Hueco Tanks State Park & Historic Site
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hueco Tanks State Park & Historic Site clear sky chart from 2005-11-06 to 2025-12-18.

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	3 3 1 4 3 3 4 3 5% 7% 65%	134302
	Night	3 3 1 4 3 3 4 3 5% 7% 63%	134191
Transparency	Day	17% 5% 6% 16% 28% 28%	129390
	Night	20% 4 6% 15% 27% 28%	130107
Seeing	Day	5% 7% 21% 31% 25% 12%	15616
	Night	5% 5% 27% 41% 20% 2	26224

By Month

Percentage Cloud Cover SW (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	4 6% 2 4 3 3 3 3 5% 6% 60%	4098
	11th to 20th	Day	1 2 1 2 2 2 2 2 4 6% 76%	4100
	21st to end	Day	4 6% 2 4 3 3 2 3 5% 5% 63%	4510
February	1st to 10th	Day	4 5% 1 3 2 2 3 4 4 7% 66%	1974
	11th to 20th	Day	4 4 2 5% 4 3 4 3 4 6% 63%	1949
	21st to end	Day	3 4 1 3 3 3 3 2 4 5% 70%	1650
March	1st to 10th	Day	2 4 1 4 2 2 3 2 5% 7% 67%	4856
	11th to 20th	Day	2 4 2 4 3 3 4 3 5% 6% 65%	5000
	21st to end	Day	2 5% 2 6% 3 3 3 3 5% 6% 61%	5634
April	1st to 10th	Day	3 3 1 3 2 3 3 2 5% 7% 70%	2400
	11th to 20th	Day	2 2 1 3 2 2 2 2 3 5% 76%	2371
	21st to end	Day	2 2 1 3 2 2 2 2 3 5% 77%	2400
May	1st to 10th	Day	1 1 2 2 2 2 2 3 4 81%	5440
	11th to 20th	Day	1 1 1 2 2 2 3 2 4 5% 76%	5405
	21st to end	Day	1 1 1 1 1 2 2 3 5% 84%	6046
June	1st to 10th	Day	3 2 1 2 2 3 3 4 5% 7% 70%	2600
	11th to 20th	Day	2 1 1 1 2 3 3 4 6% 76%	2600
	21st to end	Day	3 3 1 4 4 4 5% 4 8% 9% 55%	2600
July	1st to 10th	Day	3 3 1 5% 4 5% 5% 5% 8% 10% 52%	5879
	11th to 20th	Day	1 1 1 4 3 4 5% 5% 9% 12% 54%	5880
	21st to end	Day	4 3 2 5% 5% 5% 7% 6% 9% 11% 43%	6325
August	1st to 10th	Day	2 2 1 4 4 4 5% 5% 8% 10% 55%	5348
	11th to 20th	Day	2 2 1 4 4 5% 7% 6% 8% 10% 50%	5366
	21st to end	Day	2 2 1 4 4 5% 5% 5% 8% 10% 53%	5984
September	1st to 10th	Day	7% 4 2 6% 4 4 4 5% 5% 8% 52%	2400
	11th to 20th	Day	6% 4 2 4 3 5% 5% 4 6% 8% 54%	2400
	21st to end	Day	3 2 1 2 2 3 3 3 5% 6% 68%	2197
October	1st to 10th	Day	2 1 1 2 2 2 2 2 4 4 77%	3270
	11th to 20th	Day	2 2 1 3 2 2 3 3 3 5% 73%	3250
	21st to end	Day	2 1 2 1 1 1 1 2 3 85%	3548
November	1st to 10th	Day	2 2 1 4 3 2 2 2 4 5% 73%	2059
	11th to 20th	Day	2 2 1 4 2 3 4 3 5% 5% 69%	2042
	21st to end	Day	4 3 2 4 3 3 4 3 6% 6% 62%	1890
December	1st to 10th	Day	4 5% 2 5% 3 3 3 3 4 6% 64%	3030
	11th to 20th	Day	3 4 2 5% 3 3 3 3 4 5% 65%	3291
	21st to end	Day	3 3 1 3 2 2 3 2 4 6% 70%	4510
January	1st to 10th	Night	4 7% 1 4 3 2 3 3 5% 6% 62%	5867
	11th to 20th	Night	2 2 1 2 2 2 2 2 4 5% 75%	5880
	21st to end	Night	5% 6% 2 5% 3 2 3 3 6% 7% 59%	6468
February	1st to 10th	Night	3 3 1 3 3 3 3 3 5% 6% 66%	2422
	11th to 20th	Night	5% 4 2 4 3 3 3 3 5% 6% 62%	2338
	21st to end	Night	3 3 1 4 3 3 3 3 5% 6% 65%	1980
March	1st to 10th	Night	2 3 1 3 3 3 3 2 4 6% 68%	5029
	11th to 20th	Night	5% 4 1 3 2 3 4 3 6% 7% 63%	5000
	21st to end	Night	3 4 2 5% 3 3 4 3 4 6% 63%	5318
April	1st to 10th	Night	3 3 1 4 2 2 2 3 5% 7% 67%	2000
	11th to 20th	Night	3 3 1 4 2 2 2 2 4 6% 71%	1977
	21st to end	Night	2 2 1 2 3 2 2 2 4 3 77%	2000
May	1st to 10th	Night	3 2 1 2 1 2 2 1 3 4 80%	4540
	11th to 20th	Night	2 3 1 4 3 3 3 3 5% 7% 67%	4510
	21st to end	Night	1 1 1 2 1 2 2 2 4 4 81%	4832
June	1st to 10th	Night	2 2 1 4 3 4 4 5% 6% 7% 61%	1800
	11th to 20th	Night	2 2 1 2 2 3 4 4 5% 8% 68%	1800
	21st to end	Night	3 4 2 6% 5% 6% 6% 6% 7% 10% 45%	1800
July	1st to 10th	Night	3 3 2 6% 6% 5% 6% 5% 8% 10% 45%	4100
	11th to 20th	Night	2 2 1 4 5% 5% 6% 5% 9% 13% 48%	4100
	21st to end	Night	4 4 2 8% 6% 7% 7% 6% 9% 12% 36%	4544
August	1st to 10th	Night	3 3 2 5% 4 5% 6% 4 8% 11% 49%	4464
	11th to 20th	Night	3 4 2 7% 6% 6% 7% 6% 9% 12% 40%	4483
	21st to end	Night	3 3 2 6% 4 6% 6% 6% 10% 11% 44%	4993
September	1st to 10th	Night	5% 4 2 5% 4 4 5% 5% 7% 8% 51%	2000
	11th to 20th	Night	6% 4 2 7% 4 4 4 4 6% 8% 52%	2000
	21st to end	Night	4 3 2 4 3 4 4 3 5% 7% 62%	2195
October	1st to 10th	Night	3 2 1 2 2 2 3 2 4 5% 74%	3920
	11th to 20th	Night	4 3 2 4 3 3 3 2 3 6% 67%	3898
	21st to end	Night	2 2 1 2 1 1 2 1 2 4 82%	4252
November	1st to 10th	Night	3 2 1 3 2 2 2 3 4 6% 73%	2460
	11th to 20th	Night	2 2 1 3 3 2 3 2 5% 5% 71%	2551
	21st to end	Night	4 4 2 4 3 3 4 2 5% 7% 62%	2730
December	1st to 10th	Night	4 3 1 3 2 2 3 2 4 5% 70%	4380
	11th to 20th	Night	2 3 1 5% 3 3 3 3 4 5% 68%	5092
	21st to end	Night	3 3 1 3 2 2 2 2 3 6% 72%	6468

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	23% 3 3 10% 38% 23%	4099
	11th to 20th	Day	11% 2 2 14% 48% 23%	4100
	21st to end	Day	22% 3 3 18% 28% 25%	4510
February	1st to 10th	Day	19% 3 5% 14% 26% 33%	1974
	11th to 20th	Day	23% 3 4 16% 29% 25%	1959
	21st to end	Day	18% 2 3 10% 31% 36%	1650
March	1st to 10th	Day	16% 2 3 7% 29% 43%	4856
	11th to 20th	Day	20% 4 3 14% 28% 31%	5000
	21st to end	Day	22% 3 3 8% 30% 34%	5634
April	1st to 10th	Day	15% 2 3 12% 32% 36%	2400
	11th to 20th	Day	13% 2 2 10% 29% 44%	2374
	21st to end	Day	12% 2 3 9% 30% 45%	2400
May	1st to 10th	Day	8% 2 2 11% 28% 48%	5440
	11th to 20th	Day	11% 3 3 11% 24% 49%	5408
	21st to end	Day	5% 2 5% 11% 14% 62%	6047
June	1st to 10th	Day	14% 3 5% 15% 31% 32%	2600
	11th to 20th	Day	9% 3 4 8% 26% 50%	2600
	21st to end	Day	21% 7% 8% 18% 23% 24%	2600
July	1st to 10th	Day	22% 9% 12% 25% 19% 12%	5816
	11th to 20th	Day	17% 8% 17% 28% 22% 7%	5811
	21st to end	Day	27% 11% 17% 26% 15% 4	6142
August	1st to 10th	Day	23% 9% 11% 29% 22% 7%	3892
	11th to 20th	Day	20% 9% 12% 25% 27% 7%	3882
	21st to end	Day	24% 9% 15% 29% 19% 4	4311
September	1st to 10th	Day	29% 5% 11% 17% 20% 17%	2400
	11th to 20th	Day	27% 6% 7% 17% 27% 15%	2400
	21st to end	Day	16% 5% 6% 21% 31% 20%	2197
October	1st to 10th	Day	11% 3 4 10% 28% 43%	3270
	11th to 20th	Day	15% 3 5% 16% 28% 32%	3250
	21st to end	Day	8% 1 2 11% 38% 40%	3548
November	1st to 10th	Day	15% 2 4 20% 32% 28%	2059
	11th to 20th	Day	17% 3 4 19% 30% 27%	2042
	21st to end	Day	22% 4 5% 18% 32% 20%	1890
December	1st to 10th	Day	22% 5% 5% 18% 34% 16%	3030
	11th to 20th	Day	22% 2 4 14% 37% 21%	3289
	21st to end	Day	15% 3 3 15% 41% 23%	4510
January	1st to 10th	Night	23% 2 3 11% 40% 21%	5867
	11th to 20th	Night	13% 2 3 15% 42% 25%	5880
	21st to end	Night	23% 4 3 16% 31% 24%	6468
February	1st to 10th	Night	18% 4 4 14% 25% 35%	2422
	11th to 20th	Night	22% 3 4 13% 30% 28%	2338
	21st to end	Night	19% 3 3 9% 26% 38%	1980
March	1st to 10th	Night	17% 3 2 7% 28% 43%	5029
	11th to 20th	Night	19% 7% 4 12% 27% 31%	5000
	21st to end	Night	21% 2 3 11% 31% 32%	5318
April	1st to 10th	Night	17% 3 4 9% 32% 35%	2000
	11th to 20th	Night	15% 3 4 10% 25% 43%	1977
	21st to end	Night	13% 3 3 11% 27% 44%	2000
May	1st to 10th	Night	11% 2 2 15% 20% 49%	4537
	11th to 20th	Night	16% 3 5% 12% 20% 43%	4511
	21st to end	Night	9% 3 5% 9% 13% 62%	4833
June	1st to 10th	Night	20% 5% 7% 16% 21% 32%	1800
	11th to 20th	Night	14% 4 5% 9% 22% 46%	1800
	21st to end	Night	30% 7% 12% 13% 16% 21%	1800
July	1st to 10th	Night	30% 9% 15% 22% 16% 8%	4055
	11th to 20th	Night	22% 9% 16% 26% 21% 6%	4046
	21st to end	Night	35% 10% 17% 22% 14% 3	4415
August	1st to 10th	Night	28% 9% 13% 25% 18% 8%	3244
	11th to 20th	Night	24% 7% 10% 21% 30% 7%	3243
	21st to end	Night	29% 11% 14% 21% 19% 5%	3597
September	1st to 10th	Night	28% 8% 12% 17% 18% 17%	2000
	11th to 20th	Night	29% 7% 9% 19% 20% 18%	2000
	21st to end	Night	22% 6% 6% 17% 28% 21%	2195
October	1st to 10th	Night	13% 3 5% 9% 23% 46%	3920
	11th to 20th	Night	20% 3 5% 12% 20% 40%	3898
	21st to end	Night	10% 2 2 8% 34% 44%	4252
November	1st to 10th	Night	13% 4 3 14% 33% 32%	2460
	11th to 20th	Night	16% 3 4 16% 33% 29%	2551
	21st to end	Night	22% 3 5% 15% 33% 22%	2730
December	1st to 10th	Night	17% 3 5% 22% 37% 16%	4380
	11th to 20th	Night	18% 2 3 13% 32% 30%	5093
	21st to end	Night	15% 2 2 15% 40% 26%	6468

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	8% 9% 29% 34% 17% 2	300
	11th to 20th	Day	6% 8% 34% 31% 18% 3	300
	21st to end	Day	7% 5% 34% 34% 15% 5%	330
February	1st to 10th	Day	7% 6% 29% 35% 17% 6%	300
	11th to 20th	Day	10% 12% 35% 31% 12%	300
	21st to end	Day	10% 11% 35% 33% 10% 2	249
March	1st to 10th	Day	9% 15% 35% 33% 8% 1	450
	11th to 20th	Day	12% 15% 28% 30% 12% 4	500
	21st to end	Day	5% 17% 35% 29% 11% 2	550
April	1st to 10th	Day	7% 12% 32% 31% 15% 3	500
	11th to 20th	Day	5% 16% 36% 29% 11% 2	492
	21st to end	Day	3 14% 36% 33% 13% 2	500
May	1st to 10th	Day	2 12% 34% 34% 17% 2	503
	11th to 20th	Day	2 10% 28% 40% 17% 3	528
	21st to end	Day	2 5% 29% 42% 20% 2	573
June	1st to 10th	Day	4 3 18% 38% 29% 8%	530
	11th to 20th	Day	2 2 17% 38% 31% 8%	530
	21st to end	Day	4 2 12% 30% 36% 16%	530
July	1st to 10th	Day	3 1 6% 25% 41% 24%	526
	11th to 20th	Day	3 3 21% 38% 34%	524
	21st to end	Day	2 2 3 21% 42% 31%	575
August	1st to 10th	Day	3 1 2 16% 39% 39%	527
	11th to 20th	Day	5% 2 5% 24% 39% 25%	517
	21st to end	Day	3 1 5% 25% 36% 31%	583
September	1st to 10th	Day	7% 2 10% 29% 35% 17%	530
	11th to 20th	Day	5% 1 7% 30% 40% 17%	530
	21st to end	Day	4 3 9% 27% 39% 17%	345
October	1st to 10th	Day	4 2 14% 34% 35% 12%	330
	11th to 20th	Day	5% 6% 19% 33% 26% 11%	330
	21st to end	Day	4 7% 18% 31% 26% 13%	363
November	1st to 10th	Day	4 6% 23% 33% 24% 10%	330
	11th to 20th	Day	3 8% 22% 30% 28% 10%	330
	21st to end	Day	5% 12% 32% 32% 16% 4	330
December	1st to 10th	Day	7% 8% 26% 35% 20% 3	330
	11th to 20th	Day	4 6% 26% 41% 18% 4	321
	21st to end	Day	7% 6% 32% 38% 15% 2	330
January	1st to 10th	Night	7% 6% 31% 40% 14% 2	800
	11th to 20th	Night	5% 7% 33% 40% 14% 2	800
	21st to end	Night	8% 8% 31% 37% 15% 2	880
February	1st to 10th	Night	6% 7% 34% 37% 16% 2	800
	11th to 20th	Night	7% 9% 39% 36% 9% 1	784
	21st to end	Night	4 9% 49% 31% 6%	660
March	1st to 10th	Night	7% 10% 39% 36% 7% 1	800
	11th to 20th	Night	6% 10% 36% 37% 10% 1	800
	21st to end	Night	4 7% 43% 36% 10%	812
April	1st to 10th	Night	5% 9% 45% 32% 10% 1	600
	11th to 20th	Night	4 11% 46% 32% 8% 1	593
	21st to end	Night	3 12% 37% 40% 9%	600
May	1st to 10th	Night	5% 9% 39% 41% 6% 1	600
	11th to 20th	Night	2 6% 36% 44% 11% 1	591
	21st to end	Night	3 5% 33% 48% 11%	650
June	1st to 10th	Night	2 4 24% 50% 20% 1	600
	11th to 20th	Night	2 1 21% 55% 20% 1	600
	21st to end	Night	4 2 18% 49% 26% 2	600
July	1st to 10th	Night	3 1 12% 49% 32% 2	585
	11th to 20th	Night	4 1 8% 39% 44% 3	582
	21st to end	Night	4 8% 39% 44% 5%	657
August	1st to 10th	Night	6% 1 5% 34% 48% 7%	597
	11th to 20th	Night	4 1 9% 33% 47% 6%	594
	21st to end	Night	5% 2 6% 38% 45% 5%	660
September	1st to 10th	Night	6% 2 10% 45% 35% 3	600
	11th to 20th	Night	6% 2 12% 49% 30% 2	600
	21st to end	Night	4 2 17% 48% 27% 2	612
October	1st to 10th	Night	4 3 20% 47% 25% 2	800
	11th to 20th	Night	6% 4 25% 42% 20% 2	800
	21st to end	Night	4 5% 21% 42% 24% 4	880
November	1st to 10th	Night	4 2 25% 40% 25% 4	820
	11th to 20th	Night	3 3 29% 43% 20% 2	871
	21st to end	Night	7% 7% 28% 38% 18% 2	1050
December	1st to 10th	Night	7% 6% 26% 42% 16% 2	1050
	11th to 20th	Night	5% 5% 30% 44% 14% 1	1016
	21st to end	Night	8% 5% 27% 44% 14% 1	880

Page generated at 2025-12-15 00:13:51. Version ac07

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