Calhoun County Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Calhoun County Park clear sky chart from 2005-11-06 to 2024-11-02.

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	16% 10% 3 7% 5% 4 4 4 5% 7% 34%	100876
	Night	17% 11% 3 7% 5% 4 4 3 5% 6% 35%	98047
Transparency	Day	48% 6% 11% 21% 12% 2	100688
	Night	49% 6% 10% 20% 13% 2	97905
Seeing	Day	23% 13% 24% 22% 13% 5%	14927
	Night	22% 10% 24% 28% 14% 2	25158

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	19% 20% 10% 10% 4 3 4 2 4 5% 20%	2836
	11th to 20th	Day	18% 19% 9% 12% 8% 3 3 2 3 3 19%	2840
	21st to end	Day	24% 20% 5% 10% 5% 3 3 2 4 5% 18%	3124
February	1st to 10th	Day	21% 16% 4 8% 5% 4 4 3 3 6% 27%	1710
	11th to 20th	Day	21% 14% 6% 10% 4 4 4 2 4 5% 25%	1742
	21st to end	Day	24% 15% 4 6% 3 4 4 2 4 5% 28%	1570
March	1st to 10th	Day	20% 16% 3 8% 4 4 3 3 4 5% 29%	3430
	11th to 20th	Day	16% 8% 3 5% 5% 4 4 3 5% 7% 39%	3480
	21st to end	Day	21% 10% 3 7% 4 4 4 4 5% 7% 31%	3815
April	1st to 10th	Day	15% 12% 2 7% 5% 5% 5% 3 6% 7% 33%	2122
	11th to 20th	Day	18% 8% 2 6% 4 4 4 3 4 7% 40%	2323
	21st to end	Day	20% 7% 3 7% 4 4 4 4 6% 7% 34%	2470
May	1st to 10th	Day	21% 10% 4 8% 6% 5% 5% 4 5% 7% 27%	4082
	11th to 20th	Day	19% 9% 3 7% 5% 4 4 4 5% 7% 33%	4081
	21st to end	Day	11% 6% 2 6% 5% 5% 6% 5% 7% 10% 37%	4476
June	1st to 10th	Day	13% 6% 2 6% 6% 5% 5% 4 7% 7% 39%	2470
	11th to 20th	Day	11% 6% 2 7% 6% 6% 5% 6% 6% 9% 37%	2470
	21st to end	Day	12% 5% 3 5% 5% 5% 6% 4 8% 10% 38%	2470
July	1st to 10th	Day	9% 5% 2 7% 5% 5% 5% 5% 7% 8% 42%	4120
	11th to 20th	Day	10% 6% 2 6% 5% 5% 5% 4 7% 9% 41%	4120
	21st to end	Day	18% 8% 3 8% 5% 4 5% 4 6% 8% 30%	4466
August	1st to 10th	Day	11% 6% 3 8% 5% 6% 6% 5% 8% 10% 32%	4104
	11th to 20th	Day	11% 6% 3 7% 5% 5% 6% 5% 8% 9% 35%	4044
	21st to end	Day	6% 4 1 5% 5% 5% 5% 4 7% 9% 49%	4354
September	1st to 10th	Day	14% 6% 2 5% 3 3 4 4 5% 7% 47%	2176
	11th to 20th	Day	12% 6% 2 6% 5% 4 5% 4 5% 7% 45%	2090
	21st to end	Day	19% 7% 3 7% 4 4 4 3 4 6% 39%	2090
October	1st to 10th	Day	16% 6% 3 5% 4 3 4 3 5% 8% 44%	1957
	11th to 20th	Day	17% 7% 2 6% 4 4 4 3 5% 6% 42%	1900
	21st to end	Day	21% 7% 2 5% 3 4 4 3 4 6% 40%	2090
November	1st to 10th	Day	13% 7% 2 6% 3 3 3 3 4 6% 49%	1777
	11th to 20th	Day	14% 13% 3 7% 4 4 4 3 5% 6% 35%	1710
	21st to end	Day	17% 14% 3 6% 4 5% 4 3 4 6% 34%	1666
December	1st to 10th	Day	26% 15% 4 8% 5% 4 4 3 4 5% 22%	1520
	11th to 20th	Day	21% 16% 5% 9% 4 3 3 3 4 5% 28%	2057
	21st to end	Day	20% 19% 5% 9% 5% 5% 5% 4 6% 6% 17%	3124
January	1st to 10th	Night	18% 22% 5% 10% 5% 5% 4 3 4 4 20%	4109
	11th to 20th	Night	21% 16% 6% 12% 6% 5% 3 2 3 4 21%	4120
	21st to end	Night	26% 17% 5% 9% 5% 3 3 2 3 4 22%	4532
February	1st to 10th	Night	20% 14% 4 9% 4 4 4 3 4 5% 29%	2470
	11th to 20th	Night	23% 14% 4 8% 5% 5% 4 3 4 4 27%	2323
	21st to end	Night	24% 15% 4 7% 4 3 4 3 4 5% 27%	1884
March	1st to 10th	Night	23% 11% 3 7% 4 4 4 3 4 6% 31%	3422
	11th to 20th	Night	15% 11% 4 7% 5% 4 4 3 5% 6% 37%	3480
	21st to end	Night	17% 9% 3 7% 4 4 4 3 4 6% 40%	3817
April	1st to 10th	Night	17% 11% 3 5% 5% 4 4 4 5% 6% 35%	2057
	11th to 20th	Night	15% 7% 2 8% 4 4 4 3 6% 8% 39%	1822
	21st to end	Night	16% 7% 3 8% 5% 5% 4 4 5% 6% 40%	1710
May	1st to 10th	Night	26% 10% 4 8% 5% 5% 4 3 5% 5% 25%	2813
	11th to 20th	Night	18% 10% 3 7% 5% 4 4 3 5% 7% 34%	2812
	21st to end	Night	14% 6% 3 7% 4 5% 4 4 7% 9% 38%	3079
June	1st to 10th	Night	10% 5% 3 6% 4 4 4 5% 7% 8% 43%	1710
	11th to 20th	Night	9% 6% 2 6% 4 5% 5% 6% 7% 9% 40%	1710
	21st to end	Night	12% 5% 2 6% 4 4 5% 3 7% 10% 43%	1710
July	1st to 10th	Night	10% 6% 2 7% 5% 5% 5% 5% 8% 9% 39%	2840
	11th to 20th	Night	10% 7% 2 7% 5% 4 4 4 6% 9% 41%	2840
	21st to end	Night	12% 9% 3 8% 5% 5% 5% 4 6% 7% 35%	3087
August	1st to 10th	Night	12% 7% 3 7% 5% 6% 6% 5% 7% 10% 32%	2825
	11th to 20th	Night	13% 7% 3 7% 4 4 4 4 6% 7% 41%	2785
	21st to end	Night	7% 4 1 6% 5% 5% 4 4 6% 9% 49%	3269
September	1st to 10th	Night	12% 5% 2 6% 4 3 5% 4 6% 8% 46%	2000
	11th to 20th	Night	11% 4 2 5% 4 4 4 3 5% 7% 51%	2090
	21st to end	Night	16% 7% 2 6% 4 4 4 3 5% 5% 44%	2090
October	1st to 10th	Night	13% 5% 2 6% 3 4 5% 3 5% 7% 47%	2223
	11th to 20th	Night	15% 7% 3 6% 4 3 3 3 4 6% 46%	2280
	21st to end	Night	21% 7% 2 6% 4 4 3 2 4 5% 42%	2508
November	1st to 10th	Night	13% 7% 2 6% 4 3 4 4 5% 5% 48%	2332
	11th to 20th	Night	19% 11% 3 6% 5% 4 4 4 4 7% 35%	2470
	21st to end	Night	18% 11% 3 7% 5% 4 4 3 4 5% 36%	2507
December	1st to 10th	Night	24% 16% 5% 8% 4 3 4 4 4 4 25%	2660
	11th to 20th	Night	19% 16% 6% 9% 4 4 3 3 4 5% 27%	3129
	21st to end	Night	21% 18% 5% 9% 5% 5% 4 3 4 5% 22%	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	67% 4 11% 13% 5%	2837
	11th to 20th	Day	72% 3 7% 13% 4	2840
	21st to end	Day	69% 4 7% 15% 4 1	3124
February	1st to 10th	Day	60% 4 9% 18% 8% 1	1710
	11th to 20th	Day	61% 4 9% 17% 9% 1	1751
	21st to end	Day	58% 5% 8% 17% 10% 1	1570
March	1st to 10th	Day	57% 5% 9% 20% 9% 1	3430
	11th to 20th	Day	43% 5% 10% 27% 15% 1	3480
	21st to end	Day	51% 6% 9% 20% 12% 1	3815
April	1st to 10th	Day	49% 5% 11% 18% 13% 3	2122
	11th to 20th	Day	44% 5% 11% 19% 17% 4	2323
	21st to end	Day	47% 6% 12% 21% 12% 2	2470
May	1st to 10th	Day	56% 6% 10% 19% 8% 1	4120
	11th to 20th	Day	49% 7% 12% 18% 13% 1	4085
	21st to end	Day	37% 10% 16% 21% 12% 4	4489
June	1st to 10th	Day	40% 7% 13% 22% 16% 1	2470
	11th to 20th	Day	41% 9% 14% 21% 14% 1	2470
	21st to end	Day	39% 9% 16% 22% 14% 2	2470
July	1st to 10th	Day	38% 8% 13% 24% 13% 3	4055
	11th to 20th	Day	37% 8% 12% 28% 14% 2	4051
	21st to end	Day	50% 6% 11% 16% 14% 1	4324
August	1st to 10th	Day	42% 9% 14% 25% 9%	4091
	11th to 20th	Day	40% 8% 11% 27% 14%	4083
	21st to end	Day	31% 7% 14% 28% 19% 2	4354
September	1st to 10th	Day	36% 6% 10% 21% 22% 5%	2176
	11th to 20th	Day	37% 5% 11% 26% 18% 3	2090
	21st to end	Day	46% 5% 9% 21% 18% 1	2090
October	1st to 10th	Day	39% 4 11% 22% 21% 2	1957
	11th to 20th	Day	42% 4 10% 25% 17% 1	1900
	21st to end	Day	45% 4 8% 25% 16% 2	2090
November	1st to 10th	Day	37% 4 9% 27% 18% 5%	1777
	11th to 20th	Day	48% 3 9% 19% 17% 3	1710
	21st to end	Day	51% 5% 10% 20% 14%	1666
December	1st to 10th	Day	65% 3 9% 18% 4 1	1520
	11th to 20th	Day	60% 4 10% 17% 9%	2054
	21st to end	Day	65% 6% 12% 13% 3	3124
January	1st to 10th	Night	66% 5% 9% 13% 6% 1	4109
	11th to 20th	Night	67% 3 10% 15% 4	4120
	21st to end	Night	68% 3 8% 16% 4 1	4532
February	1st to 10th	Night	58% 4 9% 18% 9%	2470
	11th to 20th	Night	61% 4 7% 16% 10% 1	2325
	21st to end	Night	59% 5% 9% 15% 10% 3	1884
March	1st to 10th	Night	53% 5% 8% 21% 12% 1	3422
	11th to 20th	Night	47% 5% 11% 23% 14% 1	3480
	21st to end	Night	45% 5% 9% 24% 16% 2	3817
April	1st to 10th	Night	48% 6% 8% 20% 15% 3	2057
	11th to 20th	Night	42% 5% 12% 19% 15% 6%	1822
	21st to end	Night	45% 6% 11% 20% 16% 2	1710
May	1st to 10th	Night	60% 7% 8% 14% 9% 2	2840
	11th to 20th	Night	47% 8% 11% 21% 11% 2	2813
	21st to end	Night	39% 9% 16% 21% 11% 4	3087
June	1st to 10th	Night	35% 9% 13% 25% 15% 2	1710
	11th to 20th	Night	36% 11% 15% 19% 17% 2	1710
	21st to end	Night	36% 7% 16% 24% 16% 2	1710
July	1st to 10th	Night	39% 8% 13% 22% 15% 4	2795
	11th to 20th	Night	37% 8% 12% 27% 13% 2	2786
	21st to end	Night	45% 9% 10% 18% 15% 3	2988
August	1st to 10th	Night	44% 9% 15% 22% 8% 1	2814
	11th to 20th	Night	41% 6% 10% 22% 20% 1	2812
	21st to end	Night	30% 6% 12% 30% 19% 2	3269
September	1st to 10th	Night	34% 9% 12% 20% 19% 7%	2000
	11th to 20th	Night	32% 7% 12% 23% 23% 3	2090
	21st to end	Night	41% 5% 10% 23% 20% 1	2090
October	1st to 10th	Night	35% 6% 11% 24% 19% 3	2223
	11th to 20th	Night	39% 4 10% 23% 21% 3	2280
	21st to end	Night	45% 4 6% 24% 18% 3	2508
November	1st to 10th	Night	38% 5% 10% 21% 21% 6%	2332
	11th to 20th	Night	49% 4 8% 18% 17% 4	2470
	21st to end	Night	51% 4 10% 19% 14% 1	2507
December	1st to 10th	Night	63% 4 8% 18% 6% 1	2660
	11th to 20th	Night	60% 4 10% 17% 9% 1	3131
	21st to end	Night	64% 5% 9% 15% 6%	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	32% 26% 24% 14% 4 1	270
	11th to 20th	Day	39% 25% 28% 7% 1	270
	21st to end	Day	37% 25% 28% 8% 2 1	297
February	1st to 10th	Day	36% 20% 33% 7% 4	270
	11th to 20th	Day	45% 26% 22% 6% 1	270
	21st to end	Day	40% 24% 28% 8%	225
March	1st to 10th	Day	32% 19% 27% 18% 4	455
	11th to 20th	Day	27% 25% 28% 14% 4 1	460
	21st to end	Day	33% 18% 27% 17% 5%	506
April	1st to 10th	Day	31% 19% 24% 18% 7%	460
	11th to 20th	Day	25% 18% 28% 16% 8% 4	452
	21st to end	Day	29% 19% 26% 17% 7% 2	460
May	1st to 10th	Day	28% 16% 27% 16% 9% 4	463
	11th to 20th	Day	24% 11% 30% 20% 12% 4	487
	21st to end	Day	16% 8% 23% 28% 17% 8%	529
June	1st to 10th	Day	14% 9% 24% 30% 17% 6%	490
	11th to 20th	Day	13% 10% 26% 27% 18% 7%	490
	21st to end	Day	15% 9% 29% 27% 16% 5%	490
July	1st to 10th	Day	14% 6% 21% 26% 19% 15%	485
	11th to 20th	Day	10% 5% 22% 35% 18% 11%	484
	21st to end	Day	19% 5% 18% 28% 20% 9%	532
August	1st to 10th	Day	13% 5% 21% 31% 20% 10%	486
	11th to 20th	Day	13% 8% 20% 29% 20% 10%	479
	21st to end	Day	11% 5% 14% 32% 26% 12%	539
September	1st to 10th	Day	15% 6% 18% 29% 23% 9%	490
	11th to 20th	Day	13% 3 13% 31% 29% 11%	490
	21st to end	Day	22% 10% 24% 24% 15% 5%	490
October	1st to 10th	Day	17% 7% 26% 26% 20% 5%	490
	11th to 20th	Day	19% 14% 28% 21% 13% 4	490
	21st to end	Day	25% 14% 27% 23% 8% 2	539
November	1st to 10th	Day	20% 14% 29% 24% 10% 3	369
	11th to 20th	Day	29% 17% 25% 20% 7% 1	270
	21st to end	Day	25% 22% 31% 20% 2 1	248
December	1st to 10th	Day	34% 20% 27% 14% 4 1	180
	11th to 20th	Day	32% 21% 28% 14% 4	225
	21st to end	Day	35% 22% 25% 13% 5%	297
January	1st to 10th	Night	31% 18% 28% 19% 4	760
	11th to 20th	Night	34% 17% 27% 21% 3	760
	21st to end	Night	29% 18% 31% 20% 2	836
February	1st to 10th	Night	30% 14% 29% 25% 2	760
	11th to 20th	Night	34% 19% 28% 18% 1	743
	21st to end	Night	33% 15% 33% 17% 2	628
March	1st to 10th	Night	28% 15% 28% 25% 4	760
	11th to 20th	Night	28% 16% 29% 19% 7% 1	760
	21st to end	Night	27% 16% 29% 23% 5%	836
April	1st to 10th	Night	25% 16% 30% 21% 6%	760
	11th to 20th	Night	19% 13% 32% 25% 10% 1	698
	21st to end	Night	18% 10% 34% 29% 9% 1	570
May	1st to 10th	Night	21% 9% 28% 28% 13% 1	570
	11th to 20th	Night	20% 7% 27% 30% 14% 1	561
	21st to end	Night	15% 3 21% 32% 25% 3	617
June	1st to 10th	Night	10% 4 21% 39% 25% 1	570
	11th to 20th	Night	11% 3 21% 36% 26% 3	570
	21st to end	Night	14% 5% 18% 41% 21% 2	570
July	1st to 10th	Night	14% 3 16% 32% 30% 5%	555
	11th to 20th	Night	9% 3 14% 36% 33% 4	552
	21st to end	Night	12% 2 14% 35% 31% 5%	624
August	1st to 10th	Night	11% 3 10% 39% 33% 4	567
	11th to 20th	Night	11% 4 12% 38% 31% 5%	564
	21st to end	Night	13% 2 10% 35% 33% 6%	707
September	1st to 10th	Night	13% 3 15% 35% 30% 5%	760
	11th to 20th	Night	12% 3 16% 33% 33% 4	760
	21st to end	Night	19% 5% 21% 29% 23% 3	760
October	1st to 10th	Night	15% 6% 20% 30% 26% 3	760
	11th to 20th	Night	19% 8% 26% 30% 15% 2	760
	21st to end	Night	24% 10% 21% 31% 12% 1	836
November	1st to 10th	Night	17% 9% 25% 33% 15% 1	748
	11th to 20th	Night	27% 12% 26% 25% 9% 1	760
	21st to end	Night	25% 12% 26% 29% 7% 1	760
December	1st to 10th	Night	33% 15% 26% 21% 4	760
	11th to 20th	Night	26% 18% 26% 26% 5%	760
	21st to end	Night	31% 12% 28% 27% 2	836

Page generated at 2024-10-30 13:19:25. Version ac07

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