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 2024-11-03.

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% 3 1 3 3 3 3 3 5% 7% 64%	100793
	Night	5% 3 1 4 3 3 4 3 5% 7% 62%	98415
Transparency	Day	19% 5% 9% 20% 28% 19%	100551
	Night	21% 5% 9% 19% 27% 19%	98247
Seeing	Day	6% 6% 22% 33% 25% 8%	15120
	Night	6% 5% 29% 43% 16% 1	25136

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 5% 3 2 3 2 4 7% 58%	2611
	11th to 20th	Day	2 2 1 2 2 2 2 2 4 6% 75%	2860
	21st to end	Day	5% 6% 2 6% 4 4 4 3 6% 8% 54%	3218
February	1st to 10th	Day	3 5% 2 4 4 3 3 2 4 6% 65%	1900
	11th to 20th	Day	5% 6% 2 5% 2 2 3 2 3 6% 63%	1849
	21st to end	Day	2 3 2 4 3 2 3 3 3 6% 68%	1570
March	1st to 10th	Day	3 4 1 3 3 3 3 2 5% 6% 68%	3130
	11th to 20th	Day	14% 4 1 3 3 3 3 3 5% 7% 55%	3389
	21st to end	Day	3 4 2 5% 3 4 4 3 5% 8% 59%	4117
April	1st to 10th	Day	3 3 1 2 3 3 3 3 4 7% 69%	2280
	11th to 20th	Day	5% 3 2 3 2 2 2 2 4 6% 68%	2251
	21st to end	Day	3 3 1 2 2 2 2 3 4 6% 73%	2280
May	1st to 10th	Day	3 2 1 2 2 2 3 4 5% 5% 71%	3800
	11th to 20th	Day	10% 3 1 3 3 3 3 3 5% 7% 61%	4045
	21st to end	Day	4 2 1 2 2 1 2 2 4 5% 74%	4506
June	1st to 10th	Day	4 2 1 3 2 3 4 4 7% 10% 61%	2660
	11th to 20th	Day	2 2 1 2 2 2 2 3 5% 7% 72%	2660
	21st to end	Day	4 3 1 3 3 3 3 4 6% 9% 61%	2660
July	1st to 10th	Day	6% 4 2 4 4 4 4 4 7% 10% 52%	4430
	11th to 20th	Day	2 2 1 3 2 3 3 3 6% 9% 65%	4305
	21st to end	Day	5% 3 1 3 3 3 4 4 6% 10% 58%	4316
August	1st to 10th	Day	2 2 1 2 2 3 3 4 6% 10% 66%	3784
	11th to 20th	Day	3 2 1 2 2 2 4 3 5% 8% 68%	3726
	21st to end	Day	3 2 1 4 3 4 5% 5% 7% 11% 54%	4180
September	1st to 10th	Day	6% 4 1 5% 4 4 4 3 6% 7% 56%	2280
	11th to 20th	Day	8% 3 2 3 3 3 4 3 5% 6% 59%	2201
	21st to end	Day	6% 3 1 3 2 2 2 3 4 4 70%	2090
October	1st to 10th	Day	8% 3 1 4 2 3 2 3 4 5% 64%	2047
	11th to 20th	Day	7% 2 1 3 2 2 2 2 3 4 72%	1900
	21st to end	Day	5% 3 1 2 2 2 2 2 3 5% 74%	2090
November	1st to 10th	Day	4 2 1 3 2 2 3 2 3 7% 71%	1705
	11th to 20th	Day	2 3 1 3 2 2 3 2 4 6% 72%	1710
	21st to end	Day	7% 5% 1 3 2 2 2 2 4 5% 65%	1710
December	1st to 10th	Day	4 4 1 4 3 3 3 3 4 8% 63%	1710
	11th to 20th	Day	3 4 1 5% 3 3 3 3 4 8% 61%	2029
	21st to end	Day	4 5% 1 3 2 2 2 2 3 6% 70%	2794
January	1st to 10th	Night	2 5% 2 5% 4 4 4 3 5% 6% 60%	4371
	11th to 20th	Night	2 3 1 3 3 2 3 3 5% 7% 70%	4110
	21st to end	Night	4 4 1 4 3 3 5% 4 5% 8% 58%	4445
February	1st to 10th	Night	3 5% 1 4 2 3 3 3 4 7% 65%	2280
	11th to 20th	Night	5% 6% 2 4 3 3 3 3 5% 6% 62%	2218
	21st to end	Night	4 5% 1 4 2 2 2 3 4 6% 65%	1884
March	1st to 10th	Night	4 4 1 3 2 2 3 2 3 5% 71%	3734
	11th to 20th	Night	13% 6% 1 4 3 2 3 2 4 6% 56%	3583
	21st to end	Night	2 4 2 5% 3 3 3 3 5% 7% 62%	3524
April	1st to 10th	Night	3 3 1 3 3 2 3 4 5% 6% 68%	1900
	11th to 20th	Night	6% 3 1 4 3 2 2 3 4 7% 66%	1877
	21st to end	Night	4 3 1 2 2 3 3 3 4 6% 69%	1900
May	1st to 10th	Night	6% 2 1 3 3 3 2 2 3 5% 70%	3170
	11th to 20th	Night	10% 3 1 4 4 3 3 3 4 6% 59%	2858
	21st to end	Night	3 2 1 2 2 2 3 3 3 6% 74%	3076
June	1st to 10th	Night	3 3 2 4 5% 5% 5% 5% 8% 9% 51%	1520
	11th to 20th	Night	2 2 1 2 3 3 3 3 5% 8% 67%	1520
	21st to end	Night	3 3 1 3 3 4 4 5% 7% 10% 55%	1520
July	1st to 10th	Night	4 3 1 6% 4 4 6% 5% 8% 11% 49%	2540
	11th to 20th	Night	4 3 1 5% 4 4 5% 4 9% 10% 50%	2659
	21st to end	Night	6% 4 2 5% 4 3 6% 5% 10% 12% 44%	3245
August	1st to 10th	Night	3 3 2 5% 4 6% 6% 6% 8% 11% 46%	3155
	11th to 20th	Night	3 2 1 3 3 4 5% 4 7% 12% 56%	3113
	21st to end	Night	3 3 1 6% 6% 5% 7% 5% 10% 11% 42%	3487
September	1st to 10th	Night	5% 4 1 5% 4 4 5% 3 6% 8% 53%	1900
	11th to 20th	Night	8% 4 1 4 3 3 3 2 5% 7% 60%	1977
	21st to end	Night	7% 3 1 2 2 2 3 2 4 6% 68%	2090
October	1st to 10th	Night	8% 3 2 3 3 2 3 3 4 4 65%	2129
	11th to 20th	Night	7% 2 1 2 2 2 2 2 2 4 73%	2280
	21st to end	Night	6% 3 1 3 2 2 2 2 3 5% 71%	2508
November	1st to 10th	Night	4 2 1 2 2 2 2 2 4 5% 74%	2396
	11th to 20th	Night	2 3 1 2 2 3 3 2 5% 6% 73%	2470
	21st to end	Night	7% 4 1 4 2 2 3 2 4 5% 66%	2470
December	1st to 10th	Night	5% 3 2 4 2 3 3 3 4 7% 64%	2470
	11th to 20th	Night	4 4 1 4 3 4 3 3 4 7% 61%	3163
	21st to end	Night	4 4 2 4 3 3 3 2 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	16% 4 5% 13% 33% 29%	3130
	11th to 20th	Day	27% 5% 7% 21% 26% 14%	3389
	21st to end	Day	20% 5% 7% 17% 29% 22%	4117
April	1st to 10th	Day	16% 3 7% 14% 32% 28%	2280
	11th to 20th	Day	18% 4 6% 16% 27% 29%	2254
	21st to end	Day	13% 3 6% 20% 33% 24%	2280
May	1st to 10th	Day	13% 4 7% 18% 21% 36%	3800
	11th to 20th	Day	22% 6% 8% 17% 25% 22%	4049
	21st to end	Day	13% 4 6% 15% 19% 44%	4506
June	1st to 10th	Day	16% 7% 13% 25% 21% 19%	2660
	11th to 20th	Day	12% 4 7% 17% 25% 35%	2660
	21st to end	Day	19% 6% 12% 22% 23% 19%	2660
July	1st to 10th	Day	27% 6% 16% 19% 19% 13%	4361
	11th to 20th	Day	15% 6% 16% 28% 28% 7%	4230
	21st to end	Day	20% 6% 15% 28% 27% 3	4179
August	1st to 10th	Day	13% 6% 14% 31% 23% 13%	3772
	11th to 20th	Day	14% 5% 11% 24% 31% 14%	3762
	21st to end	Day	22% 7% 18% 25% 23% 5%	4179
September	1st to 10th	Day	27% 6% 12% 20% 22% 14%	2280
	11th to 20th	Day	25% 5% 8% 19% 27% 15%	2201
	21st to end	Day	17% 4 6% 19% 33% 20%	2090
October	1st to 10th	Day	22% 4 8% 19% 26% 21%	2047
	11th to 20th	Day	18% 3 6% 12% 34% 28%	1900
	21st to end	Day	15% 2 4 21% 34% 23%	2090
November	1st to 10th	Day	14% 3 6% 19% 34% 23%	1705
	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	16% 3 5% 14% 30% 33%	3734
	11th to 20th	Night	30% 5% 7% 18% 25% 15%	3583
	21st to end	Night	18% 6% 8% 17% 28% 23%	3524
April	1st to 10th	Night	16% 4 7% 14% 29% 29%	1900
	11th to 20th	Night	19% 4 8% 16% 23% 30%	1877
	21st to end	Night	17% 4 8% 20% 27% 25%	1900
May	1st to 10th	Night	16% 4 8% 13% 16% 43%	3170
	11th to 20th	Night	23% 9% 10% 17% 19% 23%	2859
	21st to end	Night	11% 5% 8% 16% 12% 49%	3077
June	1st to 10th	Night	24% 9% 12% 19% 18% 18%	1520
	11th to 20th	Night	15% 4 11% 15% 19% 37%	1520
	21st to end	Night	21% 7% 15% 20% 21% 16%	1520
July	1st to 10th	Night	27% 8% 17% 24% 19% 7%	2500
	11th to 20th	Night	26% 7% 14% 21% 27% 6%	2611
	21st to end	Night	28% 8% 14% 27% 22% 2	3143
August	1st to 10th	Night	27% 8% 13% 23% 17% 12%	3144
	11th to 20th	Night	19% 8% 11% 23% 30% 9%	3143
	21st to end	Night	30% 9% 18% 19% 19% 5%	3487
September	1st to 10th	Night	26% 7% 13% 20% 21% 13%	1900
	11th to 20th	Night	25% 5% 13% 19% 22% 17%	1977
	21st to end	Night	18% 3 8% 20% 30% 21%	2090
October	1st to 10th	Night	22% 5% 7% 17% 27% 22%	2129
	11th to 20th	Night	17% 3 5% 11% 34% 29%	2280
	21st to end	Night	17% 3 6% 17% 34% 23%	2508
November	1st to 10th	Night	14% 2 5% 16% 35% 27%	2396
	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	12% 12% 32% 31% 9% 4	398
	21st to end	Day	6% 17% 39% 25% 12% 1	506
April	1st to 10th	Day	6% 13% 36% 32% 11% 2	460
	11th to 20th	Day	8% 12% 43% 25% 10% 2	452
	21st to end	Day	6% 9% 40% 31% 12% 1	460
May	1st to 10th	Day	3 8% 36% 36% 14% 3	463
	11th to 20th	Day	8% 7% 24% 34% 24% 4	651
	21st to end	Day	6% 6% 27% 40% 19% 2	734
June	1st to 10th	Day	4 3 16% 40% 30% 8%	680
	11th to 20th	Day	1 1 22% 42% 28% 5%	680
	21st to end	Day	5% 2 13% 38% 36% 6%	680
July	1st to 10th	Day	5% 1 7% 30% 41% 15%	671
	11th to 20th	Day	2 4 27% 45% 22%	595
	21st to end	Day	2 1 4 25% 41% 28%	531
August	1st to 10th	Day	2 1 5% 28% 42% 22%	487
	11th to 20th	Day	4 1 6% 27% 41% 21%	477
	21st to end	Day	4 1 6% 29% 45% 15%	539
September	1st to 10th	Day	6% 1 8% 32% 39% 14%	490
	11th to 20th	Day	6% 1 10% 33% 38% 11%	411
	21st to end	Day	10% 1 12% 30% 38% 9%	300
October	1st to 10th	Day	12% 2 18% 25% 34% 9%	300
	11th to 20th	Day	8% 4 19% 36% 26% 7%	300
	21st to end	Day	9% 5% 19% 32% 27% 7%	330
November	1st to 10th	Day	8% 5% 31% 28% 23% 4	276
	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	9% 11% 33% 38% 9%	760
	21st to end	Night	5% 9% 44% 36% 5%	661
April	1st to 10th	Night	3 8% 46% 39% 4	570
	11th to 20th	Night	7% 10% 47% 33% 3	563
	21st to end	Night	4 10% 46% 34% 6%	570
May	1st to 10th	Night	3 6% 42% 43% 6%	570
	11th to 20th	Night	7% 6% 30% 43% 13%	561
	21st to end	Night	5% 5% 34% 48% 9%	617
June	1st to 10th	Night	3 4 28% 51% 13%	570
	11th to 20th	Night	2 2 32% 52% 11%	570
	21st to end	Night	4 2 23% 50% 20%	570
July	1st to 10th	Night	6% 1 12% 44% 36% 2	555
	11th to 20th	Night	3 1 6% 47% 42% 1	552
	21st to end	Night	3 2 6% 43% 44% 2	624
August	1st to 10th	Night	5% 1 8% 38% 46% 2	567
	11th to 20th	Night	5% 1 8% 43% 41% 2	564
	21st to end	Night	5% 1 7% 42% 43% 1	627
September	1st to 10th	Night	6% 1 9% 53% 29% 1	570
	11th to 20th	Night	9% 2 14% 54% 21% 1	570
	21st to end	Night	7% 3 17% 50% 22% 1	570
October	1st to 10th	Night	8% 2 22% 47% 20% 1	609
	11th to 20th	Night	8% 3 26% 46% 17% 1	760
	21st to end	Night	7% 5% 23% 42% 23% 1	836
November	1st to 10th	Night	5% 3 24% 50% 18%	900
	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 2024-10-31 01:39:27. Version ac07

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