South Nation Space Station
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the South Nation Space Station clear sky chart from 2005-11-06 to 2024-11-28.

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	17% 9% 3 8% 5% 5% 5% 4 5% 7% 32%	101748
	Night	18% 11% 4 8% 5% 4 4 3 5% 6% 32%	97799
Transparency	Day	50% 7% 12% 20% 10% 1	105218
	Night	52% 6% 12% 19% 10% 1	102418
Seeing	Day	22% 13% 28% 22% 11% 3	14554
	Night	23% 8% 28% 29% 11% 1	23613

By Month

Percentage Cloud Cover NE (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	17% 17% 6% 14% 6% 5% 4 3 4 4 20%	2517
	11th to 20th	Day	15% 12% 6% 14% 5% 5% 4 4 6% 5% 23%	2520
	21st to end	Day	14% 18% 6% 11% 6% 6% 5% 4 5% 5% 18%	2813
February	1st to 10th	Day	13% 16% 5% 12% 7% 4 4 4 4 5% 26%	1710
	11th to 20th	Day	13% 17% 4 11% 6% 5% 4 4 4 5% 27%	1696
	21st to end	Day	19% 13% 4 10% 6% 5% 5% 4 5% 5% 25%	1570
March	1st to 10th	Day	19% 14% 3 10% 6% 5% 4 3 5% 5% 26%	3116
	11th to 20th	Day	13% 15% 5% 11% 6% 5% 5% 3 5% 6% 27%	3410
	21st to end	Day	15% 8% 2 7% 6% 4 5% 3 4 6% 40%	4070
April	1st to 10th	Day	21% 12% 3 8% 4 4 4 3 4 5% 33%	2280
	11th to 20th	Day	21% 9% 3 6% 5% 4 4 3 5% 6% 35%	2254
	21st to end	Day	22% 10% 4 8% 6% 4 4 4 4 5% 31%	2415
May	1st to 10th	Day	20% 8% 3 8% 5% 5% 5% 4 6% 7% 29%	4426
	11th to 20th	Day	18% 8% 3 8% 5% 4 5% 3 5% 7% 33%	4398
	21st to end	Day	16% 7% 3 7% 4 5% 4 4 6% 8% 37%	4837
June	1st to 10th	Day	21% 8% 3 7% 5% 5% 5% 4 6% 7% 30%	2660
	11th to 20th	Day	13% 7% 2 6% 5% 5% 5% 5% 7% 8% 37%	2660
	21st to end	Day	20% 7% 2 7% 5% 5% 5% 5% 7% 7% 30%	2660
July	1st to 10th	Day	12% 6% 3 7% 6% 5% 6% 5% 6% 9% 35%	4440
	11th to 20th	Day	14% 6% 2 7% 5% 5% 5% 4 7% 8% 38%	4440
	21st to end	Day	11% 5% 2 5% 4 4 4 4 6% 9% 45%	4814
August	1st to 10th	Day	14% 6% 2 8% 5% 5% 6% 5% 6% 9% 35%	4423
	11th to 20th	Day	15% 6% 3 6% 4 4 5% 4 6% 9% 38%	3962
	21st to end	Day	15% 4 2 6% 5% 4 5% 4 7% 8% 39%	4180
September	1st to 10th	Day	14% 5% 2 6% 4 5% 5% 3 6% 7% 42%	2280
	11th to 20th	Day	13% 4 2 5% 3 4 4 4 5% 7% 49%	2253
	21st to end	Day	18% 6% 2 5% 4 4 4 4 5% 7% 41%	2069
October	1st to 10th	Day	21% 8% 3 6% 4 4 4 3 5% 7% 35%	1900
	11th to 20th	Day	22% 11% 3 8% 4 5% 4 4 5% 5% 30%	1900
	21st to end	Day	24% 9% 4 9% 5% 4 4 3 5% 5% 28%	1900
November	1st to 10th	Day	16% 9% 3 6% 6% 4 5% 4 5% 7% 35%	1761
	11th to 20th	Day	19% 12% 4 8% 5% 5% 5% 4 4 6% 29%	1640
	21st to end	Day	23% 13% 5% 9% 5% 5% 5% 3 4 6% 21%	1576
December	1st to 10th	Day	22% 16% 5% 10% 6% 5% 4 4 4 5% 18%	1520
	11th to 20th	Day	21% 15% 5% 9% 6% 4 4 3 4 5% 25%	1906
	21st to end	Day	27% 21% 5% 9% 4 3 3 2 3 3 20%	2772
January	1st to 10th	Night	18% 18% 6% 11% 5% 4 4 2 5% 5% 22%	4429
	11th to 20th	Night	13% 15% 6% 12% 7% 5% 6% 4 5% 5% 22%	4440
	21st to end	Night	16% 20% 7% 11% 5% 5% 4 3 4 4 22%	4842
February	1st to 10th	Night	14% 14% 6% 12% 6% 5% 6% 4 5% 6% 24%	2470
	11th to 20th	Night	13% 13% 4 12% 6% 5% 4 4 5% 5% 29%	2368
	21st to end	Night	16% 14% 4 10% 6% 5% 4 3 5% 6% 29%	1884
March	1st to 10th	Night	21% 12% 4 8% 5% 4 4 3 4 5% 30%	3724
	11th to 20th	Night	17% 17% 4 9% 5% 5% 4 3 4 6% 27%	3548
	21st to end	Night	15% 11% 3 8% 5% 4 4 3 4 5% 38%	3562
April	1st to 10th	Night	22% 11% 3 7% 5% 4 4 3 4 6% 32%	1900
	11th to 20th	Night	19% 9% 3 7% 5% 4 4 4 5% 6% 35%	1875
	21st to end	Night	21% 9% 3 7% 4 3 4 3 5% 5% 35%	1782
May	1st to 10th	Night	20% 8% 4 8% 5% 4 5% 4 6% 6% 30%	2514
	11th to 20th	Night	21% 8% 3 6% 4 4 4 4 5% 6% 36%	2495
	21st to end	Night	15% 7% 2 7% 5% 4 5% 4 6% 7% 37%	2738
June	1st to 10th	Night	16% 7% 2 7% 5% 5% 5% 4 7% 10% 32%	1520
	11th to 20th	Night	14% 7% 3 6% 4 4 4 5% 6% 6% 41%	1520
	21st to end	Night	18% 8% 2 7% 4 4 5% 4 6% 7% 35%	1520
July	1st to 10th	Night	13% 7% 3 8% 5% 5% 6% 4 7% 7% 34%	2520
	11th to 20th	Night	14% 6% 3 6% 4 4 4 3 6% 8% 42%	2520
	21st to end	Night	11% 6% 2 5% 5% 4 6% 4 6% 7% 44%	2739
August	1st to 10th	Night	13% 7% 3 8% 4 5% 5% 5% 6% 8% 37%	2506
	11th to 20th	Night	16% 7% 3 5% 4 4 4 4 5% 6% 42%	2830
	21st to end	Night	14% 5% 2 7% 4 5% 4 4 6% 7% 41%	3476
September	1st to 10th	Night	11% 6% 2 6% 5% 5% 4 4 5% 7% 45%	1900
	11th to 20th	Night	14% 6% 2 5% 3 3 4 4 5% 6% 49%	1926
	21st to end	Night	17% 6% 2 5% 4 5% 3 3 4 7% 44%	2108
October	1st to 10th	Night	18% 7% 3 7% 4 4 4 3 5% 6% 39%	2280
	11th to 20th	Night	20% 9% 3 7% 6% 5% 4 4 4 5% 33%	2280
	21st to end	Night	22% 10% 3 9% 5% 5% 4 3 4 6% 30%	2698
November	1st to 10th	Night	20% 10% 3 7% 5% 4 4 4 6% 6% 33%	2537
	11th to 20th	Night	18% 11% 4 8% 6% 5% 5% 4 4 5% 31%	2757
	21st to end	Night	21% 14% 4 9% 5% 5% 4 3 5% 6% 23%	2759
December	1st to 10th	Night	21% 16% 6% 10% 6% 5% 5% 3 4 4 19%	2660
	11th to 20th	Night	23% 15% 4 9% 5% 4 4 3 4 4 26%	3288
	21st to end	Night	30% 19% 4 9% 4 3 3 3 3 3 19%	4884

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	67% 8% 8% 11% 5% 1	2518
	11th to 20th	Day	61% 6% 12% 13% 6% 1	2520
	21st to end	Day	66% 8% 10% 10% 5%	2813
February	1st to 10th	Day	61% 5% 9% 18% 6% 2	1710
	11th to 20th	Day	59% 5% 11% 15% 9% 1	1705
	21st to end	Day	60% 5% 9% 13% 10% 1	1570
March	1st to 10th	Day	60% 5% 8% 16% 9% 1	3119
	11th to 20th	Day	58% 6% 13% 12% 10% 2	3410
	21st to end	Day	45% 5% 8% 21% 18% 3	4070
April	1st to 10th	Day	55% 4 9% 18% 12% 3	2280
	11th to 20th	Day	51% 5% 8% 20% 15% 2	2254
	21st to end	Day	55% 6% 8% 14% 13% 4	2415
May	1st to 10th	Day	52% 6% 9% 21% 10% 2	4440
	11th to 20th	Day	47% 10% 14% 18% 10% 2	4402
	21st to end	Day	44% 8% 11% 22% 14% 1	4837
June	1st to 10th	Day	53% 7% 11% 18% 11% 1	2660
	11th to 20th	Day	42% 8% 13% 22% 13% 2	2660
	21st to end	Day	49% 9% 12% 19% 10% 1	2660
July	1st to 10th	Day	44% 7% 14% 24% 11%	4370
	11th to 20th	Day	42% 7% 15% 28% 8%	4365
	21st to end	Day	35% 7% 14% 32% 11%	4661
August	1st to 10th	Day	46% 7% 16% 22% 9%	4409
	11th to 20th	Day	41% 7% 16% 28% 7%	4001
	21st to end	Day	41% 7% 17% 22% 12% 1	4180
September	1st to 10th	Day	39% 7% 14% 27% 13%	2280
	11th to 20th	Day	35% 7% 14% 30% 13% 1	2253
	21st to end	Day	42% 7% 14% 26% 10%	2069
October	1st to 10th	Day	49% 6% 10% 28% 8%	3160
	11th to 20th	Day	48% 7% 13% 25% 7%	3140
	21st to end	Day	48% 5% 20% 20% 6%	3112
November	1st to 10th	Day	49% 6% 13% 23% 7% 1	1761
	11th to 20th	Day	58% 4 12% 15% 10% 1	1640
	21st to end	Day	64% 6% 12% 12% 6% 1	1576
December	1st to 10th	Day	68% 7% 11% 10% 3	1520
	11th to 20th	Day	63% 6% 13% 14% 5%	1906
	21st to end	Day	71% 4 7% 14% 4	2772
January	1st to 10th	Night	64% 7% 15% 10% 4	4429
	11th to 20th	Night	61% 8% 13% 12% 5% 1	4440
	21st to end	Night	66% 6% 11% 10% 6% 1	4842
February	1st to 10th	Night	60% 5% 11% 16% 7% 1	2470
	11th to 20th	Night	57% 5% 10% 19% 8% 1	2370
	21st to end	Night	55% 5% 10% 17% 12% 1	1884
March	1st to 10th	Night	55% 5% 10% 18% 10% 2	3734
	11th to 20th	Night	58% 5% 11% 15% 9% 2	3549
	21st to end	Night	47% 3 9% 22% 16% 3	3562
April	1st to 10th	Night	53% 5% 10% 15% 15% 2	1900
	11th to 20th	Night	49% 5% 8% 21% 16% 1	1875
	21st to end	Night	50% 4 9% 17% 15% 3	1782
May	1st to 10th	Night	51% 9% 9% 19% 9% 3	2520
	11th to 20th	Night	46% 9% 11% 19% 13% 2	2496
	21st to end	Night	45% 8% 10% 19% 17% 2	2739
June	1st to 10th	Night	46% 9% 12% 22% 11%	1520
	11th to 20th	Night	41% 8% 10% 23% 16% 2	1520
	21st to end	Night	46% 9% 11% 18% 14% 1	1520
July	1st to 10th	Night	45% 8% 14% 20% 12% 1	2480
	11th to 20th	Night	40% 6% 15% 31% 8%	2472
	21st to end	Night	37% 7% 16% 26% 14%	2651
August	1st to 10th	Night	43% 7% 15% 26% 8%	2496
	11th to 20th	Night	41% 6% 16% 30% 7%	2857
	21st to end	Night	40% 7% 16% 23% 12% 2	3476
September	1st to 10th	Night	38% 7% 12% 27% 15% 1	1900
	11th to 20th	Night	35% 8% 12% 34% 11% 1	1926
	21st to end	Night	41% 6% 12% 30% 12%	2108
October	1st to 10th	Night	43% 6% 14% 25% 11% 1	3800
	11th to 20th	Night	45% 6% 14% 26% 9%	3779
	21st to end	Night	48% 5% 18% 19% 10%	4436
November	1st to 10th	Night	52% 5% 14% 20% 9%	2537
	11th to 20th	Night	55% 6% 11% 17% 10% 1	2757
	21st to end	Night	62% 7% 12% 14% 5%	2759
December	1st to 10th	Night	67% 6% 10% 12% 4	2660
	11th to 20th	Night	62% 5% 9% 17% 7% 1	3288
	21st to end	Night	70% 5% 7% 13% 4	4884

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	27% 13% 30% 25% 4 1	180
	11th to 20th	Day	27% 14% 36% 16% 6% 1	180
	21st to end	Day	19% 12% 35% 27% 6%	211
February	1st to 10th	Day	29% 23% 33% 13% 3	270
	11th to 20th	Day	25% 23% 37% 15% 1	303
	21st to end	Day	28% 18% 32% 21% 2	382
March	1st to 10th	Day	26% 15% 30% 23% 5%	460
	11th to 20th	Day	23% 20% 32% 20% 5% 1	460
	21st to end	Day	29% 15% 31% 16% 8% 2	506
April	1st to 10th	Day	28% 17% 29% 16% 8% 2	460
	11th to 20th	Day	31% 18% 21% 19% 10% 2	452
	21st to end	Day	29% 15% 30% 17% 7% 1	460
May	1st to 10th	Day	23% 12% 33% 23% 6% 2	463
	11th to 20th	Day	20% 16% 28% 23% 11% 3	487
	21st to end	Day	19% 13% 33% 24% 9% 2	529
June	1st to 10th	Day	25% 11% 27% 25% 11% 1	490
	11th to 20th	Day	15% 12% 29% 26% 14% 3	490
	21st to end	Day	22% 12% 25% 25% 13% 2	490
July	1st to 10th	Day	14% 8% 26% 30% 16% 6%	485
	11th to 20th	Day	13% 7% 30% 29% 17% 4	484
	21st to end	Day	14% 7% 26% 32% 18% 3	532
August	1st to 10th	Day	14% 7% 25% 31% 20% 4	486
	11th to 20th	Day	14% 6% 22% 31% 19% 8%	479
	21st to end	Day	16% 9% 24% 27% 16% 8%	539
September	1st to 10th	Day	18% 7% 27% 22% 17% 8%	490
	11th to 20th	Day	13% 8% 20% 21% 23% 15%	490
	21st to end	Day	19% 11% 26% 21% 15% 8%	490
October	1st to 10th	Day	26% 12% 23% 20% 16% 3	490
	11th to 20th	Day	27% 16% 27% 19% 10% 1	490
	21st to end	Day	31% 11% 29% 21% 7%	439
November	1st to 10th	Day	28% 16% 24% 23% 9% 1	395
	11th to 20th	Day	25% 18% 35% 15% 5% 2	240
	21st to end	Day	31% 19% 24% 20% 6%	194
December	1st to 10th	Day	32% 12% 30% 19% 7%	180
	11th to 20th	Day	26% 18% 37% 16% 2 1	180
	21st to end	Day	34% 18% 32% 13% 3 1	198
January	1st to 10th	Night	28% 11% 33% 22% 5%	760
	11th to 20th	Night	29% 10% 30% 25% 6% 1	760
	21st to end	Night	20% 9% 32% 31% 7% 1	836
February	1st to 10th	Night	21% 11% 37% 26% 5%	760
	11th to 20th	Night	21% 12% 38% 25% 5%	743
	21st to end	Night	24% 12% 30% 29% 4	628
March	1st to 10th	Night	24% 12% 31% 28% 5%	760
	11th to 20th	Night	26% 11% 34% 23% 6% 1	760
	21st to end	Night	23% 10% 32% 27% 8%	836
April	1st to 10th	Night	27% 12% 28% 28% 6%	760
	11th to 20th	Night	25% 12% 30% 26% 7% 1	751
	21st to end	Night	26% 10% 29% 27% 7% 1	642
May	1st to 10th	Night	26% 6% 28% 29% 9% 2	380
	11th to 20th	Night	24% 6% 26% 34% 10%	374
	21st to end	Night	17% 6% 34% 30% 13%	411
June	1st to 10th	Night	17% 3 27% 43% 10%	380
	11th to 20th	Night	17% 4 27% 36% 14% 1	380
	21st to end	Night	19% 4 26% 33% 17% 1	380
July	1st to 10th	Night	11% 4 24% 43% 19%	370
	11th to 20th	Night	13% 2 19% 45% 20% 1	368
	21st to end	Night	14% 3 21% 44% 19% 1	416
August	1st to 10th	Night	14% 4 14% 46% 22% 1	378
	11th to 20th	Night	15% 2 17% 34% 29% 3	583
	21st to end	Night	15% 4 21% 37% 21% 2	836
September	1st to 10th	Night	14% 4 25% 36% 20% 1	760
	11th to 20th	Night	18% 4 17% 32% 26% 3	760
	21st to end	Night	19% 6% 23% 30% 20% 2	760
October	1st to 10th	Night	23% 6% 26% 29% 16%	760
	11th to 20th	Night	26% 8% 26% 30% 9% 1	760
	21st to end	Night	26% 10% 28% 29% 6%	836
November	1st to 10th	Night	27% 8% 26% 28% 9% 1	780
	11th to 20th	Night	25% 11% 32% 22% 10%	800
	21st to end	Night	28% 12% 29% 23% 8%	789
December	1st to 10th	Night	30% 11% 30% 23% 5%	760
	11th to 20th	Night	29% 12% 29% 23% 5% 1	760
	21st to end	Night	36% 10% 31% 18% 4	836

Page generated at 2024-11-25 00:22:20. Version ac07

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