Staunton River State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Staunton River State Park clear sky chart from 2005-11-06 to 2026-01-17.

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	13% 6% 2 6% 4 4 4 4 6% 8% 43%	126696
	Night	13% 6% 2 6% 4 4 4 4 5% 7% 45%	124999
Transparency	Day	37% 6% 12% 22% 18% 5%	130301
	Night	38% 6% 10% 21% 20% 6%	129463
Seeing	Day	17% 11% 26% 25% 16% 6%	16736
	Night	16% 10% 27% 30% 15% 2	26846

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% 6% 2 4 3 2 3 2 3 4 56%	4146
	11th to 20th	Day	12% 7% 2 4 3 2 2 2 3 5% 57%	4114
	21st to end	Day	15% 7% 2 6% 4 4 4 3 3 5% 47%	4466
February	1st to 10th	Day	13% 6% 2 6% 5% 5% 4 5% 5% 8% 42%	1800
	11th to 20th	Day	22% 6% 1 4 4 4 4 3 5% 5% 43%	1762
	21st to end	Day	18% 6% 2 6% 4 4 4 4 5% 7% 40%	1765
March	1st to 10th	Day	17% 8% 2 6% 4 4 3 3 5% 7% 39%	4935
	11th to 20th	Day	11% 5% 2 5% 3 3 4 3 5% 7% 53%	4980
	21st to end	Day	16% 6% 2 6% 4 4 4 3 5% 6% 44%	5465
April	1st to 10th	Day	10% 5% 2 4 3 3 4 4 6% 7% 52%	2343
	11th to 20th	Day	10% 6% 2 6% 4 4 5% 3 4 7% 50%	2374
	21st to end	Day	14% 6% 2 6% 4 4 5% 4 5% 6% 45%	2400
May	1st to 10th	Day	10% 6% 2 7% 5% 5% 6% 5% 8% 11% 34%	5852
	11th to 20th	Day	19% 7% 3 8% 5% 5% 5% 4 7% 8% 29%	5861
	21st to end	Day	13% 5% 2 6% 4 5% 4 4 6% 9% 42%	6433
June	1st to 10th	Day	8% 5% 2 5% 4 5% 5% 5% 7% 10% 44%	2745
	11th to 20th	Day	8% 5% 2 6% 4 5% 4 4 8% 9% 45%	2800
	21st to end	Day	7% 4 2 5% 4 5% 6% 5% 7% 12% 42%	2643
July	1st to 10th	Day	7% 5% 2 7% 5% 6% 6% 5% 8% 11% 39%	5900
	11th to 20th	Day	9% 5% 2 6% 5% 6% 7% 6% 9% 14% 31%	5900
	21st to end	Day	8% 6% 2 6% 5% 5% 6% 5% 8% 11% 38%	6424
August	1st to 10th	Day	17% 8% 3 7% 5% 5% 5% 5% 7% 11% 27%	4234
	11th to 20th	Day	8% 7% 2 7% 5% 5% 5% 5% 7% 11% 37%	4052
	21st to end	Day	7% 4 2 5% 4 4 5% 4 6% 10% 51%	4312
September	1st to 10th	Day	10% 5% 2 5% 4 4 5% 4 6% 8% 47%	2400
	11th to 20th	Day	14% 6% 2 6% 5% 4 5% 3 5% 7% 42%	2293
	21st to end	Day	21% 7% 2 6% 4 4 4 4 5% 6% 37%	2142
October	1st to 10th	Day	15% 5% 3 5% 3 3 3 2 3 6% 52%	2000
	11th to 20th	Day	14% 4 2 4 3 3 3 2 4 5% 56%	2000
	21st to end	Day	12% 4 2 6% 3 4 3 3 3 6% 55%	2200
November	1st to 10th	Day	12% 5% 2 4 3 4 3 3 4 5% 55%	2057
	11th to 20th	Day	14% 5% 2 4 3 3 4 2 5% 6% 51%	2026
	21st to end	Day	14% 5% 2 4 3 4 3 4 6% 6% 50%	1680
December	1st to 10th	Day	13% 6% 2 4 3 3 4 3 4 6% 52%	2680
	11th to 20th	Day	18% 6% 2 5% 3 3 4 3 4 6% 48%	3070
	21st to end	Day	16% 5% 2 5% 4 3 4 4 6% 7% 43%	4442
January	1st to 10th	Night	12% 6% 2 5% 3 3 3 3 4 5% 54%	6019
	11th to 20th	Night	13% 6% 2 4 3 2 2 2 3 4 57%	5979
	21st to end	Night	16% 7% 2 5% 3 3 3 2 4 5% 50%	6490
February	1st to 10th	Night	17% 6% 2 5% 4 4 4 3 6% 5% 45%	2600
	11th to 20th	Night	20% 7% 2 5% 3 3 4 4 4 6% 42%	2523
	21st to end	Night	14% 8% 1 5% 4 4 3 3 5% 5% 47%	1860
March	1st to 10th	Night	16% 6% 2 6% 4 4 4 4 4 5% 44%	4918
	11th to 20th	Night	11% 4 2 4 3 3 3 3 5% 6% 55%	4980
	21st to end	Night	13% 5% 2 6% 4 3 4 3 5% 7% 48%	5467
April	1st to 10th	Night	13% 7% 2 6% 4 4 4 3 5% 6% 46%	2055
	11th to 20th	Night	10% 5% 2 4 4 4 4 3 5% 7% 50%	1975
	21st to end	Night	12% 5% 2 5% 5% 4 5% 4 5% 7% 47%	2000
May	1st to 10th	Night	13% 7% 3 9% 5% 5% 6% 4 6% 8% 34%	4086
	11th to 20th	Night	21% 9% 3 6% 4 4 4 3 6% 7% 33%	4032
	21st to end	Night	15% 5% 2 6% 4 3 4 4 5% 9% 42%	4421
June	1st to 10th	Night	10% 5% 2 5% 4 5% 4 3 7% 10% 44%	1645
	11th to 20th	Night	9% 5% 2 5% 6% 5% 5% 5% 7% 11% 41%	1600
	21st to end	Night	7% 4 2 5% 5% 6% 6% 5% 7% 11% 42%	1745
July	1st to 10th	Night	10% 6% 3 7% 5% 6% 6% 6% 8% 10% 34%	4058
	11th to 20th	Night	10% 7% 4 9% 7% 6% 7% 5% 8% 10% 26%	4057
	21st to end	Night	11% 7% 3 8% 6% 5% 6% 5% 9% 9% 32%	4427
August	1st to 10th	Night	17% 7% 3 8% 5% 5% 5% 5% 7% 10% 28%	2915
	11th to 20th	Night	7% 5% 3 7% 5% 5% 5% 5% 7% 11% 41%	2964
	21st to end	Night	8% 5% 2 5% 6% 5% 4 4 7% 10% 45%	3586
September	1st to 10th	Night	11% 7% 3 5% 4 4 4 3 6% 7% 46%	2000
	11th to 20th	Night	14% 6% 3 7% 4 4 4 4 6% 6% 43%	2103
	21st to end	Night	22% 8% 2 6% 4 4 4 4 5% 5% 37%	2256
October	1st to 10th	Night	15% 6% 1 6% 5% 3 4 3 5% 6% 47%	2400
	11th to 20th	Night	14% 6% 2 5% 3 3 3 2 3 6% 53%	2400
	21st to end	Night	13% 4 2 4 3 3 4 3 4 6% 54%	2640
November	1st to 10th	Night	12% 7% 2 5% 4 3 3 3 5% 5% 52%	2461
	11th to 20th	Night	13% 5% 2 4 3 3 3 4 5% 5% 51%	2584
	21st to end	Night	13% 4 2 5% 3 4 3 3 5% 6% 52%	2940
December	1st to 10th	Night	11% 5% 2 5% 4 4 3 3 4 5% 53%	4720
	11th to 20th	Night	18% 7% 3 7% 5% 5% 4 3 4 4 41%	5345
	21st to end	Night	15% 6% 2 5% 3 3 4 3 5% 7% 45%	6748

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% 2 5% 22% 28% 8%	4147
	11th to 20th	Day	31% 3 4 20% 31% 10%	4114
	21st to end	Day	41% 3 6% 25% 19% 4	4466
February	1st to 10th	Day	40% 5% 11% 22% 18% 4	1800
	11th to 20th	Day	44% 4 6% 21% 20% 5%	1771
	21st to end	Day	43% 6% 10% 16% 19% 6%	1765
March	1st to 10th	Day	44% 4 7% 19% 15% 11%	4935
	11th to 20th	Day	31% 5% 7% 20% 24% 12%	4980
	21st to end	Day	41% 5% 9% 20% 19% 6%	5465
April	1st to 10th	Day	30% 5% 12% 24% 21% 8%	2343
	11th to 20th	Day	34% 5% 11% 23% 21% 6%	2374
	21st to end	Day	39% 6% 12% 23% 16% 4	2400
May	1st to 10th	Day	41% 9% 17% 22% 11% 1	5887
	11th to 20th	Day	51% 7% 10% 20% 10% 1	5865
	21st to end	Day	37% 7% 14% 22% 17% 2	6447
June	1st to 10th	Day	33% 9% 15% 27% 15% 1	2745
	11th to 20th	Day	33% 9% 17% 24% 16% 2	2800
	21st to end	Day	32% 11% 17% 24% 15% 2	2643
July	1st to 10th	Day	37% 10% 17% 20% 13% 3	5835
	11th to 20th	Day	39% 13% 26% 17% 5% 1	5831
	21st to end	Day	38% 10% 16% 24% 12%	6240
August	1st to 10th	Day	49% 8% 17% 22% 5%	4221
	11th to 20th	Day	38% 9% 21% 21% 10% 1	4091
	21st to end	Day	28% 6% 17% 31% 16% 2	4312
September	1st to 10th	Day	34% 9% 15% 17% 21% 4	2400
	11th to 20th	Day	40% 6% 10% 21% 20% 3	2293
	21st to end	Day	47% 6% 10% 18% 16% 3	2142
October	1st to 10th	Day	34% 4 7% 20% 28% 7%	3260
	11th to 20th	Day	22% 3 5% 23% 30% 18%	3240
	21st to end	Day	24% 3 7% 26% 27% 13%	3538
November	1st to 10th	Day	32% 4 7% 24% 26% 6%	2057
	11th to 20th	Day	34% 4 10% 23% 22% 8%	2026
	21st to end	Day	34% 4 8% 24% 25% 5%	1680
December	1st to 10th	Day	34% 4 7% 27% 22% 6%	2680
	11th to 20th	Day	40% 3 12% 19% 21% 5%	3066
	21st to end	Day	39% 5% 13% 25% 17% 1	4442
January	1st to 10th	Night	33% 3 5% 20% 27% 12%	6019
	11th to 20th	Night	32% 3 5% 18% 35% 7%	5979
	21st to end	Night	38% 3 5% 26% 22% 5%	6490
February	1st to 10th	Night	40% 4 10% 23% 19% 4	2600
	11th to 20th	Night	43% 4 7% 19% 20% 6%	2525
	21st to end	Night	40% 4 7% 22% 19% 8%	1860
March	1st to 10th	Night	42% 4 7% 16% 22% 10%	4918
	11th to 20th	Night	30% 4 7% 16% 28% 14%	4980
	21st to end	Night	37% 4 7% 24% 22% 6%	5467
April	1st to 10th	Night	38% 6% 10% 17% 23% 7%	2055
	11th to 20th	Night	32% 5% 10% 24% 22% 7%	1975
	21st to end	Night	36% 6% 11% 24% 19% 4	2000
May	1st to 10th	Night	45% 8% 15% 20% 11% 1	4113
	11th to 20th	Night	50% 6% 12% 18% 12% 2	4033
	21st to end	Night	38% 7% 13% 25% 15% 2	4429
June	1st to 10th	Night	34% 8% 15% 24% 17% 1	1645
	11th to 20th	Night	35% 9% 18% 21% 16% 2	1600
	21st to end	Night	35% 10% 13% 23% 16% 3	1745
July	1st to 10th	Night	42% 12% 15% 18% 11% 2	4015
	11th to 20th	Night	49% 13% 19% 14% 4 1	4006
	21st to end	Night	44% 9% 16% 20% 11%	4297
August	1st to 10th	Night	49% 9% 18% 17% 7%	2904
	11th to 20th	Night	34% 9% 20% 26% 10% 1	2991
	21st to end	Night	34% 7% 11% 28% 18% 2	3586
September	1st to 10th	Night	36% 8% 12% 21% 18% 5%	2000
	11th to 20th	Night	40% 8% 9% 19% 20% 3	2103
	21st to end	Night	49% 6% 10% 16% 15% 4	2256
October	1st to 10th	Night	39% 5% 9% 18% 24% 5%	3920
	11th to 20th	Night	26% 3 6% 22% 28% 15%	3899
	21st to end	Night	24% 3 6% 28% 26% 14%	4252
November	1st to 10th	Night	35% 4 8% 21% 25% 6%	2461
	11th to 20th	Night	34% 5% 9% 18% 25% 10%	2584
	21st to end	Night	34% 4 8% 22% 26% 7%	2940
December	1st to 10th	Night	34% 4 6% 24% 27% 5%	4720
	11th to 20th	Night	47% 4 8% 18% 16% 7%	5348
	21st to end	Night	38% 4 12% 26% 18% 2	6748

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	28% 26% 29% 12% 5%	330
	11th to 20th	Day	26% 25% 37% 10% 2	318
	21st to end	Day	22% 22% 39% 14% 2	330
February	1st to 10th	Day	19% 23% 41% 14% 2	300
	11th to 20th	Day	39% 23% 28% 8% 3	309
	21st to end	Day	26% 22% 33% 18% 2	414
March	1st to 10th	Day	23% 19% 33% 18% 6%	500
	11th to 20th	Day	21% 22% 34% 17% 5% 1	500
	21st to end	Day	21% 17% 38% 18% 4 1	550
April	1st to 10th	Day	18% 20% 34% 20% 8% 1	500
	11th to 20th	Day	17% 15% 33% 22% 9% 3	492
	21st to end	Day	18% 14% 34% 24% 10% 2	500
May	1st to 10th	Day	17% 15% 34% 23% 9% 2	503
	11th to 20th	Day	18% 11% 24% 29% 15% 3	527
	21st to end	Day	19% 6% 23% 26% 20% 6%	573
June	1st to 10th	Day	10% 6% 27% 29% 21% 8%	530
	11th to 20th	Day	9% 5% 22% 32% 24% 8%	530
	21st to end	Day	9% 4 19% 33% 26% 9%	530
July	1st to 10th	Day	9% 2 14% 33% 31% 10%	525
	11th to 20th	Day	5% 2 12% 32% 34% 14%	524
	21st to end	Day	8% 2 17% 35% 26% 12%	576
August	1st to 10th	Day	15% 4 17% 28% 25% 11%	526
	11th to 20th	Day	11% 4 13% 31% 29% 11%	519
	21st to end	Day	9% 2 14% 32% 28% 15%	583
September	1st to 10th	Day	12% 5% 16% 26% 25% 15%	530
	11th to 20th	Day	16% 5% 14% 29% 24% 11%	530
	21st to end	Day	26% 8% 21% 27% 14% 5%	530
October	1st to 10th	Day	18% 7% 21% 24% 23% 8%	530
	11th to 20th	Day	15% 11% 26% 27% 18% 4	530
	21st to end	Day	16% 12% 26% 29% 12% 4	583
November	1st to 10th	Day	16% 10% 31% 27% 13% 4	535
	11th to 20th	Day	17% 16% 30% 24% 12% 1	486
	21st to end	Day	19% 20% 24% 26% 9% 2	220
December	1st to 10th	Day	25% 18% 35% 16% 4 2	220
	11th to 20th	Day	24% 15% 32% 24% 5% 1	220
	21st to end	Day	23% 17% 37% 13% 8% 2	333
January	1st to 10th	Night	19% 20% 35% 22% 4	840
	11th to 20th	Night	20% 18% 33% 25% 4	825
	21st to end	Night	19% 16% 37% 25% 3	880
February	1st to 10th	Night	20% 15% 37% 24% 4	800
	11th to 20th	Night	26% 19% 36% 17% 1	783
	21st to end	Night	19% 16% 38% 24% 3	660
March	1st to 10th	Night	18% 17% 35% 27% 4	800
	11th to 20th	Night	19% 17% 34% 24% 6%	800
	21st to end	Night	18% 14% 43% 20% 4	880
April	1st to 10th	Night	17% 18% 36% 23% 6%	800
	11th to 20th	Night	14% 14% 36% 26% 11%	791
	21st to end	Night	15% 8% 36% 33% 8%	800
May	1st to 10th	Night	15% 11% 32% 31% 11%	627
	11th to 20th	Night	19% 6% 26% 31% 17%	591
	21st to end	Night	14% 3 17% 35% 28% 3	650
June	1st to 10th	Night	10% 3 20% 42% 24% 1	445
	11th to 20th	Night	11% 2 16% 41% 26% 3	400
	21st to end	Night	8% 2 14% 44% 30% 2	545
July	1st to 10th	Night	9% 1 14% 37% 35% 5%	585
	11th to 20th	Night	6% 2 10% 37% 39% 7%	582
	21st to end	Night	7% 2 16% 40% 32% 4	657
August	1st to 10th	Night	14% 2 10% 40% 29% 5%	597
	11th to 20th	Night	11% 3 11% 37% 34% 4	644
	21st to end	Night	10% 1 13% 34% 36% 6%	880
September	1st to 10th	Night	14% 2 13% 34% 32% 6%	800
	11th to 20th	Night	16% 4 14% 30% 32% 4	800
	21st to end	Night	26% 4 16% 33% 20% 1	800
October	1st to 10th	Night	17% 4 18% 29% 26% 5%	800
	11th to 20th	Night	16% 9% 25% 30% 19% 1	800
	21st to end	Night	15% 9% 25% 32% 16% 2	880
November	1st to 10th	Night	16% 9% 26% 33% 15% 2	820
	11th to 20th	Night	15% 12% 30% 32% 11%	840
	21st to end	Night	14% 12% 32% 31% 10% 1	840
December	1st to 10th	Night	21% 13% 35% 24% 7%	840
	11th to 20th	Night	19% 10% 35% 30% 5%	840
	21st to end	Night	22% 14% 27% 31% 5%	924

Page generated at 2026-01-14 01:14:29. Version ac07

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