South Range
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the South Range clear sky chart from 2005-11-06 to 2024-03-01.

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 TypeMinimum conditions for hour to be usableOut of hours
Clear of CloudsTransparencySeeingSky Brightness
Planetary:50%(no limit)Average(no limit)Nighttime Hours
Deep Sky:70%Average(no limit)5.9Nighttime Hours
CCD Imaging:70%Below AveragePoor(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

PlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
Night
18%
23633
10%
80701
5%
23509
24%
23509
10%
62656

By Month

MonthDays of MonthPlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
January1st to 10thNight
8%
842
4%
4736
3%
817
11%
817
2%
4116
January11th to 20thNight
7%
760
5%
4241
1%
740
11%
740
2%
3658
January21st to endNight
8%
833
3%
4519
1%
814
12%
814
2%
3776
February1st to 10thNight
8%
760
5%
2470
1%
760
12%
760
4%
2161
February11th to 20thNight
7%
743
5%
2406
1%
740
13%
740
3%
2101
February21st to endNight
12%
628
6%
1940
2%
628
18%
628
8%
1559
March1st to 10thNight
10%
723
11%
2033
3%
723
18%
723
9%
1632
March11th to 20thNight
15%
720
10%
1980
3%
720
22%
720
11%
1558
March21st to endNight
16%
792
13%
2178
3%
792
24%
792
14%
1634
April1st to 10thNight
12%
622
12%
1882
3%
622
21%
622
11%
1432
April11th to 20thNight
14%
534
14%
1612
4%
534
24%
534
14%
1151
April21st to endNight
19%
540
13%
1620
4%
540
26%
540
14%
1189
May1st to 10thNight
20%
540
13%
1620
6%
540
28%
540
15%
1200
May11th to 20thNight
19%
532
15%
1485
6%
532
28%
532
17%
1082
May21st to endNight
19%
583
10%
1551
4%
582
26%
582
18%
1166
June1st to 10thNight
20%
457
11%
1357
5%
457
28%
457
15%
995
June11th to 20thNight
25%
360
13%
1260
6%
360
35%
360
16%
860
June21st to endNight
23%
360
8%
1260
5%
360
29%
360
14%
919
July1st to 10thNight
24%
350
11%
1225
6%
350
34%
350
17%
828
July11th to 20thNight
28%
396
10%
1292
7%
396
34%
396
17%
919
July21st to endNight
30%
590
12%
1672
8%
558
33%
558
20%
1201
August1st to 10thNight
31%
538
13%
1600
9%
534
34%
534
23%
1083
August11th to 20thNight
29%
532
14%
1596
8%
532
33%
532
18%
1151
August21st to endNight
34%
594
18%
1811
9%
594
41%
594
23%
1184
September1st to 10thNight
30%
540
19%
1800
11%
540
42%
540
24%
1103
September11th to 20thNight
33%
720
20%
1980
12%
720
41%
720
25%
1291
September21st to endNight
29%
720
20%
1980
9%
720
37%
720
21%
1362
October1st to 10thNight
31%
720
17%
2146
9%
720
38%
720
21%
1465
October11th to 20thNight
24%
720
17%
2160
7%
720
33%
720
17%
1494
October21st to endNight
17%
792
13%
2419
5%
792
25%
792
11%
1863
November1st to 10thNight
19%
766
12%
2461
5%
766
27%
766
11%
1824
November11th to 20thNight
17%
850
11%
2660
6%
850
22%
850
9%
2108
November21st to endNight
15%
850
7%
2660
2%
850
20%
850
8%
2135
December1st to 10thNight
9%
850
4%
2660
1%
850
13%
850
5%
2317
December11th to 20thNight
7%
850
5%
3241
1%
849
10%
849
3%
2822
December21st to endNight
9%
926
3%
5188
1%
907
14%
907
2%
4317

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 ForecastData
Points
Cloud CoverDay
20%11%5%8%6%34446%30%
78393
Night
20%13%5%10%7%34445%24%
81024
TransparencyDay
56%6%11%17%9%1
78098
Night
61%6%10%15%7%1
80854
SeeingDay
30%21%30%14%41
15652
Night
30%18%30%18%5%
23653

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
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 10thDay
18%20%7%13%12%35%33413%
2207
11th to 20thDay
18%18%8%20%10%4332311%
2685
21st to endDay
18%15%10%17%12%4433312%
3124
February1st to 10thDay
19%18%9%14%12%3333411%
1710
11th to 20thDay
17%17%8%14%14%3423414%
1663
21st to endDay
12%15%8%10%10%5%3446%23%
1513
March1st to 10thDay
16%17%8%11%10%4332422%
1928
11th to 20thDay
16%12%7%12%7%34345%27%
1980
21st to endDay
19%14%5%7%6%34345%31%
2178
April1st to 10thDay
24%14%46%5%33435%29%
2078
11th to 20thDay
20%10%3433435%7%38%
2294
21st to endDay
21%12%46%424446%33%
2340
May1st to 10thDay
22%9%47%6%33446%31%
2340
11th to 20thDay
21%8%335%34445%40%
2409
21st to endDay
21%7%35%5%3445%8%35%
2724
June1st to 10thDay
25%8%36%5%3435%7%32%
2617
11th to 20thDay
22%7%35%434446%38%
2700
21st to endDay
23%7%36%6%35%5%46%33%
2700
July1st to 10thDay
18%6%36%4345%6%8%39%
2700
11th to 20thDay
18%7%245%35%5%6%8%37%
2604
21st to endDay
19%6%36%5%35%5%5%8%35%
2548
August1st to 10thDay
16%5%26%5%345%6%7%40%
2327
11th to 20thDay
16%7%36%5%35%5%5%6%39%
2304
21st to endDay
15%6%25%433447%47%
2544
September1st to 10thDay
18%6%34423336%49%
2158
11th to 20thDay
17%6%34433347%47%
1980
21st to endDay
19%7%35%423345%44%
1980
October1st to 10thDay
20%7%25%5%34447%39%
1814
11th to 20thDay
20%11%36%43445%7%33%
1800
21st to endDay
23%12%37%6%34445%30%
1936
November1st to 10thDay
22%11%37%6%34347%30%
1615
11th to 20thDay
19%17%8%8%6%3445%6%22%
1520
21st to endDay
20%19%6%13%6%24335%19%
1520
December1st to 10thDay
25%21%7%13%5%3433313%
1520
11th to 20thDay
24%17%8%14%8%3443312%
1902
21st to endDay
24%18%11%13%8%3233412%
2431
January1st to 10thNight
18%18%8%20%10%3432212%
4748
11th to 20thNight
19%21%8%16%9%3333311%
4267
21st to endNight
18%14%7%17%12%4444412%
4532
February1st to 10thNight
19%17%8%16%10%4433411%
2470
11th to 20thNight
18%17%7%16%12%4433312%
2403
21st to endNight
13%15%7%13%9%45%5%45%20%
1940
March1st to 10thNight
15%15%8%11%9%4435%423%
2024
11th to 20thNight
19%11%7%10%6%45%445%25%
1979
21st to endNight
19%13%6%7%6%3445%6%29%
2178
April1st to 10thNight
24%15%46%6%24346%27%
1882
11th to 20thNight
22%10%36%5%2345%8%31%
1612
21st to endNight
23%13%35%5%3445%6%30%
1620
May1st to 10thNight
21%10%46%5%44446%31%
1620
11th to 20thNight
22%9%36%5%25%5%5%6%32%
1484
21st to endNight
19%8%46%6%35%449%32%
1550
June1st to 10thNight
26%8%35%5%25%46%9%27%
1357
11th to 20thNight
22%7%35%435%45%8%34%
1260
21st to endNight
21%8%39%6%45%45%7%28%
1260
July1st to 10thNight
18%8%36%5%35%47%10%31%
1260
11th to 20thNight
17%9%46%6%36%5%6%9%29%
1334
21st to endNight
19%6%36%5%46%5%7%8%32%
1770
August1st to 10thNight
14%7%37%5%35%5%6%8%37%
1612
11th to 20thNight
20%10%26%4345%5%8%32%
1596
21st to endNight
14%7%35%5%345%7%7%41%
1811
September1st to 10thNight
17%5%245%2445%7%44%
1800
11th to 20thNight
19%7%3442435%7%43%
1980
21st to endNight
20%7%25%5%345%47%39%
1980
October1st to 10thNight
20%7%25%5%3445%6%38%
2146
11th to 20thNight
17%9%36%6%34447%36%
2160
21st to endNight
27%13%47%423345%27%
2419
November1st to 10thNight
22%11%47%6%3445%5%29%
2461
11th to 20thNight
21%17%5%9%5%3445%6%21%
2660
21st to endNight
20%18%6%10%6%34345%22%
2660
December1st to 10thNight
26%20%8%13%5%3333413%
2660
11th to 20thNight
22%18%8%15%8%3333413%
3293
21st to endNight
24%20%8%12%6%2322317%
5236

Transparency (when cloud cover <= 30%)
Color Meanings:
Too cloudy to forecast Poor Below Average Average Above average Transparent
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 10thDay
74%7%13%41
2208
11th to 20thDay
78%6%8%5%2
2685
21st to endDay
73%7%13%5%1
3124
February1st to 10thDay
78%5%8%5%3
1710
11th to 20thDay
76%5%8%9%3
1671
21st to endDay
63%5%12%13%5%1
1513
March1st to 10thDay
67%49%13%6%1
1932
11th to 20thDay
60%5%10%13%11%1
1980
21st to endDay
58%5%8%17%10%2
2178
April1st to 10thDay
61%49%13%12%1
2078
11th to 20thDay
47%6%11%23%13%1
2294
21st to endDay
53%411%18%12%2
2340
May1st to 10thDay
55%5%10%18%11%1
2340
11th to 20thDay
47%6%10%22%14%2
2413
21st to endDay
49%7%12%20%11%1
2724
June1st to 10thDay
53%6%9%20%11%1
2617
11th to 20thDay
48%6%11%20%14%2
2700
21st to endDay
52%8%10%18%9%1
2700
July1st to 10thDay
43%8%13%22%13%2
2625
11th to 20thDay
45%8%14%22%10%1
2523
21st to endDay
47%8%14%22%9%1
2406
August1st to 10thDay
43%9%13%23%13%1
2314
11th to 20thDay
46%9%14%21%10%
2304
21st to endDay
39%6%12%26%16%1
2544
September1st to 10thDay
39%5%11%25%18%2
2158
11th to 20thDay
40%5%11%25%16%2
1980
21st to endDay
42%5%8%25%17%2
1980
October1st to 10thDay
45%6%11%25%12%1
1814
11th to 20thDay
51%6%12%22%9%
1800
21st to endDay
58%49%17%11%1
1936
November1st to 10thDay
56%5%11%19%8%1
1615
11th to 20thDay
63%6%10%14%5%
1520
21st to endDay
68%6%12%11%2
1520
December1st to 10thDay
76%7%7%8%2
1520
11th to 20thDay
77%5%8%7%3
1901
21st to endDay
76%6%11%42
2431
January1st to 10thNight
77%7%8%7%1
4748
11th to 20thNight
78%5%8%6%2
4267
21st to endNight
73%7%10%8%2
4532
February1st to 10thNight
77%5%8%7%3
2470
11th to 20thNight
76%6%7%8%3
2406
21st to endNight
64%7%11%12%5%1
1940
March1st to 10thNight
64%5%9%13%7%1
2033
11th to 20thNight
62%412%11%9%1
1980
21st to endNight
54%6%11%16%10%2
2178
April1st to 10thNight
60%49%13%11%2
1882
11th to 20thNight
53%5%11%20%11%1
1612
21st to endNight
55%5%10%17%11%1
1620
May1st to 10thNight
53%6%10%19%10%1
1620
11th to 20thNight
51%7%9%23%10%1
1485
21st to endNight
52%8%12%19%9%1
1551
June1st to 10thNight
53%7%12%20%7%1
1357
11th to 20thNight
48%7%12%20%11%1
1260
21st to endNight
55%7%11%16%9%2
1260
July1st to 10thNight
46%9%16%20%9%
1225
11th to 20thNight
51%7%15%17%9%1
1292
21st to endNight
47%10%13%21%8%1
1672
August1st to 10thNight
43%8%13%28%9%
1600
11th to 20thNight
49%9%14%20%8%
1596
21st to endNight
41%8%14%24%13%
1811
September1st to 10thNight
38%7%11%29%14%1
1800
11th to 20thNight
41%5%10%27%16%2
1980
21st to endNight
45%6%9%22%16%2
1980
October1st to 10thNight
47%5%12%22%13%2
2146
11th to 20thNight
48%7%14%23%9%
2160
21st to endNight
61%5%8%16%10%1
2419
November1st to 10thNight
55%7%12%17%8%
2461
11th to 20thNight
63%7%11%13%6%
2660
21st to endNight
65%6%15%11%3
2660
December1st to 10thNight
76%5%9%8%2
2660
11th to 20thNight
74%6%9%9%2
3295
21st to endNight
73%5%9%10%2
5236

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
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 10thDay
42%27%23%8%1
180
11th to 20thDay
39%30%21%9%1
283
21st to endDay
26%31%32%10%1
407
February1st to 10thDay
36%23%31%7%3
370
11th to 20thDay
39%29%23%7%2
366
21st to endDay
34%25%27%12%1
355
March1st to 10thDay
32%29%31%6%1
420
11th to 20thDay
36%27%25%9%3
420
21st to endDay
33%28%24%11%31
462
April1st to 10thDay
41%26%23%7%2
420
11th to 20thDay
33%23%30%12%2
412
21st to endDay
33%22%26%14%5%
420
May1st to 10thDay
33%27%28%10%21
423
11th to 20thDay
28%22%31%14%5%
555
21st to endDay
30%18%31%18%31
680
June1st to 10thDay
33%17%30%16%4
630
11th to 20thDay
25%18%31%20%6%
630
21st to endDay
30%14%33%18%41
630
July1st to 10thDay
24%14%35%20%7%1
620
11th to 20thDay
22%11%35%23%8%1
589
21st to endDay
22%14%40%18%6%
488
August1st to 10thDay
18%13%39%24%6%1
446
11th to 20thDay
23%9%36%21%9%2
439
21st to endDay
21%16%29%23%9%1
495
September1st to 10thDay
19%15%38%21%6%2
450
11th to 20thDay
24%18%31%18%6%2
450
21st to endDay
23%20%32%16%7%2
450
October1st to 10thDay
26%16%28%20%8%2
367
11th to 20thDay
29%16%31%16%6%2
360
21st to endDay
33%23%26%12%5%1
396
November1st to 10thDay
32%19%30%13%41
365
11th to 20thDay
39%22%26%9%4
370
21st to endDay
35%28%27%7%31
370
December1st to 10thDay
38%27%25%9%1
370
11th to 20thDay
43%28%20%8%1
366
21st to endDay
40%29%22%6%21
198
January1st to 10thNight
36%22%27%13%1
850
11th to 20thNight
40%22%25%11%2
760
21st to endNight
29%26%30%12%3
836
February1st to 10thNight
36%24%27%11%2
760
11th to 20thNight
35%26%27%9%2
743
21st to endNight
26%26%31%14%3
628
March1st to 10thNight
29%25%31%14%1
723
11th to 20thNight
30%21%28%17%4
720
21st to endNight
29%21%31%15%5%
792
April1st to 10thNight
37%19%29%12%2
622
11th to 20thNight
31%20%32%15%2
534
21st to endNight
31%16%31%17%5%
540
May1st to 10thNight
29%15%32%20%41
540
11th to 20thNight
29%16%33%19%2
532
21st to endNight
23%15%39%19%31
583
June1st to 10thNight
30%14%33%19%4
457
11th to 20thNight
24%10%36%24%5%1
360
21st to endNight
25%10%37%21%6%
360
July1st to 10thNight
22%7%40%25%5%
350
11th to 20thNight
20%10%37%24%9%
396
21st to endNight
20%6%40%30%4
590
August1st to 10thNight
17%9%38%29%7%1
538
11th to 20thNight
21%11%34%26%7%
532
21st to endNight
17%9%35%29%10%
594
September1st to 10thNight
20%10%36%25%9%1
540
11th to 20thNight
23%11%29%25%11%1
720
21st to endNight
23%14%29%23%9%2
720
October1st to 10thNight
25%11%29%24%11%1
720
11th to 20thNight
22%20%29%20%8%1
720
21st to endNight
35%21%23%18%3
792
November1st to 10thNight
31%18%26%19%6%1
766
11th to 20thNight
34%20%24%16%5%
850
21st to endNight
33%24%25%14%4
850
December1st to 10thNight
39%21%27%11%2
850
11th to 20thNight
37%28%24%9%2
850
21st to endNight
39%23%24%12%3
935
Page generated at 2024-02-27 07:30:15. Version ac07

Copyright © 2024 Attilla Danko.


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