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 2024-03-06.

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	4 3 1 3 4 3 4 4 5% 8% 61%	79615
	Night	6% 4 2 4 4 3 4 5% 5% 7% 56%	79941
Transparency	Day	21% 6% 9% 16% 24% 24%	79352
	Night	27% 6% 8% 13% 24% 22%	79723
Seeing	Day	6% 7% 23% 30% 27% 8%	13325
	Night	7% 4 20% 38% 27% 4	23346

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 1 2 2 3 5% 78%	2858
	11th to 20th	Day	2 2 1 2 2 2 2 3 4 5% 77%	2860
	21st to end	Day	3 4 1 3 4 2 4 4 4 7% 63%	3486
February	1st to 10th	Day	3 2 2 4 5% 3 3 3 4 5% 67%	1900
	11th to 20th	Day	3 3 1 2 3 2 4 3 4 6% 68%	1849
	21st to end	Day	3 2 2 2 2 3 4 5% 8% 69%	1588
March	1st to 10th	Day	4 3 2 3 3 3 4 4 6% 7% 62%	2036
	11th to 20th	Day	4 3 1 3 4 3 3 3 5% 6% 65%	1980
	21st to end	Day	2 3 1 2 2 2 3 3 5% 6% 68%	2218
April	1st to 10th	Day	3 3 2 3 2 3 4 4 5% 6% 65%	2160
	11th to 20th	Day	2 2 1 3 2 2 4 3 4 6% 71%	2134
	21st to end	Day	3 2 1 2 3 1 3 3 4 6% 71%	2160
May	1st to 10th	Day	2 2 1 2 3 2 4 4 5% 6% 70%	2160
	11th to 20th	Day	3 2 1 3 4 2 4 4 5% 6% 66%	2125
	21st to end	Day	2 2 1 2 2 1 3 4 4 6% 73%	2337
June	1st to 10th	Day	3 2 1 3 4 2 4 5% 5% 8% 62%	2160
	11th to 20th	Day	3 1 1 4 4 4 4 6% 7% 9% 56%	2272
	21st to end	Day	4 2 2 4 4 4 6% 6% 7% 9% 51%	2340
July	1st to 10th	Day	6% 4 2 6% 6% 4 7% 8% 8% 11% 37%	2340
	11th to 20th	Day	5% 2 2 4 4 3 5% 7% 8% 12% 48%	2304
	21st to end	Day	6% 4 3 5% 5% 4 7% 7% 8% 12% 38%	2349
August	1st to 10th	Day	3 2 1 3 4 4 5% 6% 8% 11% 53%	2149
	11th to 20th	Day	6% 3 2 5% 6% 5% 7% 8% 8% 11% 40%	2123
	21st to end	Day	7% 3 2 4 8% 4 7% 6% 7% 11% 41%	2376
September	1st to 10th	Day	8% 5% 3 5% 6% 4 6% 7% 7% 9% 40%	2160
	11th to 20th	Day	10% 4 1 4 5% 4 5% 5% 7% 9% 45%	2160
	21st to end	Day	8% 4 1 3 4 3 4 5% 6% 8% 55%	1994
October	1st to 10th	Day	3 2 1 3 4 3 5% 5% 7% 7% 61%	1807
	11th to 20th	Day	6% 3 2 3 3 1 3 3 4 7% 65%	1800
	21st to end	Day	4 2 1 2 1 1 2 2 3 5% 78%	1980
November	1st to 10th	Day	4 2 1 2 3 2 3 2 4 6% 73%	1859
	11th to 20th	Day	5% 2 1 2 3 2 3 3 3 5% 72%	1900
	21st to end	Day	5% 4 1 4 3 2 3 4 5% 6% 63%	1900
December	1st to 10th	Day	4 4 2 2 3 3 2 3 4 7% 65%	1900
	11th to 20th	Day	2 3 1 3 3 2 4 5% 6% 8% 62%	2404
	21st to end	Day	2 2 1 2 2 1 3 3 5% 8% 70%	3487
January	1st to 10th	Night	2 2 1 2 2 1 2 2 2 4 80%	4075
	11th to 20th	Night	3 1 1 2 2 2 4 4 4 6% 73%	4103
	21st to end	Night	5% 5% 2 4 4 3 3 4 4 7% 58%	4180
February	1st to 10th	Night	4 3 2 3 3 2 3 3 4 5% 68%	2280
	11th to 20th	Night	4 4 1 4 3 2 3 4 5% 7% 63%	2218
	21st to end	Night	3 4 2 2 2 1 4 4 5% 8% 66%	1860
March	1st to 10th	Night	5% 4 2 4 3 1 3 4 4 6% 63%	2040
	11th to 20th	Night	5% 5% 2 4 3 2 3 4 5% 7% 60%	1980
	21st to end	Night	3 3 1 3 3 2 4 3 4 7% 66%	2137
April	1st to 10th	Night	5% 3 1 3 3 2 2 4 6% 8% 64%	1800
	11th to 20th	Night	3 3 1 4 3 1 3 3 4 6% 68%	1777
	21st to end	Night	5% 3 2 4 3 2 3 3 3 5% 67%	1800
May	1st to 10th	Night	4 4 1 3 3 2 4 4 5% 6% 64%	1800
	11th to 20th	Night	7% 3 2 4 4 2 3 4 4 6% 60%	1770
	21st to end	Night	3 4 2 5% 4 3 4 4 5% 6% 62%	1939
June	1st to 10th	Night	5% 4 2 5% 6% 4 6% 6% 8% 9% 45%	1800
	11th to 20th	Night	6% 4 2 6% 7% 5% 7% 6% 7% 9% 40%	1680
	21st to end	Night	8% 5% 3 6% 7% 5% 7% 9% 7% 10% 34%	1620
July	1st to 10th	Night	9% 6% 4 10% 9% 6% 9% 7% 9% 11% 21%	1620
	11th to 20th	Night	8% 4 3 8% 8% 4 8% 8% 9% 12% 29%	1651
	21st to end	Night	8% 7% 3 8% 9% 6% 9% 8% 9% 11% 22%	1969
August	1st to 10th	Night	6% 7% 3 7% 8% 5% 8% 8% 9% 10% 29%	1790
	11th to 20th	Night	9% 7% 3 10% 8% 5% 7% 8% 9% 9% 24%	1778
	21st to end	Night	9% 6% 3 7% 10% 5% 8% 8% 8% 9% 26%	1980
September	1st to 10th	Night	12% 7% 3 9% 9% 4 6% 6% 7% 9% 27%	1800
	11th to 20th	Night	14% 6% 4 7% 7% 5% 7% 6% 7% 9% 29%	1800
	21st to end	Night	10% 5% 3 6% 6% 5% 6% 6% 8% 9% 37%	1966
October	1st to 10th	Night	6% 4 2 4 6% 3 4 4 5% 7% 55%	2146
	11th to 20th	Night	7% 3 1 4 4 2 4 4 5% 6% 59%	2160
	21st to end	Night	5% 2 1 2 2 1 3 2 3 4 74%	2376
November	1st to 10th	Night	6% 2 1 2 2 2 2 3 3 5% 73%	2220
	11th to 20th	Night	5% 3 1 3 4 2 4 3 5% 4 67%	2280
	21st to end	Night	4 4 2 4 3 2 4 3 3 5% 66%	2280
December	1st to 10th	Night	4 2 2 3 4 2 3 4 4 8% 64%	2280
	11th to 20th	Night	2 3 1 3 3 2 4 4 6% 8% 63%	2806
	21st to end	Night	4 3 1 3 3 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	21% 4 7% 12% 27% 29%	2036
	11th to 20th	Day	21% 4 5% 9% 21% 40%	1980
	21st to end	Day	17% 3 5% 7% 25% 42%	2218
April	1st to 10th	Day	19% 4 6% 9% 23% 39%	2160
	11th to 20th	Day	14% 3 7% 8% 24% 43%	2134
	21st to end	Day	15% 2 4 9% 26% 44%	2160
May	1st to 10th	Day	17% 3 5% 11% 23% 42%	2160
	11th to 20th	Day	18% 5% 7% 12% 24% 34%	2128
	21st to end	Day	13% 3 7% 13% 23% 43%	2337
June	1st to 10th	Day	17% 5% 9% 17% 30% 22%	2160
	11th to 20th	Day	21% 5% 9% 15% 26% 24%	2272
	21st to end	Day	25% 7% 12% 22% 18% 16%	2340
July	1st to 10th	Day	37% 12% 18% 17% 10% 6%	2276
	11th to 20th	Day	25% 10% 18% 24% 17% 5%	2235
	21st to end	Day	31% 14% 22% 21% 10% 1	2219
August	1st to 10th	Day	21% 10% 24% 29% 14% 3	2136
	11th to 20th	Day	33% 16% 21% 21% 8% 1	2123
	21st to end	Day	33% 12% 20% 20% 11% 3	2376
September	1st to 10th	Day	38% 11% 16% 18% 12% 5%	2160
	11th to 20th	Day	33% 10% 14% 17% 18% 7%	2160
	21st to end	Day	26% 7% 14% 21% 23% 9%	1994
October	1st to 10th	Day	20% 8% 10% 21% 26% 14%	1807
	11th to 20th	Day	20% 5% 8% 20% 25% 23%	1800
	21st to end	Day	12% 2 5% 15% 37% 29%	1980
November	1st to 10th	Day	15% 4 7% 19% 34% 22%	1859
	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	23% 4 5% 12% 30% 26%	2040
	11th to 20th	Night	26% 4 7% 8% 21% 33%	1980
	21st to end	Night	20% 4 5% 10% 24% 37%	2137
April	1st to 10th	Night	18% 3 6% 12% 26% 35%	1800
	11th to 20th	Night	18% 4 5% 8% 27% 38%	1777
	21st to end	Night	21% 2 4 10% 24% 39%	1800
May	1st to 10th	Night	22% 3 6% 10% 23% 35%	1800
	11th to 20th	Night	26% 5% 7% 10% 21% 31%	1771
	21st to end	Night	23% 4 7% 10% 19% 37%	1940
June	1st to 10th	Night	34% 8% 11% 16% 18% 13%	1800
	11th to 20th	Night	37% 7% 11% 14% 19% 12%	1680
	21st to end	Night	40% 11% 13% 16% 10% 10%	1620
July	1st to 10th	Night	52% 14% 14% 12% 6% 3	1575
	11th to 20th	Night	44% 12% 16% 17% 8% 3	1597
	21st to end	Night	49% 13% 17% 12% 8% 1	1859
August	1st to 10th	Night	43% 13% 15% 19% 8% 1	1779
	11th to 20th	Night	50% 15% 16% 11% 7% 1	1778
	21st to end	Night	48% 13% 13% 13% 9% 3	1980
September	1st to 10th	Night	51% 10% 16% 12% 7% 4	1800
	11th to 20th	Night	49% 11% 13% 11% 11% 6%	1800
	21st to end	Night	40% 11% 12% 13% 16% 8%	1966
October	1st to 10th	Night	29% 7% 10% 18% 21% 14%	2146
	11th to 20th	Night	26% 6% 9% 17% 22% 19%	2160
	21st to end	Night	16% 2 5% 16% 33% 28%	2376
November	1st to 10th	Night	15% 3 7% 16% 38% 21%	2220
	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	6% 20% 39% 25% 9% 1	441
	11th to 20th	Day	9% 16% 38% 26% 10% 2	420
	21st to end	Day	8% 18% 45% 18% 10% 1	462
April	1st to 10th	Day	6% 13% 43% 28% 9% 1	420
	11th to 20th	Day	5% 17% 41% 26% 10% 1	412
	21st to end	Day	7% 12% 40% 31% 9% 1	420
May	1st to 10th	Day	4 13% 37% 32% 12% 2	423
	11th to 20th	Day	5% 7% 33% 38% 15% 3	448
	21st to end	Day	4 7% 33% 38% 18% 1	485
June	1st to 10th	Day	6% 2 21% 38% 28% 6%	450
	11th to 20th	Day	2 1 14% 40% 38% 4	450
	21st to end	Day	4 1 7% 33% 43% 13%	450
July	1st to 10th	Day	6% 2 4 27% 43% 19%	446
	11th to 20th	Day	4 1 3 25% 55% 13%	444
	21st to end	Day	4 1 2 25% 50% 18%	487
August	1st to 10th	Day	2 2 20% 56% 20%	447
	11th to 20th	Day	6% 1 5% 24% 41% 24%	437
	21st to end	Day	7% 1 4 23% 45% 21%	495
September	1st to 10th	Day	8% 2 6% 26% 42% 16%	450
	11th to 20th	Day	8% 1 5% 23% 48% 15%	450
	21st to end	Day	8% 1 8% 25% 42% 17%	284
October	1st to 10th	Day	5% 2 12% 31% 34% 16%	270
	11th to 20th	Day	7% 4 14% 33% 30% 13%	270
	21st to end	Day	5% 6% 20% 33% 25% 12%	297
November	1st to 10th	Day	2 4 24% 33% 27% 9%	270
	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% 32% 40% 11% 1	742
	11th to 20th	Night	8% 9% 27% 41% 15% 1	720
	21st to end	Night	5% 6% 35% 39% 14% 1	751
April	1st to 10th	Night	7% 6% 37% 40% 9% 1	540
	11th to 20th	Night	4 7% 42% 40% 7%	533
	21st to end	Night	7% 8% 36% 41% 9%	540
May	1st to 10th	Night	6% 4 41% 39% 10% 1	540
	11th to 20th	Night	7% 3 29% 50% 11% 1	531
	21st to end	Night	3 5% 25% 49% 18% 1	584
June	1st to 10th	Night	6% 3 14% 48% 28% 2	540
	11th to 20th	Night	6% 1 12% 43% 36% 1	540
	21st to end	Night	7% 2 9% 38% 41% 2	540
July	1st to 10th	Night	10% 1 6% 27% 52% 4	525
	11th to 20th	Night	9% 1 6% 26% 52% 5%	522
	21st to end	Night	9% 1 5% 26% 51% 8%	591
August	1st to 10th	Night	8% 1 4 23% 53% 11%	537
	11th to 20th	Night	9% 2 7% 22% 47% 15%	534
	21st to end	Night	9% 2 6% 19% 53% 11%	594
September	1st to 10th	Night	12% 2 7% 20% 51% 8%	540
	11th to 20th	Night	15% 1 7% 26% 48% 4	540
	21st to end	Night	11% 1 7% 30% 44% 6%	540
October	1st to 10th	Night	6% 2 9% 35% 43% 6%	706
	11th to 20th	Night	8% 2 10% 43% 31% 6%	720
	21st to end	Night	4 4 12% 40% 31% 8%	792
November	1st to 10th	Night	7% 1 12% 40% 35% 6%	740
	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 2024-03-03 04:28:59. Version ac07

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