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Burnaby
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Burnaby clear sky chart from 2005-11-06 to 2024-01-16.

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
42%
22573
6%
74816
5%
22517
44%
22517
8%
62279

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
22%
850
4%
2836
3%
846
23%
846
3%
2641
January11th to 20thNight
32%
825
5%
2775
4%
825
34%
825
5%
2421
January21st to endNight
32%
798
6%
2765
5%
798
34%
798
6%
2368
February1st to 10thNight
28%
720
3%
2340
2%
720
29%
720
6%
2053
February11th to 20thNight
32%
700
7%
2274
5%
700
36%
700
7%
1918
February21st to endNight
32%
592
7%
1908
4%
592
37%
592
6%
1650
March1st to 10thNight
34%
720
5%
2102
4%
720
35%
720
7%
1832
March11th to 20thNight
31%
720
5%
1980
4%
720
33%
720
6%
1774
March21st to endNight
32%
792
4%
2120
2%
792
33%
792
7%
1882
April1st to 10thNight
36%
720
3%
1800
1%
720
37%
720
9%
1582
April11th to 20thNight
39%
621
10%
1689
5%
621
41%
621
10%
1419
April21st to endNight
42%
485
5%
1565
4%
485
43%
485
7%
1317
May1st to 10thNight
56%
360
8%
1440
11%
360
58%
360
9%
1114
May11th to 20thNight
60%
354
8%
1416
15%
354
60%
354
10%
1061
May21st to endNight
57%
388
4%
1498
6%
388
57%
388
8%
1196
June1st to 10thNight
53%
360
2%
1260
2%
360
53%
360
9%
1034
June11th to 20thNight
50%
360
1%
1260
1%
360
50%
360
8%
1047
June21st to endNight
62%
360
4%
1260
2%
360
62%
360
12%
952
July1st to 10thNight
70%
350
6%
1225
5%
350
70%
350
16%
860
July11th to 20thNight
75%
348
10%
1218
12%
348
75%
348
19%
823
July21st to endNight
82%
394
12%
1438
20%
372
84%
372
20%
901
August1st to 10thNight
78%
370
10%
1436
17%
368
78%
368
16%
957
August11th to 20thNight
82%
534
15%
1602
16%
534
82%
534
24%
1059
August21st to endNight
67%
651
12%
1839
10%
651
68%
651
17%
1373
September1st to 10thNight
72%
720
16%
1800
10%
720
72%
720
26%
1284
September11th to 20thNight
56%
720
14%
1800
9%
720
57%
720
18%
1398
September21st to endNight
51%
720
11%
2064
10%
720
52%
720
12%
1665
October1st to 10thNight
53%
720
8%
2160
8%
720
54%
720
13%
1694
October11th to 20thNight
42%
720
6%
2160
5%
720
44%
720
11%
1762
October21st to endNight
36%
792
5%
2521
4%
792
38%
792
7%
2142
November1st to 10thNight
28%
740
3%
2590
3%
740
29%
740
4%
2350
November11th to 20thNight
28%
760
5%
2660
4%
760
30%
760
5%
2338
November21st to endNight
28%
760
3%
2660
1%
760
30%
760
5%
2331
December1st to 10thNight
36%
767
4%
2675
3%
767
38%
767
6%
2323
December11th to 20thNight
22%
850
2%
3514
1%
849
23%
849
3%
3171
December21st to endNight
21%
932
2%
5166
2%
905
24%
905
2%
4587

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
26%8%36%5%34446%31%
74762
Night
30%8%35%424445%30%
75037
TransparencyDay
39%36%9%11%41
74451
Night
40%36%9%10%41
74866
SeeingDay
27%6%17%26%18%6%
14221
Night
34%5%10%26%21%5%
22581

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
50%8%35%5%3433413%
1329
11th to 20thDay
38%11%35%5%35%335%19%
1295
21st to endDay
39%10%36%5%245%5%5%16%
1587
February1st to 10thDay
36%10%46%6%4435%6%17%
1620
11th to 20thDay
34%9%36%5%34436%22%
1575
21st to endDay
26%12%5%7%6%46%336%23%
1347
March1st to 10thDay
31%12%46%6%24445%20%
1857
11th to 20thDay
38%11%36%5%3332421%
1980
21st to endDay
31%12%46%6%3445%5%20%
2235
April1st to 10thDay
31%9%46%5%46%5%5%6%19%
2160
11th to 20thDay
25%9%5%7%5%35%45%5%25%
2219
21st to endDay
26%10%46%5%35%45%6%26%
2394
May1st to 10thDay
18%8%45%6%45%5%5%6%34%
2520
11th to 20thDay
18%8%36%6%35%5%5%8%32%
2477
21st to endDay
20%8%37%6%35%46%6%32%
2772
June1st to 10thDay
24%8%36%5%4445%6%30%
2700
11th to 20thDay
23%9%47%6%36%5%5%7%25%
2700
21st to endDay
15%7%46%435%46%7%38%
2700
July1st to 10thDay
13%5%35%42445%6%50%
2700
11th to 20thDay
12%5%24424446%53%
2700
21st to endDay
8%323323347%61%
2791
August1st to 10thDay
11%5%24423345%56%
2491
11th to 20thDay
10%5%24433346%56%
2298
21st to endDay
15%5%245%345%5%8%46%
2516
September1st to 10thDay
17%6%25%423446%47%
2160
11th to 20thDay
21%7%36%43335%6%40%
2160
21st to endDay
26%6%25%42445%6%36%
1892
October1st to 10thDay
26%7%35%43345%6%34%
1800
11th to 20thDay
35%8%26%43445%6%24%
1800
21st to endDay
37%8%35%42335%5%23%
1831
November1st to 10thDay
43%8%36%5%3334417%
1488
11th to 20thDay
42%9%36%5%2333321%
1520
21st to endDay
43%8%44423445%19%
1520
December1st to 10thDay
35%12%45%42343425%
1501
11th to 20thDay
40%15%47%5%345%4412%
1685
21st to endDay
46%13%46%5%3433310%
2442
January1st to 10thNight
46%11%36%42333416%
2836
11th to 20thNight
42%8%25%424446%20%
2775
21st to endNight
35%12%46%423445%21%
2765
February1st to 10thNight
36%10%36%5%24445%20%
2340
11th to 20thNight
31%12%36%5%34445%25%
2272
21st to endNight
29%11%36%5%3445%427%
1908
March1st to 10thNight
33%9%35%5%25%45%424%
2102
11th to 20thNight
37%10%35%5%24445%22%
1979
21st to endNight
34%11%46%5%34445%20%
2120
April1st to 10thNight
30%10%36%6%45%45%5%23%
1800
11th to 20thNight
23%11%47%6%34446%28%
1689
21st to endNight
26%9%46%5%35%45%5%28%
1565
May1st to 10thNight
18%5%35%5%35%6%5%6%40%
1440
11th to 20thNight
16%6%35%7%346%6%8%36%
1416
21st to endNight
17%8%36%5%36%5%5%6%37%
1498
June1st to 10thNight
24%6%35%5%35%45%7%33%
1260
11th to 20thNight
18%10%36%5%35%5%5%9%30%
1260
21st to endNight
14%5%35%5%35%46%8%43%
1260
July1st to 10thNight
11%4245%24347%54%
1260
11th to 20thNight
10%324323447%59%
1260
21st to endNight
5%213323346%67%
1523
August1st to 10thNight
8%5%23323335%63%
1444
11th to 20thNight
7%31231235%6%65%
1602
21st to endNight
10%5%345%345%7%8%47%
1839
September1st to 10thNight
10%41443345%6%56%
1800
11th to 20thNight
22%6%245%23445%44%
1800
21st to endNight
23%7%26%423345%41%
2064
October1st to 10thNight
22%6%24435%5%4440%
2160
11th to 20thNight
33%7%24423435%31%
2160
21st to endNight
37%7%35%423445%28%
2521
November1st to 10thNight
42%9%36%5%3444419%
2590
11th to 20thNight
39%8%4443433423%
2660
21st to endNight
40%9%36%6%3433421%
2660
December1st to 10thNight
35%9%36%434335%26%
2675
11th to 20thNight
47%12%36%42343313%
3520
21st to endNight
47%12%46%42322316%
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
54%38%341
1329
11th to 20thDay
43%41%5%6%22
1295
21st to endDay
46%37%5%9%3
1587
February1st to 10thDay
48%36%8%6%2
1620
11th to 20thDay
43%37%7%8%5%
1584
21st to endDay
48%35%6%7%31
1347
March1st to 10thDay
48%36%6%7%2
1857
11th to 20thDay
48%35%6%8%31
1980
21st to endDay
47%36%6%9%2
2235
April1st to 10thDay
46%36%9%6%2
2160
11th to 20thDay
42%36%5%9%7%1
2219
21st to endDay
42%36%9%9%4
2394
May1st to 10thDay
38%36%10%13%3
2520
11th to 20thDay
34%37%11%14%4
2480
21st to endDay
41%36%9%12%2
2773
June1st to 10thDay
40%35%11%8%32
2700
11th to 20thDay
45%36%12%7%1
2700
21st to endDay
34%36%13%10%6%1
2700
July1st to 10thDay
25%37%12%17%7%2
2626
11th to 20thDay
23%36%14%21%6%1
2619
21st to endDay
18%36%12%20%11%3
2636
August1st to 10thDay
25%36%13%20%5%1
2474
11th to 20thDay
21%36%15%15%11%3
2298
21st to endDay
27%36%13%19%41
2516
September1st to 10thDay
24%35%12%17%9%4
2160
11th to 20thDay
31%35%9%13%10%2
2160
21st to endDay
35%37%10%11%6%1
1892
October1st to 10thDay
34%35%11%12%7%
1800
11th to 20thDay
41%37%10%9%21
1800
21st to endDay
43%36%8%9%4
1831
November1st to 10thDay
49%39%35%31
1488
11th to 20thDay
47%38%6%6%31
1520
21st to endDay
46%39%47%4
1520
December1st to 10thDay
44%40%5%6%5%
1501
11th to 20thDay
55%30%6%7%11
1688
21st to endDay
65%23%6%5%1
2442
January1st to 10thNight
52%38%36%1
2836
11th to 20thNight
42%41%7%7%32
2775
21st to endNight
44%36%5%10%41
2765
February1st to 10thNight
46%36%9%6%2
2340
11th to 20thNight
41%37%7%9%5%1
2274
21st to endNight
45%35%6%9%41
1908
March1st to 10thNight
45%36%9%9%2
2102
11th to 20thNight
48%35%6%7%3
1980
21st to endNight
47%35%9%7%2
2120
April1st to 10thNight
45%35%11%8%2
1800
11th to 20thNight
39%35%7%11%5%2
1689
21st to endNight
41%36%9%9%4
1565
May1st to 10thNight
33%36%13%13%5%
1440
11th to 20thNight
31%36%13%15%5%1
1416
21st to endNight
37%36%14%11%3
1498
June1st to 10thNight
38%36%12%9%32
1260
11th to 20thNight
40%36%14%8%1
1260
21st to endNight
29%37%14%11%6%3
1260
July1st to 10thNight
22%36%14%17%9%2
1225
11th to 20thNight
17%37%16%22%7%1
1218
21st to endNight
12%37%12%22%13%4
1438
August1st to 10thNight
20%36%14%21%8%1
1436
11th to 20thNight
15%35%19%16%9%6%
1602
21st to endNight
25%37%14%17%6%1
1839
September1st to 10thNight
17%36%12%20%12%4
1800
11th to 20thNight
28%35%10%12%11%3
1800
21st to endNight
35%36%9%13%5%2
2064
October1st to 10thNight
32%35%11%13%8%
2160
11th to 20thNight
37%35%11%13%3
2160
21st to endNight
41%37%7%9%5%
2521
November1st to 10thNight
47%39%46%21
2590
11th to 20thNight
44%39%7%6%3
2660
21st to endNight
44%38%7%7%4
2660
December1st to 10thNight
42%39%8%7%31
2675
11th to 20thNight
55%31%6%43
3516
21st to endNight
63%23%47%3
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%413%18%9%7%
180
11th to 20thDay
52%8%7%14%14%6%
170
21st to endDay
44%7%9%16%18%5%
194
February1st to 10thDay
45%416%20%13%1
340
11th to 20thDay
40%6%16%21%15%2
335
21st to endDay
33%9%23%22%10%3
288
March1st to 10thDay
34%7%20%22%13%4
420
11th to 20thDay
38%6%15%20%17%4
420
21st to endDay
37%8%19%21%12%3
462
April1st to 10thDay
34%8%19%21%15%2
420
11th to 20thDay
29%7%21%22%15%6%
412
21st to endDay
28%8%21%26%12%4
420
May1st to 10thDay
19%8%20%30%19%4
423
11th to 20thDay
23%415%28%21%8%
448
21st to endDay
19%6%23%28%17%7%
534
June1st to 10thDay
24%6%21%31%15%4
630
11th to 20thDay
23%8%24%28%14%2
630
21st to endDay
16%7%19%30%23%5%
630
July1st to 10thDay
16%417%35%24%5%
621
11th to 20thDay
10%6%19%35%25%5%
618
21st to endDay
8%214%39%28%9%
537
August1st to 10thDay
15%5%14%27%29%11%
447
11th to 20thDay
10%311%38%31%8%
437
21st to endDay
15%5%20%32%18%10%
495
September1st to 10thDay
20%6%20%31%18%6%
450
11th to 20thDay
21%6%15%27%26%5%
450
21st to endDay
26%418%23%21%7%
450
October1st to 10thDay
30%5%15%23%20%8%
450
11th to 20thDay
37%7%12%18%18%8%
450
21st to endDay
40%7%13%22%12%6%
362
November1st to 10thDay
42%7%14%19%17%2
180
11th to 20thDay
47%7%6%13%15%12%
180
21st to endDay
45%7%13%14%9%12%
180
December1st to 10thDay
48%6%13%8%13%12%
180
11th to 20thDay
47%5%13%16%16%3
180
21st to endDay
45%6%14%23%10%3
198
January1st to 10thNight
51%7%12%18%10%3
850
11th to 20thNight
47%5%9%22%15%2
825
21st to endNight
43%6%9%25%14%3
798
February1st to 10thNight
43%5%15%25%11%1
720
11th to 20thNight
39%6%13%28%13%1
704
21st to endNight
36%7%15%26%14%3
592
March1st to 10thNight
38%7%13%22%18%2
720
11th to 20thNight
42%6%12%25%13%3
720
21st to endNight
40%5%11%24%16%3
792
April1st to 10thNight
36%6%11%27%17%3
720
11th to 20thNight
28%8%14%29%17%5%
621
21st to endNight
30%6%11%34%16%4
485
May1st to 10thNight
21%211%34%29%3
360
11th to 20thNight
19%45%29%36%7%
354
21st to endNight
21%25%35%32%4
389
June1st to 10thNight
26%37%33%27%4
360
11th to 20thNight
20%6%13%31%26%4
360
21st to endNight
15%311%30%36%6%
360
July1st to 10thNight
11%45%31%44%5%
350
11th to 20thNight
11%25%30%43%8%
348
21st to endNight
7%1428%48%12%
394
August1st to 10thNight
11%3122%46%16%
370
11th to 20thNight
8%1224%49%14%
534
21st to endNight
14%46%26%41%10%
651
September1st to 10thNight
13%25%35%37%8%
720
11th to 20thNight
22%47%21%34%12%
720
21st to endNight
27%48%29%28%6%
720
October1st to 10thNight
26%411%25%27%7%
720
11th to 20thNight
37%310%25%19%5%
720
21st to endNight
40%411%28%12%5%
792
November1st to 10thNight
47%5%12%23%13%
740
11th to 20thNight
45%6%13%20%12%4
760
21st to endNight
42%6%12%21%14%4
760
December1st to 10thNight
38%411%27%16%4
767
11th to 20thNight
54%6%10%21%8%1
850
21st to endNight
51%7%13%21%9%1
935
Page generated at 2024-01-12 22:38:09. Version ac07

Copyright 2024 Attilla Danko


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