White Bluff
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the White Bluff clear sky chart from 2005-11-06 to 2024-01-12.

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
43%
23921
22%
74344
15%
23862
51%
23862
26%
46592

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
23%
950
20%
2648
9%
946
32%
946
20%
1809
January11th to 20thNight
19%
910
17%
2543
6%
910
27%
910
15%
1888
January21st to endNight
22%
794
23%
2378
9%
794
35%
794
21%
1573
February1st to 10thNight
21%
720
17%
2160
8%
720
29%
720
17%
1549
February11th to 20thNight
18%
703
18%
2099
8%
700
27%
700
16%
1462
February21st to endNight
16%
592
19%
1776
7%
592
26%
592
16%
1264
March1st to 10thNight
27%
720
20%
2160
9%
720
36%
720
22%
1407
March11th to 20thNight
24%
720
18%
2091
9%
720
31%
720
20%
1452
March21st to endNight
30%
648
17%
2034
10%
648
38%
648
21%
1368
April1st to 10thNight
34%
540
26%
1800
14%
540
49%
540
28%
1032
April11th to 20thNight
34%
533
27%
1775
16%
533
51%
533
27%
1049
April21st to endNight
37%
540
22%
1793
13%
540
49%
540
27%
1071
May1st to 10thNight
39%
540
22%
1620
13%
540
48%
540
29%
998
May11th to 20thNight
47%
531
18%
1593
11%
531
53%
531
31%
970
May21st to endNight
61%
583
18%
1744
12%
582
66%
582
33%
1060
June1st to 10thNight
62%
540
20%
1548
16%
540
65%
540
34%
936
June11th to 20thNight
74%
540
26%
1440
18%
540
77%
540
50%
781
June21st to endNight
72%
540
24%
1440
17%
540
75%
540
43%
834
July1st to 10thNight
71%
525
17%
1400
14%
525
72%
525
35%
881
July11th to 20thNight
70%
522
21%
1392
16%
522
72%
522
40%
838
July21st to endNight
70%
591
22%
1663
20%
558
73%
558
36%
982
August1st to 10thNight
75%
537
21%
1747
23%
534
77%
534
35%
983
August11th to 20thNight
70%
534
20%
1776
22%
534
71%
534
34%
989
August21st to endNight
71%
594
23%
1980
26%
594
72%
594
32%
1139
September1st to 10thNight
67%
540
25%
1800
27%
540
69%
540
31%
1051
September11th to 20thNight
63%
706
28%
1966
23%
706
66%
706
37%
1183
September21st to endNight
60%
720
31%
1980
22%
720
65%
720
40%
1147
October1st to 10thNight
60%
720
33%
1980
25%
720
66%
720
43%
1103
October11th to 20thNight
43%
720
29%
2052
18%
720
53%
720
32%
1238
October21st to endNight
41%
792
28%
2532
21%
792
51%
792
28%
1522
November1st to 10thNight
49%
740
29%
2406
26%
740
57%
740
32%
1353
November11th to 20thNight
36%
760
30%
2470
19%
760
52%
760
32%
1402
November21st to endNight
35%
760
25%
2470
18%
760
47%
760
25%
1510
December1st to 10thNight
28%
760
19%
2470
12%
760
38%
760
18%
1679
December11th to 20thNight
30%
759
26%
2914
15%
758
43%
758
20%
1768
December21st to endNight
23%
997
12%
4704
8%
983
33%
983
10%
3321

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
13%7%36%5%35%5%5%8%41%
74945
Night
13%7%35%5%3445%7%44%
74765
TransparencyDay
42%411%23%17%3
74658
Night
41%410%23%19%4
74573
SeeingDay
17%12%23%24%17%7%
14081
Night
17%10%24%28%17%3
23928

By Month

Percentage Cloud Cover SE (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
16%8%5%6%6%35%446%37%
1517
11th to 20thDay
20%10%47%6%34446%32%
1454
21st to endDay
15%8%45%6%24445%44%
1974
February1st to 10thDay
17%12%47%5%33436%36%
1800
11th to 20thDay
20%10%46%6%33346%34%
1748
21st to endDay
19%10%46%43435%6%35%
1480
March1st to 10thDay
16%10%26%5%445%45%40%
1800
11th to 20thDay
21%7%47%5%3445%6%34%
1867
21st to endDay
15%9%47%7%35%45%7%34%
2335
April1st to 10thDay
12%6%25%43445%7%47%
2160
11th to 20thDay
15%8%36%5%2345%6%43%
2134
21st to endDay
14%6%36%6%4446%7%40%
2164
May1st to 10thDay
16%5%36%5%345%5%7%42%
2340
11th to 20thDay
13%7%36%6%45%5%5%7%39%
2301
21st to endDay
9%5%36%6%46%6%6%10%38%
2531
June1st to 10thDay
8%6%26%6%36%7%6%9%42%
2406
11th to 20thDay
5%325%6%46%7%8%10%45%
2520
21st to endDay
5%3346%47%7%8%11%43%
2520
July1st to 10thDay
7%5%37%7%48%8%8%9%34%
2520
11th to 20thDay
7%436%7%47%7%7%11%38%
2520
21st to endDay
8%5%26%6%47%7%8%12%37%
2552
August1st to 10thDay
6%425%7%47%8%8%11%39%
2176
11th to 20thDay
8%6%47%6%47%7%6%8%37%
2125
21st to endDay
9%6%25%6%46%7%8%10%39%
2376
September1st to 10thDay
11%6%25%5%46%6%6%9%41%
2156
11th to 20thDay
14%5%25%435%447%45%
1980
21st to endDay
10%6%25%5%34447%51%
1980
October1st to 10thDay
11%423424447%55%
1980
11th to 20thDay
12%5%25%43435%6%52%
1906
21st to endDay
18%6%24423445%47%
1823
November1st to 10thDay
13%5%1432335%6%57%
1672
11th to 20thDay
14%6%3442435%6%49%
1710
21st to endDay
15%7%343345%46%46%
1710
December1st to 10thDay
22%10%35%5%34345%37%
1710
11th to 20thDay
16%10%36%5%35%5%5%6%38%
2153
21st to endDay
15%11%46%7%35%5%5%8%31%
2845
January1st to 10thNight
17%10%37%5%24346%39%
2648
11th to 20thNight
20%11%47%6%4445%5%30%
2543
21st to endNight
17%8%36%5%3445%5%40%
2378
February1st to 10thNight
20%11%5%7%5%35%345%33%
2160
11th to 20thNight
21%9%47%434345%36%
2098
21st to endNight
23%10%37%5%335%5%433%
1776
March1st to 10thNight
15%8%35%4345%5%7%41%
2160
11th to 20thNight
18%8%36%6%3445%5%37%
2091
21st to endNight
13%9%36%6%35%45%8%37%
2034
April1st to 10thNight
10%5%25%5%3445%7%48%
1800
11th to 20thNight
16%6%24433347%48%
1775
21st to endNight
12%6%345%3446%8%43%
1793
May1st to 10thNight
11%6%26%5%35%45%6%47%
1620
11th to 20thNight
10%5%35%6%335%6%10%45%
1592
21st to endNight
6%4246%46%6%7%11%44%
1744
June1st to 10thNight
8%6%346%345%6%9%47%
1548
11th to 20thNight
33134245%7%10%56%
1440
21st to endNight
3324435%7%9%13%48%
1440
July1st to 10thNight
7%335%5%35%6%8%14%41%
1440
11th to 20thNight
5%5%25%5%25%7%6%12%46%
1440
21st to endNight
5%325%6%36%6%8%12%44%
1761
August1st to 10thNight
6%425%5%35%5%6%12%47%
1758
11th to 20thNight
6%4245%35%6%7%11%46%
1776
21st to endNight
8%4245%35%5%8%10%45%
1980
September1st to 10thNight
11%5%25%435%5%5%6%49%
1800
11th to 20thNight
10%4245%3445%7%51%
1966
21st to endNight
10%3244245%5%5%56%
1980
October1st to 10thNight
9%5%23323335%62%
1980
11th to 20thNight
16%5%24434346%51%
2052
21st to endNight
16%7%2442345%6%47%
2532
November1st to 10thNight
12%5%25%423445%54%
2406
11th to 20thNight
12%5%25%32345%8%50%
2470
21st to endNight
16%7%35%423346%46%
2470
December1st to 10thNight
19%12%36%434445%36%
2470
11th to 20thNight
16%9%35%433435%45%
3042
21st to endNight
17%12%48%7%45%5%5%6%29%
4802

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
50%37%23%15%4
1518
11th to 20thDay
54%37%21%14%1
1454
21st to endDay
44%29%26%17%2
1974
February1st to 10thDay
51%38%21%14%3
1800
11th to 20thDay
53%37%21%13%3
1758
21st to endDay
52%28%17%15%6%
1480
March1st to 10thDay
48%37%18%18%6%
1800
11th to 20thDay
51%39%19%15%2
1867
21st to endDay
51%410%21%13%1
2335
April1st to 10thDay
38%410%23%22%4
2160
11th to 20thDay
43%37%22%21%5%
2134
21st to endDay
44%310%25%17%2
2164
May1st to 10thDay
42%312%27%14%2
2340
11th to 20thDay
45%412%23%15%1
2305
21st to endDay
41%7%14%24%12%2
2531
June1st to 10thDay
37%6%12%25%18%2
2406
11th to 20thDay
31%6%15%27%17%3
2520
21st to endDay
32%8%15%25%16%4
2520
July1st to 10thDay
41%7%16%20%12%3
2451
11th to 20thDay
38%7%19%21%12%3
2445
21st to endDay
37%7%18%26%10%2
2410
August1st to 10thDay
36%8%16%27%12%1
2163
11th to 20thDay
43%6%11%23%16%2
2125
21st to endDay
38%7%13%24%16%3
2376
September1st to 10thDay
40%6%10%23%18%3
2156
11th to 20thDay
39%5%8%23%22%2
1980
21st to endDay
34%49%26%22%6%
1980
October1st to 10thDay
31%49%23%27%5%
1980
11th to 20thDay
35%36%22%25%9%
1906
21st to endDay
43%35%20%23%5%
1823
November1st to 10thDay
30%38%24%29%6%
1672
11th to 20thDay
37%27%23%24%6%
1710
21st to endDay
40%37%25%19%5%
1710
December1st to 10thDay
51%26%22%16%3
1710
11th to 20thDay
48%37%21%19%2
2150
21st to endDay
53%29%22%12%2
2845
January1st to 10thNight
49%27%23%17%2
2648
11th to 20thNight
57%36%18%13%2
2543
21st to endNight
47%28%23%17%2
2378
February1st to 10thNight
55%28%18%15%1
2160
11th to 20thNight
52%36%20%15%4
2099
21st to endNight
54%38%16%14%5%
1776
March1st to 10thNight
43%5%8%16%21%8%
2160
11th to 20thNight
50%38%20%16%2
2091
21st to endNight
47%411%22%14%2
2034
April1st to 10thNight
36%310%26%21%3
1800
11th to 20thNight
38%37%21%23%8%
1775
21st to endNight
39%410%27%18%2
1793
May1st to 10thNight
39%310%25%20%3
1620
11th to 20thNight
35%6%18%23%16%2
1593
21st to endNight
33%7%18%24%15%2
1745
June1st to 10thNight
34%5%15%25%18%3
1548
11th to 20thNight
21%6%17%33%19%4
1440
21st to endNight
24%9%18%30%15%4
1440
July1st to 10thNight
33%8%18%24%14%3
1400
11th to 20thNight
29%7%19%26%14%5%
1392
21st to endNight
30%7%17%29%15%1
1663
August1st to 10thNight
30%6%17%30%17%1
1747
11th to 20thNight
29%7%20%25%17%2
1776
21st to endNight
32%7%14%28%14%5%
1980
September1st to 10thNight
35%5%11%27%18%5%
1800
11th to 20thNight
33%5%9%23%27%3
1966
21st to endNight
30%48%26%27%7%
1980
October1st to 10thNight
28%38%25%29%8%
1980
11th to 20thNight
38%27%22%23%8%
2052
21st to endNight
39%25%23%25%5%
2532
November1st to 10thNight
34%36%23%27%8%
2406
11th to 20thNight
34%36%22%27%8%
2470
21st to endNight
41%27%23%22%5%
2470
December1st to 10thNight
52%28%19%16%3
2470
11th to 20thNight
43%26%23%22%4
3044
21st to endNight
58%27%18%12%3
4802

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
24%24%35%11%6%
270
11th to 20thDay
31%27%25%13%22
245
21st to endDay
22%28%38%8%3
264
February1st to 10thDay
30%26%31%11%11
240
11th to 20thDay
39%25%28%8%1
240
21st to endDay
37%25%27%10%2
198
March1st to 10thDay
28%21%38%12%2
240
11th to 20thDay
27%26%30%13%31
307
21st to endDay
27%19%32%17%5%
462
April1st to 10thDay
21%17%31%22%7%1
420
11th to 20thDay
22%16%29%24%8%1
412
21st to endDay
20%20%29%20%10%2
420
May1st to 10thDay
19%18%28%23%9%3
423
11th to 20thDay
16%9%28%24%18%5%
447
21st to endDay
13%5%22%29%20%12%
485
June1st to 10thDay
11%5%22%25%22%14%
516
11th to 20thDay
5%419%33%27%12%
630
21st to endDay
6%5%22%32%23%12%
630
July1st to 10thDay
8%314%30%29%16%
621
11th to 20thDay
8%413%28%31%16%
618
21st to endDay
9%314%30%25%19%
493
August1st to 10thDay
9%313%30%30%15%
446
11th to 20thDay
12%312%36%30%7%
439
21st to endDay
13%211%23%34%17%
495
September1st to 10thDay
12%313%29%30%13%
450
11th to 20thDay
14%313%26%31%14%
450
21st to endDay
15%5%18%29%24%8%
450
October1st to 10thDay
13%426%27%23%7%
450
11th to 20thDay
15%16%34%23%10%2
376
21st to endDay
28%16%25%23%7%1
297
November1st to 10thDay
19%14%29%27%9%2
270
11th to 20thDay
16%22%38%19%4
270
21st to endDay
22%18%30%19%9%2
270
December1st to 10thDay
33%18%27%18%4
270
11th to 20thDay
24%23%30%16%6%1
270
21st to endDay
27%22%34%15%1
297
January1st to 10thNight
23%21%30%23%4
950
11th to 20thNight
27%21%28%20%4
910
21st to endNight
22%18%36%23%2
794
February1st to 10thNight
27%16%32%22%3
720
11th to 20thNight
28%20%30%20%2
703
21st to endNight
31%19%31%17%2
592
March1st to 10thNight
22%17%30%26%4
720
11th to 20thNight
22%17%33%21%6%1
720
21st to endNight
21%15%30%26%8%
648
April1st to 10thNight
15%13%35%28%8%1
540
11th to 20thNight
20%12%32%27%9%1
533
21st to endNight
16%11%31%29%12%1
540
May1st to 10thNight
14%9%33%27%16%2
540
11th to 20thNight
11%6%28%30%21%4
531
21st to endNight
9%219%38%27%6%
584
June1st to 10thNight
11%316%36%29%5%
540
11th to 20thNight
5%212%39%36%6%
540
21st to endNight
4216%37%34%7%
540
July1st to 10thNight
9%28%31%37%13%
525
11th to 20thNight
7%211%30%40%11%
522
21st to endNight
6%29%32%41%9%
591
August1st to 10thNight
7%27%32%45%7%
537
11th to 20thNight
8%210%39%35%6%
534
21st to endNight
10%19%30%41%9%
594
September1st to 10thNight
12%210%32%38%6%
540
11th to 20thNight
13%313%27%36%8%
706
21st to endNight
11%417%29%33%5%
720
October1st to 10thNight
12%6%18%32%27%6%
720
11th to 20thNight
20%8%24%30%16%2
720
21st to endNight
20%10%26%29%14%2
792
November1st to 10thNight
15%9%23%35%16%2
740
11th to 20thNight
15%13%33%26%12%1
760
21st to endNight
21%13%27%28%11%
760
December1st to 10thNight
27%14%28%25%6%
760
11th to 20thNight
22%12%31%26%7%1
760
21st to endNight
28%17%28%23%4
1002
Page generated at 2024-01-09 15:24:28. Version ac07

Copyright 2024 Attilla Danko


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