 4 7% 9% 54%	3200
	21st to end	Night	4 3 1 4 3 3 3 3 5% 8% 62%	3586
September	1st to 10th	Night	8% 5% 2 4 4 4 3 3 4 7% 56%	2000
	11th to 20th	Night	7% 6% 2 5% 4 4 4 3 5% 6% 53%	2082
	21st to end	Night	9% 5% 2 5% 4 3 4 3 5% 6% 55%	2200
October	1st to 10th	Night	7% 4 1 4 2 4 3 2 4 6% 62%	2254
	11th to 20th	Night	13% 4 2 4 3 3 3 2 4 5% 58%	2400
	21st to end	Night	16% 7% 2 5% 3 3 3 2 4 5% 49%	2694
November	1st to 10th	Night	12% 5% 2 4 3 3 2 3 5% 5% 56%	2666
	11th to 20th	Night	12% 5% 2 5% 3 3 3 3 5% 6% 54%	2730
	21st to end	Night	16% 6% 2 5% 3 4 3 3 4 6% 48%	2730
December	1st to 10th	Night	17% 7% 2 5% 4 3 3 3 4 5% 47%	4414
	11th to 20th	Night	18% 8% 2 5% 4 3 4 3 4 5% 44%	5298
	21st to end	Night	20% 9% 4 8% 4 4 4 3 4 5% 35%	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	46% 3 11% 23% 14% 1	3618
	11th to 20th	Day	39% 3 6% 29% 22% 1	3919
	21st to end	Day	44% 3 7% 20% 18% 7%	4488
February	1st to 10th	Day	49% 4 9% 23% 13% 2	1968
	11th to 20th	Day	49% 5% 9% 20% 13% 4	1958
	21st to end	Day	50% 3 8% 18% 15% 5%	1650
March	1st to 10th	Day	50% 3 6% 20% 15% 7%	4480
	11th to 20th	Day	38% 4 7% 24% 22% 6%	4828
	21st to end	Day	41% 4 10% 25% 19%	5918
April	1st to 10th	Day	39% 5% 10% 25% 19% 2	2400
	11th to 20th	Day	42% 4 10% 22% 17% 4	2374
	21st to end	Day	42% 6% 10% 25% 16% 1	2400
May	1st to 10th	Day	51% 7% 13% 18% 10% 1	5619
	11th to 20th	Day	49% 8% 12% 19% 11% 1	5865
	21st to end	Day	43% 7% 10% 22% 16% 2	6757
June	1st to 10th	Day	33% 8% 13% 23% 20% 2	2800
	11th to 20th	Day	29% 8% 12% 27% 20% 3	2800
	21st to end	Day	29% 10% 14% 24% 19% 5%	2800
July	1st to 10th	Day	35% 7% 13% 26% 17% 2	6291
	11th to 20th	Day	32% 8% 18% 32% 9% 2	6285
	21st to end	Day	41% 6% 20% 25% 8% 1	6402
August	1st to 10th	Day	20% 7% 16% 31% 24% 2	3893
	11th to 20th	Day	33% 6% 15% 26% 17% 3	3885
	21st to end	Day	24% 5% 10% 34% 24% 3	4311
September	1st to 10th	Day	33% 7% 11% 25% 20% 4	2400
	11th to 20th	Day	35% 7% 8% 22% 24% 4	2296
	21st to end	Day	34% 4 7% 23% 26% 6%	2200
October	1st to 10th	Day	17% 3 6% 16% 42% 16%	3493
	11th to 20th	Day	23% 3 6% 21% 31% 16%	3240
	21st to end	Day	30% 3 4 26% 31% 6%	3447
November	1st to 10th	Day	33% 4 8% 26% 25% 5%	1852
	11th to 20th	Day	36% 3 7% 23% 24% 6%	1890
	21st to end	Day	44% 4 7% 22% 19% 4	1890
December	1st to 10th	Day	41% 4 7% 29% 18% 1	2970
	11th to 20th	Day	44% 3 10% 23% 16% 3	3061
	21st to end	Day	55% 5% 10% 21% 9% 1	3982
January	1st to 10th	Night	46% 3 9% 26% 14% 1	6348
	11th to 20th	Night	41% 4 7% 24% 22% 2	6056
	21st to end	Night	44% 3 7% 23% 17% 5%	6490
February	1st to 10th	Night	50% 4 10% 18% 17% 2	2429
	11th to 20th	Night	46% 4 8% 20% 18% 4	2339
	21st to end	Night	46% 4 8% 19% 19% 5%	1980
March	1st to 10th	Night	47% 4 6% 16% 17% 9%	5373
	11th to 20th	Night	36% 4 7% 22% 17% 13%	5174
	21st to end	Night	41% 4 10% 27% 16% 2	5013
April	1st to 10th	Night	35% 4 12% 25% 20% 5%	2000
	11th to 20th	Night	37% 5% 8% 22% 21% 7%	1975
	21st to end	Night	39% 7% 10% 24% 18% 3	2000
May	1st to 10th	Night	48% 7% 14% 21% 9% 1	4337
	11th to 20th	Night	46% 8% 14% 19% 12% 1	4033
	21st to end	Night	41% 7% 10% 25% 14% 3	4130
June	1st to 10th	Night	34% 7% 11% 22% 24% 2	1600
	11th to 20th	Night	24% 6% 14% 29% 23% 5%	1600
	21st to end	Night	21% 9% 18% 26% 20% 6%	1600
July	1st to 10th	Night	33% 7% 13% 24% 20% 2	3580
	11th to 20th	Night	28% 8% 19% 30% 12% 3	3572
	21st to end	Night	34% 6% 21% 27% 11%	4141
August	1st to 10th	Night	18% 7% 13% 38% 23% 1	3229
	11th to 20th	Night	25% 7% 15% 32% 19% 3	3230
	21st to end	Night	20% 5% 11% 35% 26% 4	3586
September	1st to 10th	Night	28% 5% 10% 28% 22% 6%	2000
	11th to 20th	Night	32% 6% 8% 25% 25% 4	2082
	21st to end	Night	30% 4 12% 22% 25% 7%	2200
October	1st to 10th	Night	16% 3 5% 16% 40% 18%	3683
	11th to 20th	Night	19% 2 4 18% 40% 16%	3899
	21st to end	Night	28% 3 6% 24% 29% 11%	4342
November	1st to 10th	Night	31% 4 6% 27% 26% 6%	2666
	11th to 20th	Night	32% 3 7% 23% 25% 9%	2730
	21st to end	Night	39% 4 7% 25% 22% 3	2730
December	1st to 10th	Night	40% 3 8% 26% 21% 2	4414
	11th to 20th	Night	43% 3 8% 24% 20% 2	5300
	21st to end	Night	51% 4 10% 22% 10% 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	26% 13% 36% 20% 4 1	300
	11th to 20th	Day	23% 17% 40% 16% 3 1	300
	21st to end	Day	21% 15% 42% 18% 4	330
February	1st to 10th	Day	28% 12% 37% 17% 6% 1	300
	11th to 20th	Day	32% 16% 36% 13% 3	300
	21st to end	Day	32% 15% 31% 20% 2	249
March	1st to 10th	Day	25% 13% 37% 18% 6% 1	300
	11th to 20th	Day	22% 16% 39% 20% 2	300
	21st to end	Day	23% 13% 36% 20% 7% 1	525
April	1st to 10th	Day	21% 13% 31% 25% 9% 1	500
	11th to 20th	Day	19% 15% 29% 25% 10% 2	492
	21st to end	Day	20% 8% 34% 23% 11% 3	500
May	1st to 10th	Day	17% 13% 26% 29% 10% 4	503
	11th to 20th	Day	18% 6% 23% 26% 18% 9%	527
	21st to end	Day	11% 5% 21% 30% 22% 11%	701
June	1st to 10th	Day	12% 3 17% 25% 28% 16%	730
	11th to 20th	Day	6% 2 13% 31% 34% 13%	730
	21st to end	Day	5% 2 17% 34% 27% 15%	730
July	1st to 10th	Day	7% 2 9% 26% 30% 25%	721
	11th to 20th	Day	7% 2 9% 27% 36% 19%	718
	21st to end	Day	8% 3 8% 27% 34% 21%	794
August	1st to 10th	Day	7% 2 8% 27% 38% 17%	526
	11th to 20th	Day	12% 3 9% 25% 34% 17%	519
	21st to end	Day	10% 1 7% 22% 37% 23%	583
September	1st to 10th	Day	11% 3 8% 28% 32% 18%	530
	11th to 20th	Day	13% 1 8% 20% 37% 21%	530
	21st to end	Day	18% 4 14% 28% 24% 11%	530
October	1st to 10th	Day	9% 2 18% 31% 33% 7%	472
	11th to 20th	Day	13% 9% 31% 25% 16% 6%	330
	21st to end	Day	24% 10% 29% 22% 14% 2	363
November	1st to 10th	Day	15% 10% 29% 31% 12% 4	330
	11th to 20th	Day	11% 12% 36% 28% 12% 1	330
	21st to end	Day	21% 12% 30% 23% 12% 2	330
December	1st to 10th	Day	22% 14% 34% 21% 8% 1	330
	11th to 20th	Day	21% 13% 31% 24% 10% 1	321
	21st to end	Day	25% 17% 32% 20% 5% 1	330
January	1st to 10th	Night	23% 11% 34% 27% 5%	1000
	11th to 20th	Night	25% 11% 36% 23% 4	1000
	21st to end	Night	21% 9% 40% 27% 3	1100
February	1st to 10th	Night	26% 9% 36% 26% 4	829
	11th to 20th	Night	23% 13% 38% 24% 2	783
	21st to end	Night	24% 13% 38% 23% 2	660
March	1st to 10th	Night	22% 11% 31% 31% 5%	800
	11th to 20th	Night	21% 10% 36% 26% 6%	690
	21st to end	Night	18% 10% 33% 30% 9%	660
April	1st to 10th	Night	15% 11% 37% 28% 9%	600
	11th to 20th	Night	17% 10% 29% 32% 10% 2	593
	21st to end	Night	14% 6% 33% 34% 13% 1	600
May	1st to 10th	Night	17% 6% 28% 37% 12% 1	600
	11th to 20th	Night	14% 4 21% 39% 21% 2	591
	21st to end	Night	9% 3 17% 41% 26% 4	650
June	1st to 10th	Night	11% 2 11% 42% 30% 4	600
	11th to 20th	Night	6% 1 10% 45% 35% 3	600
	21st to end	Night	4 1 9% 42% 39% 5%	600
July	1st to 10th	Night	6% 2 5% 32% 46% 9%	585
	11th to 20th	Night	6% 1 8% 30% 47% 9%	582
	21st to end	Night	6% 2 8% 31% 44% 9%	657
August	1st to 10th	Night	4 1 5% 36% 46% 7%	597
	11th to 20th	Night	6% 2 4 41% 42% 5%	594
	21st to end	Night	8% 1 5% 30% 46% 10%	660
September	1st to 10th	Night	10% 2 7% 35% 42% 6%	600
	11th to 20th	Night	10% 2 8% 35% 38% 7%	682
	21st to end	Night	11% 5% 15% 36% 29% 5%	800
October	1st to 10th	Night	9% 3 14% 38% 31% 4	800
	11th to 20th	Night	14% 4 25% 35% 20% 1	800
	21st to end	Night	21% 5% 28% 33% 12% 1	880
November	1st to 10th	Night	14% 5% 26% 40% 13% 1	820
	11th to 20th	Night	14% 8% 34% 34% 10%	840
	21st to end	Night	19% 9% 28% 33% 10% 1	840
December	1st to 10th	Night	22% 8% 31% 30% 7%	861
	11th to 20th	Night	22% 7% 30% 33% 7%	1036
	21st to end	Night	25% 11% 32% 27% 5%	1100

Page generated at 2025-12-15 00:13:55. Version ac07

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