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 2024-11-02.

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 4 5% 7% 62%	100988
	Night	5% 4 2 5% 4 4 4 4 6% 7% 56%	98125
Transparency	Day	19% 5% 10% 17% 23% 25%	100807
	Night	26% 6% 8% 14% 23% 23%	97976
Seeing	Day	6% 7% 23% 30% 27% 8%	14246
	Night	7% 4 20% 38% 27% 4	24122

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 2 1 2 2 2 2 2 3 5% 78%	2858
	11th to 20th	Day	2 2 1 2 2 2 2 2 4 5% 77%	2860
	21st to end	Day	3 4 1 4 3 3 4 3 4 7% 63%	3486
February	1st to 10th	Day	3 3 2 4 4 3 3 2 4 5% 67%	1900
	11th to 20th	Day	2 3 1 3 3 3 3 3 4 5% 68%	1849
	21st to end	Day	3 2 2 2 2 3 4 5% 8% 69%	1588
March	1st to 10th	Day	3 3 1 4 3 4 4 3 5% 7% 62%	3444
	11th to 20th	Day	4 4 2 4 3 3 3 3 4 6% 65%	3490
	21st to end	Day	2 4 1 3 3 3 4 3 6% 6% 65%	3903
April	1st to 10th	Day	3 3 2 3 2 3 4 3 5% 6% 66%	2280
	11th to 20th	Day	2 2 1 3 2 3 4 2 4 6% 70%	2254
	21st to end	Day	3 3 1 3 3 2 3 3 4 5% 72%	2280
May	1st to 10th	Day	1 1 1 2 1 2 3 2 4 5% 78%	3765
	11th to 20th	Day	2 2 1 3 3 2 3 3 4 6% 70%	3765
	21st to end	Day	1 1 1 2 2 2 3 2 4 6% 78%	4130
June	1st to 10th	Day	3 3 1 4 4 3 4 4 6% 7% 62%	2280
	11th to 20th	Day	3 2 1 5% 4 4 5% 5% 7% 8% 57%	2399
	21st to end	Day	4 3 1 4 4 5% 5% 5% 7% 10% 51%	2470
July	1st to 10th	Day	4 3 2 5% 5% 5% 6% 5% 7% 10% 47%	4110
	11th to 20th	Day	3 2 1 3 4 5% 5% 6% 8% 12% 51%	4048
	21st to end	Day	4 4 2 4 4 5% 6% 5% 8% 11% 47%	4117
August	1st to 10th	Day	2 2 1 4 4 5% 5% 5% 8% 10% 56%	3785
	11th to 20th	Day	3 2 1 4 4 5% 6% 5% 7% 11% 51%	3726
	21st to end	Day	4 2 1 4 5% 5% 5% 5% 7% 11% 50%	4180
September	1st to 10th	Day	8% 5% 3 6% 5% 5% 6% 5% 7% 9% 39%	2280
	11th to 20th	Day	9% 4 2 5% 5% 5% 5% 4 7% 9% 46%	2280
	21st to end	Day	8% 4 1 4 3 4 4 4 6% 7% 56%	2104
October	1st to 10th	Day	3 2 1 4 3 4 5% 4 7% 6% 62%	1907
	11th to 20th	Day	6% 3 2 3 3 2 3 2 4 7% 65%	1900
	21st to end	Day	4 2 1 2 1 1 2 2 3 5% 78%	2090
November	1st to 10th	Day	4 2 1 3 2 2 2 2 4 6% 73%	1869
	11th to 20th	Day	5% 2 1 3 2 3 3 2 3 5% 72%	1900
	21st to end	Day	5% 4 1 4 3 3 3 3 5% 5% 63%	1900
December	1st to 10th	Day	4 4 2 3 3 3 2 3 4 7% 65%	1900
	11th to 20th	Day	2 3 1 4 3 3 4 4 6% 8% 62%	2404
	21st to end	Day	2 2 1 2 2 2 3 3 5% 8% 70%	3487
January	1st to 10th	Night	2 2 1 2 2 2 2 2 3 4 80%	4075
	11th to 20th	Night	3 2 1 2 2 3 4 3 4 5% 73%	4103
	21st to end	Night	5% 5% 2 5% 4 4 3 3 4 7% 58%	4180
February	1st to 10th	Night	4 3 2 3 3 3 3 3 4 5% 68%	2280
	11th to 20th	Night	4 4 1 4 3 3 3 3 5% 7% 63%	2218
	21st to end	Night	3 4 2 2 2 2 4 3 5% 8% 66%	1860
March	1st to 10th	Night	4 5% 2 5% 3 3 3 3 5% 6% 62%	3430
	11th to 20th	Night	4 5% 2 4 3 3 4 4 5% 6% 60%	3490
	21st to end	Night	4 3 1 4 3 3 3 3 5% 6% 65%	3746
April	1st to 10th	Night	4 3 1 3 3 3 2 3 6% 7% 65%	1900
	11th to 20th	Night	3 4 1 4 3 3 3 3 4 6% 67%	1877
	21st to end	Night	5% 3 1 4 3 3 3 2 3 5% 68%	1900
May	1st to 10th	Night	2 2 1 2 2 2 2 2 4 5% 75%	3140
	11th to 20th	Night	5% 3 1 4 3 3 3 3 5% 7% 65%	3140
	21st to end	Night	3 4 1 4 2 3 3 3 5% 5% 66%	3437
June	1st to 10th	Night	5% 4 2 6% 6% 6% 6% 4 8% 8% 45%	1900
	11th to 20th	Night	6% 5% 2 7% 6% 7% 6% 5% 7% 9% 42%	1773
	21st to end	Night	8% 5% 2 7% 7% 7% 7% 6% 8% 10% 33%	1710
July	1st to 10th	Night	7% 8% 3 12% 7% 8% 8% 6% 9% 9% 23%	2860
	11th to 20th	Night	5% 4 3 9% 6% 6% 7% 7% 9% 13% 32%	2917
	21st to end	Night	7% 6% 3 8% 7% 7% 7% 6% 8% 11% 30%	3446
August	1st to 10th	Night	5% 6% 3 9% 7% 8% 9% 6% 9% 9% 30%	3155
	11th to 20th	Night	6% 5% 3 10% 7% 8% 8% 7% 10% 10% 26%	3113
	21st to end	Night	6% 5% 3 9% 7% 6% 7% 6% 9% 12% 31%	3487
September	1st to 10th	Night	13% 8% 3 9% 8% 6% 6% 5% 7% 9% 27%	1900
	11th to 20th	Night	13% 7% 3 7% 6% 7% 6% 5% 7% 8% 31%	1900
	21st to end	Night	10% 5% 2 7% 5% 6% 6% 4 8% 9% 39%	2076
October	1st to 10th	Night	6% 4 2 5% 5% 4 4 3 5% 6% 57%	2266
	11th to 20th	Night	7% 3 1 5% 3 3 4 3 5% 6% 59%	2280
	21st to end	Night	5% 2 1 2 2 2 3 2 3 4 74%	2508
November	1st to 10th	Night	6% 2 1 2 2 2 2 3 3 5% 73%	2232
	11th to 20th	Night	5% 3 1 3 3 3 4 2 5% 4 67%	2280
	21st to end	Night	4 4 1 4 3 3 4 2 3 5% 66%	2280
December	1st to 10th	Night	4 3 1 3 3 3 4 3 4 8% 64%	2280
	11th to 20th	Night	2 4 1 4 2 3 4 3 6% 8% 63%	2806
	21st to end	Night	4 3 1 3 2 2 3 3 4 7% 67%	4180

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	11% 2 4 11% 28% 44%	2859
	11th to 20th	Day	12% 3 4 13% 33% 35%	2860
	21st to end	Day	22% 4 6% 22% 27% 18%	3486
February	1st to 10th	Day	22% 3 5% 9% 26% 35%	1900
	11th to 20th	Day	19% 4 6% 11% 28% 32%	1859
	21st to end	Day	14% 3 7% 10% 30% 37%	1588
March	1st to 10th	Day	20% 4 7% 10% 24% 35%	3444
	11th to 20th	Day	20% 4 5% 9% 22% 39%	3490
	21st to end	Day	17% 4 5% 7% 27% 40%	3903
April	1st to 10th	Day	18% 4 5% 9% 22% 42%	2280
	11th to 20th	Day	15% 3 7% 8% 24% 43%	2254
	21st to end	Day	15% 2 4 9% 25% 45%	2280
May	1st to 10th	Day	10% 2 3 8% 17% 60%	3800
	11th to 20th	Day	15% 3 7% 8% 21% 46%	3768
	21st to end	Day	8% 2 6% 9% 20% 55%	4141
June	1st to 10th	Day	17% 5% 9% 17% 30% 23%	2280
	11th to 20th	Day	20% 5% 8% 15% 25% 27%	2399
	21st to end	Day	25% 7% 12% 23% 19% 15%	2470
July	1st to 10th	Day	28% 10% 17% 24% 14% 7%	4046
	11th to 20th	Day	21% 9% 21% 32% 14% 3	3979
	21st to end	Day	26% 11% 17% 25% 17% 4	3988
August	1st to 10th	Day	19% 8% 20% 33% 18% 2	3772
	11th to 20th	Day	24% 10% 19% 30% 15% 2	3762
	21st to end	Day	25% 9% 20% 29% 16% 2	4179
September	1st to 10th	Day	38% 11% 16% 18% 12% 6%	2280
	11th to 20th	Day	33% 10% 13% 17% 20% 8%	2280
	21st to end	Day	25% 7% 13% 20% 23% 11%	2104
October	1st to 10th	Day	19% 8% 10% 20% 26% 17%	1907
	11th to 20th	Day	20% 5% 8% 20% 24% 24%	1900
	21st to end	Day	12% 2 4 14% 38% 29%	2090
November	1st to 10th	Day	15% 4 6% 19% 34% 22%	1869
	11th to 20th	Day	17% 3 5% 20% 33% 22%	1900
	21st to end	Day	23% 5% 6% 17% 24% 25%	1900
December	1st to 10th	Day	21% 4 7% 19% 34% 16%	1900
	11th to 20th	Day	20% 5% 6% 16% 33% 19%	2403
	21st to end	Day	13% 3 5% 13% 36% 29%	3487
January	1st to 10th	Night	12% 3 4 9% 34% 38%	4075
	11th to 20th	Night	15% 3 5% 11% 33% 32%	4103
	21st to end	Night	26% 6% 5% 20% 27% 16%	4180
February	1st to 10th	Night	19% 4 6% 12% 26% 33%	2280
	11th to 20th	Night	22% 4 7% 10% 27% 31%	2218
	21st to end	Night	17% 4 5% 12% 29% 33%	1860
March	1st to 10th	Night	24% 4 5% 9% 25% 33%	3430
	11th to 20th	Night	23% 5% 7% 7% 26% 33%	3490
	21st to end	Night	18% 5% 5% 9% 30% 33%	3746
April	1st to 10th	Night	18% 3 5% 11% 25% 37%	1900
	11th to 20th	Night	19% 5% 5% 8% 26% 38%	1877
	21st to end	Night	20% 3 4 10% 23% 40%	1900
May	1st to 10th	Night	14% 3 4 7% 15% 58%	3170
	11th to 20th	Night	19% 4 6% 8% 20% 42%	3141
	21st to end	Night	19% 3 6% 7% 15% 50%	3447
June	1st to 10th	Night	33% 7% 10% 16% 19% 14%	1900
	11th to 20th	Night	36% 7% 10% 13% 19% 15%	1773
	21st to end	Night	40% 11% 13% 16% 10% 10%	1710
July	1st to 10th	Night	51% 12% 15% 13% 6% 3	2815
	11th to 20th	Night	37% 11% 20% 25% 5% 2	2863
	21st to end	Night	42% 10% 12% 19% 16% 1	3336
August	1st to 10th	Night	43% 11% 13% 20% 12% 1	3144
	11th to 20th	Night	45% 12% 16% 18% 8% 1	3143
	21st to end	Night	41% 11% 13% 21% 11% 2	3487
September	1st to 10th	Night	50% 10% 15% 12% 7% 5%	1900
	11th to 20th	Night	47% 10% 12% 11% 12% 8%	1900
	21st to end	Night	39% 11% 12% 13% 16% 10%	2076
October	1st to 10th	Night	27% 7% 10% 17% 22% 17%	2266
	11th to 20th	Night	26% 6% 9% 17% 22% 20%	2280
	21st to end	Night	16% 2 5% 16% 34% 28%	2508
November	1st to 10th	Night	15% 3 7% 16% 38% 20%	2232
	11th to 20th	Night	21% 4 8% 17% 30% 21%	2280
	21st to end	Night	22% 4 7% 18% 25% 24%	2280
December	1st to 10th	Night	21% 4 7% 19% 34% 15%	2280
	11th to 20th	Night	19% 4 8% 16% 37% 16%	2806
	21st to end	Night	18% 3 5% 11% 33% 29%	4180

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% 8% 32% 35% 17%	270
	11th to 20th	Day	2 8% 29% 44% 16% 1	270
	21st to end	Day	6% 11% 36% 35% 11% 1	297
February	1st to 10th	Day	7% 9% 33% 31% 19% 1	270
	11th to 20th	Day	7% 13% 40% 30% 11%	270
	21st to end	Day	9% 16% 39% 28% 8%	243
March	1st to 10th	Day	7% 20% 40% 24% 8% 1	460
	11th to 20th	Day	8% 17% 38% 25% 9% 2	460
	21st to end	Day	9% 18% 44% 18% 9% 1	506
April	1st to 10th	Day	7% 15% 41% 27% 9% 2	460
	11th to 20th	Day	5% 17% 42% 26% 9% 1	452
	21st to end	Day	7% 12% 40% 31% 10% 1	460
May	1st to 10th	Day	3 13% 40% 31% 11% 2	463
	11th to 20th	Day	5% 8% 34% 37% 14% 3	488
	21st to end	Day	4 7% 34% 37% 17% 2	529
June	1st to 10th	Day	6% 2 21% 39% 27% 5%	490
	11th to 20th	Day	2 1 14% 40% 38% 5%	490
	21st to end	Day	3 1 7% 34% 42% 12%	490
July	1st to 10th	Day	5% 2 4 27% 44% 19%	486
	11th to 20th	Day	4 1 3 26% 53% 13%	484
	21st to end	Day	4 1 3 26% 48% 19%	531
August	1st to 10th	Day	2 3 21% 55% 20%	487
	11th to 20th	Day	5% 1 5% 24% 41% 24%	477
	21st to end	Day	6% 1 4 24% 44% 21%	539
September	1st to 10th	Day	7% 2 6% 27% 42% 16%	490
	11th to 20th	Day	8% 1 5% 24% 47% 16%	490
	21st to end	Day	8% 1 8% 26% 40% 17%	314
October	1st to 10th	Day	4 2 12% 31% 34% 17%	300
	11th to 20th	Day	6% 4 15% 33% 29% 13%	300
	21st to end	Day	4 5% 20% 33% 23% 13%	330
November	1st to 10th	Day	2 4 25% 33% 27% 9%	273
	11th to 20th	Day	6% 4 20% 37% 24% 8%	270
	21st to end	Day	11% 11% 29% 30% 16% 4	270
December	1st to 10th	Day	6% 6% 23% 38% 24% 3	270
	11th to 20th	Day	5% 8% 32% 40% 14% 1	270
	21st to end	Day	7% 10% 32% 35% 14% 1	297
January	1st to 10th	Night	6% 2 23% 48% 19% 2	760
	11th to 20th	Night	5% 3 21% 44% 25% 2	760
	21st to end	Night	6% 8% 27% 42% 16% 2	836
February	1st to 10th	Night	5% 8% 26% 38% 21% 3	760
	11th to 20th	Night	6% 7% 30% 43% 13% 1	744
	21st to end	Night	6% 8% 36% 38% 10%	628
March	1st to 10th	Night	8% 8% 33% 39% 11% 1	760
	11th to 20th	Night	7% 8% 29% 40% 15% 1	760
	21st to end	Night	5% 7% 36% 38% 13% 1	792
April	1st to 10th	Night	7% 6% 38% 39% 9% 1	570
	11th to 20th	Night	4 8% 41% 40% 7%	563
	21st to end	Night	6% 7% 36% 41% 8%	570
May	1st to 10th	Night	6% 4 42% 38% 9% 1	570
	11th to 20th	Night	6% 3 31% 49% 10% 1	561
	21st to end	Night	3 5% 27% 48% 17%	617
June	1st to 10th	Night	6% 3 15% 48% 27% 2	570
	11th to 20th	Night	6% 1 12% 45% 35% 1	570
	21st to end	Night	7% 2 9% 38% 41% 2	570
July	1st to 10th	Night	10% 2 6% 28% 51% 3	555
	11th to 20th	Night	9% 1 5% 27% 53% 5%	552
	21st to end	Night	9% 1 5% 27% 50% 7%	624
August	1st to 10th	Night	8% 1 4 23% 53% 11%	567
	11th to 20th	Night	9% 2 6% 23% 46% 14%	564
	21st to end	Night	9% 2 6% 19% 54% 10%	627
September	1st to 10th	Night	13% 2 7% 21% 49% 8%	570
	11th to 20th	Night	15% 1 7% 26% 48% 4	570
	21st to end	Night	11% 1 8% 31% 44% 6%	570
October	1st to 10th	Night	5% 2 9% 34% 44% 6%	746
	11th to 20th	Night	8% 2 11% 43% 31% 6%	760
	21st to end	Night	4 4 12% 42% 31% 8%	836
November	1st to 10th	Night	7% 1 12% 40% 35% 6%	744
	11th to 20th	Night	6% 2 12% 46% 31% 3	760
	21st to end	Night	7% 4 20% 41% 23% 5%	760
December	1st to 10th	Night	6% 2 20% 44% 24% 4	760
	11th to 20th	Night	5% 3 22% 48% 18% 4	760
	21st to end	Night	5% 6% 24% 43% 18% 4	836

Page generated at 2024-10-29 22:22:53. Version ac07

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