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 2024-12-02.

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	7% 5% 2 5% 3 3 4 3 5% 7% 55%	105583
	Night	7% 5% 2 5% 3 3 3 3 5% 7% 56%	102648
Transparency	Day	28% 5% 11% 27% 22% 6%	105340
	Night	28% 5% 11% 25% 24% 7%	102482
Seeing	Day	10% 8% 31% 32% 16% 3	15702
	Night	10% 9% 35% 36% 10% 1	25644

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	7% 9% 3 6% 3 4 4 4 6% 7% 48%	2538
	11th to 20th	Day	6% 9% 3 7% 4 4 4 4 6% 7% 46%	2790
	21st to end	Day	7% 9% 3 7% 3 3 3 3 4 6% 53%	3135
February	1st to 10th	Day	7% 10% 3 8% 4 3 3 3 4 7% 48%	1843
	11th to 20th	Day	5% 6% 2 6% 5% 4 4 4 5% 6% 52%	1849
	21st to end	Day	6% 6% 1 5% 4 3 4 3 5% 5% 57%	1570
March	1st to 10th	Day	8% 6% 2 3 3 2 3 2 4 7% 59%	3130
	11th to 20th	Day	8% 6% 2 4 4 3 3 3 3 6% 58%	3480
	21st to end	Day	9% 7% 2 4 4 4 5% 4 5% 7% 51%	3814
April	1st to 10th	Day	8% 5% 2 4 3 3 4 3 6% 6% 56%	2241
	11th to 20th	Day	9% 7% 2 6% 4 3 4 4 6% 6% 48%	2280
	21st to end	Day	13% 6% 2 5% 4 4 4 4 5% 6% 47%	2470
May	1st to 10th	Day	11% 6% 2 5% 4 4 4 3 5% 7% 48%	4120
	11th to 20th	Day	9% 5% 2 6% 4 3 5% 4 6% 9% 47%	4082
	21st to end	Day	10% 4 2 5% 4 4 5% 3 6% 7% 49%	4489
June	1st to 10th	Day	4 4 1 3 3 4 3 3 6% 8% 61%	2470
	11th to 20th	Day	6% 4 2 4 3 3 4 4 7% 7% 57%	2650
	21st to end	Day	4 4 1 4 3 3 4 3 6% 8% 59%	2660
July	1st to 10th	Day	6% 4 2 5% 4 5% 5% 3 6% 8% 52%	4430
	11th to 20th	Day	4 2 1 3 3 4 4 4 7% 10% 58%	4275
	21st to end	Day	4 3 1 3 3 4 5% 5% 7% 10% 57%	4466
August	1st to 10th	Day	12% 6% 2 5% 3 3 3 3 6% 7% 50%	4103
	11th to 20th	Day	7% 4 1 4 3 4 4 4 7% 8% 52%	4009
	21st to end	Day	4 3 1 3 3 3 4 4 6% 7% 62%	4180
September	1st to 10th	Day	9% 4 2 5% 2 2 3 2 4 5% 61%	2190
	11th to 20th	Day	7% 6% 1 5% 2 3 3 3 5% 6% 59%	2090
	21st to end	Day	7% 3 2 3 3 3 4 4 4 6% 61%	2090
October	1st to 10th	Day	9% 3 1 2 2 2 2 2 3 5% 70%	3480
	11th to 20th	Day	5% 3 1 3 2 3 3 3 5% 6% 66%	3214
	21st to end	Day	7% 4 1 3 2 2 2 2 4 6% 66%	3166
November	1st to 10th	Day	7% 3 2 4 3 3 3 2 5% 7% 62%	1763
	11th to 20th	Day	6% 5% 2 3 3 3 3 3 4 6% 65%	1800
	21st to end	Day	10% 5% 2 3 3 2 2 2 4 5% 62%	1800
December	1st to 10th	Day	5% 6% 3 4 4 4 3 3 5% 6% 57%	1719
	11th to 20th	Day	6% 8% 3 6% 3 3 2 3 4 6% 57%	2161
	21st to end	Day	9% 15% 5% 9% 4 4 4 3 4 6% 39%	3036
January	1st to 10th	Night	5% 8% 4 12% 5% 3 3 2 4 5% 48%	4417
	11th to 20th	Night	5% 5% 2 6% 4 4 4 3 5% 7% 55%	4170
	21st to end	Night	8% 9% 3 7% 3 3 3 3 4 5% 52%	4532
February	1st to 10th	Night	8% 8% 3 9% 4 4 3 3 4 6% 48%	2353
	11th to 20th	Night	5% 5% 2 7% 5% 4 5% 3 5% 7% 50%	2218
	21st to end	Night	5% 6% 2 6% 4 3 3 3 4 5% 58%	1884
March	1st to 10th	Night	8% 5% 1 3 2 3 3 2 5% 7% 61%	3719
	11th to 20th	Night	6% 4 2 4 3 3 3 3 6% 7% 58%	3480
	21st to end	Night	9% 7% 2 5% 4 3 4 3 5% 7% 52%	3817
April	1st to 10th	Night	8% 6% 1 5% 3 3 4 3 5% 8% 54%	1935
	11th to 20th	Night	11% 6% 2 5% 4 3 3 4 5% 7% 51%	1846
	21st to end	Night	12% 5% 2 5% 3 3 3 3 6% 7% 51%	1710
May	1st to 10th	Night	12% 6% 2 6% 4 4 4 3 5% 7% 47%	2850
	11th to 20th	Night	10% 5% 2 5% 3 4 4 4 5% 7% 50%	2823
	21st to end	Night	9% 5% 1 5% 4 4 5% 4 7% 10% 47%	3098
June	1st to 10th	Night	4 3 1 4 3 3 4 4 8% 11% 55%	1710
	11th to 20th	Night	6% 3 2 3 4 3 4 4 7% 9% 54%	1524
	21st to end	Night	5% 3 1 5% 4 4 4 4 6% 8% 56%	1520
July	1st to 10th	Night	7% 4 2 5% 4 5% 4 5% 6% 8% 50%	2540
	11th to 20th	Night	4 3 1 5% 4 4 5% 4 8% 11% 50%	2690
	21st to end	Night	3 3 1 3 3 4 4 4 7% 11% 57%	3097
August	1st to 10th	Night	8% 3 2 5% 4 4 4 4 8% 10% 48%	2836
	11th to 20th	Night	8% 5% 2 6% 3 3 4 4 6% 9% 51%	2825
	21st to end	Night	3 3 1 4 3 4 5% 4 7% 11% 55%	3487
September	1st to 10th	Night	6% 4 1 5% 3 2 2 4 4 6% 63%	1988
	11th to 20th	Night	8% 3 1 4 2 3 4 3 5% 7% 61%	2090
	21st to end	Night	7% 4 1 4 3 2 3 3 5% 5% 63%	2090
October	1st to 10th	Night	6% 3 1 2 1 2 2 2 4 5% 73%	3480
	11th to 20th	Night	5% 3 1 3 2 2 2 3 4 6% 69%	3671
	21st to end	Night	5% 3 1 3 2 2 2 2 4 6% 69%	4373
November	1st to 10th	Night	6% 3 2 3 3 2 3 3 5% 6% 65%	2535
	11th to 20th	Night	6% 4 1 3 3 3 3 2 4 5% 67%	2600
	21st to end	Night	8% 5% 1 4 3 3 3 3 4 6% 59%	2600
December	1st to 10th	Night	5% 5% 2 5% 4 3 3 3 4 8% 58%	2496
	11th to 20th	Night	7% 4 1 4 3 3 3 4 5% 6% 59%	3036
	21st to end	Night	9% 12% 4 6% 3 3 4 3 4 6% 46%	4608

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% 5% 12% 28% 19% 2	2539
	11th to 20th	Day	37% 6% 14% 22% 15% 5%	2790
	21st to end	Day	33% 5% 14% 30% 16% 3	3135
February	1st to 10th	Day	38% 3 13% 25% 16% 5%	1843
	11th to 20th	Day	32% 5% 13% 26% 17% 7%	1859
	21st to end	Day	29% 4 9% 24% 25% 10%	1570
March	1st to 10th	Day	26% 4 8% 18% 31% 12%	3130
	11th to 20th	Day	28% 4 10% 25% 28% 5%	3480
	21st to end	Day	32% 6% 16% 33% 11% 3	3814
April	1st to 10th	Day	29% 5% 10% 26% 23% 8%	2241
	11th to 20th	Day	35% 5% 10% 26% 18% 5%	2283
	21st to end	Day	35% 6% 10% 28% 18% 2	2470
May	1st to 10th	Day	33% 7% 11% 26% 12% 10%	4120
	11th to 20th	Day	32% 8% 14% 29% 16% 1	4086
	21st to end	Day	32% 8% 13% 22% 21% 4	4489
June	1st to 10th	Day	21% 7% 18% 35% 15% 4	2470
	11th to 20th	Day	25% 6% 12% 28% 22% 7%	2650
	21st to end	Day	22% 6% 9% 30% 25% 8%	2660
July	1st to 10th	Day	29% 6% 11% 24% 23% 7%	4361
	11th to 20th	Day	20% 7% 15% 26% 28% 5%	4201
	21st to end	Day	20% 7% 13% 27% 25% 8%	4325
August	1st to 10th	Day	32% 6% 13% 25% 21% 3	4090
	11th to 20th	Day	28% 7% 15% 25% 20% 4	4048
	21st to end	Day	21% 6% 14% 28% 24% 8%	4179
September	1st to 10th	Day	27% 4 7% 27% 23% 12%	2190
	11th to 20th	Day	26% 4 9% 27% 28% 6%	2090
	21st to end	Day	24% 4 9% 29% 25% 8%	2090
October	1st to 10th	Day	19% 3 5% 20% 40% 13%	3480
	11th to 20th	Day	20% 4 10% 33% 23% 11%	3214
	21st to end	Day	22% 2 6% 27% 34% 9%	3166
November	1st to 10th	Day	24% 3 8% 27% 28% 9%	1763
	11th to 20th	Day	23% 3 8% 29% 32% 7%	1800
	21st to end	Day	27% 2 8% 26% 29% 8%	1800
December	1st to 10th	Day	29% 4 12% 29% 22% 4	1719
	11th to 20th	Day	29% 2 10% 36% 20% 2	2159
	21st to end	Day	47% 4 9% 21% 17% 3	3036
January	1st to 10th	Night	39% 4 11% 26% 17% 3	4417
	11th to 20th	Night	29% 5% 14% 26% 21% 6%	4170
	21st to end	Night	35% 4 12% 25% 21% 2	4532
February	1st to 10th	Night	38% 4 12% 22% 17% 7%	2353
	11th to 20th	Night	33% 6% 10% 25% 21% 5%	2218
	21st to end	Night	30% 3 8% 22% 25% 13%	1884
March	1st to 10th	Night	24% 4 8% 22% 30% 13%	3719
	11th to 20th	Night	24% 6% 10% 24% 29% 7%	3480
	21st to end	Night	32% 5% 14% 35% 11% 3	3817
April	1st to 10th	Night	29% 5% 11% 22% 27% 7%	1935
	11th to 20th	Night	33% 5% 13% 24% 20% 6%	1846
	21st to end	Night	32% 6% 11% 27% 22% 3	1710
May	1st to 10th	Night	34% 6% 13% 21% 16% 10%	2850
	11th to 20th	Night	31% 8% 14% 26% 20% 1	2824
	21st to end	Night	30% 8% 18% 22% 16% 6%	3099
June	1st to 10th	Night	21% 7% 18% 32% 19% 4	1710
	11th to 20th	Night	25% 7% 14% 27% 22% 5%	1524
	21st to end	Night	24% 8% 11% 27% 23% 8%	1520
July	1st to 10th	Night	30% 7% 14% 18% 27% 4	2500
	11th to 20th	Night	25% 6% 15% 25% 24% 5%	2642
	21st to end	Night	21% 5% 15% 25% 24% 10%	2999
August	1st to 10th	Night	30% 6% 13% 26% 22% 3	2826
	11th to 20th	Night	31% 7% 15% 26% 18% 3	2852
	21st to end	Night	22% 5% 15% 29% 21% 8%	3487
September	1st to 10th	Night	23% 5% 9% 24% 27% 11%	1988
	11th to 20th	Night	24% 4 9% 24% 30% 9%	2090
	21st to end	Night	24% 4 8% 23% 29% 11%	2090
October	1st to 10th	Night	16% 3 6% 18% 45% 12%	3480
	11th to 20th	Night	17% 3 11% 23% 32% 13%	3671
	21st to end	Night	19% 3 7% 25% 36% 10%	4373
November	1st to 10th	Night	21% 3 9% 27% 27% 12%	2535
	11th to 20th	Night	21% 2 8% 28% 31% 10%	2600
	21st to end	Night	27% 3 8% 27% 24% 11%	2600
December	1st to 10th	Night	26% 4 12% 29% 22% 6%	2496
	11th to 20th	Night	26% 3 9% 36% 22% 4	3037
	21st to end	Night	40% 4 10% 27% 15% 3	4608

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	9% 9% 40% 32% 8% 3	270
	11th to 20th	Day	15% 11% 37% 29% 8%	270
	21st to end	Day	8% 10% 41% 33% 7%	297
February	1st to 10th	Day	16% 13% 41% 21% 8%	270
	11th to 20th	Day	11% 10% 44% 24% 7% 3	270
	21st to end	Day	8% 16% 51% 21% 4	225
March	1st to 10th	Day	11% 12% 41% 28% 8%	270
	11th to 20th	Day	17% 14% 33% 24% 11% 1	270
	21st to end	Day	16% 16% 40% 22% 5% 1	297
April	1st to 10th	Day	13% 17% 43% 21% 5% 1	421
	11th to 20th	Day	13% 19% 40% 23% 5%	481
	21st to end	Day	17% 16% 37% 20% 8% 1	650
May	1st to 10th	Day	14% 11% 33% 31% 11% 1	653
	11th to 20th	Day	15% 8% 31% 29% 14% 3	675
	21st to end	Day	14% 9% 33% 31% 11% 2	734
June	1st to 10th	Day	4 4 29% 36% 19% 7%	680
	11th to 20th	Day	6% 5% 34% 36% 17% 2	680
	21st to end	Day	6% 5% 30% 39% 18% 1	680
July	1st to 10th	Day	7% 4 20% 40% 24% 7%	671
	11th to 20th	Day	4 2 16% 47% 27% 4	668
	21st to end	Day	6% 2 15% 39% 31% 6%	739
August	1st to 10th	Day	9% 1 15% 41% 28% 5%	676
	11th to 20th	Day	7% 2 21% 41% 27% 2	646
	21st to end	Day	6% 2 22% 40% 24% 6%	539
September	1st to 10th	Day	10% 3 21% 39% 24% 4	400
	11th to 20th	Day	5% 4 25% 40% 21% 6%	300
	21st to end	Day	10% 7% 26% 32% 19% 5%	300
October	1st to 10th	Day	17% 8% 19% 34% 16% 5%	300
	11th to 20th	Day	3 12% 40% 29% 14% 3	300
	21st to end	Day	15% 12% 31% 28% 12% 2	330
November	1st to 10th	Day	11% 11% 38% 25% 12% 2	300
	11th to 20th	Day	12% 10% 40% 25% 12% 1	300
	21st to end	Day	17% 9% 32% 27% 12% 3	300
December	1st to 10th	Day	8% 7% 40% 30% 12% 3	273
	11th to 20th	Day	12% 13% 38% 29% 8% 1	270
	21st to end	Day	16% 15% 40% 23% 6%	297
January	1st to 10th	Night	9% 8% 37% 39% 6% 1	950
	11th to 20th	Night	9% 9% 38% 33% 9% 1	950
	21st to end	Night	8% 9% 43% 33% 6%	1045
February	1st to 10th	Night	12% 9% 40% 32% 6%	833
	11th to 20th	Night	9% 11% 43% 32% 5%	744
	21st to end	Night	9% 12% 46% 27% 5% 1	628
March	1st to 10th	Night	10% 15% 36% 34% 4	758
	11th to 20th	Night	14% 8% 39% 31% 8% 1	570
	21st to end	Night	16% 16% 38% 27% 3	627
April	1st to 10th	Night	13% 16% 41% 27% 3	570
	11th to 20th	Night	15% 16% 38% 26% 4	563
	21st to end	Night	16% 14% 33% 30% 7%	570
May	1st to 10th	Night	13% 12% 39% 30% 6%	570
	11th to 20th	Night	14% 9% 34% 33% 9% 1	561
	21st to end	Night	11% 11% 39% 29% 9%	617
June	1st to 10th	Night	5% 7% 37% 36% 14% 1	570
	11th to 20th	Night	8% 6% 45% 33% 8%	570
	21st to end	Night	5% 6% 36% 42% 10%	570
July	1st to 10th	Night	6% 3 27% 46% 17% 1	555
	11th to 20th	Night	4 1 24% 51% 20% 1	552
	21st to end	Night	7% 2 18% 47% 24% 1	624
August	1st to 10th	Night	7% 2 19% 52% 20% 1	567
	11th to 20th	Night	8% 3 23% 50% 15% 1	564
	21st to end	Night	5% 1 26% 47% 20% 2	627
September	1st to 10th	Night	6% 2 29% 46% 14% 2	570
	11th to 20th	Night	11% 2 36% 36% 15% 1	570
	21st to end	Night	10% 4 31% 39% 15% 1	570
October	1st to 10th	Night	12% 8% 31% 36% 12%	570
	11th to 20th	Night	10% 8% 37% 34% 10%	691
	21st to end	Night	11% 11% 32% 32% 13% 1	988
November	1st to 10th	Night	9% 9% 33% 40% 9%	975
	11th to 20th	Night	8% 11% 39% 34% 7%	1000
	21st to end	Night	11% 9% 32% 36% 11% 1	1000
December	1st to 10th	Night	9% 9% 35% 39% 7%	960
	11th to 20th	Night	12% 10% 36% 35% 7%	950
	21st to end	Night	13% 10% 36% 36% 6%	1045

Page generated at 2024-11-29 09:43:04. Version ac07

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