Durango
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Durango clear sky chart from 2005-11-06 to 2024-11-05.

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 5% 2 5% 4 4 5% 4 6% 7% 54%	104937
	Night	5% 6% 2 5% 3 3 4 3 5% 7% 57%	102857
Transparency	Day	26% 6% 11% 20% 25% 13%	104702
	Night	27% 5% 10% 20% 25% 14%	102681
Seeing	Day	9% 12% 30% 30% 16% 3	15154
	Night	8% 5% 25% 39% 21% 3	25325

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 7% 3 6% 2 2 4 4 6% 7% 56%	2858
	11th to 20th	Day	3 5% 1 4 3 4 5% 4 6% 7% 58%	2860
	21st to end	Day	4 10% 2 6% 3 3 4 4 5% 6% 54%	3146
February	1st to 10th	Day	2 8% 3 6% 4 3 4 3 5% 5% 57%	1710
	11th to 20th	Day	5% 9% 2 6% 4 4 5% 3 5% 6% 50%	1712
	21st to end	Day	4 11% 4 6% 3 4 4 3 4 6% 51%	1591
March	1st to 10th	Day	3 9% 3 6% 4 4 5% 4 6% 8% 49%	3444
	11th to 20th	Day	7% 12% 3 7% 4 4 5% 4 6% 6% 43%	3490
	21st to end	Day	4 12% 4 8% 5% 5% 5% 4 5% 6% 42%	3825
April	1st to 10th	Day	4 5% 1 5% 4 5% 5% 4 6% 7% 55%	2272
	11th to 20th	Day	3 5% 2 5% 4 4 5% 5% 6% 7% 54%	2251
	21st to end	Day	4 5% 2 4 4 5% 4 4 6% 7% 55%	2280
May	1st to 10th	Day	6% 4 1 4 3 4 4 4 5% 6% 60%	4001
	11th to 20th	Day	4 4 2 4 5% 5% 6% 6% 8% 8% 49%	4071
	21st to end	Day	3 3 1 4 2 3 4 4 5% 6% 64%	4745
June	1st to 10th	Day	3 3 1 3 3 3 4 4 5% 7% 65%	2660
	11th to 20th	Day	3 2 1 3 3 3 4 3 4 4 71%	2660
	21st to end	Day	2 2 1 4 3 4 5% 4 6% 7% 61%	2660
July	1st to 10th	Day	3 2 1 3 3 3 4 5% 6% 7% 63%	4240
	11th to 20th	Day	2 2 1 4 5% 7% 10% 8% 11% 10% 39%	4110
	21st to end	Day	4 3 2 5% 5% 5% 6% 6% 7% 9% 48%	4454
August	1st to 10th	Day	5% 4 2 6% 6% 7% 9% 7% 10% 11% 33%	4092
	11th to 20th	Day	3 3 1 5% 4 6% 7% 6% 8% 10% 47%	3884
	21st to end	Day	4 4 1 6% 4 7% 7% 7% 9% 9% 42%	4180
September	1st to 10th	Day	8% 4 2 6% 4 5% 5% 3 5% 7% 51%	2280
	11th to 20th	Day	6% 4 2 5% 4 4 4 4 6% 6% 54%	2254
	21st to end	Day	7% 2 1 4 2 2 3 2 4 6% 66%	2011
October	1st to 10th	Day	5% 3 1 3 3 2 3 3 4 5% 68%	3170
	11th to 20th	Day	11% 5% 1 4 4 4 3 3 4 6% 56%	3150
	21st to end	Day	4 3 1 2 2 2 2 2 3 5% 73%	3438
November	1st to 10th	Day	4 3 1 2 2 3 3 2 4 6% 70%	1899
	11th to 20th	Day	2 3 1 3 2 2 4 2 5% 6% 70%	1739
	21st to end	Day	7% 6% 1 3 2 3 3 3 4 4 65%	1524
December	1st to 10th	Day	6% 8% 2 3 2 3 3 3 4 6% 60%	1520
	11th to 20th	Day	7% 8% 2 5% 3 4 4 4 6% 7% 50%	1926
	21st to end	Day	5% 9% 3 5% 4 3 3 4 5% 6% 56%	2830
January	1st to 10th	Night	2 8% 3 8% 4 4 4 3 5% 6% 53%	4097
	11th to 20th	Night	3 8% 2 5% 3 3 4 3 4 6% 59%	4110
	21st to end	Night	5% 10% 3 6% 4 3 3 3 5% 6% 53%	4521
February	1st to 10th	Night	4 8% 2 4 3 2 2 2 4 7% 61%	2470
	11th to 20th	Night	6% 7% 2 4 4 3 3 3 4 5% 59%	2354
	21st to end	Night	4 10% 3 5% 3 3 3 3 4 4 59%	1860
March	1st to 10th	Night	3 11% 2 5% 4 4 4 3 5% 7% 52%	3430
	11th to 20th	Night	8% 12% 3 6% 4 4 4 3 6% 6% 44%	3490
	21st to end	Night	6% 8% 3 7% 5% 5% 5% 4 5% 7% 47%	3828
April	1st to 10th	Night	6% 6% 2 3 3 3 4 4 5% 7% 57%	1907
	11th to 20th	Night	6% 4 2 5% 4 4 4 3 5% 6% 58%	1877
	21st to end	Night	5% 5% 2 4 2 3 2 4 5% 7% 61%	1900
May	1st to 10th	Night	5% 3 1 4 3 3 3 3 4 6% 65%	2966
	11th to 20th	Night	6% 5% 2 5% 3 4 4 3 5% 7% 57%	2834
	21st to end	Night	5% 4 1 3 2 3 3 2 4 5% 68%	2838
June	1st to 10th	Night	2 3 1 3 3 2 3 3 4 8% 68%	1520
	11th to 20th	Night	4 3 1 3 2 3 2 3 4 5% 70%	1520
	21st to end	Night	4 2 1 3 3 4 5% 4 7% 8% 60%	1520
July	1st to 10th	Night	4 3 1 4 3 3 4 4 5% 6% 62%	2724
	11th to 20th	Night	2 3 1 4 5% 5% 6% 6% 9% 11% 48%	2860
	21st to end	Night	4 4 2 6% 4 5% 6% 5% 8% 8% 48%	3109
August	1st to 10th	Night	5% 5% 3 7% 5% 5% 7% 7% 11% 11% 32%	2847
	11th to 20th	Night	3 4 1 5% 4 6% 6% 5% 8% 11% 46%	2952
	21st to end	Night	5% 5% 2 7% 6% 6% 6% 4 7% 11% 41%	3487
September	1st to 10th	Night	6% 4 2 5% 5% 4 5% 5% 6% 9% 49%	1900
	11th to 20th	Night	7% 4 1 5% 4 5% 3 3 4 6% 57%	1923
	21st to end	Night	8% 3 1 3 3 2 3 2 3 4 68%	2167
October	1st to 10th	Night	7% 3 1 2 1 2 2 2 3 5% 73%	3800
	11th to 20th	Night	11% 5% 2 4 4 3 3 3 4 5% 55%	3778
	21st to end	Night	6% 3 1 3 2 2 2 2 3 4 72%	4120
November	1st to 10th	Night	5% 3 1 2 2 2 3 3 4 6% 69%	2280
	11th to 20th	Night	2 3 1 2 2 2 2 2 4 6% 73%	2418
	21st to end	Night	7% 6% 2 3 2 2 2 2 3 6% 65%	2654
December	1st to 10th	Night	5% 7% 2 4 3 2 3 3 4 5% 62%	2660
	11th to 20th	Night	6% 8% 2 5% 4 4 4 4 5% 7% 52%	3271
	21st to end	Night	7% 9% 3 5% 3 3 3 2 3 5% 58%	4865

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	28% 4 16% 27% 19% 6%	2859
	11th to 20th	Day	27% 5% 15% 34% 16% 3	2860
	21st to end	Day	32% 5% 11% 29% 20% 3	3146
February	1st to 10th	Day	30% 5% 13% 25% 20% 8%	1710
	11th to 20th	Day	34% 4 9% 23% 25% 4	1721
	21st to end	Day	35% 4 8% 16% 30% 7%	1591
March	1st to 10th	Day	29% 4 10% 23% 28% 5%	3444
	11th to 20th	Day	38% 6% 10% 27% 16% 3	3490
	21st to end	Day	40% 5% 10% 19% 23% 4	3825
April	1st to 10th	Day	27% 5% 8% 19% 28% 12%	2272
	11th to 20th	Day	26% 5% 9% 19% 27% 14%	2254
	21st to end	Day	26% 5% 8% 22% 29% 10%	2280
May	1st to 10th	Day	24% 4 7% 14% 30% 20%	4001
	11th to 20th	Day	25% 7% 12% 19% 26% 11%	4074
	21st to end	Day	17% 3 8% 9% 42% 20%	4745
June	1st to 10th	Day	18% 4 7% 18% 30% 23%	2660
	11th to 20th	Day	16% 3 6% 11% 26% 38%	2660
	21st to end	Day	19% 5% 8% 14% 24% 30%	2660
July	1st to 10th	Day	19% 6% 9% 9% 20% 37%	4176
	11th to 20th	Day	25% 13% 14% 28% 14% 6%	4041
	21st to end	Day	26% 11% 16% 21% 14% 13%	4314
August	1st to 10th	Day	34% 13% 22% 12% 10% 9%	4078
	11th to 20th	Day	27% 10% 14% 15% 20% 14%	3923
	21st to end	Day	29% 11% 14% 19% 19% 8%	4179
September	1st to 10th	Day	28% 7% 10% 18% 21% 16%	2280
	11th to 20th	Day	26% 7% 9% 16% 24% 18%	2254
	21st to end	Day	19% 4 6% 17% 38% 15%	2011
October	1st to 10th	Day	17% 5% 6% 15% 31% 26%	3170
	11th to 20th	Day	29% 4 4 22% 29% 12%	3150
	21st to end	Day	16% 2 7% 23% 42% 9%	3438
November	1st to 10th	Day	17% 3 8% 28% 35% 9%	1899
	11th to 20th	Day	16% 3 8% 28% 38% 7%	1739
	21st to end	Day	25% 3 6% 26% 28% 11%	1524
December	1st to 10th	Day	26% 5% 15% 26% 20% 8%	1520
	11th to 20th	Day	33% 7% 10% 27% 20% 3	1924
	21st to end	Day	31% 4 13% 17% 26% 10%	2830
January	1st to 10th	Night	33% 3 11% 27% 22% 3	4097
	11th to 20th	Night	29% 4 14% 29% 21% 4	4110
	21st to end	Night	32% 5% 9% 32% 18% 4	4521
February	1st to 10th	Night	26% 2 12% 28% 22% 10%	2470
	11th to 20th	Night	29% 3 10% 22% 28% 8%	2355
	21st to end	Night	30% 3 8% 17% 31% 11%	1860
March	1st to 10th	Night	31% 3 9% 22% 29% 6%	3430
	11th to 20th	Night	38% 5% 10% 21% 19% 7%	3490
	21st to end	Night	35% 4 11% 20% 23% 6%	3828
April	1st to 10th	Night	27% 5% 8% 17% 29% 14%	1907
	11th to 20th	Night	27% 3 7% 18% 27% 18%	1877
	21st to end	Night	23% 4 8% 21% 33% 12%	1900
May	1st to 10th	Night	21% 3 8% 14% 38% 16%	2966
	11th to 20th	Night	23% 6% 10% 22% 26% 13%	2835
	21st to end	Night	19% 2 8% 10% 34% 26%	2838
June	1st to 10th	Night	17% 4 8% 15% 28% 28%	1520
	11th to 20th	Night	17% 3 7% 10% 21% 43%	1520
	21st to end	Night	20% 6% 9% 13% 22% 31%	1520
July	1st to 10th	Night	23% 6% 9% 7% 10% 45%	2679
	11th to 20th	Night	25% 9% 14% 27% 14% 10%	2806
	21st to end	Night	28% 10% 16% 20% 12% 14%	3011
August	1st to 10th	Night	38% 12% 20% 9% 10% 11%	2838
	11th to 20th	Night	30% 8% 18% 12% 12% 20%	2979
	21st to end	Night	35% 7% 13% 19% 16% 9%	3487
September	1st to 10th	Night	30% 7% 12% 16% 17% 19%	1900
	11th to 20th	Night	28% 5% 8% 15% 20% 24%	1923
	21st to end	Night	22% 3 6% 13% 34% 23%	2167
October	1st to 10th	Night	16% 3 6% 10% 36% 29%	3800
	11th to 20th	Night	31% 4 5% 15% 31% 14%	3778
	21st to end	Night	17% 3 4 20% 45% 11%	4120
November	1st to 10th	Night	17% 3 6% 27% 35% 12%	2280
	11th to 20th	Night	15% 3 6% 29% 38% 9%	2418
	21st to end	Night	25% 2 7% 23% 33% 11%	2654
December	1st to 10th	Night	26% 4 13% 25% 24% 8%	2660
	11th to 20th	Night	33% 5% 10% 24% 23% 5%	3272
	21st to end	Night	32% 3 10% 18% 25% 12%	4865

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	10% 12% 37% 27% 13% 1	270
	11th to 20th	Day	17% 13% 35% 25% 9% 1	270
	21st to end	Day	6% 11% 36% 33% 12% 2	297
February	1st to 10th	Day	11% 17% 41% 26% 6%	270
	11th to 20th	Day	14% 16% 39% 25% 6%	270
	21st to end	Day	16% 20% 40% 21% 3	246
March	1st to 10th	Day	13% 20% 36% 22% 8%	460
	11th to 20th	Day	13% 20% 33% 22% 10% 1	460
	21st to end	Day	17% 29% 33% 14% 6% 1	506
April	1st to 10th	Day	14% 23% 37% 17% 7% 1	460
	11th to 20th	Day	17% 28% 31% 18% 6%	452
	21st to end	Day	13% 24% 36% 21% 5%	460
May	1st to 10th	Day	13% 23% 41% 17% 6%	463
	11th to 20th	Day	10% 16% 35% 26% 12% 2	488
	21st to end	Day	8% 16% 32% 28% 15% 2	680
June	1st to 10th	Day	4 7% 24% 41% 21% 3	680
	11th to 20th	Day	5% 7% 33% 32% 18% 5%	680
	21st to end	Day	3 8% 28% 36% 21% 4	680
July	1st to 10th	Day	4 4 21% 39% 27% 5%	564
	11th to 20th	Day	4 2 19% 35% 32% 9%	484
	21st to end	Day	5% 2 18% 40% 29% 8%	531
August	1st to 10th	Day	6% 4 18% 40% 24% 7%	487
	11th to 20th	Day	4 4 25% 41% 20% 6%	477
	21st to end	Day	6% 2 22% 40% 24% 6%	539
September	1st to 10th	Day	7% 4 21% 38% 24% 6%	490
	11th to 20th	Day	5% 4 31% 39% 16% 4	490
	21st to end	Day	8% 10% 27% 33% 17% 5%	411
October	1st to 10th	Day	11% 11% 21% 28% 23% 7%	300
	11th to 20th	Day	10% 13% 26% 30% 16% 4	300
	21st to end	Day	8% 12% 31% 30% 18% 1	330
November	1st to 10th	Day	9% 14% 30% 30% 15% 1	282
	11th to 20th	Day	7% 8% 38% 31% 13% 3	270
	21st to end	Day	14% 8% 31% 29% 15% 3	270
December	1st to 10th	Day	13% 10% 37% 27% 11% 3	270
	11th to 20th	Day	10% 11% 37% 28% 11% 3	270
	21st to end	Day	16% 14% 35% 28% 6% 1	297
January	1st to 10th	Night	7% 3 32% 39% 15% 4	760
	11th to 20th	Night	8% 4 30% 39% 16% 3	760
	21st to end	Night	10% 4 29% 37% 16% 3	836
February	1st to 10th	Night	9% 6% 34% 38% 12% 1	760
	11th to 20th	Night	9% 6% 34% 39% 11% 1	744
	21st to end	Night	11% 5% 39% 38% 6%	628
March	1st to 10th	Night	8% 7% 34% 36% 13% 2	760
	11th to 20th	Night	9% 6% 27% 39% 18% 2	760
	21st to end	Night	10% 7% 35% 35% 11% 1	836
April	1st to 10th	Night	9% 10% 36% 37% 8%	577
	11th to 20th	Night	9% 12% 30% 36% 12% 1	563
	21st to end	Night	7% 10% 32% 38% 12% 1	570
May	1st to 10th	Night	8% 8% 31% 38% 15% 1	570
	11th to 20th	Night	9% 5% 23% 43% 18% 2	561
	21st to end	Night	10% 6% 27% 37% 18% 1	617
June	1st to 10th	Night	4 4 19% 46% 26% 1	570
	11th to 20th	Night	4 4 22% 45% 24% 1	570
	21st to end	Night	4 3 18% 43% 30% 2	570
July	1st to 10th	Night	3 1 14% 40% 39% 3	555
	11th to 20th	Night	4 1 9% 37% 42% 7%	552
	21st to end	Night	4 2 8% 35% 43% 7%	624
August	1st to 10th	Night	5% 2 8% 32% 46% 7%	567
	11th to 20th	Night	5% 2 10% 39% 39% 5%	564
	21st to end	Night	6% 2 9% 38% 39% 5%	627
September	1st to 10th	Night	7% 1 10% 44% 34% 5%	570
	11th to 20th	Night	8% 2 14% 44% 29% 3	593
	21st to end	Night	8% 3 16% 40% 27% 5%	760
October	1st to 10th	Night	12% 3 23% 40% 20% 3	760
	11th to 20th	Night	6% 3 23% 44% 20% 4	760
	21st to end	Night	6% 4 25% 40% 21% 4	836
November	1st to 10th	Night	7% 3 20% 45% 22% 3	760
	11th to 20th	Night	3 5% 30% 42% 16% 4	898
	21st to end	Night	12% 5% 22% 36% 21% 4	950
December	1st to 10th	Night	9% 7% 29% 40% 13% 2	950
	11th to 20th	Night	12% 6% 29% 37% 15% 1	950
	21st to end	Night	12% 6% 30% 39% 11% 1	1037

Page generated at 2024-11-03 00:11:11. Version ac07

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