Celescina Ramah New Mexico Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Celescina Ramah New Mexico Observatory clear sky chart from 2005-11-06 to 2025-05-11.

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%	117757
	Night	3 5% 2 5% 3 3 4 3 5% 7% 60%	120128
Transparency	Day	24% 5% 8% 18% 27% 19%	117523
	Night	22% 5% 8% 18% 28% 18%	119951
Seeing	Day	6% 12% 25% 28% 20% 8%	15097
	Night	4 8% 27% 37% 22% 3	25648

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	1 6% 4 7% 3 3 3 3 5% 5% 58%	4098
	11th to 20th	Day	1 5% 3 4 2 2 3 3 4 5% 68%	4100
	21st to end	Day	3 10% 5% 8% 3 3 3 2 4 5% 55%	4510
February	1st to 10th	Day	1 7% 3 6% 4 3 4 3 5% 7% 58%	1800
	11th to 20th	Day	2 7% 3 6% 4 4 4 4 5% 8% 54%	1825
	21st to end	Day	3 8% 3 6% 3 3 4 3 4 6% 56%	1753
March	1st to 10th	Day	2 5% 3 5% 3 4 4 4 6% 8% 58%	4954
	11th to 20th	Day	2 8% 4 8% 5% 5% 6% 5% 7% 7% 44%	5000
	21st to end	Day	2 4 2 6% 4 4 4 3 5% 7% 56%	5486
April	1st to 10th	Day	2 4 2 5% 4 3 3 3 4 7% 63%	2350
	11th to 20th	Day	2 5% 1 4 3 4 4 3 5% 6% 62%	2371
	21st to end	Day	3 4 1 3 3 2 4 3 5% 6% 66%	2400
May	1st to 10th	Day	2 3 1 3 2 3 3 3 4 5% 72%	4030
	11th to 20th	Day	3 4 2 5% 4 5% 5% 5% 6% 6% 55%	4073
	21st to end	Day	2 2 1 2 2 2 2 2 3 5% 78%	4477
June	1st to 10th	Day	3 3 1 3 3 3 4 3 5% 8% 64%	2470
	11th to 20th	Day	3 2 1 3 3 3 3 2 3 5% 73%	2470
	21st to end	Day	3 3 2 5% 5% 5% 5% 4 6% 6% 55%	2470
July	1st to 10th	Day	4 3 2 5% 5% 4 4 4 5% 7% 58%	4110
	11th to 20th	Day	3 3 2 7% 6% 8% 8% 7% 8% 10% 37%	4110
	21st to end	Day	5% 5% 2 7% 6% 7% 7% 6% 9% 10% 36%	4454
August	1st to 10th	Day	6% 5% 2 8% 7% 8% 7% 5% 8% 9% 36%	4092
	11th to 20th	Day	5% 4 2 6% 5% 5% 6% 5% 7% 8% 47%	3843
	21st to end	Day	6% 5% 3 9% 7% 6% 6% 6% 7% 8% 38%	4180
September	1st to 10th	Day	8% 5% 2 6% 5% 5% 5% 4 6% 6% 47%	2280
	11th to 20th	Day	6% 4 2 5% 4 4 4 4 5% 6% 56%	2200
	21st to end	Day	5% 3 1 4 3 4 3 4 4 5% 64%	2038
October	1st to 10th	Day	3 3 1 4 3 3 3 3 4 4 68%	3170
	11th to 20th	Day	4 3 1 4 3 3 4 3 5% 6% 65%	3150
	21st to end	Day	2 2 1 2 1 1 2 2 4 6% 77%	3438
November	1st to 10th	Day	1 4 1 3 2 2 3 3 5% 6% 69%	1959
	11th to 20th	Day	2 3 1 3 2 3 3 2 4 6% 70%	2000
	21st to end	Day	2 6% 2 5% 3 3 3 3 5% 6% 62%	1738
December	1st to 10th	Day	2 4 2 3 2 2 2 2 2 5% 74%	2620
	11th to 20th	Day	3 6% 3 5% 3 2 3 2 4 7% 61%	3228
	21st to end	Day	2 6% 2 4 3 3 3 3 4 6% 63%	4510
January	1st to 10th	Night	1 6% 3 8% 5% 4 3 4 5% 6% 56%	5867
	11th to 20th	Night	2 4 2 4 3 2 2 1 4 4 71%	5880
	21st to end	Night	2 10% 4 8% 3 3 3 3 5% 5% 53%	6468
February	1st to 10th	Night	1 7% 3 6% 3 3 3 2 4 6% 63%	2600
	11th to 20th	Night	3 8% 3 5% 4 3 3 4 4 7% 56%	2459
	21st to end	Night	3 5% 2 6% 3 3 3 3 5% 5% 61%	1873
March	1st to 10th	Night	1 7% 3 5% 2 3 3 3 4 6% 62%	4940
	11th to 20th	Night	3 9% 5% 7% 3 4 4 3 5% 7% 50%	5000
	21st to end	Night	1 5% 2 4 3 3 3 3 5% 7% 63%	5489
April	1st to 10th	Night	2 4 1 4 3 3 3 3 4 8% 65%	2049
	11th to 20th	Night	3 4 2 3 3 3 4 3 4 6% 66%	1977
	21st to end	Night	2 4 1 4 3 2 3 3 4 5% 70%	2000
May	1st to 10th	Night	3 4 1 3 2 2 3 3 4 5% 71%	3156
	11th to 20th	Night	3 4 1 4 3 3 4 4 5% 6% 62%	2838
	21st to end	Night	2 1 1 1 1 1 2 2 3 4 81%	3110
June	1st to 10th	Night	4 3 1 3 3 3 4 4 4 7% 64%	1710
	11th to 20th	Night	2 2 1 3 2 3 3 2 4 6% 73%	1710
	21st to end	Night	5% 4 2 5% 5% 4 5% 4 6% 7% 53%	1710
July	1st to 10th	Night	4 3 2 5% 4 5% 4 4 5% 6% 58%	2860
	11th to 20th	Night	3 4 2 7% 7% 6% 7% 7% 10% 11% 36%	2860
	21st to end	Night	4 5% 3 7% 5% 6% 8% 7% 10% 12% 34%	3109
August	1st to 10th	Night	3 4 2 9% 6% 7% 8% 7% 11% 11% 31%	2847
	11th to 20th	Night	5% 5% 2 7% 6% 7% 7% 6% 8% 10% 37%	2995
	21st to end	Night	5% 4 2 7% 6% 7% 8% 8% 11% 10% 33%	3487
September	1st to 10th	Night	6% 5% 2 8% 5% 5% 5% 4 7% 8% 44%	1900
	11th to 20th	Night	4 3 1 5% 4 4 4 3 4 7% 60%	1975
	21st to end	Night	4 3 1 4 3 3 3 3 4 6% 67%	2141
October	1st to 10th	Night	3 3 1 3 3 2 3 2 4 5% 70%	3800
	11th to 20th	Night	7% 3 1 4 3 3 4 3 5% 7% 62%	3778
	21st to end	Night	2 3 1 2 2 2 3 3 4 5% 74%	4120
November	1st to 10th	Night	1 3 1 3 2 2 4 3 5% 5% 71%	2340
	11th to 20th	Night	2 3 1 3 2 2 2 3 4 5% 74%	2400
	21st to end	Night	3 6% 2 5% 3 3 3 3 4 6% 63%	2629
December	1st to 10th	Night	2 4 1 3 2 2 2 2 4 6% 73%	4570
	11th to 20th	Night	2 6% 2 4 3 3 3 3 5% 8% 62%	5013
	21st to end	Night	2 6% 2 4 2 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	26% 3 6% 26% 31% 8%	4099
	11th to 20th	Day	17% 3 8% 23% 23% 26%	4100
	21st to end	Day	30% 4 4 13% 24% 25%	4510
February	1st to 10th	Day	24% 5% 8% 21% 26% 16%	1800
	11th to 20th	Day	27% 4 7% 24% 24% 14%	1834
	21st to end	Day	27% 4 6% 17% 26% 21%	1753
March	1st to 10th	Day	20% 5% 6% 14% 35% 20%	4954
	11th to 20th	Day	30% 9% 6% 15% 27% 12%	5000
	21st to end	Day	22% 5% 7% 27% 31% 8%	5486
April	1st to 10th	Day	20% 3 7% 18% 35% 17%	2350
	11th to 20th	Day	21% 4 6% 15% 33% 21%	2374
	21st to end	Day	18% 3 7% 19% 36% 16%	2400
May	1st to 10th	Day	14% 3 5% 14% 39% 25%	4030
	11th to 20th	Day	23% 8% 8% 13% 29% 19%	4076
	21st to end	Day	11% 3 4 7% 28% 47%	4477
June	1st to 10th	Day	17% 4 7% 14% 29% 29%	2470
	11th to 20th	Day	15% 3 5% 8% 23% 46%	2470
	21st to end	Day	26% 6% 9% 12% 23% 24%	2470
July	1st to 10th	Day	25% 6% 7% 11% 13% 39%	4046
	11th to 20th	Day	37% 9% 13% 24% 12% 5%	4041
	21st to end	Day	38% 9% 20% 22% 10% 2	4314
August	1st to 10th	Day	41% 8% 20% 14% 10% 6%	4078
	11th to 20th	Day	32% 7% 12% 22% 17% 10%	3882
	21st to end	Day	39% 7% 15% 18% 16% 5%	4179
September	1st to 10th	Day	35% 7% 9% 15% 20% 14%	2280
	11th to 20th	Day	26% 6% 8% 14% 25% 20%	2200
	21st to end	Day	20% 5% 7% 16% 29% 23%	2038
October	1st to 10th	Day	19% 5% 4 13% 25% 35%	3170
	11th to 20th	Day	20% 3 4 15% 39% 20%	3150
	21st to end	Day	10% 2 4 15% 39% 30%	3438
November	1st to 10th	Day	14% 3 7% 23% 34% 19%	1959
	11th to 20th	Day	15% 3 7% 19% 38% 18%	2000
	21st to end	Day	23% 4 7% 17% 31% 18%	1738
December	1st to 10th	Day	15% 2 5% 24% 37% 16%	2620
	11th to 20th	Day	24% 3 6% 21% 36% 10%	3227
	21st to end	Day	21% 4 8% 25% 28% 13%	4510
January	1st to 10th	Night	25% 4 9% 21% 33% 9%	5867
	11th to 20th	Night	15% 4 5% 23% 31% 22%	5880
	21st to end	Night	30% 4 6% 12% 23% 24%	6468
February	1st to 10th	Night	22% 4 9% 22% 26% 18%	2600
	11th to 20th	Night	26% 3 8% 23% 23% 17%	2460
	21st to end	Night	21% 4 6% 18% 33% 18%	1873
March	1st to 10th	Night	20% 4 5% 17% 36% 19%	4940
	11th to 20th	Night	30% 7% 6% 18% 28% 12%	5000
	21st to end	Night	17% 5% 8% 28% 36% 7%	5489
April	1st to 10th	Night	18% 2 8% 22% 33% 17%	2049
	11th to 20th	Night	18% 3 6% 17% 33% 23%	1977
	21st to end	Night	16% 4 7% 17% 38% 18%	2000
May	1st to 10th	Night	13% 4 7% 13% 45% 19%	3156
	11th to 20th	Night	19% 6% 9% 15% 32% 18%	2839
	21st to end	Night	8% 3 5% 8% 30% 47%	3110
June	1st to 10th	Night	19% 5% 5% 15% 27% 29%	1710
	11th to 20th	Night	13% 4 6% 10% 22% 46%	1710
	21st to end	Night	26% 7% 12% 14% 16% 25%	1710
July	1st to 10th	Night	24% 7% 10% 11% 10% 38%	2815
	11th to 20th	Night	34% 11% 15% 25% 8% 7%	2806
	21st to end	Night	37% 10% 25% 19% 8% 1	3011
August	1st to 10th	Night	40% 9% 23% 14% 8% 6%	2838
	11th to 20th	Night	39% 8% 18% 13% 11% 10%	3022
	21st to end	Night	39% 9% 19% 16% 11% 6%	3487
September	1st to 10th	Night	33% 9% 12% 16% 17% 14%	1900
	11th to 20th	Night	23% 5% 10% 16% 25% 21%	1975
	21st to end	Night	19% 4 7% 15% 30% 25%	2141
October	1st to 10th	Night	17% 4 5% 13% 29% 32%	3800
	11th to 20th	Night	23% 4 4 17% 32% 20%	3778
	21st to end	Night	13% 3 3 14% 40% 26%	4120
November	1st to 10th	Night	14% 3 6% 24% 35% 18%	2340
	11th to 20th	Night	13% 3 6% 20% 37% 21%	2400
	21st to end	Night	23% 3 7% 16% 32% 19%	2629
December	1st to 10th	Night	14% 2 5% 28% 29% 21%	4570
	11th to 20th	Night	20% 3 6% 18% 37% 15%	5013
	21st to end	Night	20% 4 8% 22% 31% 13%	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% 17% 34% 29% 10% 2	300
	11th to 20th	Day	8% 20% 27% 25% 17% 2	300
	21st to end	Day	2 13% 38% 28% 15% 5%	330
February	1st to 10th	Day	4 17% 37% 26% 14% 2	300
	11th to 20th	Day	7% 22% 33% 30% 8%	300
	21st to end	Day	10% 30% 28% 23% 8% 2	352
March	1st to 10th	Day	7% 27% 28% 27% 11% 1	500
	11th to 20th	Day	12% 21% 30% 21% 13% 2	500
	21st to end	Day	11% 26% 36% 18% 8% 2	550
April	1st to 10th	Day	7% 19% 35% 25% 10% 4	500
	11th to 20th	Day	10% 24% 32% 24% 9% 1	492
	21st to end	Day	8% 19% 35% 25% 12% 2	500
May	1st to 10th	Day	5% 17% 37% 27% 11% 3	503
	11th to 20th	Day	4 12% 31% 31% 16% 6%	489
	21st to end	Day	4 16% 32% 30% 14% 4	529
June	1st to 10th	Day	5% 7% 25% 33% 25% 5%	490
	11th to 20th	Day	3 10% 27% 30% 21% 9%	490
	21st to end	Day	3 6% 26% 34% 22% 10%	490
July	1st to 10th	Day	5% 1 13% 36% 32% 13%	486
	11th to 20th	Day	7% 1 6% 25% 35% 27%	484
	21st to end	Day	7% 1 8% 21% 36% 28%	531
August	1st to 10th	Day	7% 2 9% 28% 34% 20%	487
	11th to 20th	Day	8% 2 10% 31% 30% 19%	477
	21st to end	Day	7% 2 11% 30% 31% 19%	539
September	1st to 10th	Day	9% 3 15% 27% 33% 14%	490
	11th to 20th	Day	5% 3 21% 36% 27% 9%	490
	21st to end	Day	6% 6% 23% 29% 26% 11%	438
October	1st to 10th	Day	4 9% 24% 26% 23% 14%	300
	11th to 20th	Day	7% 9% 23% 28% 22% 11%	300
	21st to end	Day	6% 11% 19% 27% 28% 8%	330
November	1st to 10th	Day	4 13% 27% 34% 19% 2	300
	11th to 20th	Day	4 10% 19% 36% 24% 7%	300
	21st to end	Day	5% 17% 30% 25% 16% 7%	300
December	1st to 10th	Day	6% 14% 21% 34% 20% 5%	300
	11th to 20th	Day	7% 15% 30% 27% 17% 3	300
	21st to end	Day	11% 21% 30% 24% 12% 3	330
January	1st to 10th	Night	4 9% 29% 36% 18% 3	800
	11th to 20th	Night	7% 9% 32% 37% 15% 2	800
	21st to end	Night	5% 11% 31% 33% 17% 3	880
February	1st to 10th	Night	4 11% 36% 34% 13% 2	800
	11th to 20th	Night	5% 12% 39% 33% 9% 1	784
	21st to end	Night	5% 14% 41% 32% 8%	660
March	1st to 10th	Night	3 16% 37% 32% 12% 1	800
	11th to 20th	Night	6% 14% 29% 35% 16% 1	800
	21st to end	Night	3 13% 37% 35% 11%	880
April	1st to 10th	Night	3 14% 39% 35% 9%	649
	11th to 20th	Night	4 15% 40% 33% 8% 1	593
	21st to end	Night	3 12% 41% 33% 10% 1	600
May	1st to 10th	Night	4 9% 38% 39% 11% 1	600
	11th to 20th	Night	3 7% 30% 43% 15% 1	563
	21st to end	Night	2 7% 35% 40% 15% 1	617
June	1st to 10th	Night	4 4 28% 48% 15% 1	570
	11th to 20th	Night	3 4 29% 47% 16% 1	570
	21st to end	Night	4 4 18% 46% 27% 2	570
July	1st to 10th	Night	4 1 12% 43% 37% 3	555
	11th to 20th	Night	5% 5% 33% 49% 8%	552
	21st to end	Night	7% 1 7% 27% 47% 10%	624
August	1st to 10th	Night	4 1 4 30% 51% 10%	567
	11th to 20th	Night	6% 1 7% 34% 45% 7%	564
	21st to end	Night	5% 1 7% 32% 47% 7%	627
September	1st to 10th	Night	8% 2 8% 40% 39% 3	570
	11th to 20th	Night	3 2 12% 45% 34% 4	645
	21st to end	Night	4 4 18% 40% 29% 5%	760
October	1st to 10th	Night	5% 3 28% 39% 23% 2	760
	11th to 20th	Night	3 5% 22% 44% 23% 3	760
	21st to end	Night	3 7% 25% 36% 25% 4	836
November	1st to 10th	Night	2 7% 24% 39% 23% 4	780
	11th to 20th	Night	2 7% 26% 39% 23% 4	800
	21st to end	Night	6% 13% 25% 31% 22% 3	909
December	1st to 10th	Night	7% 10% 25% 39% 18% 2	1000
	11th to 20th	Night	7% 12% 34% 30% 17% 1	923
	21st to end	Night	6% 14% 33% 35% 12% 2	880

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