El Morro National Monument Visitor Center
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the El Morro National Monument Visitor Center clear sky chart from 2005-11-06 to 2025-02-25.

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 5% 2 5% 4 4 4 4 5% 7% 58%	112561
	Night	3 5% 2 5% 3 3 4 3 5% 7% 60%	114995
Transparency	Day	23% 6% 9% 17% 26% 18%	112327
	Night	21% 6% 9% 18% 27% 18%	114818
Seeing	Day	7% 11% 24% 28% 21% 9%	14802
	Night	5% 7% 24% 38% 23% 3	25384

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	2 7% 4 8% 3 3 3 3 4 5% 58%	4098
	11th to 20th	Day	2 6% 2 4 2 2 3 3 4 5% 68%	4100
	21st to end	Day	3 11% 5% 6% 3 3 3 3 5% 4 54%	4510
February	1st to 10th	Day	1 8% 3 6% 4 3 3 2 5% 7% 58%	1800
	11th to 20th	Day	2 8% 3 6% 3 4 4 3 5% 8% 53%	1821
	21st to end	Day	3 9% 3 5% 3 4 4 4 4 6% 55%	1712
March	1st to 10th	Day	2 5% 2 5% 3 3 4 4 6% 9% 58%	3444
	11th to 20th	Day	3 9% 3 8% 6% 5% 5% 5% 6% 7% 44%	3490
	21st to end	Day	2 6% 3 6% 4 4 4 4 5% 7% 55%	3825
April	1st to 10th	Day	2 4 2 5% 4 3 3 3 5% 7% 63%	2231
	11th to 20th	Day	2 4 2 4 3 4 4 4 5% 6% 62%	2251
	21st to end	Day	3 4 1 3 3 3 4 3 5% 7% 64%	2280
May	1st to 10th	Day	2 2 1 3 2 3 3 2 4 5% 73%	3913
	11th to 20th	Day	3 4 2 5% 5% 5% 6% 5% 6% 6% 55%	4071
	21st to end	Day	2 2 1 2 2 2 2 2 4 4 78%	4477
June	1st to 10th	Day	2 3 1 3 3 3 4 4 5% 8% 64%	2470
	11th to 20th	Day	2 2 1 3 2 3 2 3 3 4 73%	2470
	21st to end	Day	3 3 2 6% 5% 5% 5% 4 6% 7% 56%	2470
July	1st to 10th	Day	3 3 2 5% 5% 5% 5% 4 5% 7% 58%	4110
	11th to 20th	Day	3 3 2 7% 7% 8% 9% 6% 8% 10% 36%	4110
	21st to end	Day	4 4 2 7% 7% 7% 7% 6% 8% 10% 36%	4454
August	1st to 10th	Day	4 4 3 8% 8% 8% 8% 6% 7% 9% 35%	4092
	11th to 20th	Day	4 4 2 7% 6% 5% 6% 5% 7% 8% 46%	3848
	21st to end	Day	5% 4 3 9% 7% 6% 7% 5% 7% 9% 37%	4180
September	1st to 10th	Day	7% 5% 2 7% 6% 5% 5% 5% 6% 6% 47%	2280
	11th to 20th	Day	5% 4 2 6% 4 4 4 4 5% 7% 56%	2196
	21st to end	Day	4 3 1 4 3 4 4 3 5% 5% 64%	2041
October	1st to 10th	Day	3 3 1 4 3 3 3 3 5% 5% 67%	3170
	11th to 20th	Day	3 3 1 4 3 3 4 3 6% 5% 64%	3150
	21st to end	Day	2 2 1 2 1 2 2 2 4 6% 77%	3438
November	1st to 10th	Day	1 4 1 3 2 2 2 3 5% 5% 70%	1959
	11th to 20th	Day	2 3 1 3 3 3 3 3 4 6% 70%	2000
	21st to end	Day	2 7% 2 5% 3 3 3 3 5% 5% 63%	1739
December	1st to 10th	Day	2 4 2 3 2 2 2 2 3 4 74%	2620
	11th to 20th	Day	3 6% 2 5% 4 3 2 2 4 7% 61%	3231
	21st to end	Day	2 7% 2 4 3 3 3 3 4 6% 63%	4510
January	1st to 10th	Night	1 7% 3 8% 4 4 3 3 5% 6% 56%	5867
	11th to 20th	Night	2 6% 1 4 2 3 2 2 4 4 70%	5880
	21st to end	Night	3 11% 4 7% 3 3 3 3 4 5% 53%	6468
February	1st to 10th	Night	2 8% 3 5% 3 3 3 3 3 6% 62%	2600
	11th to 20th	Night	4 9% 2 5% 4 3 4 3 4 7% 56%	2463
	21st to end	Night	3 7% 3 5% 4 3 3 3 5% 6% 60%	1831
March	1st to 10th	Night	1 6% 2 4 3 3 2 2 4 7% 67%	3430
	11th to 20th	Night	5% 12% 3 7% 4 3 3 3 5% 6% 48%	3490
	21st to end	Night	2 9% 3 5% 3 3 3 3 5% 6% 59%	3828
April	1st to 10th	Night	3 4 1 3 4 2 3 3 5% 7% 65%	1948
	11th to 20th	Night	3 5% 1 4 3 3 4 3 4 6% 66%	1877
	21st to end	Night	2 4 2 3 3 3 3 2 4 6% 68%	1900
May	1st to 10th	Night	3 3 1 3 2 2 3 2 4 5% 71%	3053
	11th to 20th	Night	2 4 2 4 4 3 4 3 5% 6% 62%	2834
	21st to end	Night	1 2 1 1 2 2 2 4 4 81%	3110
June	1st to 10th	Night	3 3 2 3 3 3 4 4 5% 7% 64%	1710
	11th to 20th	Night	2 2 1 2 2 3 2 3 4 6% 73%	1710
	21st to end	Night	3 4 2 5% 6% 4 5% 5% 6% 7% 54%	1710
July	1st to 10th	Night	3 3 2 5% 4 4 4 4 6% 6% 58%	2860
	11th to 20th	Night	3 4 2 8% 7% 6% 7% 7% 10% 11% 36%	2860
	21st to end	Night	3 5% 2 7% 6% 5% 8% 7% 11% 12% 34%	3109
August	1st to 10th	Night	2 4 3 9% 7% 7% 8% 8% 12% 10% 31%	2847
	11th to 20th	Night	4 4 2 8% 6% 7% 8% 6% 9% 10% 36%	2991
	21st to end	Night	4 4 2 7% 5% 7% 8% 8% 11% 10% 33%	3487
September	1st to 10th	Night	6% 6% 2 7% 6% 4 5% 5% 7% 8% 44%	1900
	11th to 20th	Night	4 4 2 4 3 3 4 4 4 6% 61%	1980
	21st to end	Night	4 3 1 4 3 3 3 3 3 6% 66%	2137
October	1st to 10th	Night	3 3 1 3 3 3 3 3 4 6% 69%	3800
	11th to 20th	Night	6% 4 2 4 3 3 4 3 5% 6% 62%	3778
	21st to end	Night	2 2 1 3 2 2 3 3 4 5% 74%	4120
November	1st to 10th	Night	2 3 1 3 2 1 3 4 5% 5% 70%	2340
	11th to 20th	Night	2 3 1 3 1 2 2 3 4 5% 73%	2400
	21st to end	Night	4 7% 2 5% 3 3 3 2 4 6% 63%	2629
December	1st to 10th	Night	3 4 1 3 1 2 2 3 3 6% 72%	4570
	11th to 20th	Night	2 6% 1 4 2 3 3 2 5% 8% 62%	5010
	21st to end	Night	2 6% 2 4 3 3 3 3 5% 5% 64%	6468

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	25% 5% 7% 25% 31% 7%	4099
	11th to 20th	Day	16% 5% 8% 23% 23% 25%	4100
	21st to end	Day	29% 5% 6% 12% 24% 24%	4510
February	1st to 10th	Day	25% 4 9% 20% 26% 16%	1800
	11th to 20th	Day	28% 4 7% 23% 24% 14%	1830
	21st to end	Day	27% 5% 6% 16% 26% 19%	1712
March	1st to 10th	Day	17% 7% 9% 20% 35% 12%	3444
	11th to 20th	Day	28% 16% 10% 16% 20% 9%	3490
	21st to end	Day	20% 8% 10% 23% 31% 7%	3825
April	1st to 10th	Day	20% 4 7% 19% 34% 17%	2231
	11th to 20th	Day	21% 4 7% 15% 33% 20%	2254
	21st to end	Day	19% 4 8% 19% 35% 15%	2280
May	1st to 10th	Day	13% 4 5% 14% 40% 25%	3913
	11th to 20th	Day	22% 9% 9% 13% 29% 18%	4074
	21st to end	Day	12% 2 4 8% 28% 46%	4477
June	1st to 10th	Day	17% 5% 8% 13% 29% 28%	2470
	11th to 20th	Day	15% 3 5% 9% 23% 45%	2470
	21st to end	Day	26% 6% 9% 13% 22% 24%	2470
July	1st to 10th	Day	25% 7% 7% 10% 13% 38%	4046
	11th to 20th	Day	35% 12% 14% 23% 10% 5%	4041
	21st to end	Day	34% 15% 19% 20% 10% 2	4314
August	1st to 10th	Day	40% 12% 20% 13% 10% 6%	4078
	11th to 20th	Day	31% 9% 13% 21% 16% 10%	3887
	21st to end	Day	38% 9% 16% 17% 16% 4	4179
September	1st to 10th	Day	35% 7% 10% 14% 19% 14%	2280
	11th to 20th	Day	26% 6% 10% 13% 25% 20%	2196
	21st to end	Day	20% 6% 7% 16% 28% 22%	2041
October	1st to 10th	Day	19% 6% 5% 13% 24% 33%	3170
	11th to 20th	Day	20% 4 6% 14% 37% 19%	3150
	21st to end	Day	11% 2 5% 16% 36% 29%	3438
November	1st to 10th	Day	15% 3 8% 23% 33% 18%	1959
	11th to 20th	Day	16% 3 7% 19% 37% 19%	2000
	21st to end	Day	23% 5% 7% 16% 31% 18%	1739
December	1st to 10th	Day	15% 3 5% 24% 36% 16%	2620
	11th to 20th	Day	24% 4 5% 22% 36% 9%	3230
	21st to end	Day	22% 4 9% 25% 27% 13%	4510
January	1st to 10th	Night	23% 7% 9% 20% 32% 9%	5867
	11th to 20th	Night	15% 4 8% 22% 30% 22%	5880
	21st to end	Night	29% 6% 6% 12% 24% 24%	6468
February	1st to 10th	Night	23% 4 9% 20% 26% 17%	2600
	11th to 20th	Night	27% 5% 7% 23% 22% 17%	2464
	21st to end	Night	23% 4 7% 17% 33% 17%	1831
March	1st to 10th	Night	14% 6% 7% 24% 37% 13%	3430
	11th to 20th	Night	28% 14% 9% 18% 23% 8%	3490
	21st to end	Night	17% 8% 9% 28% 30% 7%	3828
April	1st to 10th	Night	17% 4 7% 23% 33% 16%	1948
	11th to 20th	Night	18% 4 7% 17% 32% 22%	1877
	21st to end	Night	17% 4 7% 18% 37% 16%	1900
May	1st to 10th	Night	12% 5% 7% 13% 44% 20%	3053
	11th to 20th	Night	18% 8% 9% 15% 31% 17%	2835
	21st to end	Night	8% 3 5% 9% 32% 44%	3110
June	1st to 10th	Night	18% 6% 5% 14% 27% 29%	1710
	11th to 20th	Night	13% 4 6% 10% 22% 46%	1710
	21st to end	Night	26% 8% 11% 14% 16% 25%	1710
July	1st to 10th	Night	25% 8% 9% 10% 11% 38%	2815
	11th to 20th	Night	33% 12% 16% 24% 8% 7%	2806
	21st to end	Night	33% 15% 24% 19% 8% 1	3011
August	1st to 10th	Night	37% 15% 21% 13% 9% 6%	2838
	11th to 20th	Night	35% 12% 18% 12% 12% 10%	3018
	21st to end	Night	36% 14% 16% 17% 10% 6%	3487
September	1st to 10th	Night	32% 9% 13% 16% 16% 14%	1900
	11th to 20th	Night	23% 6% 11% 15% 25% 21%	1980
	21st to end	Night	19% 5% 8% 15% 29% 24%	2137
October	1st to 10th	Night	15% 4 7% 14% 28% 32%	3800
	11th to 20th	Night	21% 5% 6% 16% 31% 20%	3778
	21st to end	Night	14% 3 5% 15% 39% 26%	4120
November	1st to 10th	Night	14% 4 6% 23% 36% 18%	2340
	11th to 20th	Night	13% 4 6% 20% 37% 21%	2400
	21st to end	Night	23% 3 7% 16% 33% 18%	2629
December	1st to 10th	Night	14% 3 6% 27% 29% 22%	4570
	11th to 20th	Night	20% 3 7% 17% 37% 16%	5010
	21st to end	Night	20% 5% 8% 22% 31% 14%	6468

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	7% 14% 36% 29% 11% 3	300
	11th to 20th	Day	9% 15% 29% 26% 17% 4	300
	21st to end	Day	4 13% 30% 32% 17% 5%	330
February	1st to 10th	Day	4 14% 35% 28% 15% 3	300
	11th to 20th	Day	10% 16% 32% 32% 9% 1	300
	21st to end	Day	12% 24% 30% 24% 8% 2	339
March	1st to 10th	Day	7% 24% 29% 25% 13% 2	460
	11th to 20th	Day	14% 18% 27% 24% 16% 1	460
	21st to end	Day	11% 24% 37% 19% 8% 2	506
April	1st to 10th	Day	7% 19% 34% 25% 12% 4	460
	11th to 20th	Day	9% 21% 34% 23% 10% 2	452
	21st to end	Day	7% 18% 35% 24% 14% 2	460
May	1st to 10th	Day	6% 17% 34% 29% 13% 2	463
	11th to 20th	Day	6% 11% 31% 28% 17% 7%	488
	21st to end	Day	4 16% 31% 28% 16% 5%	529
June	1st to 10th	Day	4 7% 23% 34% 24% 7%	490
	11th to 20th	Day	3 9% 26% 30% 22% 11%	490
	21st to end	Day	4 5% 24% 35% 23% 9%	490
July	1st to 10th	Day	7% 2 10% 34% 33% 14%	486
	11th to 20th	Day	6% 1 6% 24% 35% 29%	484
	21st to end	Day	7% 2 5% 20% 39% 28%	531
August	1st to 10th	Day	7% 3 8% 25% 36% 21%	487
	11th to 20th	Day	7% 2 11% 30% 29% 21%	477
	21st to end	Day	7% 1 11% 28% 33% 20%	539
September	1st to 10th	Day	8% 4 11% 26% 34% 16%	490
	11th to 20th	Day	6% 4 18% 38% 27% 8%	490
	21st to end	Day	6% 7% 22% 28% 27% 11%	441
October	1st to 10th	Day	4 10% 22% 27% 22% 16%	300
	11th to 20th	Day	7% 9% 20% 31% 23% 10%	300
	21st to end	Day	7% 9% 18% 29% 28% 9%	330
November	1st to 10th	Day	5% 12% 26% 36% 19% 2	300
	11th to 20th	Day	4 8% 18% 36% 28% 6%	300
	21st to end	Day	6% 16% 27% 29% 15% 7%	300
December	1st to 10th	Day	9% 8% 22% 33% 23% 4	300
	11th to 20th	Day	7% 10% 34% 27% 18% 4	300
	21st to end	Day	14% 15% 29% 26% 12% 3	330
January	1st to 10th	Night	6% 6% 27% 39% 19% 3	800
	11th to 20th	Night	8% 7% 30% 40% 14% 3	800
	21st to end	Night	6% 10% 27% 36% 17% 3	880
February	1st to 10th	Night	6% 8% 35% 34% 15% 2	800
	11th to 20th	Night	6% 11% 34% 38% 10% 1	784
	21st to end	Night	7% 12% 36% 36% 9%	646
March	1st to 10th	Night	4 13% 33% 35% 14% 1	760
	11th to 20th	Night	8% 11% 27% 36% 18% 1	760
	21st to end	Night	5% 10% 32% 39% 13% 1	836
April	1st to 10th	Night	4 11% 38% 37% 10% 1	618
	11th to 20th	Night	5% 13% 36% 35% 10% 1	563
	21st to end	Night	4 11% 37% 36% 10% 2	570
May	1st to 10th	Night	4 8% 35% 42% 10% 1	570
	11th to 20th	Night	3 7% 29% 43% 17% 1	561
	21st to end	Night	2 7% 30% 43% 16% 1	617
June	1st to 10th	Night	3 4 21% 52% 19% 1	570
	11th to 20th	Night	3 4 23% 51% 18% 1	570
	21st to end	Night	4 3 15% 47% 29% 2	570
July	1st to 10th	Night	5% 2 10% 40% 41% 3	555
	11th to 20th	Night	6% 1 4 28% 52% 8%	552
	21st to end	Night	7% 2 6% 24% 50% 11%	624
August	1st to 10th	Night	4 1 5% 26% 54% 10%	567
	11th to 20th	Night	5% 3 5% 32% 47% 8%	564
	21st to end	Night	5% 2 6% 32% 49% 7%	627
September	1st to 10th	Night	8% 2 9% 40% 37% 3	570
	11th to 20th	Night	5% 2 11% 44% 34% 4	650
	21st to end	Night	4 4 18% 37% 31% 6%	760
October	1st to 10th	Night	5% 3 26% 41% 22% 3	760
	11th to 20th	Night	3 4 21% 46% 22% 4	760
	21st to end	Night	3 5% 23% 38% 25% 5%	836
November	1st to 10th	Night	3 5% 23% 42% 23% 4	780
	11th to 20th	Night	4 5% 24% 41% 23% 4	800
	21st to end	Night	7% 11% 24% 33% 22% 3	904
December	1st to 10th	Night	8% 8% 22% 42% 18% 2	1000
	11th to 20th	Night	9% 9% 29% 34% 17% 1	920
	21st to end	Night	7% 10% 31% 38% 11% 2	880

Page generated at 2025-02-22 04:51:39. Version ac07

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