Chihuahua
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Chihuahua clear sky chart from 2005-11-06 to 2026-10-14.

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	3 3 1 3 3 3 4 3 5% 7% 63%	148425
	Night	5% 4 2 5% 4 4 4 4 5% 7% 57%	143794
Transparency	Day	18% 5% 9% 16% 24% 27%	152076
	Night	25% 5% 7% 14% 24% 25%	148247
Seeing	Day	6% 7% 22% 30% 26% 9%	16791
	Night	7% 4 20% 39% 27% 3	26594

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	2 3 1 2 2 2 2 2 4 6% 75%	5320
	11th to 20th	Day	2 2 1 2 1 2 2 3 4 5% 75%	5340
	21st to end	Day	3 3 1 4 3 4 4 3 5% 8% 62%	6467
February	1st to 10th	Day	3 3 2 4 4 3 3 2 4 5% 66%	2100
	11th to 20th	Day	2 3 1 3 3 3 4 3 4 6% 69%	2049
	21st to end	Day	3 2 2 2 2 3 4 5% 7% 71%	1750
March	1st to 10th	Day	2 2 1 3 2 3 4 3 5% 6% 67%	5064
	11th to 20th	Day	2 2 1 3 2 2 2 2 4 5% 73%	5110
	21st to end	Day	2 3 1 3 2 3 3 3 5% 6% 69%	5711
April	1st to 10th	Day	3 3 1 3 2 3 4 3 5% 6% 66%	2520
	11th to 20th	Day	2 2 1 3 2 3 4 2 5% 6% 68%	2494
	21st to end	Day	3 3 1 3 3 2 3 3 4 5% 71%	2520
May	1st to 10th	Day	2 2 1 2 1 2 3 2 4 5% 76%	7022
	11th to 20th	Day	3 4 2 5% 4 3 4 4 5% 6% 62%	7032
	21st to end	Day	2 2 1 3 3 2 3 3 5% 6% 71%	7737
June	1st to 10th	Day	2 3 1 4 3 3 4 4 6% 7% 63%	2520
	11th to 20th	Day	3 2 1 5% 3 5% 5% 4 7% 9% 57%	2652
	21st to end	Day	4 3 1 4 5% 5% 6% 6% 7% 10% 48%	2730
July	1st to 10th	Day	4 3 1 5% 4 5% 5% 5% 7% 10% 51%	7650
	11th to 20th	Day	4 3 2 5% 5% 6% 6% 6% 8% 12% 43%	7536
	21st to end	Day	2 2 1 3 3 4 5% 5% 7% 10% 57%	7684
August	1st to 10th	Day	1 2 1 4 3 4 5% 5% 8% 11% 57%	5545
	11th to 20th	Day	3 2 1 4 4 5% 7% 6% 8% 11% 49%	5483
	21st to end	Day	3 2 1 3 3 3 4 3 5% 8% 63%	6079
September	1st to 10th	Day	8% 5% 3 6% 5% 5% 6% 5% 7% 9% 40%	2520
	11th to 20th	Day	8% 4 1 5% 5% 5% 5% 4 7% 9% 46%	2520
	21st to end	Day	7% 4 1 4 3 4 4 4 6% 8% 54%	2326
October	1st to 10th	Day	4 2 1 3 3 4 5% 3 7% 6% 62%	2107
	11th to 20th	Day	5% 3 1 3 3 2 3 2 4 7% 66%	2030
	21st to end	Day	3 2 1 2 1 1 2 2 3 5% 79%	2200
November	1st to 10th	Day	3 1 1 3 2 2 2 2 3 5% 76%	2059
	11th to 20th	Day	4 2 1 3 2 3 2 2 3 5% 73%	2100
	21st to end	Day	4 4 1 4 3 3 3 3 6% 5% 63%	2100
December	1st to 10th	Day	3 6% 2 3 3 3 3 3 5% 6% 63%	3370
	11th to 20th	Day	2 2 1 3 2 2 3 3 4 6% 72%	3874
	21st to end	Day	1 2 1 2 1 2 2 2 4 6% 78%	5104
January	1st to 10th	Night	2 3 1 3 2 2 2 2 3 4 74%	7583
	11th to 20th	Night	3 3 1 2 2 2 3 3 4 5% 72%	7617
	21st to end	Night	3 4 2 5% 3 4 4 3 5% 7% 59%	7746
February	1st to 10th	Night	4 3 2 3 3 3 3 3 4 6% 67%	2520
	11th to 20th	Night	4 4 1 4 3 3 3 3 5% 7% 64%	2458
	21st to end	Night	2 4 1 2 2 2 3 3 5% 8% 68%	2050
March	1st to 10th	Night	3 3 1 4 2 2 3 3 6% 6% 66%	5050
	11th to 20th	Night	3 3 1 3 2 2 3 3 4 6% 69%	5110
	21st to end	Night	4 3 1 3 2 2 3 2 4 6% 69%	5484
April	1st to 10th	Night	4 3 1 3 3 3 3 3 6% 7% 64%	2100
	11th to 20th	Night	3 4 1 5% 3 3 3 3 4 7% 64%	2077
	21st to end	Night	5% 3 1 4 3 3 3 3 4 5% 68%	2100
May	1st to 10th	Night	3 2 1 3 2 2 3 2 4 5% 73%	5861
	11th to 20th	Night	7% 6% 2 4 3 3 3 3 4 6% 57%	5860
	21st to end	Night	4 5% 1 4 3 3 3 3 4 6% 63%	6448
June	1st to 10th	Night	4 4 2 6% 6% 5% 6% 4 8% 8% 47%	2100
	11th to 20th	Night	6% 5% 2 7% 6% 7% 6% 5% 7% 9% 41%	1959
	21st to end	Night	9% 6% 2 8% 7% 7% 7% 6% 8% 10% 31%	1890
July	1st to 10th	Night	8% 6% 3 10% 7% 7% 7% 6% 9% 10% 27%	5338
	11th to 20th	Night	9% 7% 4 10% 7% 6% 7% 6% 8% 10% 26%	5446
	21st to end	Night	6% 6% 2 9% 6% 7% 7% 6% 8% 10% 33%	6423
August	1st to 10th	Night	3 4 2 7% 6% 7% 8% 6% 10% 12% 34%	4625
	11th to 20th	Night	4 4 2 11% 8% 9% 9% 7% 10% 10% 25%	4583
	21st to end	Night	4 4 2 7% 5% 5% 6% 5% 7% 10% 46%	5069
September	1st to 10th	Night	13% 8% 3 9% 8% 6% 6% 5% 7% 9% 27%	2100
	11th to 20th	Night	12% 7% 3 8% 6% 7% 6% 5% 7% 8% 31%	2100
	21st to end	Night	10% 5% 3 7% 5% 6% 6% 4 7% 9% 37%	2294
October	1st to 10th	Night	6% 4 2 5% 5% 4 4 3 5% 6% 55%	2505
	11th to 20th	Night	7% 3 1 5% 3 4 4 3 5% 7% 58%	2436
	21st to end	Night	5% 2 1 2 2 2 3 2 3 4 75%	2640
November	1st to 10th	Night	6% 1 1 2 2 2 2 2 3 4 75%	2460
	11th to 20th	Night	5% 3 1 3 3 2 3 2 5% 4 68%	2520
	21st to end	Night	4 4 2 4 3 3 4 2 3 5% 67%	2520
December	1st to 10th	Night	3 4 1 5% 4 3 4 3 6% 7% 59%	4040
	11th to 20th	Night	1 3 1 3 1 2 2 3 4 6% 74%	4566
	21st to end	Night	2 2 1 2 2 2 2 2 3 6% 76%	6116

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	14% 2 3 17% 33% 31%	5321
	11th to 20th	Day	13% 2 3 13% 30% 38%	5340
	21st to end	Day	21% 4 4 20% 29% 22%	6467
February	1st to 10th	Day	22% 3 4 10% 25% 36%	2100
	11th to 20th	Day	18% 3 6% 11% 30% 32%	2059
	21st to end	Day	13% 3 6% 9% 30% 38%	1750
March	1st to 10th	Day	17% 3 5% 7% 20% 47%	5064
	11th to 20th	Day	15% 3 4 6% 18% 54%	5110
	21st to end	Day	15% 3 4 9% 26% 43%	5713
April	1st to 10th	Day	18% 4 6% 10% 22% 41%	2520
	11th to 20th	Day	16% 4 6% 9% 24% 42%	2494
	21st to end	Day	16% 2 4 9% 25% 44%	2520
May	1st to 10th	Day	11% 2 3 8% 16% 60%	7057
	11th to 20th	Day	23% 3 5% 10% 19% 41%	7035
	21st to end	Day	13% 3 4 11% 20% 49%	7749
June	1st to 10th	Day	17% 5% 8% 16% 29% 24%	2520
	11th to 20th	Day	21% 4 8% 14% 25% 28%	2652
	21st to end	Day	26% 8% 12% 21% 18% 15%	2730
July	1st to 10th	Day	24% 10% 17% 22% 18% 8%	7586
	11th to 20th	Day	30% 10% 21% 28% 10% 2	7467
	21st to end	Day	19% 9% 19% 26% 25% 3	7516
August	1st to 10th	Day	18% 7% 18% 35% 20% 2	5532
	11th to 20th	Day	24% 11% 24% 26% 12% 2	5519
	21st to end	Day	18% 7% 14% 25% 28% 9%	6078
September	1st to 10th	Day	37% 11% 16% 18% 12% 6%	2520
	11th to 20th	Day	32% 9% 14% 19% 19% 7%	2520
	21st to end	Day	26% 8% 13% 21% 22% 10%	2326
October	1st to 10th	Day	12% 5% 6% 13% 27% 36%	3377
	11th to 20th	Day	13% 4 7% 19% 26% 31%	3280
	21st to end	Day	7% 2 3 11% 44% 33%	3548
November	1st to 10th	Day	14% 3 6% 17% 33% 27%	2059
	11th to 20th	Day	17% 2 4 19% 33% 24%	2100
	21st to end	Day	23% 5% 6% 18% 25% 24%	2100
December	1st to 10th	Day	22% 4 4 16% 32% 22%	3370
	11th to 20th	Day	16% 3 4 13% 39% 25%	3873
	21st to end	Day	10% 2 4 10% 38% 36%	5104
January	1st to 10th	Night	15% 2 3 18% 33% 27%	7583
	11th to 20th	Night	15% 3 4 12% 32% 34%	7617
	21st to end	Night	25% 4 4 18% 30% 19%	7746
February	1st to 10th	Night	20% 3 5% 12% 25% 34%	2520
	11th to 20th	Night	20% 4 7% 10% 28% 31%	2458
	21st to end	Night	16% 4 5% 11% 31% 34%	2050
March	1st to 10th	Night	19% 4 3 6% 23% 45%	5050
	11th to 20th	Night	16% 3 5% 5% 23% 48%	5110
	21st to end	Night	17% 4 3 10% 28% 38%	5484
April	1st to 10th	Night	19% 3 6% 12% 24% 36%	2100
	11th to 20th	Night	21% 4 5% 9% 25% 36%	2077
	21st to end	Night	20% 3 4 10% 24% 40%	2100
May	1st to 10th	Night	16% 3 4 8% 15% 55%	5888
	11th to 20th	Night	29% 3 4 9% 18% 37%	5861
	21st to end	Night	22% 4 5% 10% 16% 43%	6461
June	1st to 10th	Night	32% 7% 10% 16% 19% 17%	2100
	11th to 20th	Night	36% 7% 10% 12% 20% 15%	1959
	21st to end	Night	42% 11% 12% 15% 10% 9%	1890
July	1st to 10th	Night	48% 10% 13% 14% 12% 3	5295
	11th to 20th	Night	48% 10% 17% 19% 5% 2	5395
	21st to end	Night	40% 9% 11% 20% 19% 1	6280
August	1st to 10th	Night	35% 10% 12% 26% 14% 2	4614
	11th to 20th	Night	46% 12% 17% 17% 7%	4613
	21st to end	Night	31% 9% 10% 20% 22% 8%	5069
September	1st to 10th	Night	50% 11% 15% 12% 7% 5%	2100
	11th to 20th	Night	47% 11% 12% 11% 11% 7%	2100
	21st to end	Night	40% 11% 12% 13% 15% 9%	2294
October	1st to 10th	Night	19% 5% 6% 11% 24% 35%	4025
	11th to 20th	Night	22% 5% 6% 16% 23% 28%	3934
	21st to end	Night	11% 2 3 14% 41% 29%	4252
November	1st to 10th	Night	14% 3 7% 15% 36% 26%	2460
	11th to 20th	Night	20% 4 7% 16% 31% 22%	2520
	21st to end	Night	21% 4 7% 18% 28% 23%	2520
December	1st to 10th	Night	25% 4 5% 20% 29% 18%	4040
	11th to 20th	Night	13% 3 5% 13% 44% 22%	4566
	21st to end	Night	13% 2 4 11% 38% 32%	6116

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	7% 8% 31% 33% 18% 2	330
	11th to 20th	Day	4 7% 30% 41% 17% 1	330
	21st to end	Day	7% 11% 35% 33% 13% 1	363
February	1st to 10th	Day	7% 9% 30% 31% 19% 4	330
	11th to 20th	Day	7% 13% 39% 30% 10% 1	330
	21st to end	Day	7% 14% 38% 30% 9% 2	293
March	1st to 10th	Day	8% 19% 40% 24% 9% 1	540
	11th to 20th	Day	8% 18% 36% 25% 10% 3	540
	21st to end	Day	9% 16% 41% 20% 12% 2	594
April	1st to 10th	Day	8% 15% 40% 27% 9% 1	540
	11th to 20th	Day	6% 16% 40% 26% 9% 1	532
	21st to end	Day	7% 13% 39% 31% 10% 1	540
May	1st to 10th	Day	4 13% 40% 29% 12% 2	543
	11th to 20th	Day	5% 9% 34% 35% 14% 3	568
	21st to end	Day	4 7% 34% 35% 18% 2	617
June	1st to 10th	Day	5% 2 21% 40% 27% 5%	570
	11th to 20th	Day	2 2 14% 39% 37% 6%	570
	21st to end	Day	3 1 7% 34% 41% 14%	570
July	1st to 10th	Day	5% 2 4 27% 42% 19%	566
	11th to 20th	Day	4 1 3 27% 49% 15%	564
	21st to end	Day	3 1 2 27% 46% 20%	619
August	1st to 10th	Day	2 1 3 23% 52% 20%	567
	11th to 20th	Day	5% 1 5% 23% 41% 25%	557
	21st to end	Day	5% 1 4 27% 41% 22%	627
September	1st to 10th	Day	7% 2 5% 27% 41% 18%	570
	11th to 20th	Day	7% 1 5% 26% 44% 17%	570
	21st to end	Day	8% 2 9% 26% 38% 18%	376
October	1st to 10th	Day	5% 2 11% 31% 34% 18%	360
	11th to 20th	Day	6% 3 14% 33% 29% 14%	339
	21st to end	Day	4 5% 21% 32% 25% 13%	363
November	1st to 10th	Day	2 5% 24% 33% 25% 11%	330
	11th to 20th	Day	5% 5% 20% 38% 25% 7%	330
	21st to end	Day	9% 10% 30% 31% 16% 3	330
December	1st to 10th	Day	6% 7% 25% 37% 22% 3	330
	11th to 20th	Day	4 6% 28% 38% 18% 5%	330
	21st to end	Day	6% 9% 30% 34% 17% 5%	363
January	1st to 10th	Night	6% 3 23% 48% 19% 2	840
	11th to 20th	Night	5% 3 21% 45% 23% 1	840
	21st to end	Night	6% 7% 28% 43% 15% 1	924
February	1st to 10th	Night	6% 7% 24% 40% 21% 3	840
	11th to 20th	Night	5% 7% 32% 43% 13% 1	824
	21st to end	Night	5% 8% 35% 40% 11% 1	692
March	1st to 10th	Night	7% 8% 34% 39% 10% 1	840
	11th to 20th	Night	7% 8% 29% 40% 14% 1	840
	21st to end	Night	4 6% 34% 40% 14% 1	875
April	1st to 10th	Night	7% 8% 37% 39% 8% 1	630
	11th to 20th	Night	4 8% 41% 40% 6%	623
	21st to end	Night	6% 7% 37% 42% 8%	630
May	1st to 10th	Night	6% 5% 43% 37% 9%	630
	11th to 20th	Night	7% 4 31% 47% 10% 1	621
	21st to end	Night	4 5% 27% 48% 16% 1	683
June	1st to 10th	Night	5% 3 16% 49% 25% 1	630
	11th to 20th	Night	7% 1 12% 46% 33% 1	630
	21st to end	Night	8% 3 9% 36% 41% 2	630
July	1st to 10th	Night	9% 2 6% 30% 50% 3	615
	11th to 20th	Night	9% 1 6% 28% 51% 5%	612
	21st to end	Night	9% 2 5% 28% 50% 7%	690
August	1st to 10th	Night	7% 1 4 26% 52% 10%	627
	11th to 20th	Night	8% 2 6% 23% 47% 13%	624
	21st to end	Night	8% 2 6% 21% 54% 10%	693
September	1st to 10th	Night	13% 3 6% 22% 49% 7%	630
	11th to 20th	Night	14% 2 7% 27% 47% 3	630
	21st to end	Night	11% 2 8% 31% 43% 6%	630
October	1st to 10th	Night	6% 2 8% 35% 44% 5%	825
	11th to 20th	Night	8% 2 10% 42% 32% 6%	812
	21st to end	Night	4 4 11% 42% 31% 8%	880
November	1st to 10th	Night	6% 1 13% 40% 35% 5%	820
	11th to 20th	Night	6% 2 13% 47% 30% 3	840
	21st to end	Night	6% 4 20% 45% 22% 4	840
December	1st to 10th	Night	6% 2 20% 46% 22% 4	840
	11th to 20th	Night	5% 3 20% 49% 20% 3	840
	21st to end	Night	4 6% 23% 43% 20% 4	924

Page generated at 2026-10-11 02:06:30. Version ac07

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