Calhoun Falls State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Calhoun Falls State Park clear sky chart from 2005-11-06 to 2024-11-11.

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%	101133
	Night	14% 6% 2 6% 4 4 4 4 6% 7% 43%	97993
Transparency	Day	38% 5% 11% 21% 19% 6%	104901
	Night	38% 5% 10% 19% 20% 7%	102364
Seeing	Day	17% 8% 22% 25% 19% 9%	15132
	Night	16% 8% 21% 31% 21% 3	25169

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% 5% 2 5% 4 4 3 3 6% 8% 43%	2836
	11th to 20th	Day	14% 5% 2 4 4 2 4 2 4 5% 53%	2840
	21st to end	Day	25% 6% 2 4 3 3 2 2 4 4 45%	3124
February	1st to 10th	Day	16% 6% 2 6% 5% 4 4 5% 5% 6% 42%	1843
	11th to 20th	Day	21% 5% 2 5% 4 3 3 3 4 6% 44%	1848
	21st to end	Day	19% 7% 2 6% 4 5% 3 4 6% 5% 40%	1570
March	1st to 10th	Day	23% 7% 3 7% 3 3 3 2 4 5% 39%	3375
	11th to 20th	Day	11% 4 2 5% 4 4 4 3 5% 6% 52%	3480
	21st to end	Day	20% 6% 2 5% 4 4 4 3 4 5% 42%	3815
April	1st to 10th	Day	11% 4 2 5% 4 4 4 4 6% 6% 49%	2090
	11th to 20th	Day	11% 5% 2 7% 4 4 4 4 5% 7% 48%	2213
	21st to end	Day	10% 5% 2 5% 4 4 4 3 5% 7% 52%	2470
May	1st to 10th	Day	10% 7% 2 6% 4 5% 4 4 6% 9% 42%	4082
	11th to 20th	Day	17% 7% 2 7% 4 4 3 3 6% 7% 39%	4081
	21st to end	Day	7% 4 2 5% 4 4 5% 4 7% 10% 48%	4476
June	1st to 10th	Day	9% 6% 2 6% 5% 5% 5% 5% 7% 11% 37%	2470
	11th to 20th	Day	6% 3 1 6% 6% 5% 5% 5% 9% 10% 44%	2470
	21st to end	Day	5% 5% 2 6% 5% 7% 6% 7% 8% 10% 41%	2470
July	1st to 10th	Day	9% 7% 3 8% 5% 6% 6% 5% 8% 10% 33%	4120
	11th to 20th	Day	6% 5% 2 7% 5% 5% 6% 5% 9% 12% 38%	4120
	21st to end	Day	8% 7% 3 9% 7% 7% 8% 7% 9% 12% 23%	4466
August	1st to 10th	Day	14% 6% 3 7% 5% 5% 5% 5% 8% 11% 30%	4104
	11th to 20th	Day	10% 5% 2 6% 5% 5% 6% 5% 7% 10% 41%	4044
	21st to end	Day	7% 4 1 5% 5% 5% 5% 4 7% 8% 49%	4071
September	1st to 10th	Day	9% 5% 3 5% 5% 6% 6% 6% 8% 9% 40%	2090
	11th to 20th	Day	14% 6% 2 6% 4 5% 4 3 6% 8% 42%	2090
	21st to end	Day	14% 7% 1 5% 4 4 4 4 5% 7% 45%	2090
October	1st to 10th	Day	13% 5% 2 5% 2 2 2 2 5% 5% 56%	2076
	11th to 20th	Day	12% 4 1 4 3 2 3 3 4 6% 58%	1900
	21st to end	Day	10% 5% 2 4 3 3 3 3 4 4 58%	2090
November	1st to 10th	Day	13% 6% 2 5% 3 3 3 2 4 5% 52%	1912
	11th to 20th	Day	14% 5% 2 4 3 3 3 3 5% 5% 52%	1710
	21st to end	Day	14% 6% 2 5% 4 3 3 3 5% 6% 49%	1710
December	1st to 10th	Day	19% 8% 3 5% 4 4 4 3 4 6% 40%	1710
	11th to 20th	Day	18% 5% 2 5% 3 4 3 3 4 5% 47%	2153
	21st to end	Day	22% 7% 2 5% 3 3 4 3 4 6% 41%	3124
January	1st to 10th	Night	18% 6% 2 5% 3 4 4 3 4 6% 46%	4109
	11th to 20th	Night	12% 6% 2 6% 4 4 5% 4 5% 6% 47%	4120
	21st to end	Night	22% 7% 2 5% 3 3 3 3 3 4 45%	4532
February	1st to 10th	Night	17% 6% 2 5% 4 3 4 4 5% 5% 46%	2333
	11th to 20th	Night	19% 7% 2 5% 4 4 3 2 4 5% 45%	2218
	21st to end	Night	17% 6% 2 5% 4 4 4 3 4 6% 45%	1884
March	1st to 10th	Night	23% 8% 3 5% 4 2 3 3 5% 6% 38%	3478
	11th to 20th	Night	11% 4 1 4 3 3 4 4 6% 7% 51%	3480
	21st to end	Night	19% 6% 2 6% 4 3 3 4 4 6% 42%	3817
April	1st to 10th	Night	12% 4 2 5% 5% 3 4 4 6% 5% 50%	2090
	11th to 20th	Night	11% 6% 2 5% 4 3 3 2 4 6% 54%	1930
	21st to end	Night	9% 4 2 6% 3 4 4 3 4 6% 53%	1710
May	1st to 10th	Night	11% 6% 2 6% 5% 4 5% 4 7% 8% 41%	2813
	11th to 20th	Night	16% 5% 2 6% 5% 4 4 4 6% 7% 42%	2812
	21st to end	Night	7% 4 1 6% 4 4 4 4 7% 11% 47%	3079
June	1st to 10th	Night	10% 5% 2 6% 5% 5% 5% 5% 7% 11% 37%	1710
	11th to 20th	Night	6% 5% 2 6% 6% 4 5% 5% 7% 12% 42%	1710
	21st to end	Night	8% 4 2 5% 6% 5% 6% 4 9% 12% 39%	1710
July	1st to 10th	Night	13% 7% 3 8% 5% 6% 7% 5% 8% 10% 29%	2840
	11th to 20th	Night	6% 5% 2 7% 6% 6% 8% 7% 10% 13% 30%	2840
	21st to end	Night	10% 9% 4 10% 7% 6% 6% 6% 10% 11% 22%	3087
August	1st to 10th	Night	12% 7% 3 7% 5% 7% 7% 6% 10% 12% 24%	2825
	11th to 20th	Night	10% 6% 3 8% 6% 5% 5% 5% 7% 10% 34%	2785
	21st to end	Night	6% 4 2 6% 5% 5% 6% 4 6% 8% 47%	3547
September	1st to 10th	Night	10% 5% 2 6% 5% 5% 5% 4 7% 10% 41%	2090
	11th to 20th	Night	14% 8% 3 7% 5% 5% 4 3 6% 8% 38%	2090
	21st to end	Night	14% 6% 1 5% 4 4 5% 3 5% 7% 46%	2090
October	1st to 10th	Night	11% 5% 2 5% 3 3 3 3 4 6% 53%	2104
	11th to 20th	Night	11% 4 2 5% 4 3 3 2 4 5% 56%	2280
	21st to end	Night	11% 4 2 4 2 3 3 2 4 5% 59%	2508
November	1st to 10th	Night	12% 5% 1 5% 3 3 3 3 4 6% 54%	2381
	11th to 20th	Night	15% 5% 2 4 3 4 3 3 3 6% 53%	2477
	21st to end	Night	16% 4 2 5% 3 3 4 4 5% 7% 47%	2470
December	1st to 10th	Night	17% 7% 2 5% 4 4 4 4 5% 6% 43%	2470
	11th to 20th	Night	17% 6% 2 5% 2 2 3 2 3 5% 52%	3042
	21st to end	Night	20% 7% 2 6% 4 4 4 3 6% 7% 37%	4532

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% 3 6% 23% 21% 8%	2837
	11th to 20th	Day	35% 2 5% 21% 29% 8%	2840
	21st to end	Day	44% 2 3 18% 25% 7%	3124
February	1st to 10th	Day	43% 4 8% 20% 20% 6%	1843
	11th to 20th	Day	42% 3 5% 20% 23% 7%	1858
	21st to end	Day	45% 4 8% 15% 20% 8%	1570
March	1st to 10th	Day	50% 3 7% 16% 13% 11%	3375
	11th to 20th	Day	34% 4 8% 17% 28% 11%	3480
	21st to end	Day	45% 3 7% 20% 21% 4	3815
April	1st to 10th	Day	35% 3 11% 20% 25% 6%	2090
	11th to 20th	Day	35% 4 9% 19% 22% 11%	2213
	21st to end	Day	32% 4 10% 28% 22% 4	2470
May	1st to 10th	Day	39% 5% 14% 24% 15% 3	4120
	11th to 20th	Day	44% 5% 12% 24% 14% 1	4085
	21st to end	Day	30% 6% 16% 24% 21% 1	4489
June	1st to 10th	Day	39% 7% 18% 24% 10% 2	2470
	11th to 20th	Day	31% 7% 18% 28% 14% 1	2470
	21st to end	Day	35% 10% 17% 22% 13% 4	2470
July	1st to 10th	Day	42% 9% 18% 21% 7% 1	4055
	11th to 20th	Day	35% 11% 26% 22% 5% 2	4051
	21st to end	Day	49% 13% 19% 13% 6%	4324
August	1st to 10th	Day	46% 7% 17% 24% 5%	4091
	11th to 20th	Day	36% 7% 18% 21% 16% 2	4083
	21st to end	Day	29% 8% 14% 25% 18% 5%	4071
September	1st to 10th	Day	38% 8% 14% 18% 18% 4	2090
	11th to 20th	Day	41% 6% 11% 18% 22% 3	2090
	21st to end	Day	40% 5% 9% 22% 18% 7%	2090
October	1st to 10th	Day	29% 4 5% 17% 34% 11%	3453
	11th to 20th	Day	20% 2 5% 16% 29% 28%	3140
	21st to end	Day	25% 2 4 24% 31% 14%	3428
November	1st to 10th	Day	36% 3 7% 17% 27% 10%	1912
	11th to 20th	Day	34% 3 6% 22% 25% 10%	1710
	21st to end	Day	37% 3 8% 21% 25% 7%	1710
December	1st to 10th	Day	46% 4 7% 20% 17% 6%	1710
	11th to 20th	Day	40% 2 6% 19% 22% 11%	2150
	21st to end	Day	45% 3 6% 20% 23% 3	3124
January	1st to 10th	Night	39% 4 5% 18% 26% 8%	4109
	11th to 20th	Night	38% 4 5% 20% 26% 8%	4120
	21st to end	Night	45% 3 4 15% 26% 7%	4532
February	1st to 10th	Night	40% 3 8% 20% 21% 8%	2333
	11th to 20th	Night	43% 2 5% 18% 23% 8%	2219
	21st to end	Night	42% 3 8% 17% 21% 10%	1884
March	1st to 10th	Night	47% 4 10% 15% 16% 7%	3478
	11th to 20th	Night	31% 4 8% 14% 28% 15%	3480
	21st to end	Night	43% 3 7% 19% 18% 10%	3817
April	1st to 10th	Night	34% 4 9% 19% 25% 8%	2090
	11th to 20th	Night	33% 2 6% 23% 24% 11%	1930
	21st to end	Night	32% 4 10% 27% 21% 6%	1710
May	1st to 10th	Night	39% 6% 14% 24% 15% 3	2840
	11th to 20th	Night	42% 5% 14% 22% 17% 1	2813
	21st to end	Night	29% 7% 14% 27% 22% 2	3087
June	1st to 10th	Night	39% 7% 19% 21% 12% 2	1710
	11th to 20th	Night	33% 8% 18% 25% 14% 3	1710
	21st to end	Night	36% 9% 19% 19% 13% 4	1710
July	1st to 10th	Night	46% 10% 19% 16% 6% 1	2795
	11th to 20th	Night	39% 13% 23% 20% 4 1	2786
	21st to end	Night	52% 12% 19% 12% 4 1	2988
August	1st to 10th	Night	47% 10% 20% 20% 4	2814
	11th to 20th	Night	44% 8% 19% 18% 9% 1	2812
	21st to end	Night	33% 8% 14% 25% 17% 4	3547
September	1st to 10th	Night	38% 8% 16% 17% 17% 5%	2090
	11th to 20th	Night	42% 6% 12% 19% 19% 3	2090
	21st to end	Night	37% 5% 11% 20% 19% 7%	2090
October	1st to 10th	Night	28% 5% 7% 18% 34% 8%	3507
	11th to 20th	Night	20% 2 4 17% 27% 29%	3779
	21st to end	Night	24% 3 4 21% 30% 18%	4120
November	1st to 10th	Night	33% 3 8% 19% 26% 12%	2381
	11th to 20th	Night	34% 3 5% 18% 26% 13%	2477
	21st to end	Night	37% 3 6% 21% 26% 8%	2470
December	1st to 10th	Night	43% 4 8% 20% 19% 6%	2470
	11th to 20th	Night	37% 2 7% 17% 28% 9%	3044
	21st to end	Night	47% 3 5% 22% 19% 3	4532

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	24% 19% 35% 19% 3	270
	11th to 20th	Day	27% 17% 30% 23% 3 1	270
	21st to end	Day	29% 18% 37% 12% 4 1	297
February	1st to 10th	Day	24% 18% 37% 17% 3	270
	11th to 20th	Day	37% 13% 35% 14% 1	270
	21st to end	Day	32% 19% 38% 11% 1	225
March	1st to 10th	Day	21% 13% 34% 23% 8%	422
	11th to 20th	Day	21% 16% 37% 18% 8%	460
	21st to end	Day	22% 17% 34% 18% 8% 1	506
April	1st to 10th	Day	24% 11% 30% 23% 11% 1	460
	11th to 20th	Day	15% 12% 33% 24% 13% 2	452
	21st to end	Day	14% 10% 26% 28% 16% 5%	460
May	1st to 10th	Day	15% 9% 32% 22% 17% 5%	463
	11th to 20th	Day	17% 5% 15% 30% 21% 11%	487
	21st to end	Day	14% 4 15% 27% 26% 13%	529
June	1st to 10th	Day	14% 5% 12% 30% 27% 12%	490
	11th to 20th	Day	9% 4 14% 29% 27% 18%	490
	21st to end	Day	9% 2 16% 34% 24% 15%	490
July	1st to 10th	Day	10% 2 10% 23% 34% 21%	485
	11th to 20th	Day	10% 1 6% 25% 39% 19%	484
	21st to end	Day	8% 2 8% 29% 34% 19%	532
August	1st to 10th	Day	14% 3 12% 24% 29% 17%	486
	11th to 20th	Day	13% 3 9% 25% 32% 18%	479
	21st to end	Day	14% 2 8% 26% 30% 20%	539
September	1st to 10th	Day	12% 2 10% 29% 32% 16%	490
	11th to 20th	Day	19% 1 10% 26% 31% 13%	490
	21st to end	Day	18% 3 17% 25% 28% 10%	490
October	1st to 10th	Day	17% 4 20% 32% 16% 10%	490
	11th to 20th	Day	11% 6% 25% 29% 23% 5%	490
	21st to end	Day	15% 6% 27% 29% 19% 4	539
November	1st to 10th	Day	20% 7% 23% 30% 16% 4	450
	11th to 20th	Day	20% 10% 39% 22% 8% 1	270
	21st to end	Day	18% 10% 35% 23% 13% 2	270
December	1st to 10th	Day	30% 10% 32% 23% 4	270
	11th to 20th	Day	27% 9% 34% 22% 6% 1	270
	21st to end	Day	30% 16% 30% 14% 6% 3	297
January	1st to 10th	Night	23% 16% 27% 28% 6%	760
	11th to 20th	Night	21% 13% 29% 28% 9%	760
	21st to end	Night	22% 17% 33% 25% 4	836
February	1st to 10th	Night	22% 13% 27% 32% 7%	760
	11th to 20th	Night	23% 15% 33% 25% 3	743
	21st to end	Night	22% 16% 31% 28% 4	628
March	1st to 10th	Night	20% 12% 31% 31% 6%	760
	11th to 20th	Night	18% 13% 33% 26% 9% 1	760
	21st to end	Night	17% 12% 32% 30% 9%	836
April	1st to 10th	Night	16% 13% 31% 29% 12%	760
	11th to 20th	Night	16% 10% 25% 32% 15%	687
	21st to end	Night	11% 6% 27% 36% 19% 1	570
May	1st to 10th	Night	11% 7% 23% 38% 19% 2	570
	11th to 20th	Night	14% 3 21% 35% 24% 4	561
	21st to end	Night	13% 2 11% 35% 33% 6%	617
June	1st to 10th	Night	12% 2 13% 36% 32% 5%	570
	11th to 20th	Night	6% 3 14% 28% 38% 10%	570
	21st to end	Night	10% 2 11% 36% 34% 8%	570
July	1st to 10th	Night	11% 3 7% 29% 38% 12%	555
	11th to 20th	Night	11% 1 5% 30% 43% 11%	552
	21st to end	Night	8% 3 7% 30% 45% 8%	624
August	1st to 10th	Night	11% 3 7% 28% 41% 10%	567
	11th to 20th	Night	13% 2 6% 32% 38% 8%	564
	21st to end	Night	12% 3 9% 26% 39% 11%	694
September	1st to 10th	Night	11% 3 8% 30% 39% 9%	760
	11th to 20th	Night	17% 2 10% 28% 38% 5%	760
	21st to end	Night	17% 3 14% 31% 30% 5%	760
October	1st to 10th	Night	13% 5% 18% 32% 27% 6%	760
	11th to 20th	Night	14% 5% 21% 33% 23% 4	760
	21st to end	Night	14% 9% 20% 32% 23% 3	836
November	1st to 10th	Night	15% 6% 23% 33% 20% 3	780
	11th to 20th	Night	18% 10% 26% 31% 13% 1	763
	21st to end	Night	18% 9% 25% 32% 16% 1	760
December	1st to 10th	Night	21% 13% 23% 32% 10% 1	760
	11th to 20th	Night	20% 11% 24% 31% 13% 1	760
	21st to end	Night	29% 12% 22% 29% 7%	836

Page generated at 2024-11-08 06:44:48. Version ac07

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