Enchanted Rock State Natural Area
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Enchanted Rock State Natural Area clear sky chart from 2005-11-06 to 2024-09-14.

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	9% 5% 2 5% 4 4 4 4 5% 7% 52%	100454
	Night	9% 4 1 4 3 3 4 3 5% 7% 56%	97565
Transparency	Day	32% 6% 11% 22% 20% 10%	100265
	Night	29% 6% 11% 21% 21% 12%	97425
Seeing	Day	11% 8% 24% 32% 20% 5%	14714
	Night	11% 8% 31% 37% 13% 1	24597

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	10% 10% 2 4 2 2 2 3 3 6% 57%	2847
	11th to 20th	Day	13% 5% 1 3 2 3 3 3 4 5% 58%	2850
	21st to end	Day	14% 6% 2 5% 3 3 3 2 4 7% 50%	3427
February	1st to 10th	Day	14% 6% 2 6% 3 2 3 2 4 6% 51%	1900
	11th to 20th	Day	13% 6% 2 5% 3 2 4 3 4 7% 50%	1849
	21st to end	Day	14% 6% 1 5% 3 3 3 2 4 6% 53%	1570
March	1st to 10th	Day	12% 7% 3 6% 4 4 3 3 4 6% 48%	3314
	11th to 20th	Day	18% 6% 2 7% 5% 4 5% 4 5% 6% 38%	3480
	21st to end	Day	9% 5% 2 5% 4 4 5% 4 6% 7% 50%	3814
April	1st to 10th	Day	10% 6% 2 6% 5% 3 3 3 5% 7% 48%	2090
	11th to 20th	Day	15% 6% 2 6% 4 3 4 3 4 6% 47%	2154
	21st to end	Day	10% 5% 2 5% 5% 4 3 3 4 5% 52%	2384
May	1st to 10th	Day	15% 5% 2 7% 5% 5% 4 4 7% 8% 38%	4082
	11th to 20th	Day	13% 6% 2 6% 4 4 4 4 5% 5% 47%	4082
	21st to end	Day	9% 5% 1 5% 5% 5% 6% 5% 7% 8% 42%	4477
June	1st to 10th	Day	4 3 1 4 4 4 5% 4 7% 9% 54%	2470
	11th to 20th	Day	5% 4 1 4 3 4 5% 4 6% 10% 55%	2470
	21st to end	Day	6% 4 1 4 4 5% 6% 5% 7% 10% 48%	2470
July	1st to 10th	Day	6% 3 1 4 5% 5% 6% 4 7% 9% 50%	4120
	11th to 20th	Day	3 3 1 3 3 4 4 4 6% 10% 58%	4120
	21st to end	Day	7% 4 2 5% 4 4 6% 4 8% 11% 45%	4465
August	1st to 10th	Day	1 1 1 2 2 3 2 3 5% 9% 71%	3986
	11th to 20th	Day	4 2 1 3 3 3 3 3 5% 9% 62%	3726
	21st to end	Day	3 2 1 5% 5% 5% 5% 6% 7% 10% 49%	4091
September	1st to 10th	Day	10% 5% 1 7% 5% 4 4 3 5% 7% 49%	2090
	11th to 20th	Day	11% 5% 2 6% 4 3 5% 5% 6% 7% 46%	2013
	21st to end	Day	9% 3 1 5% 3 4 5% 4 6% 8% 53%	1980
October	1st to 10th	Day	6% 4 2 4 3 3 3 3 5% 8% 59%	1980
	11th to 20th	Day	11% 5% 1 4 3 3 3 3 4 5% 57%	1900
	21st to end	Day	11% 4 2 3 3 3 2 3 4 4 61%	1980
November	1st to 10th	Day	11% 6% 1 5% 3 3 3 4 5% 6% 53%	1847
	11th to 20th	Day	8% 4 2 4 4 3 3 4 5% 7% 56%	1710
	21st to end	Day	14% 5% 2 5% 4 4 4 2 3 5% 52%	1710
December	1st to 10th	Day	13% 6% 2 4 2 3 3 2 6% 7% 53%	1710
	11th to 20th	Day	12% 6% 2 6% 4 3 3 3 6% 6% 49%	2161
	21st to end	Day	11% 6% 2 4 2 3 2 2 4 4 59%	3135
January	1st to 10th	Night	12% 7% 2 4 2 3 2 2 3 5% 57%	4108
	11th to 20th	Night	11% 4 1 3 2 1 2 2 3 4 67%	4120
	21st to end	Night	15% 7% 2 5% 3 3 3 2 3 7% 49%	4267
February	1st to 10th	Night	12% 6% 2 5% 4 3 3 3 5% 5% 53%	2280
	11th to 20th	Night	14% 6% 2 4 3 3 3 2 4 7% 53%	2218
	21st to end	Night	13% 6% 2 4 3 3 4 3 5% 7% 51%	1884
March	1st to 10th	Night	9% 6% 2 5% 4 4 4 3 6% 8% 48%	3542
	11th to 20th	Night	17% 6% 2 5% 4 5% 5% 4 5% 7% 40%	3480
	21st to end	Night	8% 6% 2 5% 4 4 4 3 5% 7% 52%	3817
April	1st to 10th	Night	8% 4 1 4 4 4 4 4 7% 7% 53%	2090
	11th to 20th	Night	11% 5% 2 4 4 4 3 3 5% 6% 51%	1970
	21st to end	Night	10% 4 2 4 4 3 3 4 5% 8% 54%	1796
May	1st to 10th	Night	16% 6% 2 4 4 3 3 3 6% 8% 45%	2823
	11th to 20th	Night	9% 5% 1 5% 4 3 4 3 5% 7% 54%	2823
	21st to end	Night	9% 4 1 5% 4 4 5% 4 7% 10% 48%	3090
June	1st to 10th	Night	3 2 1 3 2 4 3 4 6% 11% 63%	1710
	11th to 20th	Night	3 2 1 3 2 2 3 4 7% 8% 65%	1710
	21st to end	Night	4 4 1 3 3 3 4 4 6% 9% 60%	1710
July	1st to 10th	Night	4 3 1 4 3 3 4 3 6% 9% 59%	2850
	11th to 20th	Night	2 2 1 3 2 3 3 3 5% 9% 67%	2850
	21st to end	Night	3 3 1 4 3 4 5% 5% 8% 12% 52%	3098
August	1st to 10th	Night	1 1 1 2 2 2 2 3 4 7% 76%	2949
	11th to 20th	Night	3 2 1 3 2 3 4 4 6% 9% 65%	3113
	21st to end	Night	3 3 1 4 3 3 4 4 8% 11% 57%	3570
September	1st to 10th	Night	8% 4 1 4 2 4 4 4 7% 9% 53%	2090
	11th to 20th	Night	10% 4 1 4 3 4 4 4 6% 10% 48%	2024
	21st to end	Night	8% 3 1 3 3 3 4 4 6% 7% 57%	1980
October	1st to 10th	Night	4 2 1 3 2 3 3 3 5% 7% 67%	1980
	11th to 20th	Night	11% 3 1 4 3 3 3 3 5% 7% 58%	2042
	21st to end	Night	11% 5% 1 4 2 3 2 3 3 4 62%	2376
November	1st to 10th	Night	10% 4 1 4 3 2 3 2 4 7% 60%	2227
	11th to 20th	Night	7% 4 1 4 3 3 4 3 5% 7% 60%	2470
	21st to end	Night	14% 5% 1 4 3 3 4 4 4 7% 50%	2470
December	1st to 10th	Night	11% 5% 2 3 3 3 3 3 5% 6% 55%	2470
	11th to 20th	Night	10% 8% 2 6% 3 4 4 3 5% 5% 49%	3036
	21st to end	Night	10% 5% 2 5% 3 3 3 2 4 5% 58%	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	31% 4 3 16% 27% 19%	2848
	11th to 20th	Day	30% 3 6% 13% 32% 16%	2850
	21st to end	Day	36% 3 7% 12% 29% 13%	3427
February	1st to 10th	Day	37% 3 7% 13% 21% 19%	1900
	11th to 20th	Day	35% 5% 6% 19% 18% 17%	1859
	21st to end	Day	34% 4 5% 17% 22% 18%	1570
March	1st to 10th	Day	39% 4 7% 13% 20% 17%	3314
	11th to 20th	Day	47% 6% 10% 10% 16% 10%	3480
	21st to end	Day	33% 6% 10% 16% 20% 14%	3814
April	1st to 10th	Day	37% 5% 8% 18% 18% 14%	2090
	11th to 20th	Day	40% 4 8% 16% 21% 12%	2154
	21st to end	Day	36% 5% 6% 22% 21% 10%	2384
May	1st to 10th	Day	43% 7% 13% 13% 17% 7%	4120
	11th to 20th	Day	38% 6% 8% 16% 21% 10%	4086
	21st to end	Day	36% 9% 13% 26% 13% 4	4489
June	1st to 10th	Day	26% 7% 14% 28% 21% 4	2470
	11th to 20th	Day	26% 7% 12% 27% 22% 6%	2470
	21st to end	Day	29% 10% 14% 23% 19% 6%	2470
July	1st to 10th	Day	30% 7% 17% 38% 9% 1	4056
	11th to 20th	Day	21% 5% 15% 36% 18% 4	4051
	21st to end	Day	28% 7% 19% 32% 14% 1	4325
August	1st to 10th	Day	12% 4 11% 38% 32% 1	3972
	11th to 20th	Day	19% 5% 21% 38% 14% 3	3762
	21st to end	Day	28% 7% 19% 24% 19% 3	4090
September	1st to 10th	Day	36% 7% 10% 21% 18% 10%	2090
	11th to 20th	Day	37% 8% 12% 18% 18% 6%	2013
	21st to end	Day	29% 7% 10% 21% 21% 11%	1980
October	1st to 10th	Day	25% 6% 12% 21% 27% 11%	1980
	11th to 20th	Day	31% 5% 7% 15% 24% 18%	1900
	21st to end	Day	28% 4 5% 17% 26% 21%	1980
November	1st to 10th	Day	34% 5% 8% 20% 22% 11%	1847
	11th to 20th	Day	29% 6% 9% 18% 22% 17%	1710
	21st to end	Day	38% 3 5% 17% 22% 15%	1710
December	1st to 10th	Day	33% 3 8% 21% 24% 10%	1710
	11th to 20th	Day	36% 5% 8% 12% 22% 17%	2159
	21st to end	Day	31% 3 5% 14% 28% 19%	3135
January	1st to 10th	Night	32% 3 3 14% 28% 20%	4108
	11th to 20th	Night	24% 2 4 17% 28% 25%	4120
	21st to end	Night	39% 4 5% 12% 27% 14%	4267
February	1st to 10th	Night	35% 4 7% 12% 22% 20%	2280
	11th to 20th	Night	35% 5% 5% 16% 21% 17%	2218
	21st to end	Night	36% 5% 6% 13% 22% 20%	1884
March	1st to 10th	Night	34% 7% 8% 15% 23% 13%	3542
	11th to 20th	Night	44% 6% 10% 13% 16% 11%	3480
	21st to end	Night	33% 6% 10% 18% 19% 14%	3817
April	1st to 10th	Night	31% 6% 10% 19% 18% 16%	2090
	11th to 20th	Night	35% 6% 10% 14% 20% 16%	1970
	21st to end	Night	33% 6% 9% 21% 21% 10%	1796
May	1st to 10th	Night	40% 8% 9% 19% 13% 10%	2850
	11th to 20th	Night	31% 6% 12% 22% 18% 11%	2824
	21st to end	Night	32% 7% 15% 28% 13% 5%	3099
June	1st to 10th	Night	17% 8% 16% 33% 22% 3	1710
	11th to 20th	Night	17% 6% 17% 31% 23% 7%	1710
	21st to end	Night	22% 7% 15% 31% 21% 4	1710
July	1st to 10th	Night	22% 7% 24% 39% 8% 1	2805
	11th to 20th	Night	17% 5% 20% 37% 19% 2	2796
	21st to end	Night	21% 6% 25% 36% 11%	2999
August	1st to 10th	Night	10% 4 14% 39% 33% 1	2939
	11th to 20th	Night	16% 6% 27% 36% 13% 2	3143
	21st to end	Night	21% 9% 23% 25% 20% 2	3570
September	1st to 10th	Night	27% 8% 14% 23% 19% 9%	2090
	11th to 20th	Night	31% 9% 15% 23% 16% 6%	2024
	21st to end	Night	27% 7% 13% 21% 21% 12%	1980
October	1st to 10th	Night	18% 6% 15% 26% 23% 12%	1980
	11th to 20th	Night	28% 5% 9% 16% 23% 19%	2042
	21st to end	Night	29% 4 5% 16% 23% 22%	2376
November	1st to 10th	Night	28% 5% 7% 20% 24% 15%	2227
	11th to 20th	Night	25% 6% 7% 22% 22% 18%	2470
	21st to end	Night	36% 4 8% 15% 21% 16%	2470
December	1st to 10th	Night	30% 5% 9% 19% 24% 13%	2470
	11th to 20th	Night	38% 4 6% 13% 20% 20%	3037
	21st to end	Night	32% 4 4 14% 29% 17%	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	16% 16% 38% 24% 5% 1	270
	11th to 20th	Day	21% 13% 32% 26% 7% 1	270
	21st to end	Day	14% 16% 40% 23% 6%	297
February	1st to 10th	Day	21% 18% 32% 23% 6%	270
	11th to 20th	Day	21% 20% 36% 20% 4	270
	21st to end	Day	21% 20% 39% 18% 3	225
March	1st to 10th	Day	17% 17% 41% 21% 4	270
	11th to 20th	Day	18% 17% 39% 20% 6%	270
	21st to end	Day	13% 21% 45% 17% 4	297
April	1st to 10th	Day	14% 21% 42% 19% 3	270
	11th to 20th	Day	16% 20% 39% 19% 5%	352
	21st to end	Day	14% 15% 44% 20% 6%	564
May	1st to 10th	Day	12% 14% 39% 28% 7%	653
	11th to 20th	Day	16% 10% 33% 28% 10% 2	675
	21st to end	Day	13% 7% 30% 36% 14% 1	734
June	1st to 10th	Day	5% 2 23% 42% 24% 4	680
	11th to 20th	Day	5% 2 19% 52% 18% 4	680
	21st to end	Day	5% 1 13% 44% 30% 6%	680
July	1st to 10th	Day	6% 2 10% 39% 33% 11%	671
	11th to 20th	Day	4 1 6% 42% 41% 7%	668
	21st to end	Day	3 1 6% 40% 38% 12%	739
August	1st to 10th	Day	2 4 41% 40% 12%	610
	11th to 20th	Day	7% 2 6% 35% 38% 12%	477
	21st to end	Day	4 1 5% 30% 42% 17%	489
September	1st to 10th	Day	11% 7% 24% 40% 18%	300
	11th to 20th	Day	6% 6% 30% 42% 15%	279
	21st to end	Day	11% 1 6% 32% 37% 14%	270
October	1st to 10th	Day	5% 3 12% 36% 36% 7%	270
	11th to 20th	Day	11% 5% 23% 35% 22% 3	270
	21st to end	Day	21% 13% 25% 25% 16%	297
November	1st to 10th	Day	19% 5% 27% 36% 11% 3	270
	11th to 20th	Day	13% 14% 27% 31% 10% 4	270
	21st to end	Day	21% 17% 33% 20% 6% 3	270
December	1st to 10th	Day	16% 8% 33% 30% 11% 3	270
	11th to 20th	Day	15% 16% 39% 23% 7%	270
	21st to end	Day	17% 13% 35% 26% 8%	297
January	1st to 10th	Night	15% 9% 39% 30% 7%	950
	11th to 20th	Night	16% 11% 36% 32% 5%	950
	21st to end	Night	16% 11% 37% 30% 6%	884
February	1st to 10th	Night	16% 12% 41% 26% 5%	760
	11th to 20th	Night	17% 13% 43% 25% 3	744
	21st to end	Night	16% 17% 46% 20% 1	628
March	1st to 10th	Night	14% 16% 40% 28% 1	646
	11th to 20th	Night	15% 11% 42% 28% 4	570
	21st to end	Night	9% 14% 51% 23% 3	627
April	1st to 10th	Night	8% 13% 52% 24% 3	570
	11th to 20th	Night	14% 13% 49% 21% 3	563
	21st to end	Night	11% 10% 53% 20% 6%	570
May	1st to 10th	Night	10% 13% 47% 27% 4	570
	11th to 20th	Night	10% 8% 41% 30% 9% 1	561
	21st to end	Night	8% 7% 40% 34% 11%	617
June	1st to 10th	Night	2 1 28% 50% 19% 1	570
	11th to 20th	Night	4 1 36% 48% 11%	570
	21st to end	Night	4 2 20% 52% 20% 2	570
July	1st to 10th	Night	4 2 12% 53% 26% 2	555
	11th to 20th	Night	3 1 12% 58% 25% 1	552
	21st to end	Night	2 11% 59% 25% 3	624
August	1st to 10th	Night	1 7% 59% 30% 2	567
	11th to 20th	Night	5% 1 7% 55% 30% 2	564
	21st to end	Night	4 1 7% 52% 31% 5%	627
September	1st to 10th	Night	9% 1 10% 45% 30% 5%	570
	11th to 20th	Night	11% 9% 42% 35% 3	552
	21st to end	Night	8% 1 14% 47% 29% 1	540
October	1st to 10th	Night	5% 2 16% 50% 25% 1	540
	11th to 20th	Night	12% 3 25% 44% 14% 1	602
	21st to end	Night	13% 10% 31% 29% 16% 1	792
November	1st to 10th	Night	11% 5% 27% 42% 14% 1	747
	11th to 20th	Night	8% 8% 33% 37% 13% 1	950
	21st to end	Night	16% 10% 33% 31% 9% 1	950
December	1st to 10th	Night	13% 7% 33% 37% 8%	950
	11th to 20th	Night	16% 11% 35% 33% 5%	950
	21st to end	Night	13% 12% 37% 32% 7%	1045

Page generated at 2024-09-11 09:00:05. Version ac07

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