Santa Fe
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Santa Fe clear sky chart from 2005-11-06 to 2025-07-06.

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 4 2 4 3 3 4 4 6% 7% 59%	123557
	Night	4 5% 2 5% 3 3 4 3 5% 7% 59%	124142
Transparency	Day	22% 6% 10% 20% 26% 15%	123315
	Night	23% 5% 10% 20% 27% 15%	123971
Seeing	Day	7% 14% 30% 30% 16% 2	16050
	Night	6% 7% 34% 37% 15% 1	26164

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 8% 4 5% 2 3 3 3 4 6% 60%	3957
	11th to 20th	Day	2 5% 3 5% 3 2 3 2 4 5% 67%	4100
	21st to end	Day	3 6% 2 6% 3 4 4 4 5% 5% 59%	4510
February	1st to 10th	Day	2 9% 3 5% 3 3 3 2 5% 7% 58%	1834
	11th to 20th	Day	4 7% 3 6% 3 3 3 3 5% 7% 56%	1949
	21st to end	Day	3 10% 2 4 3 3 3 3 4 6% 59%	1650
March	1st to 10th	Day	2 7% 2 5% 3 3 3 3 5% 6% 62%	4700
	11th to 20th	Day	2 8% 4 7% 4 4 5% 4 6% 8% 49%	5000
	21st to end	Day	2 6% 2 5% 4 3 4 3 6% 8% 58%	5695
April	1st to 10th	Day	4 5% 2 4 3 4 3 3 5% 6% 60%	2400
	11th to 20th	Day	3 7% 3 5% 3 3 4 3 4 5% 60%	2371
	21st to end	Day	4 5% 1 3 3 3 3 3 6% 8% 62%	2400
May	1st to 10th	Day	4 4 1 4 3 4 5% 4 6% 7% 57%	5440
	11th to 20th	Day	3 3 1 3 2 3 4 4 5% 7% 64%	5689
	21st to end	Day	1 2 1 2 2 3 3 3 6% 7% 70%	6925
June	1st to 10th	Day	2 2 1 3 3 3 4 5% 7% 9% 61%	2800
	11th to 20th	Day	2 2 1 2 3 3 3 3 5% 6% 70%	2800
	21st to end	Day	6% 4 2 5% 4 4 5% 4 6% 8% 55%	2800
July	1st to 10th	Day	2 3 1 4 3 4 6% 5% 8% 9% 54%	4501
	11th to 20th	Day	2 2 1 4 4 5% 8% 7% 11% 13% 43%	4114
	21st to end	Day	3 4 2 6% 5% 6% 8% 8% 11% 11% 36%	4454
August	1st to 10th	Day	3 3 1 5% 5% 6% 8% 7% 11% 11% 38%	3974
	11th to 20th	Day	3 2 1 3 3 4 5% 5% 8% 11% 57%	3726
	21st to end	Day	4 4 2 6% 5% 6% 8% 5% 10% 11% 40%	4180
September	1st to 10th	Day	6% 5% 1 4 4 5% 5% 4 7% 8% 50%	2280
	11th to 20th	Day	6% 4 1 4 4 4 4 4 6% 7% 58%	2280
	21st to end	Day	3 2 1 4 3 3 3 2 5% 7% 67%	2074
October	1st to 10th	Day	4 2 1 3 2 3 2 2 3 5% 71%	3170
	11th to 20th	Day	5% 3 2 4 3 4 4 3 5% 6% 61%	3150
	21st to end	Day	4 3 1 3 1 1 2 2 3 4 76%	3438
November	1st to 10th	Day	2 4 2 3 2 2 3 2 4 8% 68%	1877
	11th to 20th	Day	3 2 1 3 2 2 3 4 4 6% 69%	1800
	21st to end	Day	5% 6% 3 4 2 3 3 2 3 6% 64%	1800
December	1st to 10th	Day	2 4 1 2 2 2 2 1 3 6% 76%	2689
	11th to 20th	Day	3 4 2 5% 3 3 3 3 4 8% 63%	3026
	21st to end	Day	3 5% 2 4 3 2 2 2 3 6% 69%	4004
January	1st to 10th	Night	1 6% 3 7% 4 4 4 3 5% 6% 56%	6037
	11th to 20th	Night	2 4 2 4 3 3 3 3 4 6% 66%	5880
	21st to end	Night	3 6% 2 7% 3 3 4 3 5% 6% 58%	6468
February	1st to 10th	Night	3 8% 3 6% 2 2 3 2 4 6% 62%	2565
	11th to 20th	Night	6% 8% 3 5% 3 3 3 2 5% 7% 56%	2338
	21st to end	Night	5% 8% 2 5% 2 2 2 3 3 5% 63%	1980
March	1st to 10th	Night	3 9% 2 5% 3 3 3 3 4 5% 61%	5167
	11th to 20th	Night	6% 9% 3 6% 3 4 3 3 4 5% 55%	5000
	21st to end	Night	4 6% 2 5% 3 3 3 2 4 6% 61%	5270
April	1st to 10th	Night	4 5% 2 4 3 3 3 3 6% 6% 61%	2000
	11th to 20th	Night	4 7% 2 4 3 3 3 3 5% 6% 60%	1977
	21st to end	Night	5% 5% 1 4 3 2 4 3 5% 5% 63%	2000
May	1st to 10th	Night	6% 5% 2 5% 5% 4 4 4 6% 6% 53%	4540
	11th to 20th	Night	3 4 1 4 4 4 4 4 6% 7% 59%	4193
	21st to end	Night	3 3 1 3 3 3 4 3 5% 7% 65%	3972
June	1st to 10th	Night	3 3 1 4 5% 4 5% 5% 6% 9% 57%	1600
	11th to 20th	Night	2 3 1 3 3 3 3 3 5% 7% 66%	1600
	21st to end	Night	5% 4 1 5% 4 4 6% 4 7% 8% 51%	1600
July	1st to 10th	Night	3 3 1 5% 5% 6% 6% 4 7% 7% 52%	2580
	11th to 20th	Night	3 4 2 6% 5% 5% 7% 6% 10% 13% 39%	2851
	21st to end	Night	7% 5% 2 6% 4 5% 7% 6% 10% 11% 38%	3109
August	1st to 10th	Night	3 4 2 8% 7% 7% 8% 6% 10% 12% 32%	2963
	11th to 20th	Night	3 3 1 6% 5% 6% 7% 6% 8% 11% 43%	3113
	21st to end	Night	3 4 2 9% 6% 7% 8% 7% 10% 11% 33%	3487
September	1st to 10th	Night	5% 3 1 5% 4 4 5% 4 8% 9% 52%	1900
	11th to 20th	Night	5% 4 1 5% 3 4 4 3 7% 7% 56%	1900
	21st to end	Night	5% 3 2 3 2 3 3 3 4 6% 66%	2103
October	1st to 10th	Night	4 3 1 3 2 2 2 2 3 4 74%	3800
	11th to 20th	Night	5% 3 1 5% 3 3 4 3 5% 5% 62%	3778
	21st to end	Night	3 2 1 2 1 1 2 2 4 4 78%	4120
November	1st to 10th	Night	3 3 1 2 2 2 3 2 4 6% 72%	2400
	11th to 20th	Night	3 2 1 3 2 2 3 2 4 5% 74%	2600
	21st to end	Night	6% 7% 2 3 3 3 3 2 4 5% 62%	2600
December	1st to 10th	Night	3 4 1 3 2 2 2 2 4 5% 74%	4496
	11th to 20th	Night	3 3 1 3 2 2 3 3 6% 8% 66%	5181
	21st to end	Night	3 7% 2 4 3 2 3 2 4 6% 65%	6974

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% 4 7% 27% 31% 6%	3958
	11th to 20th	Day	18% 4 11% 25% 22% 21%	4100
	21st to end	Day	24% 6% 8% 16% 31% 15%	4510
February	1st to 10th	Day	26% 5% 12% 20% 25% 11%	1834
	11th to 20th	Day	26% 5% 9% 23% 24% 12%	1959
	21st to end	Day	25% 3 7% 16% 31% 18%	1650
March	1st to 10th	Day	21% 2 6% 15% 33% 23%	4700
	11th to 20th	Day	27% 5% 11% 19% 27% 11%	5000
	21st to end	Day	22% 3 9% 27% 31% 7%	5695
April	1st to 10th	Day	23% 4 8% 21% 29% 15%	2400
	11th to 20th	Day	25% 5% 7% 17% 29% 17%	2374
	21st to end	Day	20% 5% 9% 22% 31% 13%	2400
May	1st to 10th	Day	26% 5% 10% 17% 26% 15%	5440
	11th to 20th	Day	18% 5% 8% 16% 32% 21%	5692
	21st to end	Day	12% 5% 11% 16% 22% 35%	6926
June	1st to 10th	Day	17% 7% 12% 21% 24% 19%	2800
	11th to 20th	Day	15% 5% 7% 15% 23% 36%	2800
	21st to end	Day	25% 6% 11% 19% 21% 18%	2800
July	1st to 10th	Day	24% 11% 12% 15% 18% 20%	4432
	11th to 20th	Day	25% 13% 19% 29% 9% 4	4044
	21st to end	Day	34% 14% 18% 24% 8% 3	4314
August	1st to 10th	Day	32% 14% 21% 17% 12% 5%	3960
	11th to 20th	Day	19% 8% 15% 28% 19% 10%	3762
	21st to end	Day	34% 12% 16% 21% 15% 2	4179
September	1st to 10th	Day	29% 9% 13% 20% 20% 9%	2280
	11th to 20th	Day	25% 8% 11% 18% 24% 15%	2280
	21st to end	Day	17% 5% 8% 22% 34% 14%	2074
October	1st to 10th	Day	18% 3 5% 16% 31% 28%	3170
	11th to 20th	Day	27% 4 6% 15% 31% 18%	3150
	21st to end	Day	14% 2 4 15% 41% 24%	3438
November	1st to 10th	Day	16% 3 7% 19% 39% 15%	1877
	11th to 20th	Day	16% 3 7% 25% 36% 12%	1800
	21st to end	Day	23% 4 6% 19% 29% 18%	1800
December	1st to 10th	Day	12% 3 6% 26% 36% 17%	2689
	11th to 20th	Day	22% 3 8% 20% 38% 9%	3024
	21st to end	Day	19% 3 8% 24% 35% 12%	4004
January	1st to 10th	Night	27% 3 8% 23% 26% 12%	6037
	11th to 20th	Night	17% 4 12% 23% 26% 17%	5880
	21st to end	Night	25% 4 9% 17% 31% 14%	6468
February	1st to 10th	Night	25% 3 11% 22% 25% 13%	2565
	11th to 20th	Night	28% 4 8% 25% 23% 13%	2338
	21st to end	Night	24% 3 6% 15% 33% 19%	1980
March	1st to 10th	Night	23% 3 7% 13% 35% 21%	5167
	11th to 20th	Night	28% 5% 7% 17% 31% 12%	5000
	21st to end	Night	21% 4 9% 28% 31% 6%	5270
April	1st to 10th	Night	23% 3 7% 22% 28% 16%	2000
	11th to 20th	Night	23% 4 8% 20% 26% 19%	1977
	21st to end	Night	21% 5% 10% 19% 33% 12%	2000
May	1st to 10th	Night	27% 6% 11% 18% 21% 17%	4537
	11th to 20th	Night	20% 6% 10% 19% 25% 20%	4194
	21st to end	Night	16% 5% 12% 14% 17% 37%	3972
June	1st to 10th	Night	22% 9% 14% 19% 19% 18%	1600
	11th to 20th	Night	16% 5% 8% 14% 22% 35%	1600
	21st to end	Night	29% 7% 13% 15% 17% 19%	1600
July	1st to 10th	Night	28% 10% 14% 15% 14% 19%	2540
	11th to 20th	Night	27% 11% 24% 28% 7% 4	2798
	21st to end	Night	33% 11% 22% 25% 9%	3011
August	1st to 10th	Night	37% 12% 20% 15% 10% 5%	2954
	11th to 20th	Night	28% 11% 19% 18% 17% 7%	3143
	21st to end	Night	38% 11% 16% 23% 10% 3	3487
September	1st to 10th	Night	25% 9% 16% 23% 19% 8%	1900
	11th to 20th	Night	24% 7% 14% 16% 24% 15%	1900
	21st to end	Night	19% 6% 9% 20% 32% 14%	2103
October	1st to 10th	Night	15% 3 6% 16% 37% 22%	3800
	11th to 20th	Night	25% 4 5% 16% 29% 21%	3778
	21st to end	Night	11% 2 5% 20% 38% 24%	4120
November	1st to 10th	Night	15% 3 6% 23% 38% 15%	2400
	11th to 20th	Night	14% 3 7% 23% 38% 15%	2600
	21st to end	Night	25% 3 7% 18% 30% 17%	2600
December	1st to 10th	Night	14% 3 6% 28% 33% 16%	4496
	11th to 20th	Night	18% 3 7% 20% 38% 14%	5182
	21st to end	Night	21% 3 9% 23% 34% 10%	6974

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	9% 21% 43% 21% 6%	300
	11th to 20th	Day	11% 22% 41% 22% 4	300
	21st to end	Day	4 19% 44% 22% 10% 1	330
February	1st to 10th	Day	5% 24% 45% 23% 4	300
	11th to 20th	Day	9% 25% 47% 17% 3	300
	21st to end	Day	12% 33% 39% 14% 3	249
March	1st to 10th	Day	9% 26% 37% 24% 4	383
	11th to 20th	Day	12% 26% 35% 22% 5% 1	500
	21st to end	Day	11% 34% 33% 19% 3	550
April	1st to 10th	Day	12% 25% 41% 19% 3 1	500
	11th to 20th	Day	13% 32% 35% 16% 4	492
	21st to end	Day	8% 30% 40% 20% 3	500
May	1st to 10th	Day	10% 21% 42% 21% 6% 1	503
	11th to 20th	Day	7% 16% 37% 29% 9% 2	592
	21st to end	Day	5% 15% 34% 35% 11% 1	789
June	1st to 10th	Day	3 7% 27% 43% 20% 1	730
	11th to 20th	Day	4 9% 28% 37% 21% 2	730
	21st to end	Day	7% 7% 21% 37% 25% 4	730
July	1st to 10th	Day	3 1 18% 38% 35% 5%	697
	11th to 20th	Day	3 1 8% 37% 39% 12%	487
	21st to end	Day	2 1 10% 34% 43% 10%	531
August	1st to 10th	Day	3 2 11% 40% 36% 8%	487
	11th to 20th	Day	4 2 19% 38% 33% 4	477
	21st to end	Day	6% 1 17% 40% 31% 5%	539
September	1st to 10th	Day	5% 2 17% 42% 28% 6%	490
	11th to 20th	Day	5% 4 28% 41% 18% 4	490
	21st to end	Day	5% 7% 28% 36% 20% 5%	314
October	1st to 10th	Day	7% 12% 25% 35% 20% 1	300
	11th to 20th	Day	9% 12% 32% 29% 16% 2	300
	21st to end	Day	10% 12% 33% 31% 12% 2	330
November	1st to 10th	Day	7% 20% 39% 26% 8%	300
	11th to 20th	Day	4 12% 42% 29% 12%	300
	21st to end	Day	8% 22% 38% 21% 10% 1	300
December	1st to 10th	Day	5% 19% 39% 26% 11%	300
	11th to 20th	Day	5% 20% 45% 24% 6%	300
	21st to end	Day	11% 26% 42% 18% 3	330
January	1st to 10th	Night	5% 9% 40% 35% 11% 1	879
	11th to 20th	Night	6% 8% 45% 31% 9% 1	800
	21st to end	Night	7% 7% 43% 33% 9% 1	880
February	1st to 10th	Night	6% 9% 46% 32% 7%	800
	11th to 20th	Night	8% 10% 49% 28% 5%	784
	21st to end	Night	10% 10% 54% 24% 2	660
March	1st to 10th	Night	7% 12% 43% 31% 7%	800
	11th to 20th	Night	7% 12% 37% 35% 10%	800
	21st to end	Night	5% 13% 44% 32% 5%	790
April	1st to 10th	Night	6% 14% 47% 29% 4	600
	11th to 20th	Night	8% 16% 40% 30% 6%	593
	21st to end	Night	6% 12% 45% 32% 5%	600
May	1st to 10th	Night	7% 9% 39% 36% 10%	600
	11th to 20th	Night	6% 8% 35% 37% 13% 1	591
	21st to end	Night	5% 10% 36% 40% 10%	650
June	1st to 10th	Night	3 4 29% 47% 17% 1	600
	11th to 20th	Night	2 4 31% 47% 15% 1	600
	21st to end	Night	5% 5% 18% 49% 24% 1	600
July	1st to 10th	Night	4 2 13% 47% 33% 1	570
	11th to 20th	Night	4 9% 38% 44% 5%	552
	21st to end	Night	5% 1 8% 33% 47% 6%	624
August	1st to 10th	Night	4 2 9% 34% 46% 7%	567
	11th to 20th	Night	5% 2 12% 44% 34% 4	564
	21st to end	Night	3 1 11% 42% 39% 5%	627
September	1st to 10th	Night	5% 1 11% 47% 32% 3	570
	11th to 20th	Night	7% 1 13% 49% 28% 2	570
	21st to end	Night	6% 3 22% 48% 20% 1	597
October	1st to 10th	Night	7% 5% 25% 45% 18% 1	760
	11th to 20th	Night	5% 5% 29% 44% 15% 2	760
	21st to end	Night	5% 6% 33% 37% 17% 3	836
November	1st to 10th	Night	4 5% 33% 41% 15% 1	840
	11th to 20th	Night	3 6% 38% 39% 13% 2	1000
	21st to end	Night	9% 7% 38% 32% 13% 2	1000
December	1st to 10th	Night	7% 8% 41% 35% 8% 1	1000
	11th to 20th	Night	9% 8% 42% 34% 8%	1000
	21st to end	Night	10% 11% 45% 30% 5%	1100

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