Palmetto State Park
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Palmetto 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	12% 6% 2 6% 5% 4 4 4 6% 8% 44%	101075
	Night	13% 6% 2 5% 4 3 4 3 5% 7% 49%	98204
Transparency	Day	37% 6% 11% 21% 17% 8%	104869
	Night	34% 5% 12% 21% 18% 10%	102537
Seeing	Day	13% 6% 18% 27% 26% 10%	14794
	Night	15% 6% 23% 36% 18% 2	24694

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	16% 9% 2 7% 4 3 3 2 4 5% 45%	2847
	11th to 20th	Day	18% 5% 2 4 2 2 2 2 4 6% 53%	2850
	21st to end	Day	22% 8% 2 4 3 3 3 3 6% 6% 40%	3304
February	1st to 10th	Day	22% 8% 2 5% 3 3 3 3 5% 5% 42%	1900
	11th to 20th	Day	20% 8% 3 6% 3 3 3 3 4 5% 42%	1849
	21st to end	Day	18% 8% 2 4 4 3 4 3 4 6% 45%	1588
March	1st to 10th	Day	15% 8% 3 8% 5% 5% 4 3 5% 7% 37%	3436
	11th to 20th	Day	19% 9% 4 9% 6% 6% 5% 3 4 5% 31%	3480
	21st to end	Day	17% 8% 2 5% 4 3 3 3 4 6% 45%	3814
April	1st to 10th	Day	14% 8% 2 6% 5% 4 3 4 5% 7% 41%	2090
	11th to 20th	Day	16% 8% 3 7% 5% 4 4 3 4 5% 41%	2066
	21st to end	Day	14% 7% 2 6% 5% 4 4 3 5% 6% 44%	2366
May	1st to 10th	Day	18% 8% 3 8% 5% 5% 5% 4 5% 7% 32%	4082
	11th to 20th	Day	13% 7% 3 7% 5% 4 5% 4 6% 7% 40%	4082
	21st to end	Day	8% 5% 2 6% 5% 5% 6% 4 8% 9% 41%	4477
June	1st to 10th	Day	5% 3 1 5% 5% 5% 6% 6% 8% 9% 46%	2470
	11th to 20th	Day	6% 3 1 6% 6% 5% 5% 5% 7% 10% 44%	2470
	21st to end	Day	6% 6% 2 7% 6% 6% 7% 6% 8% 11% 36%	2470
July	1st to 10th	Day	7% 5% 2 5% 6% 5% 5% 4 7% 9% 45%	4120
	11th to 20th	Day	6% 5% 2 7% 6% 5% 6% 5% 8% 11% 39%	4120
	21st to end	Day	11% 7% 3 7% 6% 6% 5% 5% 7% 11% 34%	4465
August	1st to 10th	Day	2 2 1 3 3 3 4 4 5% 9% 65%	4104
	11th to 20th	Day	3 2 1 4 3 4 6% 5% 8% 13% 50%	3796
	21st to end	Day	5% 4 2 5% 5% 6% 6% 5% 8% 11% 44%	3926
September	1st to 10th	Day	7% 6% 2 8% 6% 6% 5% 4 7% 7% 42%	2090
	11th to 20th	Day	9% 7% 3 7% 5% 5% 5% 4 6% 7% 41%	2090
	21st to end	Day	7% 4 2 6% 4 4 6% 4 6% 9% 48%	2090
October	1st to 10th	Day	6% 3 2 4 5% 4 4 4 6% 8% 54%	2090
	11th to 20th	Day	12% 5% 2 4 3 4 4 4 4 7% 50%	1931
	21st to end	Day	10% 5% 2 5% 3 3 4 3 4 5% 56%	2090
November	1st to 10th	Day	12% 8% 2 6% 4 4 4 3 5% 7% 44%	1958
	11th to 20th	Day	12% 6% 2 6% 4 3 3 3 4 6% 50%	1848
	21st to end	Day	18% 7% 3 6% 3 4 3 3 5% 6% 43%	1710
December	1st to 10th	Day	17% 8% 3 5% 5% 4 3 3 5% 6% 41%	1710
	11th to 20th	Day	17% 8% 3 6% 4 4 4 3 4 5% 42%	2161
	21st to end	Day	16% 7% 2 5% 3 3 3 3 4 5% 50%	3135
January	1st to 10th	Night	20% 7% 2 5% 3 3 2 2 3 6% 48%	4108
	11th to 20th	Night	14% 5% 2 3 2 1 2 2 2 4 61%	4120
	21st to end	Night	24% 7% 2 6% 3 3 3 2 4 7% 39%	4390
February	1st to 10th	Night	20% 7% 2 4 4 3 3 3 5% 5% 43%	2280
	11th to 20th	Night	20% 8% 2 4 3 2 2 2 3 6% 47%	2218
	21st to end	Night	22% 6% 2 4 4 3 3 3 5% 5% 43%	1865
March	1st to 10th	Night	21% 10% 2 6% 4 4 5% 3 5% 5% 35%	3419
	11th to 20th	Night	25% 10% 3 7% 5% 3 4 3 4 6% 30%	3480
	21st to end	Night	15% 8% 2 5% 4 3 4 3 5% 5% 47%	3817
April	1st to 10th	Night	13% 7% 2 6% 4 4 4 3 6% 7% 44%	2090
	11th to 20th	Night	16% 8% 3 5% 4 3 3 3 5% 7% 43%	2063
	21st to end	Night	14% 8% 3 6% 5% 3 3 3 4 7% 44%	1807
May	1st to 10th	Night	24% 9% 3 6% 4 3 3 3 5% 6% 35%	2823
	11th to 20th	Night	13% 6% 2 6% 4 4 5% 3 6% 7% 45%	2823
	21st to end	Night	11% 7% 2 6% 4 4 5% 4 6% 11% 40%	3090
June	1st to 10th	Night	5% 4 1 4 4 3 4 3 6% 9% 57%	1710
	11th to 20th	Night	4 3 1 3 4 4 4 3 7% 9% 57%	1710
	21st to end	Night	6% 6% 1 4 4 5% 5% 5% 6% 8% 49%	1710
July	1st to 10th	Night	5% 4 1 5% 4 4 4 5% 7% 9% 53%	2850
	11th to 20th	Night	5% 4 2 6% 4 4 5% 4 7% 11% 48%	2850
	21st to end	Night	8% 6% 2 7% 5% 4 4 4 7% 11% 41%	3098
August	1st to 10th	Night	1 1 2 2 2 2 3 4 8% 75%	2836
	11th to 20th	Night	2 2 1 3 3 3 5% 5% 8% 10% 59%	3039
	21st to end	Night	5% 3 1 4 2 3 4 4 7% 12% 56%	3730
September	1st to 10th	Night	7% 5% 2 6% 4 4 4 4 5% 9% 50%	2090
	11th to 20th	Night	8% 5% 2 5% 4 5% 4 4 6% 8% 48%	2090
	21st to end	Night	7% 3 2 5% 4 5% 4 3 6% 8% 53%	2090
October	1st to 10th	Night	4 3 2 3 4 3 3 3 5% 8% 62%	2090
	11th to 20th	Night	11% 4 2 5% 3 3 4 3 4 6% 56%	2228
	21st to end	Night	11% 5% 1 4 3 2 3 2 3 4 61%	2508
November	1st to 10th	Night	13% 6% 2 6% 3 3 4 2 4 6% 51%	2340
	11th to 20th	Night	11% 6% 2 5% 4 3 3 3 4 5% 54%	2334
	21st to end	Night	16% 6% 2 6% 4 3 4 2 4 6% 46%	2470
December	1st to 10th	Night	17% 7% 2 5% 4 3 3 2 4 5% 47%	2470
	11th to 20th	Night	18% 8% 3 5% 4 3 3 3 4 6% 42%	3036
	21st to end	Night	17% 7% 2 4 2 3 3 3 3 5% 51%	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	43% 4 4 13% 24% 12%	2848
	11th to 20th	Day	33% 2 7% 19% 24% 14%	2850
	21st to end	Day	44% 4 4 11% 27% 10%	3304
February	1st to 10th	Day	45% 4 6% 12% 20% 14%	1900
	11th to 20th	Day	44% 4 6% 17% 17% 12%	1859
	21st to end	Day	41% 5% 8% 16% 17% 13%	1588
March	1st to 10th	Day	46% 5% 9% 17% 16% 7%	3436
	11th to 20th	Day	55% 6% 6% 9% 16% 8%	3480
	21st to end	Day	40% 4 9% 17% 20% 10%	3814
April	1st to 10th	Day	42% 6% 8% 16% 16% 12%	2090
	11th to 20th	Day	45% 4 7% 15% 17% 11%	2066
	21st to end	Day	41% 6% 6% 20% 18% 9%	2366
May	1st to 10th	Day	49% 8% 10% 17% 11% 5%	4120
	11th to 20th	Day	41% 8% 9% 17% 20% 6%	4086
	21st to end	Day	33% 8% 14% 32% 11% 1	4489
June	1st to 10th	Day	28% 10% 14% 26% 20% 2	2470
	11th to 20th	Day	32% 7% 15% 24% 19% 4	2470
	21st to end	Day	39% 8% 15% 24% 12% 2	2470
July	1st to 10th	Day	33% 6% 21% 33% 6% 1	4056
	11th to 20th	Day	37% 7% 19% 25% 12% 1	4051
	21st to end	Day	42% 8% 17% 26% 6%	4325
August	1st to 10th	Day	16% 6% 11% 44% 22% 1	4090
	11th to 20th	Day	23% 6% 28% 33% 8% 2	3834
	21st to end	Day	31% 9% 19% 23% 16% 1	3925
September	1st to 10th	Day	39% 7% 13% 19% 15% 7%	2090
	11th to 20th	Day	40% 8% 12% 18% 17% 5%	2090
	21st to end	Day	31% 6% 12% 21% 16% 14%	2090
October	1st to 10th	Day	18% 4 7% 13% 22% 37%	3480
	11th to 20th	Day	23% 4 8% 19% 27% 19%	3184
	21st to end	Day	28% 4 6% 19% 27% 16%	3428
November	1st to 10th	Day	38% 6% 9% 18% 18% 11%	1958
	11th to 20th	Day	35% 4 11% 17% 19% 14%	1848
	21st to end	Day	44% 4 8% 14% 19% 12%	1710
December	1st to 10th	Day	44% 4 8% 18% 19% 7%	1710
	11th to 20th	Day	43% 5% 7% 10% 21% 13%	2159
	21st to end	Day	38% 3 5% 18% 23% 13%	3135
January	1st to 10th	Night	39% 3 7% 14% 19% 18%	4108
	11th to 20th	Night	29% 2 6% 17% 30% 16%	4120
	21st to end	Night	47% 3 4 12% 24% 10%	4390
February	1st to 10th	Night	43% 4 7% 12% 18% 16%	2280
	11th to 20th	Night	42% 3 7% 17% 19% 14%	2218
	21st to end	Night	43% 5% 6% 16% 16% 14%	1865
March	1st to 10th	Night	50% 5% 9% 15% 14% 7%	3419
	11th to 20th	Night	55% 7% 8% 12% 11% 7%	3480
	21st to end	Night	39% 6% 10% 15% 20% 10%	3817
April	1st to 10th	Night	38% 5% 10% 19% 16% 12%	2090
	11th to 20th	Night	40% 4 10% 15% 15% 15%	2063
	21st to end	Night	41% 5% 9% 20% 16% 9%	1807
May	1st to 10th	Night	49% 7% 9% 19% 11% 6%	2850
	11th to 20th	Night	37% 7% 12% 20% 18% 7%	2824
	21st to end	Night	35% 8% 17% 30% 9%	3099
June	1st to 10th	Night	23% 7% 18% 29% 22% 2	1710
	11th to 20th	Night	22% 5% 15% 32% 20% 4	1710
	21st to end	Night	30% 8% 18% 28% 13% 2	1710
July	1st to 10th	Night	25% 7% 24% 37% 5%	2805
	11th to 20th	Night	30% 7% 22% 28% 13%	2796
	21st to end	Night	36% 7% 24% 26% 6%	2999
August	1st to 10th	Night	10% 4 17% 48% 19%	2826
	11th to 20th	Night	18% 7% 34% 33% 6% 1	3067
	21st to end	Night	21% 11% 26% 28% 13% 2	3730
September	1st to 10th	Night	30% 8% 19% 22% 14% 7%	2090
	11th to 20th	Night	32% 9% 16% 23% 16% 5%	2090
	21st to end	Night	28% 5% 17% 21% 16% 13%	2090
October	1st to 10th	Night	14% 4 7% 17% 20% 38%	3480
	11th to 20th	Night	19% 3 9% 18% 28% 22%	3701
	21st to end	Night	21% 3 5% 25% 29% 17%	4120
November	1st to 10th	Night	35% 5% 9% 19% 20% 13%	2340
	11th to 20th	Night	33% 5% 10% 18% 20% 14%	2334
	21st to end	Night	39% 4 9% 16% 18% 13%	2470
December	1st to 10th	Night	39% 4 7% 21% 18% 11%	2470
	11th to 20th	Night	43% 4 6% 11% 19% 16%	3037
	21st to end	Night	37% 3 6% 14% 28% 12%	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	22% 9% 35% 23% 10% 1	270
	11th to 20th	Day	24% 11% 24% 28% 10% 2	270
	21st to end	Day	22% 11% 32% 24% 11%	297
February	1st to 10th	Day	29% 14% 24% 23% 10% 1	270
	11th to 20th	Day	25% 14% 31% 20% 8% 1	270
	21st to end	Day	27% 11% 38% 22% 2	225
March	1st to 10th	Day	23% 10% 37% 23% 7% 1	270
	11th to 20th	Day	16% 11% 43% 23% 6% 1	270
	21st to end	Day	20% 10% 35% 27% 7% 1	297
April	1st to 10th	Day	18% 12% 38% 23% 9%	270
	11th to 20th	Day	18% 13% 31% 26% 9% 2	264
	21st to end	Day	18% 10% 33% 26% 11% 1	546
May	1st to 10th	Day	16% 10% 35% 29% 10% 1	653
	11th to 20th	Day	15% 6% 24% 35% 18% 2	675
	21st to end	Day	11% 5% 24% 35% 22% 3	734
June	1st to 10th	Day	6% 2 11% 37% 34% 9%	680
	11th to 20th	Day	6% 2 11% 40% 33% 7%	680
	21st to end	Day	6% 3 8% 32% 35% 15%	680
July	1st to 10th	Day	7% 2 6% 27% 40% 18%	671
	11th to 20th	Day	5% 1 4 22% 50% 18%	668
	21st to end	Day	4 2 4 27% 45% 18%	739
August	1st to 10th	Day	2 2 2 22% 48% 24%	676
	11th to 20th	Day	5% 1 3 25% 41% 26%	523
	21st to end	Day	6% 3 5% 18% 31% 38%	389
September	1st to 10th	Day	7% 2 5% 20% 38% 28%	300
	11th to 20th	Day	6% 2 3 20% 40% 31%	300
	21st to end	Day	9% 1 4 24% 38% 24%	300
October	1st to 10th	Day	7% 1 9% 27% 37% 18%	300
	11th to 20th	Day	10% 4 14% 30% 31% 11%	300
	21st to end	Day	15% 8% 23% 22% 23% 8%	330
November	1st to 10th	Day	18% 5% 18% 34% 18% 7%	300
	11th to 20th	Day	18% 5% 21% 31% 21% 4	270
	21st to end	Day	25% 10% 30% 20% 12% 3	270
December	1st to 10th	Day	21% 7% 23% 30% 13% 6%	270
	11th to 20th	Day	22% 13% 24% 29% 12%	270
	21st to end	Day	22% 9% 31% 25% 11% 2	297
January	1st to 10th	Night	22% 7% 29% 32% 9%	950
	11th to 20th	Night	21% 10% 27% 33% 8%	950
	21st to end	Night	24% 7% 27% 35% 7%	955
February	1st to 10th	Night	26% 10% 28% 31% 5%	760
	11th to 20th	Night	25% 10% 32% 30% 4	744
	21st to end	Night	27% 12% 35% 23% 3	609
March	1st to 10th	Night	23% 11% 33% 31% 3	570
	11th to 20th	Night	22% 7% 36% 29% 5%	570
	21st to end	Night	17% 9% 39% 30% 4	627
April	1st to 10th	Night	16% 9% 44% 28% 3	570
	11th to 20th	Night	18% 9% 37% 31% 6%	563
	21st to end	Night	18% 8% 42% 24% 8%	570
May	1st to 10th	Night	16% 9% 42% 28% 5%	570
	11th to 20th	Night	14% 5% 33% 38% 10% 1	561
	21st to end	Night	11% 3 34% 38% 14%	617
June	1st to 10th	Night	5% 3 16% 52% 22% 1	570
	11th to 20th	Night	5% 1 25% 50% 17% 1	570
	21st to end	Night	6% 3 12% 44% 31% 5%	570
July	1st to 10th	Night	6% 3 8% 45% 32% 5%	555
	11th to 20th	Night	3 1 9% 47% 36% 4	552
	21st to end	Night	5% 8% 45% 37% 5%	624
August	1st to 10th	Night	1 1 6% 50% 38% 4	567
	11th to 20th	Night	4 1 5% 49% 38% 4	564
	21st to end	Night	7% 1 4 36% 46% 6%	627
September	1st to 10th	Night	9% 1 5% 35% 44% 5%	570
	11th to 20th	Night	10% 2 4 36% 44% 4	570
	21st to end	Night	9% 1 11% 35% 41% 4	570
October	1st to 10th	Night	4 1 9% 46% 35% 4	570
	11th to 20th	Night	12% 4 19% 42% 22% 2	708
	21st to end	Night	12% 7% 25% 33% 21% 2	836
November	1st to 10th	Night	14% 5% 19% 41% 19% 1	780
	11th to 20th	Night	14% 5% 24% 39% 16% 2	810
	21st to end	Night	19% 8% 27% 31% 14% 1	950
December	1st to 10th	Night	21% 7% 23% 37% 12% 1	950
	11th to 20th	Night	25% 9% 26% 32% 8%	950
	21st to end	Night	21% 8% 26% 37% 9% 1	1045

Page generated at 2024-11-08 05:44:51. Version ac07

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