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 2026-06-16.

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	10% 5% 2 5% 4 4 4 4 5% 7% 51%	137779
	Night	9% 5% 2 4 3 3 4 3 5% 7% 55%	134621
Transparency	Day	32% 5% 10% 21% 21% 12%	141584
	Night	29% 5% 11% 21% 21% 14%	138883
Seeing	Day	11% 8% 24% 32% 20% 5%	16986
	Night	11% 8% 32% 36% 13% 1	26940

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	9% 7% 3 4 2 3 3 3 4 6% 58%	5289
	11th to 20th	Day	11% 5% 1 4 3 3 3 3 4 5% 58%	5310
	21st to end	Day	18% 7% 2 6% 4 3 3 2 4 6% 45%	6366
February	1st to 10th	Day	14% 6% 2 5% 3 3 3 2 4 6% 52%	2100
	11th to 20th	Day	13% 6% 2 5% 3 2 4 3 5% 7% 50%	2049
	21st to end	Day	13% 6% 2 5% 3 2 3 2 4 6% 55%	1730
March	1st to 10th	Day	9% 6% 2 5% 3 3 3 3 4 6% 56%	4868
	11th to 20th	Day	12% 4 1 5% 3 3 3 3 4 5% 55%	5090
	21st to end	Day	9% 5% 2 5% 3 4 5% 4 6% 6% 52%	5583
April	1st to 10th	Day	10% 7% 2 7% 5% 3 4 3 5% 7% 46%	2310
	11th to 20th	Day	15% 7% 2 6% 4 3 4 3 5% 6% 46%	2384
	21st to end	Day	10% 6% 2 6% 5% 5% 3 4 4 5% 50%	2635
May	1st to 10th	Day	15% 5% 2 6% 4 4 4 4 6% 9% 40%	7617
	11th to 20th	Day	10% 6% 2 7% 4 4 5% 4 6% 8% 43%	7627
	21st to end	Day	11% 6% 2 6% 5% 5% 5% 5% 7% 9% 39%	8392
June	1st to 10th	Day	5% 3 1 5% 4 5% 5% 4 7% 9% 52%	2730
	11th to 20th	Day	5% 4 1 4 3 4 5% 4 7% 10% 54%	2666
	21st to end	Day	6% 4 1 4 4 5% 6% 5% 7% 10% 49%	2600
July	1st to 10th	Day	12% 6% 2 6% 5% 5% 5% 4 6% 9% 39%	5900
	11th to 20th	Day	3 3 1 4 4 4 5% 4 7% 11% 53%	5900
	21st to end	Day	5% 4 2 5% 3 4 5% 4 7% 11% 50%	6422
August	1st to 10th	Day	1 1 1 2 2 3 2 3 5% 9% 71%	4112
	11th to 20th	Day	4 2 1 3 3 3 4 3 5% 9% 62%	3846
	21st to end	Day	3 2 1 5% 5% 5% 5% 6% 7% 10% 50%	4220
September	1st to 10th	Day	10% 5% 1 7% 5% 4 4 3 5% 7% 49%	2200
	11th to 20th	Day	10% 5% 2 6% 4 3 5% 4 6% 8% 47%	2200
	21st to end	Day	8% 3 1 5% 3 4 5% 4 6% 8% 54%	2200
October	1st to 10th	Day	5% 4 2 3 3 3 3 3 5% 7% 61%	2200
	11th to 20th	Day	10% 4 1 4 3 3 3 3 4 6% 59%	2110
	21st to end	Day	10% 4 1 3 3 3 2 3 4 4 63%	2200
November	1st to 10th	Day	11% 5% 2 5% 3 3 3 3 5% 6% 54%	2045
	11th to 20th	Day	8% 3 2 4 3 3 3 4 5% 6% 59%	1890
	21st to end	Day	13% 5% 2 5% 4 3 4 2 3 6% 52%	1890
December	1st to 10th	Day	19% 8% 3 6% 3 3 3 2 4 5% 44%	3030
	11th to 20th	Day	10% 6% 3 7% 4 4 4 3 6% 6% 46%	3481
	21st to end	Day	9% 5% 2 4 2 3 2 2 4 5% 62%	4587
January	1st to 10th	Night	10% 5% 2 4 3 3 2 2 4 5% 59%	7634
	11th to 20th	Night	8% 3 1 3 2 2 2 2 5% 6% 67%	7680
	21st to end	Night	20% 8% 2 6% 3 3 3 2 3 5% 44%	7889
February	1st to 10th	Night	11% 6% 2 4 4 2 3 3 5% 5% 55%	2520
	11th to 20th	Night	13% 6% 2 5% 3 2 3 2 4 7% 53%	2458
	21st to end	Night	12% 6% 1 4 3 3 4 3 5% 7% 52%	2076
March	1st to 10th	Night	8% 5% 2 4 3 4 4 3 7% 9% 51%	5212
	11th to 20th	Night	12% 4 1 4 3 4 4 3 4 5% 55%	5090
	21st to end	Night	9% 6% 2 5% 3 3 3 3 6% 8% 54%	5588
April	1st to 10th	Night	8% 4 1 5% 4 4 4 4 6% 7% 52%	2310
	11th to 20th	Night	10% 5% 2 5% 4 4 4 3 6% 7% 50%	2180
	21st to end	Night	10% 5% 2 4 4 3 3 4 5% 9% 51%	1984
May	1st to 10th	Night	17% 6% 2 5% 4 3 4 3 5% 8% 43%	5266
	11th to 20th	Night	6% 5% 2 6% 5% 5% 6% 4 6% 8% 48%	5265
	21st to end	Night	9% 5% 2 6% 4 5% 4 4 7% 11% 42%	5793
June	1st to 10th	Night	2 2 1 3 2 4 4 4 7% 11% 61%	1890
	11th to 20th	Night	3 2 1 3 3 2 3 4 7% 9% 64%	1845
	21st to end	Night	4 3 1 3 3 3 4 4 6% 10% 60%	1800
July	1st to 10th	Night	7% 5% 2 7% 4 4 5% 4 6% 10% 47%	4078
	11th to 20th	Night	2 2 1 3 2 4 3 4 7% 11% 62%	4077
	21st to end	Night	3 2 1 4 3 4 5% 5% 8% 12% 54%	4449
August	1st to 10th	Night	1 2 2 2 2 3 4 7% 77%	3043
	11th to 20th	Night	3 2 1 3 2 2 4 4 6% 10% 65%	3213
	21st to end	Night	3 2 1 4 3 3 4 4 8% 11% 57%	3683
September	1st to 10th	Night	8% 4 2 4 3 4 4 4 6% 9% 53%	2200
	11th to 20th	Night	10% 4 1 4 3 5% 4 4 6% 10% 49%	2200
	21st to end	Night	8% 3 1 3 3 3 4 4 7% 7% 58%	2200
October	1st to 10th	Night	4 2 1 3 2 2 3 3 5% 7% 69%	2200
	11th to 20th	Night	10% 3 1 3 2 3 3 3 5% 6% 61%	2270
	21st to end	Night	10% 5% 1 3 2 3 2 3 3 4 63%	2640
November	1st to 10th	Night	10% 4 1 4 3 2 3 2 4 6% 61%	2469
	11th to 20th	Night	6% 4 1 4 3 3 3 2 5% 7% 61%	2730
	21st to end	Night	13% 5% 2 4 3 3 4 4 4 6% 52%	2730
December	1st to 10th	Night	17% 7% 3 5% 3 4 4 3 5% 5% 45%	4380
	11th to 20th	Night	9% 7% 2 6% 4 4 4 3 5% 6% 49%	4946
	21st to end	Night	8% 5% 2 5% 3 3 3 2 4 5% 61%	6633

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	30% 3 5% 24% 26% 11%	5290
	11th to 20th	Day	30% 2 4 15% 28% 21%	5310
	21st to end	Day	43% 2 6% 12% 25% 12%	6366
February	1st to 10th	Day	36% 3 6% 13% 21% 20%	2100
	11th to 20th	Day	35% 4 7% 20% 18% 15%	2059
	21st to end	Day	33% 3 5% 17% 24% 18%	1730
March	1st to 10th	Day	31% 3 6% 16% 18% 26%	4868
	11th to 20th	Day	33% 4 7% 8% 15% 33%	5090
	21st to end	Day	32% 5% 9% 19% 22% 14%	5585
April	1st to 10th	Day	38% 4 8% 17% 17% 14%	2310
	11th to 20th	Day	41% 4 8% 16% 20% 11%	2384
	21st to end	Day	38% 5% 7% 21% 19% 10%	2635
May	1st to 10th	Day	41% 5% 12% 19% 18% 5%	7655
	11th to 20th	Day	38% 4 9% 15% 22% 10%	7631
	21st to end	Day	40% 6% 12% 25% 13% 3	8405
June	1st to 10th	Day	27% 7% 13% 29% 20% 4	2730
	11th to 20th	Day	26% 7% 13% 26% 22% 6%	2666
	21st to end	Day	28% 10% 15% 25% 18% 5%	2600
July	1st to 10th	Day	42% 5% 17% 29% 7%	5836
	11th to 20th	Day	25% 4 18% 34% 16% 3	5831
	21st to end	Day	26% 6% 19% 29% 19% 2	6240
August	1st to 10th	Day	12% 4 11% 39% 32% 1	4098
	11th to 20th	Day	19% 5% 21% 38% 14% 2	3882
	21st to end	Day	28% 7% 19% 24% 19% 3	4219
September	1st to 10th	Day	36% 6% 9% 20% 18% 10%	2200
	11th to 20th	Day	35% 8% 12% 20% 20% 5%	2200
	21st to end	Day	28% 6% 10% 22% 21% 13%	2200
October	1st to 10th	Day	14% 4 7% 12% 27% 36%	3590
	11th to 20th	Day	22% 3 6% 20% 25% 24%	3415
	21st to end	Day	22% 3 4 18% 38% 14%	3538
November	1st to 10th	Day	33% 5% 7% 18% 23% 13%	2045
	11th to 20th	Day	27% 5% 8% 19% 22% 18%	1890
	21st to end	Day	37% 3 5% 19% 22% 15%	1890
December	1st to 10th	Day	45% 3 5% 17% 20% 11%	3030
	11th to 20th	Day	38% 4 8% 12% 23% 15%	3479
	21st to end	Day	27% 3 4 16% 27% 22%	4587
January	1st to 10th	Night	30% 3 5% 19% 29% 14%	7635
	11th to 20th	Night	21% 2 3 18% 30% 26%	7680
	21st to end	Night	46% 2 3 10% 23% 16%	7889
February	1st to 10th	Night	33% 4 7% 13% 23% 21%	2520
	11th to 20th	Night	35% 4 6% 18% 21% 16%	2458
	21st to end	Night	35% 4 5% 13% 23% 20%	2076
March	1st to 10th	Night	30% 5% 7% 19% 21% 16%	5212
	11th to 20th	Night	32% 4 7% 11% 16% 29%	5090
	21st to end	Night	31% 5% 8% 20% 22% 15%	5588
April	1st to 10th	Night	32% 6% 10% 19% 17% 17%	2310
	11th to 20th	Night	36% 6% 11% 14% 19% 15%	2180
	21st to end	Night	34% 6% 10% 20% 19% 10%	1984
May	1st to 10th	Night	42% 6% 11% 19% 15% 8%	5293
	11th to 20th	Night	34% 5% 13% 17% 18% 13%	5266
	21st to end	Night	37% 5% 19% 26% 10% 3	5805
June	1st to 10th	Night	18% 8% 17% 34% 20% 3	1890
	11th to 20th	Night	17% 6% 18% 31% 22% 6%	1845
	21st to end	Night	21% 7% 16% 31% 20% 4	1800
July	1st to 10th	Night	34% 6% 23% 30% 6% 1	4035
	11th to 20th	Night	17% 5% 25% 36% 16% 2	4026
	21st to end	Night	21% 6% 23% 32% 15% 3	4320
August	1st to 10th	Night	10% 3 14% 39% 33% 1	3033
	11th to 20th	Night	16% 6% 27% 36% 13% 2	3243
	21st to end	Night	21% 9% 23% 25% 21% 2	3683
September	1st to 10th	Night	28% 8% 13% 23% 19% 9%	2200
	11th to 20th	Night	31% 8% 15% 25% 16% 6%	2200
	21st to end	Night	25% 7% 12% 22% 21% 13%	2200
October	1st to 10th	Night	11% 4 9% 15% 23% 39%	3590
	11th to 20th	Night	19% 3 9% 19% 29% 20%	3691
	21st to end	Night	20% 3 5% 22% 34% 16%	4252
November	1st to 10th	Night	27% 5% 7% 19% 25% 16%	2469
	11th to 20th	Night	24% 6% 8% 21% 22% 19%	2730
	21st to end	Night	35% 4 8% 16% 21% 16%	2730
December	1st to 10th	Night	42% 4 7% 16% 19% 13%	4380
	11th to 20th	Night	37% 3 7% 13% 22% 19%	4947
	21st to end	Night	28% 3 4 18% 28% 18%	6633

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% 15% 39% 24% 5% 1	330
	11th to 20th	Day	19% 15% 32% 27% 7% 1	330
	21st to end	Day	15% 17% 41% 21% 5%	363
February	1st to 10th	Day	20% 16% 33% 24% 6%	330
	11th to 20th	Day	19% 19% 38% 20% 4	330
	21st to end	Day	18% 18% 41% 19% 4	273
March	1st to 10th	Day	19% 17% 40% 21% 4	330
	11th to 20th	Day	18% 17% 40% 19% 6%	330
	21st to end	Day	12% 18% 43% 20% 6% 1	363
April	1st to 10th	Day	15% 19% 42% 20% 5%	330
	11th to 20th	Day	17% 20% 39% 19% 5%	422
	21st to end	Day	15% 16% 43% 21% 5%	655
May	1st to 10th	Day	13% 13% 39% 27% 7%	753
	11th to 20th	Day	16% 11% 35% 26% 10% 2	775
	21st to end	Day	12% 7% 30% 36% 13% 1	844
June	1st to 10th	Day	5% 2 25% 41% 22% 4	780
	11th to 20th	Day	6% 2 20% 51% 18% 3	756
	21st to end	Day	5% 1 14% 43% 31% 6%	730
July	1st to 10th	Day	8% 2 10% 38% 32% 10%	721
	11th to 20th	Day	4 1 6% 42% 40% 7%	718
	21st to end	Day	3 1 7% 40% 37% 12%	794
August	1st to 10th	Day	2 4 41% 40% 13%	656
	11th to 20th	Day	7% 2 6% 35% 38% 13%	517
	21st to end	Day	4 1 5% 31% 41% 18%	530
September	1st to 10th	Day	11% 1 7% 25% 39% 17%	330
	11th to 20th	Day	5% 1 7% 31% 43% 14%	330
	21st to end	Day	10% 1 7% 35% 35% 13%	330
October	1st to 10th	Day	4 3 11% 37% 35% 10%	330
	11th to 20th	Day	9% 4 22% 40% 21% 3	330
	21st to end	Day	18% 13% 26% 26% 18% 1	363
November	1st to 10th	Day	18% 7% 27% 33% 14% 2	330
	11th to 20th	Day	12% 12% 28% 33% 11% 4	330
	21st to end	Day	20% 16% 35% 19% 7% 3	330
December	1st to 10th	Day	18% 9% 32% 29% 9% 2	330
	11th to 20th	Day	14% 15% 37% 24% 9% 2	330
	21st to end	Day	15% 13% 34% 28% 9% 1	363
January	1st to 10th	Night	15% 9% 39% 30% 6%	1050
	11th to 20th	Night	14% 12% 37% 32% 5%	1050
	21st to end	Night	17% 11% 37% 29% 6%	976
February	1st to 10th	Night	15% 11% 43% 26% 5%	840
	11th to 20th	Night	16% 14% 41% 26% 3	824
	21st to end	Night	16% 17% 46% 20% 1	692
March	1st to 10th	Night	14% 17% 41% 27% 1	714
	11th to 20th	Night	15% 11% 43% 27% 4	630
	21st to end	Night	10% 13% 50% 24% 3	693
April	1st to 10th	Night	9% 13% 50% 25% 2	630
	11th to 20th	Night	13% 15% 48% 21% 3	623
	21st to end	Night	12% 11% 52% 19% 6%	630
May	1st to 10th	Night	11% 13% 46% 28% 3	630
	11th to 20th	Night	10% 9% 40% 30% 9% 1	621
	21st to end	Night	8% 7% 40% 34% 11%	683
June	1st to 10th	Night	2 1 30% 48% 18% 1	630
	11th to 20th	Night	4 2 37% 47% 11%	615
	21st to end	Night	4 2 20% 52% 19% 2	600
July	1st to 10th	Night	5% 2 12% 53% 26% 2	585
	11th to 20th	Night	3 1 12% 58% 25% 1	582
	21st to end	Night	2 12% 58% 25% 2	657
August	1st to 10th	Night	1 7% 59% 30% 2	597
	11th to 20th	Night	5% 1 8% 55% 30% 3	594
	21st to end	Night	4 1 7% 51% 32% 5%	660
September	1st to 10th	Night	9% 2 10% 45% 30% 5%	600
	11th to 20th	Night	11% 1 9% 43% 35% 2	600
	21st to end	Night	8% 1 14% 49% 28% 1	600
October	1st to 10th	Night	5% 2 15% 51% 27% 1	600
	11th to 20th	Night	11% 3 25% 45% 15% 1	670
	21st to end	Night	12% 10% 32% 29% 16% 1	880
November	1st to 10th	Night	11% 6% 27% 42% 14% 1	829
	11th to 20th	Night	8% 8% 34% 36% 13% 1	1050
	21st to end	Night	16% 10% 33% 31% 9%	1050
December	1st to 10th	Night	14% 8% 34% 36% 8%	1050
	11th to 20th	Night	16% 11% 35% 32% 6%	1050
	21st to end	Night	12% 11% 37% 32% 7%	1155

Page generated at 2026-06-13 01:31:39. Version ac07

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