Cedar Bluff State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cedar Bluff State Park clear sky chart from 2005-11-06 to 2026-03-03.

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	8% 5% 2 5% 3 3 4 3 5% 7% 56%	140181
	Night	7% 5% 2 5% 3 3 3 3 5% 7% 55%	138295
Transparency	Day	28% 5% 11% 27% 23% 7%	135022
	Night	28% 4 11% 26% 24% 8%	134465
Seeing	Day	10% 8% 31% 32% 15% 3	17349
	Night	10% 9% 35% 36% 9% 1	27414

By Month

Percentage Cloud Cover SW (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	8% 8% 2 6% 3 3 4 3 5% 6% 51%	4720
	11th to 20th	Day	3 7% 2 8% 4 4 4 3 5% 6% 53%	5211
	21st to end	Day	6% 8% 3 7% 4 3 3 2 4 5% 55%	5812
February	1st to 10th	Day	6% 9% 3 7% 4 3 3 3 4 7% 50%	2037
	11th to 20th	Day	5% 6% 2 7% 5% 5% 5% 4 5% 6% 50%	2049
	21st to end	Day	6% 5% 1 4 4 3 4 3 5% 5% 59%	1730
March	1st to 10th	Day	7% 6% 2 5% 3 3 3 2 4 6% 60%	4520
	11th to 20th	Day	6% 6% 2 4 3 3 3 3 4 6% 60%	4980
	21st to end	Day	7% 5% 2 4 3 4 4 4 5% 7% 55%	5464
April	1st to 10th	Day	8% 5% 2 4 3 3 4 3 6% 6% 56%	2359
	11th to 20th	Day	9% 7% 2 6% 4 3 4 4 6% 6% 49%	2402
	21st to end	Day	14% 6% 2 5% 4 4 4 4 5% 6% 47%	2600
May	1st to 10th	Day	12% 5% 2 5% 4 4 4 3 5% 6% 51%	5900
	11th to 20th	Day	7% 4 2 4 3 3 4 3 5% 7% 58%	5862
	21st to end	Day	17% 5% 2 5% 4 3 4 3 5% 6% 45%	6446
June	1st to 10th	Day	5% 4 1 3 3 4 3 3 6% 8% 60%	2600
	11th to 20th	Day	6% 4 2 4 3 3 4 4 6% 7% 58%	2790
	21st to end	Day	4 4 1 4 3 3 4 3 6% 8% 59%	2800
July	1st to 10th	Day	5% 4 2 5% 4 4 4 3 6% 9% 53%	6339
	11th to 20th	Day	5% 3 1 4 3 3 4 4 6% 9% 58%	6120
	21st to end	Day	5% 3 1 4 3 4 4 4 6% 9% 56%	6424
August	1st to 10th	Day	11% 5% 2 5% 3 3 3 4 6% 7% 50%	5801
	11th to 20th	Day	6% 3 1 4 3 4 4 4 7% 10% 54%	5775
	21st to end	Day	14% 5% 2 5% 3 3 4 3 5% 6% 50%	5984
September	1st to 10th	Day	9% 5% 2 5% 2 3 3 2 5% 5% 60%	2305
	11th to 20th	Day	7% 6% 1 5% 2 3 3 3 5% 7% 59%	2200
	21st to end	Day	7% 3 2 4 3 3 4 4 4 6% 61%	2200
October	1st to 10th	Day	9% 2 1 2 2 2 2 2 3 5% 70%	3590
	11th to 20th	Day	5% 3 1 3 2 3 3 3 5% 6% 66%	3316
	21st to end	Day	7% 4 1 3 2 2 2 2 4 6% 65%	3268
November	1st to 10th	Day	6% 3 2 4 2 3 3 2 5% 6% 64%	1853
	11th to 20th	Day	6% 4 2 3 3 3 3 2 4 6% 65%	1890
	21st to end	Day	10% 5% 2 3 3 3 2 2 4 6% 61%	1890
December	1st to 10th	Day	4 4 2 3 2 2 3 2 4 4 69%	3030
	11th to 20th	Day	4 5% 2 4 2 2 2 2 4 5% 66%	3481
	21st to end	Day	9% 13% 4 8% 3 3 4 3 5% 6% 42%	4433
January	1st to 10th	Night	7% 8% 3 9% 4 4 3 3 4 6% 49%	8201
	11th to 20th	Night	3 5% 2 5% 4 4 4 3 4 6% 60%	7756
	21st to end	Night	6% 8% 3 8% 4 3 3 3 4 5% 52%	8402
February	1st to 10th	Night	7% 7% 3 9% 4 4 3 3 4 6% 50%	2600
	11th to 20th	Night	6% 6% 2 7% 5% 4 4 3 5% 7% 49%	2458
	21st to end	Night	5% 5% 2 6% 4 3 3 3 4 5% 59%	2076
March	1st to 10th	Night	6% 5% 2 3 2 3 3 2 4 6% 64%	5383
	11th to 20th	Night	6% 4 1 4 3 3 3 4 6% 6% 60%	4980
	21st to end	Night	8% 7% 2 5% 4 4 4 4 6% 7% 48%	5467
April	1st to 10th	Night	8% 6% 2 5% 3 4 4 3 5% 8% 53%	2037
	11th to 20th	Night	11% 6% 2 5% 4 3 3 4 5% 7% 51%	1944
	21st to end	Night	13% 5% 2 5% 3 3 3 3 6% 7% 51%	1800
May	1st to 10th	Night	12% 5% 2 6% 4 4 4 3 6% 7% 48%	4080
	11th to 20th	Night	7% 4 1 4 3 3 3 3 5% 6% 59%	4053
	21st to end	Night	17% 6% 2 5% 3 3 4 3 6% 8% 44%	4451
June	1st to 10th	Night	4 3 1 4 3 3 4 4 8% 11% 56%	1800
	11th to 20th	Night	6% 3 2 3 4 3 3 4 7% 9% 55%	1604
	21st to end	Night	5% 3 2 5% 4 4 4 4 6% 9% 55%	1600
July	1st to 10th	Night	6% 4 2 5% 4 4 5% 5% 7% 9% 51%	3640
	11th to 20th	Night	7% 4 2 6% 5% 4 6% 5% 7% 10% 45%	3855
	21st to end	Night	5% 4 1 4 4 4 4 3 6% 10% 55%	4449
August	1st to 10th	Night	8% 4 2 6% 4 5% 4 4 7% 11% 46%	4011
	11th to 20th	Night	6% 4 2 5% 3 4 4 4 6% 10% 51%	4069
	21st to end	Night	11% 6% 2 6% 3 4 5% 4 6% 9% 45%	4993
September	1st to 10th	Night	6% 4 1 5% 2 2 2 4 4 6% 63%	2093
	11th to 20th	Night	8% 3 1 4 2 3 4 3 5% 7% 60%	2200
	21st to end	Night	8% 4 1 4 3 2 3 3 5% 5% 62%	2200
October	1st to 10th	Night	6% 3 1 2 1 2 2 2 4 5% 72%	3590
	11th to 20th	Night	5% 3 1 3 2 3 2 3 4 6% 69%	3788
	21st to end	Night	6% 3 1 3 2 2 2 2 4 6% 68%	4513
November	1st to 10th	Night	6% 3 2 3 3 2 3 3 5% 6% 65%	2665
	11th to 20th	Night	6% 4 1 3 3 2 3 2 4 5% 67%	2730
	21st to end	Night	9% 5% 1 4 3 3 3 3 4 6% 58%	2730
December	1st to 10th	Night	4 4 2 4 3 2 3 2 3 6% 67%	4380
	11th to 20th	Night	4 4 1 4 3 3 3 3 4 6% 64%	4946
	21st to end	Night	9% 12% 4 6% 3 3 4 3 4 6% 46%	6751

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	34% 3 10% 27% 23% 4	4723
	11th to 20th	Day	31% 5% 9% 26% 22% 7%	5211
	21st to end	Day	33% 4 10% 24% 24% 5%	5812
February	1st to 10th	Day	36% 3 12% 26% 17% 6%	2037
	11th to 20th	Day	34% 5% 14% 25% 16% 7%	2059
	21st to end	Day	26% 4 9% 24% 26% 11%	1730
March	1st to 10th	Day	27% 3 6% 17% 30% 16%	4520
	11th to 20th	Day	26% 4 7% 19% 29% 16%	4980
	21st to end	Day	28% 5% 15% 38% 12% 2	5464
April	1st to 10th	Day	29% 4 9% 26% 23% 8%	2359
	11th to 20th	Day	35% 5% 10% 26% 19% 5%	2405
	21st to end	Day	36% 6% 10% 28% 18% 3	2600
May	1st to 10th	Day	33% 6% 12% 26% 17% 7%	5900
	11th to 20th	Day	25% 6% 11% 23% 23% 12%	5866
	21st to end	Day	38% 6% 11% 21% 21% 3	6447
June	1st to 10th	Day	22% 7% 18% 34% 16% 4	2600
	11th to 20th	Day	25% 6% 12% 28% 23% 7%	2790
	21st to end	Day	23% 6% 9% 29% 25% 8%	2800
July	1st to 10th	Day	26% 6% 11% 26% 25% 6%	6271
	11th to 20th	Day	22% 6% 16% 26% 26% 4	6046
	21st to end	Day	24% 6% 11% 31% 22% 6%	6240
August	1st to 10th	Day	32% 6% 13% 25% 21% 3	4220
	11th to 20th	Day	28% 7% 15% 25% 20% 5%	4177
	21st to end	Day	22% 6% 14% 28% 23% 8%	4311
September	1st to 10th	Day	27% 4 7% 28% 22% 11%	2305
	11th to 20th	Day	26% 4 9% 28% 28% 6%	2200
	21st to end	Day	24% 4 9% 29% 26% 8%	2200
October	1st to 10th	Day	19% 3 5% 20% 40% 12%	3590
	11th to 20th	Day	20% 4 10% 32% 24% 10%	3316
	21st to end	Day	22% 2 6% 26% 34% 9%	3268
November	1st to 10th	Day	23% 3 8% 29% 29% 9%	1853
	11th to 20th	Day	22% 3 8% 29% 31% 7%	1890
	21st to end	Day	28% 2 9% 26% 28% 7%	1890
December	1st to 10th	Day	20% 2 10% 36% 24% 8%	3030
	11th to 20th	Day	22% 2 9% 41% 25% 2	3479
	21st to end	Day	44% 3 8% 23% 18% 4	4433
January	1st to 10th	Night	37% 3 11% 24% 21% 4	8202
	11th to 20th	Night	26% 4 10% 26% 26% 9%	7756
	21st to end	Night	35% 4 10% 22% 21% 8%	8402
February	1st to 10th	Night	37% 3 11% 23% 18% 7%	2600
	11th to 20th	Night	34% 6% 10% 25% 20% 5%	2458
	21st to end	Night	28% 3 8% 22% 27% 13%	2076
March	1st to 10th	Night	23% 3 6% 20% 31% 17%	5383
	11th to 20th	Night	23% 5% 8% 18% 28% 19%	4980
	21st to end	Night	34% 5% 13% 35% 11% 2	5467
April	1st to 10th	Night	29% 5% 11% 22% 26% 6%	2037
	11th to 20th	Night	33% 5% 13% 24% 20% 6%	1944
	21st to end	Night	33% 6% 11% 26% 21% 3	1800
May	1st to 10th	Night	35% 6% 13% 24% 16% 7%	4080
	11th to 20th	Night	24% 6% 11% 27% 22% 10%	4054
	21st to end	Night	37% 7% 15% 20% 16% 5%	4452
June	1st to 10th	Night	21% 6% 18% 31% 19% 5%	1800
	11th to 20th	Night	24% 7% 14% 28% 23% 5%	1604
	21st to end	Night	24% 8% 11% 27% 23% 7%	1600
July	1st to 10th	Night	28% 7% 17% 21% 25% 3	3600
	11th to 20th	Night	32% 6% 14% 23% 22% 4	3807
	21st to end	Night	24% 5% 14% 29% 21% 7%	4320
August	1st to 10th	Night	30% 6% 13% 26% 22% 3	2916
	11th to 20th	Night	31% 7% 15% 26% 18% 3	2943
	21st to end	Night	24% 5% 15% 28% 21% 7%	3597
September	1st to 10th	Night	23% 5% 10% 25% 26% 11%	2093
	11th to 20th	Night	24% 5% 9% 25% 29% 9%	2200
	21st to end	Night	25% 4 7% 24% 29% 11%	2200
October	1st to 10th	Night	17% 3 6% 18% 45% 12%	3590
	11th to 20th	Night	18% 3 11% 23% 32% 13%	3788
	21st to end	Night	19% 3 7% 25% 36% 10%	4513
November	1st to 10th	Night	21% 3 9% 28% 28% 12%	2665
	11th to 20th	Night	21% 2 8% 29% 31% 9%	2730
	21st to end	Night	28% 4 8% 27% 23% 10%	2730
December	1st to 10th	Night	22% 3 10% 37% 24% 5%	4380
	11th to 20th	Night	22% 3 7% 35% 27% 6%	4947
	21st to end	Night	40% 4 9% 29% 16% 3	6751

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	11% 8% 38% 32% 9% 2	330
	11th to 20th	Day	13% 12% 38% 29% 8%	330
	21st to end	Day	8% 10% 43% 31% 8%	363
February	1st to 10th	Day	13% 14% 42% 23% 7%	330
	11th to 20th	Day	13% 12% 43% 23% 7% 2	330
	21st to end	Day	7% 15% 52% 23% 3	273
March	1st to 10th	Day	12% 13% 40% 26% 8%	306
	11th to 20th	Day	18% 15% 34% 22% 10% 1	300
	21st to end	Day	16% 16% 41% 22% 5% 1	330
April	1st to 10th	Day	14% 18% 41% 20% 6% 1	459
	11th to 20th	Day	12% 20% 40% 23% 5%	523
	21st to end	Day	18% 16% 37% 21% 7% 1	700
May	1st to 10th	Day	14% 11% 32% 31% 12% 1	703
	11th to 20th	Day	15% 9% 31% 29% 14% 3	725
	21st to end	Day	15% 10% 32% 30% 11% 2	789
June	1st to 10th	Day	6% 5% 29% 35% 18% 7%	730
	11th to 20th	Day	6% 5% 33% 36% 17% 2	730
	21st to end	Day	6% 6% 31% 38% 18% 1	730
July	1st to 10th	Day	7% 3 20% 40% 23% 6%	721
	11th to 20th	Day	4 2 17% 46% 27% 4	718
	21st to end	Day	6% 2 15% 40% 30% 6%	794
August	1st to 10th	Day	9% 2 16% 41% 27% 5%	726
	11th to 20th	Day	6% 2 21% 41% 27% 3	695
	21st to end	Day	8% 2 21% 40% 23% 6%	583
September	1st to 10th	Day	9% 3 21% 39% 24% 3	435
	11th to 20th	Day	4 5% 25% 39% 21% 6%	330
	21st to end	Day	10% 7% 26% 33% 19% 5%	330
October	1st to 10th	Day	17% 8% 21% 33% 15% 5%	330
	11th to 20th	Day	4 13% 41% 27% 13% 2	330
	21st to end	Day	15% 13% 33% 26% 11% 2	363
November	1st to 10th	Day	11% 11% 39% 26% 12% 2	330
	11th to 20th	Day	12% 9% 40% 25% 13% 1	330
	21st to end	Day	18% 9% 31% 27% 11% 2	330
December	1st to 10th	Day	8% 8% 41% 28% 11% 3	330
	11th to 20th	Day	11% 12% 42% 26% 8% 1	330
	21st to end	Day	15% 13% 38% 28% 6% 1	363
January	1st to 10th	Night	10% 8% 37% 39% 6% 1	1050
	11th to 20th	Night	9% 10% 38% 33% 8% 1	1050
	21st to end	Night	8% 9% 44% 33% 6%	1155
February	1st to 10th	Night	11% 9% 42% 32% 6%	920
	11th to 20th	Night	10% 12% 43% 31% 4	824
	21st to end	Night	9% 11% 46% 28% 5% 1	692
March	1st to 10th	Night	11% 15% 35% 34% 4	806
	11th to 20th	Night	14% 9% 39% 31% 7% 1	600
	21st to end	Night	16% 16% 38% 27% 3	660
April	1st to 10th	Night	13% 16% 41% 27% 3	600
	11th to 20th	Night	15% 17% 39% 25% 4	593
	21st to end	Night	16% 15% 33% 29% 7%	600
May	1st to 10th	Night	13% 12% 38% 31% 7%	600
	11th to 20th	Night	13% 9% 34% 33% 9% 1	591
	21st to end	Night	13% 10% 39% 29% 8%	650
June	1st to 10th	Night	6% 7% 38% 36% 13% 1	600
	11th to 20th	Night	8% 6% 44% 34% 8%	600
	21st to end	Night	5% 7% 37% 41% 10%	600
July	1st to 10th	Night	6% 3 28% 46% 16% 1	585
	11th to 20th	Night	4 1 24% 51% 20% 1	582
	21st to end	Night	7% 2 18% 48% 24% 1	657
August	1st to 10th	Night	6% 2 20% 51% 20% 1	597
	11th to 20th	Night	8% 3 24% 50% 15% 1	594
	21st to end	Night	6% 2 25% 46% 19% 2	660
September	1st to 10th	Night	7% 2 29% 47% 14% 2	600
	11th to 20th	Night	11% 2 36% 36% 15% 1	600
	21st to end	Night	11% 4 31% 39% 15% 1	600
October	1st to 10th	Night	13% 8% 31% 36% 12%	600
	11th to 20th	Night	10% 9% 38% 33% 10%	728
	21st to end	Night	12% 11% 32% 32% 12% 1	1040
November	1st to 10th	Night	8% 9% 35% 40% 8%	1025
	11th to 20th	Night	8% 10% 39% 35% 7%	1050
	21st to end	Night	12% 9% 32% 36% 10% 1	1050
December	1st to 10th	Night	10% 9% 36% 39% 7%	1050
	11th to 20th	Night	11% 10% 39% 34% 6%	1050
	21st to end	Night	13% 9% 35% 36% 7%	1155

Page generated at 2026-02-28 00:40:26. Version ac07

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