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 2025-02-21.

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 3 5% 7% 51%	109211
	Night	9% 5% 2 4 3 3 3 3 5% 7% 56%	109628
Transparency	Day	31% 5% 10% 21% 21% 11%	113055
	Night	29% 5% 10% 21% 21% 14%	113911
Seeing	Day	11% 8% 24% 32% 20% 5%	15194
	Night	11% 8% 31% 37% 13% 1	25275

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	11% 8% 4 4 2 2 3 2 3 5% 55%	4077
	11th to 20th	Day	12% 5% 1 4 2 3 3 3 4 6% 57%	4080
	21st to end	Day	19% 7% 2 5% 3 3 2 2 3 6% 48%	4920
February	1st to 10th	Day	14% 6% 2 5% 3 2 3 2 4 6% 52%	2000
	11th to 20th	Day	13% 6% 2 5% 3 2 4 3 5% 7% 50%	1949
	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% 5% 7% 47%	2090
	21st to end	Day	9% 3 1 5% 3 4 5% 4 6% 8% 54%	2090
October	1st to 10th	Day	5% 4 2 4 3 3 3 3 5% 7% 61%	2090
	11th to 20th	Day	11% 4 1 4 3 3 3 3 4 5% 58%	2005
	21st to end	Day	10% 4 1 3 3 3 2 3 4 4 62%	2090
November	1st to 10th	Day	11% 6% 2 5% 3 3 3 4 5% 6% 52%	1946
	11th to 20th	Day	8% 3 2 4 4 3 3 4 5% 7% 58%	1800
	21st to end	Day	13% 5% 2 5% 4 3 4 2 3 6% 53%	1800
December	1st to 10th	Day	20% 8% 3 6% 3 3 3 2 4 5% 43%	2940
	11th to 20th	Day	10% 6% 3 7% 4 4 4 3 7% 6% 46%	3391
	21st to end	Day	9% 5% 2 4 2 3 2 2 4 5% 62%	4488
January	1st to 10th	Night	12% 6% 3 4 2 3 2 2 3 5% 56%	5888
	11th to 20th	Night	9% 3 1 3 1 1 2 2 4 6% 67%	5900
	21st to end	Night	21% 8% 2 5% 3 3 3 2 3 6% 46%	6099
February	1st to 10th	Night	12% 6% 2 4 4 3 3 3 5% 5% 54%	2400
	11th to 20th	Night	14% 6% 2 4 3 3 3 2 3 7% 53%	2338
	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 5% 4 4 6% 10% 48%	2090
	21st to end	Night	8% 3 1 3 3 3 4 4 6% 7% 58%	2090
October	1st to 10th	Night	4 2 1 3 2 2 3 3 5% 7% 68%	2090
	11th to 20th	Night	10% 3 1 4 3 3 3 3 5% 6% 60%	2156
	21st to end	Night	10% 5% 1 3 2 3 2 3 4 4 62%	2508
November	1st to 10th	Night	10% 4 1 4 3 3 4 2 4 6% 59%	2348
	11th to 20th	Night	7% 4 1 4 3 3 4 2 5% 7% 61%	2600
	21st to end	Night	13% 4 1 4 3 3 4 4 5% 7% 52%	2600
December	1st to 10th	Night	17% 7% 3 5% 3 4 4 3 5% 5% 44%	4250
	11th to 20th	Night	9% 7% 2 6% 4 4 4 3 5% 6% 49%	4816
	21st to end	Night	8% 5% 2 5% 3 3 3 2 4 5% 61%	6490

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	33% 4 3 23% 23% 14%	4078
	11th to 20th	Day	30% 3 5% 16% 27% 19%	4080
	21st to end	Day	40% 2 6% 10% 26% 15%	4920
February	1st to 10th	Day	36% 3 6% 13% 21% 20%	2000
	11th to 20th	Day	35% 5% 6% 20% 18% 16%	1959
	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	36% 8% 12% 19% 20% 6%	2090
	21st to end	Day	28% 7% 10% 21% 21% 13%	2090
October	1st to 10th	Day	14% 4 7% 12% 27% 37%	3480
	11th to 20th	Day	22% 4 6% 19% 24% 25%	3310
	21st to end	Day	22% 3 4 18% 39% 14%	3428
November	1st to 10th	Day	35% 5% 8% 19% 22% 12%	1946
	11th to 20th	Day	28% 6% 9% 18% 22% 19%	1800
	21st to end	Day	36% 3 5% 19% 22% 15%	1800
December	1st to 10th	Day	45% 3 5% 17% 19% 10%	2940
	11th to 20th	Day	38% 5% 9% 12% 23% 15%	3389
	21st to end	Day	27% 3 4 16% 27% 23%	4488
January	1st to 10th	Night	33% 3 4 19% 27% 14%	5888
	11th to 20th	Night	21% 2 3 20% 29% 25%	5900
	21st to end	Night	44% 3 3 10% 21% 18%	6099
February	1st to 10th	Night	35% 4 7% 12% 22% 21%	2400
	11th to 20th	Night	35% 5% 5% 18% 20% 17%	2338
	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% 8% 15% 24% 16% 6%	2090
	21st to end	Night	26% 7% 12% 21% 20% 14%	2090
October	1st to 10th	Night	11% 4 8% 15% 22% 39%	3480
	11th to 20th	Night	20% 3 9% 18% 30% 20%	3577
	21st to end	Night	20% 3 5% 22% 34% 16%	4120
November	1st to 10th	Night	29% 5% 8% 19% 23% 16%	2348
	11th to 20th	Night	25% 6% 7% 21% 22% 19%	2600
	21st to end	Night	34% 4 8% 16% 21% 16%	2600
December	1st to 10th	Night	42% 4 7% 16% 19% 12%	4250
	11th to 20th	Night	37% 3 7% 13% 22% 18%	4817
	21st to end	Night	29% 3 4 17% 28% 19%	6490

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	17% 15% 38% 24% 5% 1	300
	11th to 20th	Day	20% 14% 32% 26% 7% 1	300
	21st to end	Day	15% 17% 40% 22% 5%	330
February	1st to 10th	Day	21% 17% 32% 25% 6%	300
	11th to 20th	Day	20% 20% 36% 20% 3	300
	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	5% 7% 29% 43% 15%	300
	21st to end	Day	10% 1 6% 34% 36% 13%	300
October	1st to 10th	Day	5% 3 11% 37% 35% 9%	300
	11th to 20th	Day	10% 5% 21% 40% 21% 3	300
	21st to end	Day	19% 12% 25% 25% 18% 1	330
November	1st to 10th	Day	18% 7% 27% 33% 11% 2	300
	11th to 20th	Day	12% 13% 29% 30% 11% 5%	300
	21st to end	Day	20% 16% 35% 19% 6% 3	300
December	1st to 10th	Day	18% 8% 32% 29% 10% 2	300
	11th to 20th	Day	14% 15% 39% 24% 7% 1	300
	21st to end	Day	17% 14% 35% 26% 9%	330
January	1st to 10th	Night	15% 9% 39% 30% 6%	1000
	11th to 20th	Night	15% 12% 37% 31% 5%	1000
	21st to end	Night	17% 12% 37% 29% 6%	930
February	1st to 10th	Night	16% 12% 41% 26% 5%	800
	11th to 20th	Night	17% 14% 42% 25% 3	784
	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% 1 8% 42% 35% 2	570
	21st to end	Night	8% 1 14% 48% 28% 1	570
October	1st to 10th	Night	5% 2 15% 50% 26% 1	570
	11th to 20th	Night	11% 3 25% 45% 14% 1	636
	21st to end	Night	12% 10% 31% 29% 17% 1	836
November	1st to 10th	Night	12% 6% 27% 41% 14% 1	788
	11th to 20th	Night	8% 8% 34% 36% 13% 1	1000
	21st to end	Night	16% 11% 33% 31% 9% 1	1000
December	1st to 10th	Night	14% 7% 33% 37% 8%	1000
	11th to 20th	Night	16% 11% 35% 33% 6%	1000
	21st to end	Night	13% 11% 37% 32% 7%	1100

Page generated at 2025-02-18 02:26:26. Version ac07

Copyright © 2025 Attilla Danko.