Observatorio Carl Sagan en el Campus Hermosillo
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Observatorio Carl Sagan en el Campus Hermosillo clear sky chart from 2005-11-06 to 2026-05-02.

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
Transparency	Day	15% 3 6% 12% 21% 43%	135620
	Night	17% 3 6% 10% 22% 42%	135446
Seeing	Day	4 4 19% 35% 27% 11%	17001
	Night	4 1 14% 43% 32% 6%	27209

By Month

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	16% 1 5% 12% 28% 37%	5321
	11th to 20th	Day	11% 1 3 5% 21% 59%	5340
	21st to end	Day	26% 1 4 10% 21% 38%	5844
February	1st to 10th	Day	18% 2 5% 7% 22% 46%	2054
	11th to 20th	Day	21% 2 5% 7% 26% 38%	2060
	21st to end	Day	17% 1 4 7% 24% 45%	1897
March	1st to 10th	Day	20% 1 3 5% 22% 50%	5064
	11th to 20th	Day	15% 1 4 10% 26% 44%	5110
	21st to end	Day	18% 1 4 4 23% 50%	5607
April	1st to 10th	Day	14% 1 2 5% 21% 56%	2310
	11th to 20th	Day	11% 1 1 4 20% 62%	2393
	21st to end	Day	8% 2 4 20% 66%	2520
May	1st to 10th	Day	4 1 3 15% 77%	5618
	11th to 20th	Day	8% 1 2 4 16% 69%	5844
	21st to end	Day	6% 2 1 10% 80%	6424
June	1st to 10th	Day	10% 1 3 4 24% 58%	2600
	11th to 20th	Day	7% 1 3 4 24% 61%	2600
	21st to end	Day	15% 4 7% 11% 27% 36%	2600
July	1st to 10th	Day	19% 7% 17% 23% 18% 16%	5816
	11th to 20th	Day	22% 8% 17% 29% 20% 4	5811
	21st to end	Day	22% 7% 16% 26% 13% 16%	6217
August	1st to 10th	Day	19% 8% 18% 31% 21% 4	4208
	11th to 20th	Day	22% 8% 16% 32% 18% 4	4070
	21st to end	Day	18% 6% 13% 26% 25% 12%	4060
September	1st to 10th	Day	29% 6% 12% 20% 20% 13%	2200
	11th to 20th	Day	15% 4 6% 17% 31% 27%	2200
	21st to end	Day	14% 3 5% 13% 30% 35%	2200
October	1st to 10th	Day	6% 1 3 9% 24% 56%	3501
	11th to 20th	Day	9% 1 3 8% 28% 50%	3250
	21st to end	Day	6% 1 2 7% 16% 69%	3548
November	1st to 10th	Day	10% 1 3 9% 22% 55%	2059
	11th to 20th	Day	15% 1 3 8% 26% 47%	2100
	21st to end	Day	22% 2 5% 12% 26% 34%	2027
December	1st to 10th	Day	14% 1 3 7% 18% 57%	3040
	11th to 20th	Day	18% 1 3 7% 19% 52%	3498
	21st to end	Day	10% 1 4 9% 36% 40%	4609
January	1st to 10th	Night	17% 2 5% 12% 29% 35%	7605
	11th to 20th	Night	12% 1 2 4 21% 60%	7650
	21st to end	Night	28% 1 4 9% 24% 33%	8370
February	1st to 10th	Night	20% 2 4 7% 23% 45%	2562
	11th to 20th	Night	22% 2 5% 11% 24% 36%	2459
	21st to end	Night	21% 2 2 6% 24% 45%	1907
March	1st to 10th	Night	21% 1 3 4 22% 48%	5050
	11th to 20th	Night	13% 1 4 12% 25% 44%	5110
	21st to end	Night	19% 1 3 6% 23% 48%	5610
April	1st to 10th	Night	12% 1 3 6% 26% 52%	2310
	11th to 20th	Night	14% 1 1 5% 22% 57%	2177
	21st to end	Night	9% 1 2 5% 18% 65%	2100
May	1st to 10th	Night	3 1 2 20% 73%	4377
	11th to 20th	Night	9% 1 2 4 16% 68%	4075
	21st to end	Night	7% 2 1 13% 78%	4474
June	1st to 10th	Night	9% 1 2 5% 23% 59%	1800
	11th to 20th	Night	9% 1 3 5% 22% 60%	1800
	21st to end	Night	20% 4 8% 10% 24% 34%	1800
July	1st to 10th	Night	28% 6% 16% 19% 17% 13%	4055
	11th to 20th	Night	32% 8% 17% 28% 12% 2	4046
	21st to end	Night	31% 9% 17% 20% 9% 14%	4344
August	1st to 10th	Night	32% 9% 19% 24% 13% 3	2928
	11th to 20th	Night	30% 10% 16% 27% 14% 3	3053
	21st to end	Night	19% 7% 16% 25% 25% 9%	3850
September	1st to 10th	Night	30% 9% 14% 20% 18% 8%	2200
	11th to 20th	Night	15% 3 7% 21% 29% 26%	2200
	21st to end	Night	12% 3 7% 19% 27% 33%	2200
October	1st to 10th	Night	7% 1 3 8% 26% 55%	3694
	11th to 20th	Night	10% 1 2 10% 28% 49%	3898
	21st to end	Night	5% 2 5% 19% 67%	4252
November	1st to 10th	Night	10% 1 3 9% 22% 54%	2460
	11th to 20th	Night	17% 2 3 7% 28% 44%	2520
	21st to end	Night	24% 2 4 12% 27% 33%	2588
December	1st to 10th	Night	14% 1 3 9% 21% 52%	4370
	11th to 20th	Night	16% 1 3 6% 22% 51%	4941
	21st to end	Night	14% 1 4 7% 32% 41%	6611

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	5% 4 23% 42% 25% 2	330
	11th to 20th	Day	5% 2 18% 42% 28% 5%	330
	21st to end	Day	5% 6% 28% 36% 21% 3	363
February	1st to 10th	Day	5% 6% 23% 37% 23% 4	494
	11th to 20th	Day	10% 9% 28% 37% 15% 1	535
	21st to end	Day	6% 8% 34% 37% 12% 3	446
March	1st to 10th	Day	9% 9% 30% 34% 15% 3	540
	11th to 20th	Day	6% 7% 29% 31% 20% 7%	540
	21st to end	Day	4 9% 32% 35% 15% 5%	594
April	1st to 10th	Day	3 9% 33% 30% 19% 6%	540
	11th to 20th	Day	3 9% 35% 37% 12% 5%	532
	21st to end	Day	1 9% 34% 33% 18% 6%	540
May	1st to 10th	Day	2 9% 32% 34% 17% 6%	508
	11th to 20th	Day	2 5% 30% 40% 21% 2	528
	21st to end	Day	1 5% 25% 45% 22% 3	573
June	1st to 10th	Day	2 2 20% 47% 26% 4	530
	11th to 20th	Day	1 1 16% 48% 26% 8%	530
	21st to end	Day	2 1 13% 39% 34% 12%	530
July	1st to 10th	Day	3 9% 35% 33% 20%	526
	11th to 20th	Day	4 1 5% 31% 39% 22%	524
	21st to end	Day	7% 1 8% 27% 35% 21%	575
August	1st to 10th	Day	3 1 6% 25% 39% 27%	527
	11th to 20th	Day	5% 2 3 25% 37% 29%	517
	21st to end	Day	3 1 4 19% 42% 30%	583
September	1st to 10th	Day	7% 2 6% 25% 38% 23%	530
	11th to 20th	Day	4 1 5% 32% 39% 20%	530
	21st to end	Day	4 1 10% 31% 37% 18%	530
October	1st to 10th	Day	3 1 10% 34% 37% 16%	470
	11th to 20th	Day	5% 11% 26% 35% 24%	330
	21st to end	Day	1 1 12% 32% 36% 18%	363
November	1st to 10th	Day	4 2 13% 32% 40% 10%	330
	11th to 20th	Day	3 4 13% 34% 35% 11%	330
	21st to end	Day	8% 4 21% 35% 27% 5%	330
December	1st to 10th	Day	5% 3 15% 44% 25% 7%	330
	11th to 20th	Day	3 2 15% 46% 29% 5%	330
	21st to end	Day	6% 4 18% 47% 20% 7%	363
January	1st to 10th	Night	3 1 15% 51% 27% 2	840
	11th to 20th	Night	3 1 18% 50% 26% 2	840
	21st to end	Night	9% 2 24% 44% 20% 2	924
February	1st to 10th	Night	5% 2 19% 48% 23% 3	840
	11th to 20th	Night	7% 1 24% 47% 20% 1	824
	21st to end	Night	4 1 26% 52% 14% 2	692
March	1st to 10th	Night	7% 3 24% 47% 18% 1	840
	11th to 20th	Night	4 3 18% 50% 22% 2	840
	21st to end	Night	4 2 21% 49% 23% 2	924
April	1st to 10th	Night	2 1 20% 53% 22% 1	840
	11th to 20th	Night	3 2 22% 52% 21% 1	723
	21st to end	Night	1 1 20% 55% 22%	630
May	1st to 10th	Night	1 2 18% 56% 23% 1	603
	11th to 20th	Night	1 15% 52% 30% 1	591
	21st to end	Night	1 1 11% 54% 32% 2	650
June	1st to 10th	Night	2 1 9% 46% 39% 3	600
	11th to 20th	Night	2 1 7% 45% 42% 3	600
	21st to end	Night	2 1 9% 36% 48% 5%	600
July	1st to 10th	Night	4 1 9% 32% 44% 10%	585
	11th to 20th	Night	5% 1 8% 29% 47% 9%	582
	21st to end	Night	7% 3 11% 24% 40% 16%	657
August	1st to 10th	Night	3 1 8% 26% 47% 16%	597
	11th to 20th	Night	4 1 7% 21% 47% 20%	594
	21st to end	Night	5% 1 6% 22% 46% 20%	809
September	1st to 10th	Night	8% 2 5% 21% 47% 18%	800
	11th to 20th	Night	4 1 3 26% 55% 12%	800
	21st to end	Night	3 1 5% 33% 50% 8%	800
October	1st to 10th	Night	2 5% 39% 47% 7%	800
	11th to 20th	Night	5% 1 9% 40% 40% 6%	800
	21st to end	Night	1 1 9% 44% 38% 7%	880
November	1st to 10th	Night	1 9% 45% 38% 7%	820
	11th to 20th	Night	4 1 11% 44% 33% 6%	840
	21st to end	Night	7% 2 18% 46% 24% 4	840
December	1st to 10th	Night	6% 1 12% 51% 26% 4	840
	11th to 20th	Night	4 2 14% 55% 23% 3	840
	21st to end	Night	4 1 18% 50% 24% 3	924

Page generated at 2026-04-28 23:21:47. Version ac07

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