Fort Sumner
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Fort Sumner clear sky chart from 2005-11-06 to 2024-03-18.

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 3 1 3 3 2 3 4 5% 7% 64%	78904
	Night	5% 3 2 3 3 2 4 4 5% 7% 63%	80931
Transparency	Day	20% 5% 9% 20% 28% 18%	78626
	Night	20% 5% 9% 20% 28% 18%	80732
Seeing	Day	6% 5% 23% 33% 25% 8%	14183
	Night	6% 5% 29% 43% 16% 1	24418

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	4 10% 3 4 4 2 3 3 4 7% 58%	2611
	11th to 20th	Day	2 2 1 2 2 1 2 2 4 6% 75%	2860
	21st to end	Day	5% 6% 2 5% 4 3 4 4 6% 8% 54%	3218
February	1st to 10th	Day	3 5% 2 3 4 2 3 3 4 6% 65%	1900
	11th to 20th	Day	5% 5% 3 4 3 1 3 2 4 6% 63%	1849
	21st to end	Day	2 3 2 3 3 2 3 4 3 6% 68%	1570
March	1st to 10th	Day	4 4 1 3 3 2 4 4 5% 8% 61%	1900
	11th to 20th	Day	6% 4 2 3 3 2 4 3 5% 7% 61%	1996
	21st to end	Day	3 3 1 3 3 2 3 3 5% 8% 65%	2341
April	1st to 10th	Day	3 3 1 2 3 2 3 3 4 7% 70%	2160
	11th to 20th	Day	5% 3 2 3 3 2 3 3 4 6% 67%	2131
	21st to end	Day	4 3 1 2 2 1 2 3 4 6% 72%	2160
May	1st to 10th	Day	3 2 1 2 3 2 3 4 5% 6% 67%	2160
	11th to 20th	Day	9% 3 1 2 3 3 3 4 5% 7% 60%	2279
	21st to end	Day	5% 2 1 3 2 1 4 4 6% 8% 64%	2535
June	1st to 10th	Day	4 2 1 2 2 2 4 5% 7% 10% 62%	2520
	11th to 20th	Day	2 1 1 2 2 1 3 3 5% 7% 72%	2520
	21st to end	Day	4 3 1 3 3 2 3 4 6% 9% 63%	2520
July	1st to 10th	Day	5% 3 1 4 4 3 5% 5% 7% 10% 53%	2520
	11th to 20th	Day	3 3 1 3 3 3 4 5% 6% 9% 60%	2451
	21st to end	Day	3 2 2 3 4 3 5% 4 7% 10% 58%	2469
August	1st to 10th	Day	3 2 1 3 4 3 5% 6% 7% 11% 55%	2149
	11th to 20th	Day	6% 3 2 3 4 2 4 5% 7% 10% 54%	2123
	21st to end	Day	4 2 2 3 4 3 5% 6% 7% 10% 54%	2376
September	1st to 10th	Day	7% 3 2 4 4 3 4 4 6% 7% 56%	2160
	11th to 20th	Day	8% 3 2 3 3 2 4 4 5% 6% 58%	2086
	21st to end	Day	6% 2 1 2 3 1 2 3 4 4 70%	1980
October	1st to 10th	Day	9% 4 1 3 3 2 2 3 4 6% 63%	1940
	11th to 20th	Day	7% 2 1 2 2 1 2 2 3 4 73%	1800
	21st to end	Day	5% 3 1 2 2 2 2 2 3 4 74%	1980
November	1st to 10th	Day	4 2 1 2 2 2 2 3 3 7% 71%	1687
	11th to 20th	Day	2 3 1 3 2 1 3 3 4 6% 72%	1710
	21st to end	Day	7% 5% 2 3 3 2 3 3 3 6% 65%	1710
December	1st to 10th	Day	4 4 1 4 4 2 4 4 4 8% 63%	1710
	11th to 20th	Day	4 4 2 4 3 2 3 4 4 8% 62%	2029
	21st to end	Day	4 4 1 3 3 1 2 2 3 6% 70%	2794
January	1st to 10th	Night	2 5% 2 5% 4 3 4 4 5% 7% 60%	4371
	11th to 20th	Night	3 2 1 2 3 2 3 4 5% 7% 70%	4110
	21st to end	Night	4 4 1 3 4 3 5% 5% 5% 8% 58%	4445
February	1st to 10th	Night	3 4 2 3 3 2 3 4 4 7% 65%	2280
	11th to 20th	Night	6% 5% 2 3 3 2 4 3 4 6% 62%	2218
	21st to end	Night	4 4 2 3 3 2 3 4 4 6% 65%	1884
March	1st to 10th	Night	5% 4 2 3 3 2 3 4 4 7% 63%	2280
	11th to 20th	Night	8% 5% 2 3 3 2 3 4 4 6% 61%	2125
	21st to end	Night	4 4 2 3 3 2 3 4 4 6% 64%	2013
April	1st to 10th	Night	3 2 2 2 3 1 3 4 5% 6% 68%	1800
	11th to 20th	Night	6% 2 1 4 3 2 3 3 4 7% 65%	1777
	21st to end	Night	4 3 2 2 2 2 3 3 4 7% 68%	1800
May	1st to 10th	Night	3 2 1 3 4 2 4 4 4 6% 67%	1800
	11th to 20th	Night	7% 4 1 3 5% 2 4 4 4 6% 60%	1614
	21st to end	Night	4 2 1 2 2 2 5% 4 4 8% 65%	1736
June	1st to 10th	Night	3 2 2 3 5% 4 5% 7% 8% 10% 51%	1440
	11th to 20th	Night	2 2 1 2 3 3 3 4 5% 8% 67%	1440
	21st to end	Night	3 3 1 3 4 3 5% 5% 7% 10% 58%	1440
July	1st to 10th	Night	4 3 2 3 4 3 5% 6% 7% 11% 53%	1440
	11th to 20th	Night	3 2 2 3 5% 3 5% 6% 7% 12% 52%	1503
	21st to end	Night	3 3 2 4 5% 3 6% 6% 9% 11% 49%	1847
August	1st to 10th	Night	4 3 2 4 5% 4 5% 6% 8% 12% 46%	1790
	11th to 20th	Night	6% 3 1 4 4 3 6% 6% 8% 12% 48%	1778
	21st to end	Night	4 3 1 3 5% 3 5% 6% 8% 12% 51%	1980
September	1st to 10th	Night	5% 3 2 5% 4 3 5% 4 6% 9% 53%	1800
	11th to 20th	Night	9% 4 2 4 3 2 3 3 5% 7% 58%	1872
	21st to end	Night	7% 2 1 2 2 1 2 3 4 6% 68%	1980
October	1st to 10th	Night	9% 3 2 3 4 1 3 4 4 5% 63%	2016
	11th to 20th	Night	7% 2 1 2 2 1 1 2 2 4 75%	2160
	21st to end	Night	6% 3 1 2 2 2 2 3 3 5% 71%	2376
November	1st to 10th	Night	4 2 1 2 2 1 3 2 3 5% 74%	2370
	11th to 20th	Night	2 3 1 2 2 2 3 3 4 6% 73%	2470
	21st to end	Night	7% 3 1 3 3 1 3 3 4 5% 66%	2470
December	1st to 10th	Night	5% 3 2 3 3 2 3 3 4 7% 64%	2470
	11th to 20th	Night	4 4 2 4 4 2 4 4 4 8% 62%	3163
	21st to end	Night	4 4 2 4 3 2 3 3 4 6% 65%	4873

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% 4 7% 19% 35% 9%	2612
	11th to 20th	Day	11% 3 9% 28% 37% 11%	2860
	21st to end	Day	27% 6% 9% 17% 30% 11%	3218
February	1st to 10th	Day	21% 3 7% 20% 29% 20%	1900
	11th to 20th	Day	25% 3 5% 19% 29% 20%	1859
	21st to end	Day	17% 3 4 14% 35% 26%	1570
March	1st to 10th	Day	22% 3 6% 18% 29% 22%	1900
	11th to 20th	Day	22% 4 6% 19% 29% 20%	1996
	21st to end	Day	18% 3 7% 18% 30% 23%	2341
April	1st to 10th	Day	16% 4 7% 14% 32% 27%	2160
	11th to 20th	Day	19% 4 6% 16% 28% 27%	2134
	21st to end	Day	14% 3 6% 20% 33% 23%	2160
May	1st to 10th	Day	17% 4 8% 18% 25% 29%	2160
	11th to 20th	Day	24% 6% 9% 18% 24% 19%	2283
	21st to end	Day	18% 6% 9% 19% 21% 28%	2535
June	1st to 10th	Day	15% 6% 13% 25% 20% 19%	2520
	11th to 20th	Day	12% 4 7% 17% 25% 35%	2520
	21st to end	Day	18% 6% 11% 20% 24% 20%	2520
July	1st to 10th	Day	24% 8% 17% 18% 19% 14%	2451
	11th to 20th	Day	18% 7% 14% 27% 24% 10%	2376
	21st to end	Day	18% 8% 22% 28% 20% 3	2332
August	1st to 10th	Day	20% 8% 17% 30% 19% 6%	2136
	11th to 20th	Day	23% 8% 17% 24% 20% 8%	2123
	21st to end	Day	23% 8% 15% 25% 21% 8%	2376
September	1st to 10th	Day	27% 6% 13% 20% 21% 14%	2160
	11th to 20th	Day	26% 5% 9% 20% 26% 15%	2086
	21st to end	Day	17% 4 6% 20% 33% 19%	1980
October	1st to 10th	Day	23% 4 9% 19% 25% 19%	1940
	11th to 20th	Day	17% 3 5% 11% 35% 28%	1800
	21st to end	Day	16% 3 5% 21% 34% 22%	1980
November	1st to 10th	Day	14% 3 6% 19% 34% 24%	1687
	11th to 20th	Day	15% 4 5% 23% 34% 20%	1710
	21st to end	Day	22% 3 4 17% 31% 23%	1710
December	1st to 10th	Day	21% 3 8% 25% 31% 12%	1710
	11th to 20th	Day	22% 5% 7% 22% 27% 17%	2027
	21st to end	Day	18% 2 5% 22% 32% 20%	2794
January	1st to 10th	Night	22% 5% 8% 23% 34% 8%	4371
	11th to 20th	Night	14% 4 11% 23% 36% 11%	4110
	21st to end	Night	20% 7% 9% 22% 31% 11%	4445
February	1st to 10th	Night	20% 4 7% 19% 28% 23%	2280
	11th to 20th	Night	23% 4 6% 19% 24% 23%	2218
	21st to end	Night	20% 2 5% 13% 31% 29%	1884
March	1st to 10th	Night	21% 4 6% 16% 27% 25%	2280
	11th to 20th	Night	25% 4 6% 17% 29% 20%	2125
	21st to end	Night	20% 4 8% 19% 25% 24%	2013
April	1st to 10th	Night	16% 4 7% 15% 30% 28%	1800
	11th to 20th	Night	20% 4 8% 16% 24% 28%	1777
	21st to end	Night	17% 4 8% 19% 26% 25%	1800
May	1st to 10th	Night	19% 4 9% 15% 21% 32%	1800
	11th to 20th	Night	25% 6% 9% 18% 21% 22%	1615
	21st to end	Night	17% 6% 10% 19% 14% 32%	1737
June	1st to 10th	Night	24% 9% 12% 19% 18% 18%	1440
	11th to 20th	Night	15% 4 11% 15% 19% 36%	1440
	21st to end	Night	20% 7% 15% 20% 22% 17%	1440
July	1st to 10th	Night	22% 9% 19% 24% 18% 8%	1400
	11th to 20th	Night	22% 9% 15% 25% 20% 9%	1455
	21st to end	Night	24% 12% 19% 25% 17% 3	1744
August	1st to 10th	Night	26% 10% 16% 27% 16% 5%	1779
	11th to 20th	Night	25% 11% 16% 25% 15% 8%	1778
	21st to end	Night	23% 9% 19% 24% 18% 8%	1980
September	1st to 10th	Night	26% 7% 14% 20% 19% 13%	1800
	11th to 20th	Night	26% 6% 13% 19% 21% 16%	1872
	21st to end	Night	18% 3 8% 21% 30% 20%	1980
October	1st to 10th	Night	23% 5% 7% 17% 27% 20%	2016
	11th to 20th	Night	16% 3 5% 11% 35% 30%	2160
	21st to end	Night	17% 3 6% 17% 34% 23%	2376
November	1st to 10th	Night	14% 2 5% 16% 35% 27%	2370
	11th to 20th	Night	13% 2 5% 21% 37% 21%	2470
	21st to end	Night	22% 2 6% 17% 33% 20%	2470
December	1st to 10th	Night	21% 4 8% 24% 28% 16%	2470
	11th to 20th	Night	22% 4 7% 19% 35% 14%	3164
	21st to end	Night	20% 3 7% 19% 34% 16%	4873

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	8% 7% 33% 37% 13% 3	270
	11th to 20th	Day	8% 9% 34% 36% 11% 2	270
	21st to end	Day	5% 7% 30% 40% 16% 3	297
February	1st to 10th	Day	6% 10% 34% 36% 14%	270
	11th to 20th	Day	8% 8% 41% 31% 11% 1	270
	21st to end	Day	6% 11% 44% 33% 5% 1	225
March	1st to 10th	Day	3 10% 40% 31% 16% 1	270
	11th to 20th	Day	13% 12% 32% 30% 9% 4	387
	21st to end	Day	6% 18% 39% 24% 13% 1	462
April	1st to 10th	Day	5% 11% 37% 33% 12% 2	420
	11th to 20th	Day	8% 12% 42% 25% 10% 2	412
	21st to end	Day	7% 9% 41% 30% 12% 1	420
May	1st to 10th	Day	3 7% 37% 36% 14% 3	423
	11th to 20th	Day	8% 7% 23% 35% 23% 4	602
	21st to end	Day	6% 6% 26% 40% 20% 2	679
June	1st to 10th	Day	4 2 16% 41% 30% 8%	630
	11th to 20th	Day	1 1 21% 42% 28% 6%	630
	21st to end	Day	4 2 13% 38% 36% 6%	630
July	1st to 10th	Day	5% 1 7% 29% 42% 16%	621
	11th to 20th	Day	3 4 26% 45% 23%	549
	21st to end	Day	2 3 25% 40% 29%	487
August	1st to 10th	Day	2 1 5% 27% 43% 23%	447
	11th to 20th	Day	5% 1 6% 26% 40% 22%	437
	21st to end	Day	4 1 6% 28% 47% 15%	495
September	1st to 10th	Day	6% 1 8% 32% 39% 14%	450
	11th to 20th	Day	6% 1 9% 33% 40% 12%	376
	21st to end	Day	9% 1 13% 29% 39% 9%	270
October	1st to 10th	Day	14% 2 19% 25% 32% 8%	270
	11th to 20th	Day	8% 3 19% 39% 24% 7%	270
	21st to end	Day	9% 4 20% 33% 26% 7%	297
November	1st to 10th	Day	9% 6% 31% 27% 23% 4	270
	11th to 20th	Day	2 6% 27% 40% 18% 7%	270
	21st to end	Day	12% 11% 28% 30% 17% 3	270
December	1st to 10th	Day	6% 10% 29% 38% 15% 3	270
	11th to 20th	Day	5% 7% 31% 43% 12% 1	270
	21st to end	Day	8% 10% 38% 33% 9% 2	297
January	1st to 10th	Night	4 6% 34% 44% 12%	917
	11th to 20th	Night	5% 4 40% 41% 9% 1	760
	21st to end	Night	6% 5% 34% 46% 9%	836
February	1st to 10th	Night	6% 7% 41% 39% 7%	760
	11th to 20th	Night	8% 7% 39% 41% 5%	744
	21st to end	Night	7% 8% 47% 36% 1	628
March	1st to 10th	Night	7% 6% 39% 43% 5%	760
	11th to 20th	Night	10% 11% 33% 37% 9%	752
	21st to end	Night	5% 9% 44% 36% 6%	627
April	1st to 10th	Night	3 7% 47% 39% 4	540
	11th to 20th	Night	7% 9% 47% 33% 4	533
	21st to end	Night	4 10% 46% 34% 6%	540
May	1st to 10th	Night	3 6% 42% 43% 6%	540
	11th to 20th	Night	7% 6% 30% 44% 13%	531
	21st to end	Night	5% 4 33% 49% 9%	584
June	1st to 10th	Night	3 4 29% 51% 13%	540
	11th to 20th	Night	2 2 31% 54% 11%	540
	21st to end	Night	4 2 24% 50% 20%	540
July	1st to 10th	Night	6% 1 11% 44% 37% 2	525
	11th to 20th	Night	3 1 6% 46% 43% 1	522
	21st to end	Night	3 2 6% 41% 46% 2	591
August	1st to 10th	Night	5% 8% 37% 47% 3	537
	11th to 20th	Night	5% 1 8% 42% 42% 2	534
	21st to end	Night	5% 1 7% 43% 43% 2	594
September	1st to 10th	Night	6% 1 9% 53% 30% 1	540
	11th to 20th	Night	10% 2 13% 53% 22% 1	540
	21st to end	Night	7% 3 17% 50% 23% 1	540
October	1st to 10th	Night	8% 3 23% 47% 19% 1	576
	11th to 20th	Night	8% 3 27% 46% 16% 1	720
	21st to end	Night	7% 4 22% 42% 23% 1	792
November	1st to 10th	Night	5% 3 24% 50% 18%	890
	11th to 20th	Night	3 5% 31% 43% 17% 1	950
	21st to end	Night	9% 4 29% 43% 14% 1	950
December	1st to 10th	Night	7% 6% 34% 44% 9%	950
	11th to 20th	Night	5% 6% 35% 45% 9%	950
	21st to end	Night	8% 7% 39% 39% 7%	1045

Page generated at 2024-03-15 12:01:43. Version ac07

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