Bella Bella
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Bella Bella clear sky chart from 2005-11-06 to 2024-02-05.

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
29%
22824
6%
80955
5%
22683
31%
22683
8%
66128

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
15%
844
6%
4723
6%
816
19%
816
3%
4155
January11th to 20thNight
14%
844
14%
4637
4%
820
18%
820
3%
3367
January21st to endNight
21%
933
4%
4996
5%
902
25%
902
4%
4522
February1st to 10thNight
18%
822
9%
2581
5%
822
22%
822
7%
2178
February11th to 20thNight
25%
704
12%
2278
9%
702
29%
702
9%
1813
February21st to endNight
25%
592
13%
1866
8%
592
31%
592
11%
1439
March1st to 10thNight
23%
720
7%
2160
4%
720
26%
720
10%
1760
March11th to 20thNight
22%
720
7%
1983
5%
720
23%
720
7%
1730
March21st to endNight
26%
786
7%
2172
6%
786
26%
786
10%
1833
April1st to 10thNight
32%
540
4%
1711
3%
540
32%
540
9%
1406
April11th to 20thNight
31%
533
9%
1601
8%
533
32%
533
12%
1280
April21st to endNight
35%
540
7%
1620
6%
540
37%
540
13%
1251
May1st to 10thNight
41%
428
5%
1418
5%
428
41%
428
12%
1081
May11th to 20thNight
42%
354
5%
1239
6%
354
42%
354
12%
971
May21st to endNight
47%
389
2%
1358
2%
388
47%
388
13%
1029
June1st to 10thNight
39%
360
0%
1260
0%
360
39%
360
10%
996
June11th to 20thNight
42%
360
0%
1260
0%
360
42%
360
9%
1016
June21st to endNight
41%
360
0%
1260
0%
360
41%
360
12%
972
July1st to 10thNight
50%
350
0%
1225
0%
350
50%
350
15%
876
July11th to 20thNight
49%
348
1%
1218
1%
348
49%
348
15%
898
July21st to endNight
54%
394
3%
1302
3%
372
57%
372
18%
899
August1st to 10thNight
54%
509
5%
1397
5%
507
54%
507
20%
1024
August11th to 20thNight
54%
534
9%
1576
10%
534
54%
534
19%
1124
August21st to endNight
38%
594
6%
1782
6%
594
38%
594
11%
1441
September1st to 10thNight
42%
571
5%
1691
4%
571
42%
571
15%
1290
September11th to 20thNight
44%
720
11%
1980
9%
720
45%
720
19%
1492
September21st to endNight
27%
720
6%
1980
4%
720
29%
720
7%
1720
October1st to 10thNight
34%
720
6%
2090
5%
720
35%
720
13%
1648
October11th to 20thNight
27%
720
5%
2276
4%
720
28%
720
8%
1933
October21st to endNight
27%
792
7%
2574
6%
792
29%
792
9%
2097
November1st to 10thNight
15%
740
5%
2572
3%
740
18%
740
5%
2235
November11th to 20thNight
18%
798
6%
2740
6%
798
19%
798
6%
2361
November21st to endNight
18%
850
6%
2850
3%
850
21%
850
6%
2411
December1st to 10thNight
27%
850
12%
2850
9%
850
31%
850
10%
2236
December11th to 20thNight
19%
850
4%
3516
2%
849
23%
849
5%
3038
December21st to endNight
18%
935
5%
5213
5%
905
23%
905
3%
4606

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
37%11%46%5%34345%20%
77647
Night
41%11%36%42333420%
81183
TransparencyDay
70%311%10%41
77348
Night
71%310%10%5%1
81062
SeeingDay
37%9%16%20%14%4
15049
Night
44%8%10%18%16%5%
22840

By Month

Percentage Cloud Cover NW (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
42%16%5%6%5%3333411%
2219
11th to 20thDay
41%11%24323335%23%
2199
21st to endDay
59%12%25%3123337%
2666
February1st to 10thDay
48%10%26%31233318%
1473
11th to 20thDay
36%12%35%423336%21%
1571
21st to endDay
34%15%4442332225%
1390
March1st to 10thDay
37%15%45%42333420%
1800
11th to 20thDay
37%19%47%6%3323314%
1976
21st to endDay
37%14%35%5%3434418%
2182
April1st to 10thDay
37%14%47%6%3344415%
2249
11th to 20thDay
34%11%46%5%3445%6%19%
2308
21st to endDay
37%9%46%6%24345%19%
2340
May1st to 10thDay
32%11%46%5%24345%23%
2541
11th to 20thDay
28%11%36%5%46%445%24%
2656
21st to endDay
30%10%46%5%2445%6%24%
2917
June1st to 10thDay
37%10%45%5%34445%18%
2700
11th to 20thDay
39%10%47%5%34445%16%
2700
21st to endDay
37%9%45%5%34346%20%
2700
July1st to 10thDay
29%8%36%5%34346%29%
2700
11th to 20thDay
31%9%46%5%24446%24%
2700
21st to endDay
30%8%45%5%33446%28%
2938
August1st to 10thDay
22%7%46%5%45%5%5%7%30%
2534
11th to 20thDay
26%10%47%423447%29%
2324
21st to endDay
38%11%47%6%24335%17%
2574
September1st to 10thDay
33%10%46%5%33346%22%
2266
11th to 20thDay
31%9%46%434446%24%
1980
21st to endDay
42%9%46%5%33345%15%
1980
October1st to 10thDay
35%9%36%423445%25%
1869
11th to 20thDay
45%9%48%7%4433411%
1683
21st to endDay
43%9%25%5%24345%19%
1782
November1st to 10thDay
50%9%36%5%2232315%
1506
11th to 20thDay
50%12%45%5%2323212%
1437
21st to endDay
46%11%36%43232216%
1330
December1st to 10thDay
39%10%34423445%21%
1330
11th to 20thDay
51%12%2442233215%
1685
21st to endDay
52%13%36%5%232229%
2442
January1st to 10thNight
46%17%46%4332339%
4726
11th to 20thNight
41%9%24424345%23%
4699
21st to endNight
62%10%343122229%
4996
February1st to 10thNight
48%11%3442223319%
2581
11th to 20thNight
39%13%36%42323423%
2276
21st to endNight
33%14%25%433335%26%
1866
March1st to 10thNight
34%15%46%5%3443420%
2160
11th to 20thNight
39%17%47%42333314%
1982
21st to endNight
40%14%46%42323418%
2172
April1st to 10thNight
33%15%47%5%2334420%
1711
11th to 20thNight
35%13%46%422345%22%
1601
21st to endNight
35%10%36%433335%27%
1620
May1st to 10thNight
34%11%44423345%28%
1418
11th to 20thNight
29%9%38%6%345%5%5%23%
1239
21st to endNight
28%7%38%5%33446%28%
1358
June1st to 10thNight
37%9%35%434345%23%
1260
11th to 20thNight
36%9%35%425%5%5%6%21%
1260
21st to endNight
34%10%36%434346%23%
1260
July1st to 10thNight
28%8%36%5%2445%5%32%
1260
11th to 20thNight
31%8%35%424446%30%
1260
21st to endNight
27%8%3442335%5%36%
1379
August1st to 10thNight
22%9%36%5%33446%35%
1404
11th to 20thNight
24%6%35%5%2435%6%37%
1576
21st to endNight
35%9%36%434335%24%
1782
September1st to 10thNight
30%9%36%6%24445%28%
1691
11th to 20thNight
29%9%35%5%23335%31%
1980
21st to endNight
44%10%36%5%3433416%
1980
October1st to 10thNight
37%9%36%43233425%
2090
11th to 20thNight
44%10%37%5%3243416%
2276
21st to endNight
43%9%36%333335%19%
2574
November1st to 10thNight
48%12%46%42332213%
2572
11th to 20thNight
48%12%36%42333313%
2740
21st to endNight
47%12%36%42222316%
2850
December1st to 10thNight
36%11%36%422335%22%
2850
11th to 20thNight
49%12%35%5%2322314%
3520
21st to endNight
50%15%36%42222210%
5214

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
79%27%9%3
2219
11th to 20thDay
66%26%9%8%8%
2220
21st to endDay
85%145%41
2666
February1st to 10thDay
75%15%6%8%5%
1473
11th to 20thDay
68%37%14%7%1
1580
21st to endDay
67%36%11%9%4
1390
March1st to 10thDay
70%47%9%9%2
1800
11th to 20thDay
80%15%8%42
1976
21st to endDay
71%29%14%4
2182
April1st to 10thDay
77%28%8%41
2249
11th to 20thDay
70%37%11%8%1
2308
21st to endDay
71%29%12%5%1
2340
May1st to 10thDay
66%315%12%3
2541
11th to 20thDay
65%415%12%3
2659
21st to endDay
65%415%11%5%
2918
June1st to 10thDay
71%413%8%22
2700
11th to 20thDay
75%314%8%1
2700
21st to endDay
69%416%10%2
2700
July1st to 10thDay
60%420%13%3
2626
11th to 20thDay
63%5%19%11%1
2619
21st to endDay
57%6%21%14%2
2775
August1st to 10thDay
54%6%21%16%3
2516
11th to 20thDay
58%5%15%17%4
2324
21st to endDay
72%414%8%2
2574
September1st to 10thDay
65%417%10%31
2266
11th to 20thDay
62%411%17%5%1
1980
21st to endDay
76%39%9%3
1980
October1st to 10thDay
65%214%13%41
1869
11th to 20thDay
80%39%6%2
1683
21st to endDay
70%37%14%7%
1782
November1st to 10thDay
78%25%10%41
1506
11th to 20thDay
82%25%45%1
1437
21st to endDay
76%25%8%6%2
1330
December1st to 10thDay
67%38%14%7%2
1330
11th to 20thDay
78%26%7%42
1688
21st to endDay
84%145%32
2442
January1st to 10thNight
83%25%7%3
4726
11th to 20thNight
65%27%8%9%8%
4740
21st to endNight
85%146%3
4996
February1st to 10thNight
75%247%7%5%
2581
11th to 20thNight
69%27%14%7%2
2278
21st to endNight
65%29%14%8%3
1866
March1st to 10thNight
70%29%11%6%2
2160
11th to 20thNight
78%36%7%5%2
1983
21st to endNight
74%29%11%4
2172
April1st to 10thNight
70%412%9%5%1
1711
11th to 20thNight
68%27%14%8%1
1601
21st to endNight
65%212%17%41
1620
May1st to 10thNight
61%5%17%13%3
1418
11th to 20thNight
64%5%16%11%41
1239
21st to endNight
60%5%19%12%4
1358
June1st to 10thNight
67%415%11%12
1260
11th to 20thNight
68%5%17%9%1
1260
21st to endNight
64%319%12%2
1260
July1st to 10thNight
56%422%15%2
1225
11th to 20thNight
58%424%13%1
1218
21st to endNight
50%6%28%13%3
1302
August1st to 10thNight
53%6%22%18%2
1397
11th to 20thNight
51%6%21%17%4
1576
21st to endNight
67%5%15%11%2
1782
September1st to 10thNight
61%421%11%21
1691
11th to 20thNight
57%414%19%6%
1980
21st to endNight
76%47%9%31
1980
October1st to 10thNight
66%213%14%41
2090
11th to 20thNight
75%311%9%3
2276
21st to endNight
71%38%12%7%1
2574
November1st to 10thNight
80%26%6%5%1
2572
11th to 20thNight
79%25%8%5%2
2740
21st to endNight
77%16%8%6%1
2850
December1st to 10thNight
66%39%12%9%1
2850
11th to 20thNight
78%347%6%2
3516
21st to endNight
82%25%5%32
5214

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
48%16%17%10%6%3
180
11th to 20thDay
55%13%12%11%8%1
180
21st to endDay
55%8%15%13%8%2
331
February1st to 10thDay
50%12%18%13%7%
353
11th to 20thDay
40%13%18%16%11%2
335
21st to endDay
46%15%19%10%9%1
280
March1st to 10thDay
37%11%21%17%10%3
340
11th to 20thDay
41%16%15%17%10%2
419
21st to endDay
42%8%17%17%13%2
462
April1st to 10thDay
43%12%18%17%9%2
420
11th to 20thDay
33%8%19%21%15%4
412
21st to endDay
37%10%20%17%13%4
420
May1st to 10thDay
32%8%17%24%16%2
512
11th to 20thDay
28%6%19%29%14%4
625
21st to endDay
32%7%23%26%10%2
680
June1st to 10thDay
40%9%16%21%12%2
630
11th to 20thDay
36%9%19%19%13%3
630
21st to endDay
33%5%15%26%15%5%
630
July1st to 10thDay
26%6%14%27%22%5%
621
11th to 20thDay
29%8%17%23%19%5%
618
21st to endDay
30%6%12%24%21%7%
684
August1st to 10thDay
24%5%14%24%27%6%
626
11th to 20thDay
26%6%13%29%20%6%
463
21st to endDay
41%7%14%20%15%4
495
September1st to 10thDay
39%6%14%20%15%7%
450
11th to 20thDay
34%8%13%20%20%5%
450
21st to endDay
41%10%20%15%11%4
450
October1st to 10thDay
35%10%12%20%16%7%
450
11th to 20thDay
43%10%16%16%9%5%
391
21st to endDay
42%12%16%17%11%2
396
November1st to 10thDay
48%11%18%12%11%1
198
11th to 20thDay
51%12%14%11%7%6%
180
21st to endDay
49%14%12%11%9%5%
180
December1st to 10thDay
41%12%12%17%13%5%
180
11th to 20thDay
51%8%10%19%9%2
180
21st to endDay
55%8%12%17%7%2
198
January1st to 10thNight
53%12%13%11%9%2
850
11th to 20thNight
56%9%13%13%7%1
850
21st to endNight
53%7%11%16%10%3
935
February1st to 10thNight
53%11%12%17%6%1
822
11th to 20thNight
45%10%11%19%12%3
706
21st to endNight
45%10%13%20%10%2
592
March1st to 10thNight
40%10%18%19%13%1
720
11th to 20thNight
47%10%12%19%11%1
720
21st to endNight
46%8%10%17%15%2
786
April1st to 10thNight
40%7%9%21%19%4
540
11th to 20thNight
40%6%13%21%17%5%
533
21st to endNight
40%6%9%24%18%3
540
May1st to 10thNight
37%6%7%20%23%6%
428
11th to 20thNight
31%410%27%23%5%
354
21st to endNight
31%45%26%29%5%
389
June1st to 10thNight
38%46%17%28%8%
360
11th to 20thNight
38%5%5%21%23%9%
360
21st to endNight
38%35%23%24%8%
360
July1st to 10thNight
31%2418%31%14%
350
11th to 20thNight
32%45%17%30%12%
348
21st to endNight
27%6%316%35%12%
394
August1st to 10thNight
26%5%314%32%20%
509
11th to 20thNight
29%1417%37%13%
534
21st to endNight
40%45%17%28%5%
594
September1st to 10thNight
33%6%7%21%22%11%
571
11th to 20thNight
32%7%6%18%24%13%
720
21st to endNight
47%7%9%18%16%3
720
October1st to 10thNight
40%6%9%21%19%6%
720
11th to 20thNight
47%7%9%17%14%5%
720
21st to endNight
47%7%10%21%11%3
792
November1st to 10thNight
55%9%13%16%6%1
740
11th to 20thNight
53%11%11%16%8%2
798
21st to endNight
52%11%10%16%9%2
850
December1st to 10thNight
42%10%14%19%12%3
850
11th to 20thNight
48%12%12%17%8%3
850
21st to endNight
53%11%12%17%7%1
935
Page generated at 2024-02-02 02:20:32. Version ac07

Copyright 2024 Attilla Danko


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