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 2024-01-15.

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% 5% 2 5% 5% 3 5% 5% 6% 8% 44%	74576
	Night	14% 5% 2 5% 5% 3 4 5% 5% 7% 45%	75173
Transparency	Day	38% 7% 12% 22% 17% 4	74297
	Night	38% 6% 10% 21% 19% 5%	74971
Seeing	Day	17% 11% 25% 25% 16% 6%	14062
	Night	16% 10% 26% 30% 16% 2	24170

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	17% 7% 2 4 4 2 5% 4 4 6% 46%	1706
	11th to 20th	Day	17% 7% 3 5% 5% 2 4 4 4 6% 46%	1656
	21st to end	Day	18% 6% 2 4 4 2 4 3 5% 6% 47%	1782
February	1st to 10th	Day	14% 6% 2 5% 5% 3 4 6% 5% 8% 41%	1620
	11th to 20th	Day	21% 6% 1 3 4 3 3 4 4 5% 45%	1581
	21st to end	Day	19% 6% 2 6% 5% 3 4 5% 5% 7% 39%	1583
March	1st to 10th	Day	14% 6% 2 3 3 3 3 4 5% 6% 50%	1980
	11th to 20th	Day	16% 6% 3 5% 4 3 4 5% 5% 8% 42%	1980
	21st to end	Day	17% 8% 3 4 5% 4 4 4 5% 6% 40%	2178
April	1st to 10th	Day	10% 4 2 3 3 2 4 4 6% 8% 54%	2108
	11th to 20th	Day	11% 5% 2 5% 4 3 5% 4 4 8% 49%	2134
	21st to end	Day	15% 4 3 5% 4 3 5% 5% 5% 6% 45%	2160
May	1st to 10th	Day	14% 4 1 5% 5% 3 5% 5% 7% 9% 42%	2330
	11th to 20th	Day	16% 5% 3 6% 5% 3 5% 5% 6% 8% 38%	2301
	21st to end	Day	13% 5% 2 5% 6% 3 5% 5% 7% 9% 39%	2531
June	1st to 10th	Day	9% 4 2 4 5% 3 6% 6% 6% 10% 44%	2470
	11th to 20th	Day	9% 4 2 5% 5% 3 5% 5% 8% 9% 45%	2520
	21st to end	Day	8% 4 3 5% 5% 4 6% 7% 7% 11% 41%	2379
July	1st to 10th	Day	7% 4 2 6% 6% 4 6% 6% 7% 12% 38%	2340
	11th to 20th	Day	6% 4 2 5% 5% 4 7% 7% 9% 12% 40%	2340
	21st to end	Day	7% 4 2 6% 7% 5% 7% 7% 8% 9% 37%	2547
August	1st to 10th	Day	10% 5% 3 5% 6% 5% 6% 7% 6% 11% 35%	2327
	11th to 20th	Day	11% 8% 3 6% 6% 4 6% 7% 7% 9% 35%	2241
	21st to end	Day	10% 5% 2 6% 6% 4 6% 5% 6% 10% 40%	2376
September	1st to 10th	Day	11% 4 2 5% 5% 3 5% 5% 6% 9% 46%	2160
	11th to 20th	Day	13% 5% 3 6% 5% 3 5% 4 6% 7% 44%	2065
	21st to end	Day	20% 6% 2 5% 4 3 5% 5% 4 6% 39%	1928
October	1st to 10th	Day	15% 5% 3 4 4 3 3 3 3 6% 51%	1800
	11th to 20th	Day	15% 4 2 3 4 2 4 3 4 5% 54%	1800
	21st to end	Day	12% 4 2 5% 4 3 3 3 3 6% 54%	1980
November	1st to 10th	Day	12% 5% 2 4 4 2 4 3 4 6% 55%	1857
	11th to 20th	Day	15% 5% 2 4 3 2 4 3 5% 5% 51%	1834
	21st to end	Day	15% 4 2 3 3 3 3 5% 6% 6% 50%	1520
December	1st to 10th	Day	17% 7% 2 4 4 3 4 5% 6% 7% 40%	1520
	11th to 20th	Day	17% 4 2 3 3 2 3 3 3 6% 55%	1910
	21st to end	Day	18% 5% 2 4 4 2 5% 5% 6% 8% 42%	3032
January	1st to 10th	Night	16% 6% 2 4 4 3 4 3 4 6% 47%	2459
	11th to 20th	Night	16% 6% 3 5% 5% 3 4 4 4 6% 43%	2393
	21st to end	Night	15% 6% 3 4 4 2 4 3 4 5% 49%	2574
February	1st to 10th	Night	17% 6% 3 4 4 3 4 4 6% 6% 45%	2340
	11th to 20th	Night	19% 6% 3 4 4 2 4 4 4 6% 43%	2264
	21st to end	Night	16% 8% 1 4 4 3 4 4 4 6% 46%	1668
March	1st to 10th	Night	13% 5% 2 4 4 3 3 4 4 5% 52%	1980
	11th to 20th	Night	17% 6% 2 5% 5% 3 4 4 6% 7% 42%	1980
	21st to end	Night	16% 6% 3 6% 5% 3 4 4 5% 7% 42%	2178
April	1st to 10th	Night	13% 6% 3 5% 4 2 4 4 5% 6% 47%	1850
	11th to 20th	Night	11% 5% 2 4 5% 2 5% 4 5% 7% 51%	1775
	21st to end	Night	14% 5% 2 4 5% 3 5% 5% 5% 6% 46%	1800
May	1st to 10th	Night	13% 5% 2 5% 4 3 5% 6% 5% 8% 44%	1645
	11th to 20th	Night	16% 5% 2 5% 5% 3 4 5% 6% 8% 39%	1592
	21st to end	Night	13% 5% 2 6% 5% 2 4 5% 5% 9% 43%	1744
June	1st to 10th	Night	11% 3 2 4 5% 3 4 5% 6% 11% 45%	1481
	11th to 20th	Night	9% 5% 2 4 6% 3 5% 5% 6% 12% 42%	1440
	21st to end	Night	8% 4 2 5% 5% 4 7% 6% 7% 11% 41%	1569
July	1st to 10th	Night	8% 4 3 5% 6% 4 5% 7% 8% 11% 41%	1620
	11th to 20th	Night	5% 4 3 5% 6% 3 7% 7% 9% 11% 41%	1620
	21st to end	Night	7% 4 3 6% 6% 4 7% 6% 7% 12% 39%	1771
August	1st to 10th	Night	9% 5% 3 7% 7% 3 6% 6% 7% 9% 38%	1611
	11th to 20th	Night	10% 6% 4 6% 5% 4 5% 7% 7% 11% 36%	1642
	21st to end	Night	9% 5% 2 5% 8% 5% 5% 7% 8% 10% 37%	1980
September	1st to 10th	Night	11% 6% 3 5% 5% 3 4 5% 6% 7% 46%	1800
	11th to 20th	Night	13% 6% 4 5% 4 3 5% 5% 6% 6% 44%	1892
	21st to end	Night	21% 8% 2 5% 5% 3 4 4 4 6% 38%	2030
October	1st to 10th	Night	16% 5% 1 4 5% 2 4 4 5% 6% 46%	2160
	11th to 20th	Night	14% 6% 2 5% 4 3 3 3 3 6% 52%	2160
	21st to end	Night	13% 4 2 3 4 3 5% 4 4 6% 53%	2376
November	1st to 10th	Night	12% 7% 2 5% 4 2 3 3 5% 5% 52%	2221
	11th to 20th	Night	13% 5% 3 4 3 2 3 5% 5% 6% 51%	2336
	21st to end	Night	13% 4 2 4 4 3 4 4 4 6% 52%	2660
December	1st to 10th	Night	17% 7% 2 6% 5% 3 4 4 4 5% 42%	2660
	11th to 20th	Night	16% 6% 2 4 5% 3 4 3 4 5% 49%	3285
	21st to end	Night	17% 7% 3 4 4 3 3 5% 5% 7% 42%	4617

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	40% 4 9% 23% 19% 5%	1707
	11th to 20th	Day	40% 5% 9% 22% 20% 4	1656
	21st to end	Day	39% 3 8% 24% 20% 5%	1782
February	1st to 10th	Day	41% 5% 11% 22% 17% 4	1620
	11th to 20th	Day	43% 4 6% 21% 20% 5%	1590
	21st to end	Day	45% 6% 11% 15% 17% 6%	1583
March	1st to 10th	Day	36% 4 8% 24% 22% 6%	1980
	11th to 20th	Day	41% 5% 11% 19% 17% 7%	1980
	21st to end	Day	45% 5% 9% 20% 15% 4	2178
April	1st to 10th	Day	28% 5% 12% 24% 22% 9%	2108
	11th to 20th	Day	35% 5% 11% 22% 21% 7%	2134
	21st to end	Day	40% 6% 12% 23% 16% 5%	2160
May	1st to 10th	Day	37% 7% 16% 21% 15% 3	2330
	11th to 20th	Day	43% 7% 13% 24% 10% 3	2305
	21st to end	Day	40% 7% 16% 26% 11%	2531
June	1st to 10th	Day	33% 9% 16% 26% 15% 1	2470
	11th to 20th	Day	33% 9% 17% 23% 15% 2	2520
	21st to end	Day	34% 11% 16% 23% 14% 2	2379
July	1st to 10th	Day	37% 10% 15% 21% 15% 2	2275
	11th to 20th	Day	32% 12% 21% 21% 12% 2	2271
	21st to end	Day	38% 11% 16% 23% 12%	2405
August	1st to 10th	Day	40% 11% 16% 25% 8% 1	2314
	11th to 20th	Day	42% 11% 16% 18% 11% 1	2241
	21st to end	Day	39% 8% 17% 22% 12% 3	2376
September	1st to 10th	Day	35% 9% 15% 17% 20% 4	2160
	11th to 20th	Day	39% 7% 10% 21% 20% 3	2065
	21st to end	Day	45% 6% 8% 20% 17% 3	1928
October	1st to 10th	Day	37% 5% 9% 24% 22% 4	1800
	11th to 20th	Day	33% 5% 7% 28% 22% 6%	1800
	21st to end	Day	33% 5% 6% 25% 23% 8%	1980
November	1st to 10th	Day	32% 5% 7% 23% 27% 6%	1857
	11th to 20th	Day	35% 4 10% 21% 22% 8%	1834
	21st to end	Day	33% 5% 8% 24% 25% 5%	1520
December	1st to 10th	Day	42% 6% 10% 22% 17% 3	1520
	11th to 20th	Day	33% 4 8% 25% 22% 8%	1906
	21st to end	Day	38% 6% 12% 24% 18% 2	3032
January	1st to 10th	Night	40% 4 8% 19% 22% 7%	2459
	11th to 20th	Night	42% 5% 9% 20% 20% 4	2393
	21st to end	Night	38% 4 6% 23% 24% 5%	2574
February	1st to 10th	Night	40% 4 10% 23% 18% 4	2340
	11th to 20th	Night	43% 4 7% 20% 20% 6%	2266
	21st to end	Night	41% 4 7% 22% 19% 8%	1668
March	1st to 10th	Night	34% 5% 9% 23% 22% 7%	1980
	11th to 20th	Night	42% 5% 8% 19% 21% 5%	1980
	21st to end	Night	42% 5% 9% 20% 18% 4	2178
April	1st to 10th	Night	38% 5% 10% 17% 24% 7%	1850
	11th to 20th	Night	33% 5% 9% 23% 22% 7%	1775
	21st to end	Night	38% 5% 10% 24% 19% 5%	1800
May	1st to 10th	Night	37% 8% 12% 24% 16% 3	1645
	11th to 20th	Night	41% 8% 13% 21% 13% 3	1593
	21st to end	Night	38% 8% 13% 25% 15% 1	1745
June	1st to 10th	Night	33% 9% 16% 25% 16% 1	1481
	11th to 20th	Night	35% 9% 17% 21% 15% 2	1440
	21st to end	Night	36% 11% 13% 22% 16% 3	1569
July	1st to 10th	Night	34% 12% 15% 21% 14% 4	1575
	11th to 20th	Night	30% 13% 20% 24% 10% 3	1566
	21st to end	Night	35% 11% 19% 24% 11%	1672
August	1st to 10th	Night	39% 12% 18% 17% 12% 1	1600
	11th to 20th	Night	40% 11% 16% 19% 13% 2	1642
	21st to end	Night	39% 11% 16% 22% 9% 3	1980
September	1st to 10th	Night	36% 8% 12% 21% 17% 6%	1800
	11th to 20th	Night	39% 8% 10% 19% 21% 3	1892
	21st to end	Night	48% 6% 9% 17% 17% 4	2030
October	1st to 10th	Night	38% 6% 9% 22% 21% 4	2160
	11th to 20th	Night	35% 4 7% 25% 22% 7%	2160
	21st to end	Night	33% 4 7% 23% 25% 8%	2376
November	1st to 10th	Night	35% 4 8% 21% 25% 7%	2221
	11th to 20th	Night	33% 5% 9% 18% 24% 11%	2336
	21st to end	Night	34% 4 8% 22% 26% 7%	2660
December	1st to 10th	Night	44% 5% 8% 21% 18% 4	2660
	11th to 20th	Night	38% 4 8% 21% 22% 7%	3288
	21st to end	Night	40% 4 8% 25% 20% 2	4617

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	27% 26% 30% 13% 5%	270
	11th to 20th	Day	25% 25% 38% 11% 2	252
	21st to end	Day	23% 23% 37% 14% 3	264
February	1st to 10th	Day	22% 23% 39% 13% 3	240
	11th to 20th	Day	37% 24% 29% 8% 2	248
	21st to end	Day	27% 22% 32% 17% 2	346
March	1st to 10th	Day	22% 20% 35% 17% 6%	420
	11th to 20th	Day	22% 23% 35% 15% 5% 1	420
	21st to end	Day	22% 18% 34% 20% 5% 1	462
April	1st to 10th	Day	18% 19% 32% 21% 9% 1	420
	11th to 20th	Day	17% 16% 32% 22% 10% 4	412
	21st to end	Day	19% 14% 33% 22% 10% 2	420
May	1st to 10th	Day	18% 15% 34% 23% 9% 2	423
	11th to 20th	Day	17% 10% 24% 30% 16% 4	447
	21st to end	Day	19% 4 21% 27% 22% 7%	485
June	1st to 10th	Day	10% 6% 26% 29% 22% 7%	450
	11th to 20th	Day	11% 5% 24% 30% 22% 9%	450
	21st to end	Day	10% 4 22% 34% 23% 8%	450
July	1st to 10th	Day	9% 2 15% 32% 31% 11%	445
	11th to 20th	Day	4 2 14% 32% 35% 13%	444
	21st to end	Day	7% 1 18% 37% 26% 10%	488
August	1st to 10th	Day	12% 4 17% 28% 26% 13%	446
	11th to 20th	Day	12% 4 13% 29% 30% 12%	439
	21st to end	Day	10% 2 13% 31% 28% 16%	495
September	1st to 10th	Day	13% 5% 14% 25% 26% 17%	450
	11th to 20th	Day	15% 6% 13% 29% 24% 12%	450
	21st to end	Day	25% 8% 21% 26% 16% 5%	450
October	1st to 10th	Day	19% 7% 22% 23% 22% 7%	450
	11th to 20th	Day	15% 9% 26% 27% 18% 5%	450
	21st to end	Day	15% 11% 27% 31% 12% 3	495
November	1st to 10th	Day	17% 9% 29% 26% 14% 4	455
	11th to 20th	Day	18% 15% 28% 25% 13% 1	414
	21st to end	Day	19% 18% 23% 28% 10% 2	180
December	1st to 10th	Day	24% 18% 34% 16% 5% 2	180
	11th to 20th	Day	24% 15% 29% 24% 6% 1	180
	21st to end	Day	24% 16% 38% 13% 8% 2	272
January	1st to 10th	Night	20% 19% 35% 22% 4	760
	11th to 20th	Night	20% 16% 33% 26% 5%	737
	21st to end	Night	19% 16% 37% 26% 3	792
February	1st to 10th	Night	20% 16% 36% 24% 4	720
	11th to 20th	Night	26% 19% 37% 17% 1	703
	21st to end	Night	20% 15% 39% 23% 3	592
March	1st to 10th	Night	17% 17% 35% 28% 4	720
	11th to 20th	Night	20% 16% 33% 23% 7%	720
	21st to end	Night	19% 13% 41% 22% 5%	792
April	1st to 10th	Night	17% 17% 35% 24% 7%	720
	11th to 20th	Night	14% 14% 34% 26% 12%	711
	21st to end	Night	16% 8% 35% 33% 8%	720
May	1st to 10th	Night	14% 11% 32% 31% 11%	565
	11th to 20th	Night	19% 5% 26% 31% 18%	531
	21st to end	Night	14% 3 15% 35% 30% 3	584
June	1st to 10th	Night	10% 2 19% 43% 25% 1	401
	11th to 20th	Night	12% 3 17% 39% 27% 3	360
	21st to end	Night	8% 2 15% 45% 28% 2	489
July	1st to 10th	Night	9% 1 14% 35% 36% 6%	525
	11th to 20th	Night	5% 1 11% 37% 40% 6%	522
	21st to end	Night	7% 1 16% 40% 32% 3	591
August	1st to 10th	Night	12% 2 10% 40% 30% 5%	537
	11th to 20th	Night	11% 3 11% 36% 35% 4	578
	21st to end	Night	11% 1 12% 33% 36% 7%	792
September	1st to 10th	Night	14% 2 12% 33% 33% 6%	720
	11th to 20th	Night	14% 4 15% 29% 33% 4	720
	21st to end	Night	25% 4 17% 33% 21% 1	720
October	1st to 10th	Night	18% 4 18% 29% 25% 5%	720
	11th to 20th	Night	16% 9% 25% 29% 19% 1	720
	21st to end	Night	15% 10% 26% 33% 15% 2	792
November	1st to 10th	Night	16% 8% 27% 32% 16% 2	740
	11th to 20th	Night	16% 11% 29% 33% 12%	760
	21st to end	Night	15% 11% 31% 32% 10% 1	760
December	1st to 10th	Night	21% 13% 33% 24% 8%	760
	11th to 20th	Night	19% 10% 35% 31% 5%	760
	21st to end	Night	23% 14% 26% 31% 5%	836

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