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 2024-04-10.

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	5% 6% 2 4 4 3 5% 5% 5% 7% 54%	83394
	Night	5% 6% 2 4 4 2 4 4 5% 6% 57%	85504
Transparency	Day	28% 6% 10% 21% 24% 12%	83119
	Night	28% 4 10% 21% 24% 12%	85300
Seeing	Day	9% 12% 30% 30% 15% 3	14316
	Night	8% 5% 24% 39% 21% 3	24650

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 5% 3 2 4 5% 6% 7% 56%	2858
	11th to 20th	Day	3 5% 1 4 3 3 5% 5% 6% 8% 58%	2860
	21st to end	Day	4 10% 2 5% 4 2 3 5% 5% 6% 54%	3146
February	1st to 10th	Day	2 8% 3 6% 4 2 4 4 4 5% 57%	1710
	11th to 20th	Day	5% 8% 2 6% 5% 3 5% 4 5% 6% 51%	1712
	21st to end	Day	4 10% 4 6% 4 2 5% 4 4 6% 51%	1591
March	1st to 10th	Day	3 9% 3 5% 5% 3 5% 5% 6% 8% 49%	3444
	11th to 20th	Day	7% 11% 3 6% 5% 3 5% 5% 6% 6% 43%	3490
	21st to end	Day	4 12% 4 7% 6% 4 5% 5% 5% 6% 42%	3825
April	1st to 10th	Day	4 5% 1 4 5% 3 5% 5% 5% 8% 55%	2261
	11th to 20th	Day	4 5% 2 4 5% 3 4 6% 6% 7% 54%	2131
	21st to end	Day	4 5% 2 4 4 3 5% 4 6% 8% 55%	2160
May	1st to 10th	Day	5% 4 2 4 4 3 5% 5% 5% 7% 56%	2270
	11th to 20th	Day	5% 5% 2 4 5% 3 5% 7% 7% 7% 49%	2301
	21st to end	Day	5% 4 2 4 4 3 4 4 5% 7% 59%	2672
June	1st to 10th	Day	3 3 1 2 3 3 4 5% 5% 7% 65%	2520
	11th to 20th	Day	3 2 1 2 3 2 4 4 4 4 72%	2520
	21st to end	Day	2 2 1 3 4 3 5% 6% 6% 7% 62%	2520
July	1st to 10th	Day	4 3 2 4 5% 4 6% 7% 7% 8% 49%	2414
	11th to 20th	Day	3 3 2 5% 7% 5% 8% 7% 9% 10% 43%	2340
	21st to end	Day	7% 5% 3 6% 7% 4 7% 8% 9% 10% 34%	2545
August	1st to 10th	Day	6% 5% 2 5% 6% 5% 7% 6% 8% 8% 42%	2328
	11th to 20th	Day	4 4 2 5% 6% 4 7% 7% 7% 9% 45%	2220
	21st to end	Day	6% 4 2 5% 4 4 7% 7% 7% 8% 46%	2376
September	1st to 10th	Day	8% 4 2 5% 5% 4 5% 4 5% 8% 51%	2160
	11th to 20th	Day	6% 3 2 4 5% 3 5% 5% 6% 6% 54%	2136
	21st to end	Day	7% 2 1 3 3 2 3 3 4 6% 66%	1906
October	1st to 10th	Day	9% 4 2 3 4 2 4 4 4 7% 56%	1800
	11th to 20th	Day	5% 3 1 2 3 2 2 3 2 5% 73%	1800
	21st to end	Day	4 4 1 2 3 2 3 3 3 5% 69%	1980
November	1st to 10th	Day	4 3 1 2 2 2 3 2 4 5% 71%	1859
	11th to 20th	Day	2 3 1 2 3 2 3 3 4 6% 70%	1739
	21st to end	Day	7% 6% 1 3 2 2 3 3 4 4 65%	1524
December	1st to 10th	Day	6% 7% 2 3 2 2 3 4 4 6% 61%	1520
	11th to 20th	Day	7% 7% 2 4 4 3 4 5% 5% 8% 50%	1926
	21st to end	Day	5% 8% 3 4 4 2 3 4 5% 5% 56%	2830
January	1st to 10th	Night	2 8% 3 7% 6% 3 4 4 5% 6% 53%	4097
	11th to 20th	Night	3 7% 3 4 4 2 4 3 4 7% 59%	4110
	21st to end	Night	5% 10% 3 5% 5% 2 3 3 5% 6% 54%	4521
February	1st to 10th	Night	4 8% 2 4 3 2 3 3 4 7% 62%	2470
	11th to 20th	Night	6% 7% 2 4 4 2 3 4 4 5% 59%	2354
	21st to end	Night	4 10% 3 4 3 2 3 3 4 4 59%	1860
March	1st to 10th	Night	3 10% 3 4 4 3 4 4 5% 7% 52%	3430
	11th to 20th	Night	8% 11% 3 5% 5% 3 4 4 6% 6% 44%	3490
	21st to end	Night	6% 7% 3 6% 6% 4 5% 5% 5% 7% 47%	3828
April	1st to 10th	Night	6% 5% 2 3 4 2 4 5% 5% 7% 57%	1907
	11th to 20th	Night	6% 4 2 4 5% 2 4 4 5% 6% 58%	1777
	21st to end	Night	5% 5% 2 4 2 2 3 4 5% 7% 62%	1800
May	1st to 10th	Night	6% 4 2 4 4 2 4 4 4 7% 60%	1687
	11th to 20th	Night	8% 6% 2 4 4 3 4 4 5% 6% 56%	1594
	21st to end	Night	7% 6% 1 3 4 3 4 4 5% 6% 58%	1600
June	1st to 10th	Night	2 3 1 3 3 2 3 4 4 8% 68%	1440
	11th to 20th	Night	4 3 1 3 2 2 3 3 4 5% 71%	1440
	21st to end	Night	3 2 1 3 3 3 5% 5% 6% 8% 62%	1440
July	1st to 10th	Night	4 3 2 5% 5% 3 6% 9% 6% 10% 47%	1540
	11th to 20th	Night	3 4 3 4 6% 3 5% 7% 8% 9% 48%	1620
	21st to end	Night	5% 5% 3 5% 7% 4 7% 9% 10% 10% 35%	1773
August	1st to 10th	Night	5% 3 3 5% 5% 3 6% 7% 8% 8% 46%	1611
	11th to 20th	Night	5% 5% 2 3 4 3 5% 6% 7% 9% 49%	1678
	21st to end	Night	4 4 2 4 5% 3 5% 5% 6% 10% 50%	1980
September	1st to 10th	Night	6% 4 2 4 6% 3 5% 7% 6% 9% 49%	1800
	11th to 20th	Night	7% 4 1 4 5% 3 4 4 4 6% 56%	1821
	21st to end	Night	8% 3 1 3 3 2 3 3 3 4 68%	2052
October	1st to 10th	Night	12% 4 1 3 3 2 3 3 5% 5% 58%	2160
	11th to 20th	Night	4 3 1 2 2 1 2 3 3 4 75%	2160
	21st to end	Night	5% 3 1 3 2 2 2 3 4 5% 71%	2376
November	1st to 10th	Night	5% 3 1 2 2 2 3 3 4 6% 70%	2220
	11th to 20th	Night	2 3 1 2 2 2 2 3 4 6% 73%	2418
	21st to end	Night	7% 6% 2 3 2 2 3 2 3 6% 65%	2654
December	1st to 10th	Night	5% 7% 2 4 4 1 3 3 4 5% 62%	2660
	11th to 20th	Night	6% 8% 2 4 4 3 4 5% 5% 6% 52%	3271
	21st to end	Night	7% 8% 3 4 4 2 3 3 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%	2261
	11th to 20th	Day	27% 5% 9% 20% 26% 13%	2134
	21st to end	Day	26% 5% 8% 23% 29% 9%	2160
May	1st to 10th	Day	26% 5% 8% 20% 31% 10%	2270
	11th to 20th	Day	30% 7% 11% 19% 24% 9%	2304
	21st to end	Day	24% 5% 8% 15% 30% 18%	2672
June	1st to 10th	Day	18% 5% 7% 18% 29% 23%	2520
	11th to 20th	Day	15% 3 6% 12% 26% 38%	2520
	21st to end	Day	19% 5% 7% 14% 24% 31%	2520
July	1st to 10th	Day	28% 9% 12% 14% 15% 23%	2350
	11th to 20th	Day	28% 10% 15% 19% 16% 11%	2271
	21st to end	Day	37% 12% 19% 17% 11% 3	2404
August	1st to 10th	Day	34% 11% 14% 13% 14% 15%	2313
	11th to 20th	Day	30% 9% 11% 16% 19% 14%	2220
	21st to end	Day	29% 8% 12% 19% 21% 10%	2376
September	1st to 10th	Day	29% 7% 10% 16% 20% 17%	2160
	11th to 20th	Day	25% 7% 10% 16% 24% 18%	2136
	21st to end	Day	20% 4 7% 16% 38% 15%	1906
October	1st to 10th	Day	27% 6% 9% 18% 23% 17%	1800
	11th to 20th	Day	17% 2 4 19% 38% 20%	1800
	21st to end	Day	20% 3 8% 24% 36% 10%	1980
November	1st to 10th	Day	17% 2 8% 28% 35% 9%	1859
	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	26% 5% 8% 18% 29% 14%	1907
	11th to 20th	Night	28% 3 7% 19% 26% 17%	1777
	21st to end	Night	23% 4 7% 21% 32% 12%	1800
May	1st to 10th	Night	26% 4 7% 18% 33% 12%	1687
	11th to 20th	Night	29% 6% 10% 20% 25% 11%	1595
	21st to end	Night	27% 4 10% 16% 25% 18%	1600
June	1st to 10th	Night	17% 4 8% 15% 28% 28%	1440
	11th to 20th	Night	17% 2 7% 11% 19% 44%	1440
	21st to end	Night	18% 5% 9% 12% 23% 33%	1440
July	1st to 10th	Night	30% 9% 14% 12% 10% 26%	1495
	11th to 20th	Night	30% 10% 14% 18% 12% 17%	1566
	21st to end	Night	36% 15% 20% 15% 9% 4	1674
August	1st to 10th	Night	31% 11% 16% 13% 13% 17%	1602
	11th to 20th	Night	29% 8% 15% 15% 16% 17%	1678
	21st to end	Night	28% 8% 15% 19% 18% 12%	1980
September	1st to 10th	Night	30% 7% 12% 15% 16% 19%	1800
	11th to 20th	Night	29% 5% 9% 15% 19% 24%	1821
	21st to end	Night	22% 3 6% 13% 34% 22%	2052
October	1st to 10th	Night	28% 4 9% 16% 21% 23%	2160
	11th to 20th	Night	16% 3 5% 14% 37% 25%	2160
	21st to end	Night	18% 3 6% 22% 35% 16%	2376
November	1st to 10th	Night	17% 3 6% 27% 35% 13%	2220
	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% 24% 36% 18% 7% 1	457
	11th to 20th	Day	18% 28% 30% 17% 6%	412
	21st to end	Day	15% 26% 34% 20% 5%	420
May	1st to 10th	Day	10% 23% 43% 18% 6%	423
	11th to 20th	Day	10% 17% 34% 26% 12% 2	448
	21st to end	Day	8% 15% 32% 27% 15% 2	627
June	1st to 10th	Day	4 7% 25% 39% 21% 3	630
	11th to 20th	Day	4 7% 32% 33% 18% 5%	630
	21st to end	Day	3 8% 27% 36% 22% 5%	630
July	1st to 10th	Day	4 3 19% 39% 29% 6%	520
	11th to 20th	Day	4 2 20% 34% 31% 9%	444
	21st to end	Day	5% 1 16% 40% 30% 8%	487
August	1st to 10th	Day	7% 4 18% 41% 23% 7%	447
	11th to 20th	Day	4 4 25% 40% 20% 7%	437
	21st to end	Day	5% 2 22% 41% 24% 6%	495
September	1st to 10th	Day	8% 4 22% 38% 23% 6%	450
	11th to 20th	Day	4 4 30% 40% 17% 5%	450
	21st to end	Day	8% 10% 27% 32% 16% 6%	376
October	1st to 10th	Day	12% 11% 22% 26% 21% 7%	270
	11th to 20th	Day	9% 13% 26% 32% 16% 4	270
	21st to end	Day	8% 13% 30% 30% 19% 1	297
November	1st to 10th	Day	10% 14% 30% 29% 16% 1	270
	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	10% 12% 29% 37% 12% 1	533
	21st to end	Night	7% 10% 32% 37% 12% 1	540
May	1st to 10th	Night	8% 7% 30% 39% 16% 1	540
	11th to 20th	Night	9% 5% 23% 42% 19% 2	531
	21st to end	Night	10% 5% 28% 36% 19% 2	584
June	1st to 10th	Night	4 4 19% 45% 27% 1	540
	11th to 20th	Night	4 3 20% 47% 24% 1	540
	21st to end	Night	4 2 17% 43% 32% 2	540
July	1st to 10th	Night	3 1 11% 41% 42% 3	525
	11th to 20th	Night	4 1 9% 35% 43% 8%	522
	21st to end	Night	5% 2 6% 34% 45% 8%	591
August	1st to 10th	Night	4 2 7% 32% 47% 7%	537
	11th to 20th	Night	5% 2 10% 38% 40% 5%	534
	21st to end	Night	6% 1 8% 39% 41% 6%	594
September	1st to 10th	Night	7% 1 10% 43% 35% 5%	540
	11th to 20th	Night	9% 1 12% 45% 30% 3	561
	21st to end	Night	8% 3 14% 41% 28% 5%	720
October	1st to 10th	Night	12% 3 22% 38% 21% 3	720
	11th to 20th	Night	5% 3 22% 45% 21% 4	720
	21st to end	Night	6% 4 22% 41% 22% 4	792
November	1st to 10th	Night	7% 2 19% 46% 22% 3	740
	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 2024-04-07 07:28:13. Version ac07

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