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Las Cruces
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Las Cruces clear sky chart from 2005-11-06 to 2025-11-03.

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	2 2 1 3 2 3 3 3 5% 7% 68%	134377
	Night	3 3 1 4 3 3 4 3 5% 7% 64%	133150
Transparency	Day	16% 4 7% 15% 28% 31%	129427
	Night	19% 4 6% 14% 27% 30%	129104
Seeing	Day	5% 7% 19% 29% 26% 14%	15593
	Night	5% 4 21% 44% 24% 2	25927

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	3 5% 2 4 3 3 3 3 5% 6% 63%	4098
	11th to 20th	Day	1 2 2 2 1 2 2 4 6% 78%	4100
	21st to end	Day	5% 4 1 3 2 2 3 3 5% 6% 67%	4510
February	1st to 10th	Day	3 3 1 3 2 2 3 3 5% 5% 70%	1878
	11th to 20th	Day	4 4 2 5% 3 2 3 3 4 5% 65%	1949
	21st to end	Day	3 3 1 4 2 3 3 2 4 6% 70%	1667
March	1st to 10th	Day	2 3 1 4 2 3 3 2 5% 7% 68%	4954
	11th to 20th	Day	4 4 1 4 3 2 3 3 4 6% 67%	5000
	21st to end	Day	2 3 1 4 3 3 4 3 5% 7% 64%	5543
April	1st to 10th	Day	2 2 1 2 2 2 3 3 5% 7% 71%	2400
	11th to 20th	Day	2 2 1 2 2 1 2 2 3 4 78%	2371
	21st to end	Day	2 2 1 2 2 2 1 2 3 5% 80%	2400
May	1st to 10th	Day	1 1 1 1 1 2 2 3 4 84%	5440
	11th to 20th	Day	1 1 1 1 2 2 2 4 6% 80%	5405
	21st to end	Day	1 1 1 1 1 2 3 5% 85%	6310
June	1st to 10th	Day	2 2 1 2 2 2 2 2 5% 7% 73%	2600
	11th to 20th	Day	2 1 1 2 2 2 2 3 4 5% 77%	2600
	21st to end	Day	3 4 2 4 3 4 5% 4 6% 9% 57%	2600
July	1st to 10th	Day	3 2 1 4 4 4 5% 4 7% 8% 58%	5879
	11th to 20th	Day	1 1 1 3 3 4 5% 5% 7% 11% 61%	5880
	21st to end	Day	3 3 1 5% 5% 5% 6% 6% 9% 12% 46%	6401
August	1st to 10th	Day	2 2 3 2 3 4 4 7% 10% 61%	5484
	11th to 20th	Day	2 2 1 3 4 4 5% 4 7% 10% 58%	5366
	21st to end	Day	2 2 1 4 3 4 5% 4 7% 9% 58%	5984
September	1st to 10th	Day	5% 4 2 6% 4 4 5% 3 6% 8% 53%	2400
	11th to 20th	Day	6% 3 1 4 3 3 4 4 5% 8% 59%	2400
	21st to end	Day	3 2 1 3 2 2 2 2 5% 5% 72%	2149
October	1st to 10th	Day	2 2 1 2 2 2 2 1 3 4 79%	3270
	11th to 20th	Day	3 3 1 3 3 2 2 2 4 4 74%	3250
	21st to end	Day	1 1 1 1 1 1 1 2 3 86%	3548
November	1st to 10th	Day	2 2 1 3 2 2 3 2 4 6% 74%	1979
	11th to 20th	Day	2 2 1 3 3 2 3 3 6% 6% 69%	2000
	21st to end	Day	6% 4 1 3 3 4 3 3 5% 7% 63%	1856
December	1st to 10th	Day	6% 4 1 4 2 3 3 2 5% 5% 65%	2886
	11th to 20th	Day	3 4 2 5% 2 2 3 2 4 6% 67%	3310
	21st to end	Day	3 2 1 3 2 2 3 3 4 6% 72%	4510
January	1st to 10th	Night	5% 6% 2 4 2 2 3 3 5% 7% 61%	5867
	11th to 20th	Night	1 2 1 2 2 2 2 3 4 5% 76%	5880
	21st to end	Night	5% 5% 1 4 2 3 3 3 6% 6% 62%	6468
February	1st to 10th	Night	2 3 1 3 3 4 4 3 5% 7% 66%	2520
	11th to 20th	Night	5% 4 1 3 3 3 3 2 4 7% 65%	2338
	21st to end	Night	2 3 1 3 3 2 3 2 5% 7% 68%	1958
March	1st to 10th	Night	3 3 1 3 2 2 3 3 5% 6% 69%	4940
	11th to 20th	Night	4 5% 1 4 3 3 3 3 4 6% 64%	5000
	21st to end	Night	2 4 2 5% 3 3 4 3 4 6% 63%	5426
April	1st to 10th	Night	1 2 1 3 3 3 3 4 5% 7% 69%	2000
	11th to 20th	Night	3 3 1 3 2 2 3 3 5% 5% 70%	1977
	21st to end	Night	2 2 1 2 2 2 3 2 4 5% 76%	2000
May	1st to 10th	Night	2 2 1 2 1 2 2 2 3 4 79%	4540
	11th to 20th	Night	2 3 1 3 2 3 3 3 4 6% 69%	4510
	21st to end	Night	1 1 1 2 2 2 2 3 3 82%	4570
June	1st to 10th	Night	2 2 1 4 3 3 5% 4 5% 8% 63%	1800
	11th to 20th	Night	2 1 1 3 3 3 2 3 5% 7% 71%	1800
	21st to end	Night	3 4 1 5% 5% 5% 7% 5% 8% 10% 46%	1800
July	1st to 10th	Night	3 3 2 5% 5% 5% 6% 6% 9% 10% 47%	4100
	11th to 20th	Night	2 2 1 6% 5% 6% 7% 6% 9% 13% 44%	4100
	21st to end	Night	3 4 2 8% 6% 6% 7% 7% 10% 12% 35%	4472
August	1st to 10th	Night	2 3 1 6% 5% 5% 6% 5% 7% 12% 48%	4327
	11th to 20th	Night	3 3 1 5% 5% 6% 7% 6% 9% 13% 43%	4483
	21st to end	Night	3 3 2 7% 6% 6% 6% 5% 8% 11% 42%	4993
September	1st to 10th	Night	5% 4 2 4 4 5% 5% 5% 7% 9% 50%	2000
	11th to 20th	Night	5% 4 2 5% 4 4 4 4 7% 8% 55%	2000
	21st to end	Night	3 3 1 3 3 3 4 3 4 7% 66%	2245
October	1st to 10th	Night	2 2 1 3 2 2 2 2 4 5% 76%	3920
	11th to 20th	Night	4 3 1 4 3 3 3 2 3 4 71%	3898
	21st to end	Night	2 1 1 1 1 2 2 3 4 81%	4252
November	1st to 10th	Night	2 2 1 2 2 3 2 2 4 7% 74%	2364
	11th to 20th	Night	2 2 1 3 3 2 2 3 4 6% 72%	2400
	21st to end	Night	5% 4 1 4 3 3 3 3 5% 6% 63%	2515
December	1st to 10th	Night	4 3 1 3 1 2 2 2 3 4 74%	4299
	11th to 20th	Night	2 2 1 4 3 3 3 3 5% 6% 67%	4920
	21st to end	Night	3 3 1 3 2 2 2 2 4 5% 73%	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% 2 5% 10% 40% 21%	4099
	11th to 20th	Day	9% 2 4 14% 48% 23%	4100
	21st to end	Day	18% 3 5% 19% 31% 25%	4510
February	1st to 10th	Day	17% 2 4 15% 28% 33%	1878
	11th to 20th	Day	21% 2 5% 15% 30% 27%	1959
	21st to end	Day	18% 1 3 8% 30% 40%	1667
March	1st to 10th	Day	15% 2 3 6% 31% 42%	4954
	11th to 20th	Day	19% 3 5% 14% 26% 33%	5000
	21st to end	Day	18% 2 5% 9% 31% 34%	5543
April	1st to 10th	Day	12% 2 4 11% 31% 40%	2400
	11th to 20th	Day	11% 1 3 7% 27% 51%	2374
	21st to end	Day	9% 2 3 8% 27% 51%	2400
May	1st to 10th	Day	6% 1 3 9% 27% 54%	5440
	11th to 20th	Day	8% 2 5% 9% 22% 53%	5408
	21st to end	Day	5% 1 3 8% 13% 69%	6311
June	1st to 10th	Day	12% 2 5% 12% 29% 40%	2600
	11th to 20th	Day	10% 2 4 7% 22% 56%	2600
	21st to end	Day	22% 5% 9% 14% 21% 29%	2600
July	1st to 10th	Day	20% 7% 11% 19% 23% 19%	5816
	11th to 20th	Day	14% 6% 17% 28% 26% 10%	5811
	21st to end	Day	26% 9% 18% 23% 18% 6%	6217
August	1st to 10th	Day	18% 8% 12% 28% 26% 7%	3990
	11th to 20th	Day	18% 6% 12% 19% 34% 11%	3882
	21st to end	Day	23% 7% 15% 24% 25% 6%	4311
September	1st to 10th	Day	27% 5% 9% 19% 22% 18%	2400
	11th to 20th	Day	22% 5% 9% 15% 29% 20%	2400
	21st to end	Day	13% 3 7% 20% 32% 25%	2149
October	1st to 10th	Day	11% 3 4 9% 26% 47%	3270
	11th to 20th	Day	15% 3 5% 12% 29% 36%	3250
	21st to end	Day	7% 1 2 10% 33% 46%	3548
November	1st to 10th	Day	13% 2 6% 17% 35% 28%	1979
	11th to 20th	Day	15% 3 4 17% 30% 31%	2000
	21st to end	Day	21% 3 6% 16% 32% 21%	1856
December	1st to 10th	Day	20% 4 6% 21% 32% 17%	2886
	11th to 20th	Day	21% 3 4 15% 40% 18%	3309
	21st to end	Day	14% 2 6% 18% 40% 20%	4510
January	1st to 10th	Night	23% 2 4 12% 42% 16%	5867
	11th to 20th	Night	11% 2 4 14% 47% 22%	5880
	21st to end	Night	22% 3 6% 16% 30% 24%	6468
February	1st to 10th	Night	18% 2 6% 16% 23% 35%	2520
	11th to 20th	Night	20% 2 5% 13% 30% 29%	2338
	21st to end	Night	17% 3 3 10% 27% 40%	1958
March	1st to 10th	Night	16% 2 4 7% 32% 40%	4940
	11th to 20th	Night	21% 3 5% 12% 27% 31%	5000
	21st to end	Night	21% 3 5% 9% 30% 32%	5426
April	1st to 10th	Night	14% 3 5% 8% 32% 38%	2000
	11th to 20th	Night	15% 2 5% 9% 23% 46%	1977
	21st to end	Night	11% 2 4 10% 25% 48%	2000
May	1st to 10th	Night	10% 2 3 13% 19% 53%	4537
	11th to 20th	Night	15% 3 5% 10% 19% 48%	4511
	21st to end	Night	10% 1 4 7% 12% 66%	4571
June	1st to 10th	Night	19% 4 6% 13% 21% 37%	1800
	11th to 20th	Night	14% 3 5% 8% 18% 52%	1800
	21st to end	Night	29% 6% 10% 16% 16% 23%	1800
July	1st to 10th	Night	27% 9% 15% 18% 19% 12%	4055
	11th to 20th	Night	26% 9% 16% 20% 21% 8%	4046
	21st to end	Night	36% 9% 18% 20% 11% 6%	4344
August	1st to 10th	Night	29% 8% 12% 25% 19% 7%	3145
	11th to 20th	Night	22% 7% 11% 17% 28% 15%	3243
	21st to end	Night	37% 9% 12% 21% 16% 6%	3597
September	1st to 10th	Night	28% 7% 12% 16% 20% 18%	2000
	11th to 20th	Night	25% 6% 10% 17% 21% 21%	2000
	21st to end	Night	19% 4 7% 15% 30% 25%	2245
October	1st to 10th	Night	13% 3 5% 9% 20% 51%	3920
	11th to 20th	Night	18% 3 5% 11% 20% 43%	3898
	21st to end	Night	9% 2 2 8% 30% 49%	4252
November	1st to 10th	Night	13% 2 6% 13% 32% 34%	2364
	11th to 20th	Night	14% 3 5% 15% 33% 31%	2400
	21st to end	Night	23% 3 6% 14% 30% 25%	2515
December	1st to 10th	Night	15% 3 3 22% 37% 20%	4299
	11th to 20th	Night	18% 3 4 15% 37% 23%	4920
	21st to end	Night	15% 2 4 17% 42% 20%	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% 6% 27% 39% 17% 3	300
	11th to 20th	Day	8% 4 21% 43% 18% 6%	300
	21st to end	Day	7% 5% 29% 32% 19% 8%	330
February	1st to 10th	Day	8% 6% 21% 37% 21% 7%	300
	11th to 20th	Day	12% 8% 26% 37% 15% 2	300
	21st to end	Day	12% 14% 28% 32% 12% 3	266
March	1st to 10th	Day	9% 16% 31% 32% 10% 2	500
	11th to 20th	Day	12% 16% 24% 29% 15% 4	500
	21st to end	Day	9% 18% 35% 25% 11% 3	550
April	1st to 10th	Day	7% 13% 31% 28% 18% 4	500
	11th to 20th	Day	6% 20% 32% 26% 13% 3	492
	21st to end	Day	6% 16% 31% 30% 14% 2	500
May	1st to 10th	Day	3 14% 31% 32% 14% 6%	503
	11th to 20th	Day	2 10% 27% 35% 21% 4	528
	21st to end	Day	2 6% 31% 37% 21% 3	573
June	1st to 10th	Day	4 5% 17% 34% 28% 12%	530
	11th to 20th	Day	3 3 19% 32% 34% 10%	530
	21st to end	Day	4 2 11% 28% 34% 21%	530
July	1st to 10th	Day	3 1 6% 22% 39% 29%	526
	11th to 20th	Day	3 3 20% 38% 35%	524
	21st to end	Day	3 1 3 18% 35% 40%	575
August	1st to 10th	Day	3 1 2 13% 39% 43%	527
	11th to 20th	Day	4 1 7% 21% 42% 26%	517
	21st to end	Day	4 1 2 20% 34% 39%	583
September	1st to 10th	Day	5% 2 8% 25% 38% 22%	530
	11th to 20th	Day	3 1 10% 29% 37% 19%	530
	21st to end	Day	5% 2 10% 29% 38% 17%	390
October	1st to 10th	Day	4 4 14% 29% 32% 18%	330
	11th to 20th	Day	5% 6% 14% 28% 35% 12%	330
	21st to end	Day	5% 5% 14% 31% 31% 14%	363
November	1st to 10th	Day	4 6% 23% 31% 27% 9%	306
	11th to 20th	Day	2 5% 17% 29% 39% 8%	300
	21st to end	Day	10% 7% 22% 36% 20% 5%	300
December	1st to 10th	Day	8% 8% 15% 39% 25% 6%	300
	11th to 20th	Day	5% 6% 24% 42% 19% 4	300
	21st to end	Day	7% 4 27% 43% 16% 2	330
January	1st to 10th	Night	6% 3 25% 48% 16% 3	800
	11th to 20th	Night	4 3 26% 48% 17% 2	800
	21st to end	Night	7% 5% 27% 44% 16% 1	880
February	1st to 10th	Night	3 4 30% 45% 16% 2	800
	11th to 20th	Night	7% 6% 33% 42% 11% 1	784
	21st to end	Night	5% 7% 43% 38% 7%	660
March	1st to 10th	Night	8% 8% 31% 43% 10% 1	800
	11th to 20th	Night	6% 7% 30% 43% 13% 1	800
	21st to end	Night	4 8% 33% 43% 11% 1	855
April	1st to 10th	Night	3 8% 40% 38% 10% 1	600
	11th to 20th	Night	5% 9% 36% 38% 11% 1	593
	21st to end	Night	3 10% 35% 42% 10% 1	600
May	1st to 10th	Night	5% 5% 36% 46% 8%	600
	11th to 20th	Night	3 5% 27% 51% 14% 1	591
	21st to end	Night	3 5% 28% 51% 13%	650
June	1st to 10th	Night	3 3 20% 50% 24% 1	600
	11th to 20th	Night	2 1 20% 53% 24% 1	600
	21st to end	Night	3 2 11% 48% 35% 2	600
July	1st to 10th	Night	3 2 6% 41% 43% 5%	585
	11th to 20th	Night	3 1 5% 31% 55% 6%	582
	21st to end	Night	4 1 3 29% 54% 9%	657
August	1st to 10th	Night	4 1 4 26% 56% 9%	597
	11th to 20th	Night	4 1 5% 23% 59% 8%	594
	21st to end	Night	3 1 5% 30% 55% 6%	660
September	1st to 10th	Night	5% 1 7% 39% 45% 4	600
	11th to 20th	Night	6% 2 6% 45% 40% 2	600
	21st to end	Night	5% 1 9% 47% 35% 3	706
October	1st to 10th	Night	4 2 12% 52% 27% 2	800
	11th to 20th	Night	5% 3 18% 48% 25% 2	800
	21st to end	Night	4 2 14% 45% 29% 5%	880
November	1st to 10th	Night	4 2 15% 46% 30% 4	788
	11th to 20th	Night	4 2 19% 49% 24% 2	800
	21st to end	Night	7% 5% 21% 44% 20% 3	915
December	1st to 10th	Night	7% 5% 20% 47% 21% 1	1000
	11th to 20th	Night	6% 4 23% 51% 16% 1	870
	21st to end	Night	6% 4 25% 49% 15% 1	880

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