Mount Kobau Star Party
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Mount Kobau Star Party clear sky chart from 2005-11-05 to 2018-03-21.

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
33%
15429
13%
49040
7%
15402
40%
15402
20%
31744

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 15thNight
24%
778
7%
2716
3%
776
29%
776
10%
2080
January16th to endNight
28%
832
8%
2912
5%
832
32%
832
10%
2229
February1st to 15thNight
27%
761
8%
2564
4%
760
34%
760
13%
1860
February16th to endNight
31%
684
13%
2124
7%
684
39%
684
19%
1420
March1st to 15thNight
29%
780
10%
2338
6%
780
34%
780
16%
1648
March16th to endNight
24%
792
12%
2067
3%
792
30%
792
20%
1466
April1st to 15thNight
33%
719
13%
1799
4%
719
37%
719
26%
1232
April16th to endNight
30%
523
16%
1603
9%
523
37%
523
26%
946
May1st to 15thNight
32%
359
17%
1439
13%
359
47%
359
25%
720
May16th to endNight
39%
374
10%
1496
10%
374
46%
374
21%
829
June1st to 15thNight
36%
360
6%
1308
2%
360
39%
360
24%
740
June16th to endNight
35%
360
10%
1136
1%
360
39%
360
32%
608
July1st to 15thNight
51%
340
11%
1273
7%
340
56%
340
41%
543
July16th to endNight
49%
376
21%
1416
19%
354
69%
354
46%
550
August1st to 15thNight
60%
360
24%
1432
26%
358
70%
358
42%
574
August16th to endNight
50%
654
30%
1800
17%
654
58%
654
51%
869
September1st to 15thNight
51%
720
28%
1800
11%
720
58%
720
51%
941
September16th to endNight
47%
716
27%
1941
15%
716
55%
716
40%
1077
October1st to 15thNight
36%
720
16%
2160
11%
720
44%
720
28%
1296
October16th to endNight
38%
768
15%
2460
8%
768
48%
768
21%
1594
November1st to 15thNight
25%
760
10%
2583
5%
760
32%
760
13%
1882
November16th to endNight
23%
780
8%
2730
3%
780
29%
780
10%
2034
December1st to 15thNight
23%
974
9%
2924
3%
974
29%
974
12%
2242
December16th to endNight
20%
939
10%
3019
4%
939
27%
939
10%
2364

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
9%9%47%6%46%5%5%7%34%
49811
Night
6%8%47%6%35%5%6%7%38%
49205
Cloud CoverDay
8%8%36%6%35%5%6%7%37%
49811
Night
7%9%47%5%345%5%7%39%
49209
TransparencyDay
43%5%15%22%11%2
49479
Night
43%416%22%10%1
49041
SeeingDay
12%24%31%22%7%1
6382
Night
10%19%28%27%12%1
15436

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 15thDay
5%12%6%10%8%36%5%6%8%25%
1552
16th to endDay
5%13%5%8%7%35%5%6%8%29%
1664
February1st to 15thDay
5%13%5%7%8%46%6%6%8%26%
1627
16th to endDay
314%6%9%7%46%7%6%7%24%
1635
March1st to 15thDay
7%15%48%7%5%7%6%6%7%23%
1950
16th to endDay
9%17%6%11%7%36%5%5%6%19%
2284
April1st to 15thDay
8%17%5%9%9%46%46%6%22%
2149
16th to endDay
8%11%47%8%46%5%6%7%28%
2354
May1st to 15thDay
10%10%37%6%46%5%6%7%33%
2511
16th to endDay
17%9%38%6%46%45%7%25%
2615
June1st to 15thDay
18%7%36%7%46%5%46%28%
2646
16th to endDay
14%7%36%7%46%5%5%6%31%
2819
July1st to 15thDay
7%425%6%35%445%50%
2607
16th to endDay
6%3144245%46%54%
2657
August1st to 15thDay
5%2245%35%5%6%6%51%
2520
16th to endDay
6%4145%35%45%6%51%
2400
September1st to 15thDay
7%314423346%58%
2160
16th to endDay
9%6%36%5%345%36%44%
2015
October1st to 15thDay
10%6%46%5%45%46%6%39%
1800
16th to endDay
14%8%38%5%35%45%7%33%
1764
November1st to 15thDay
9%14%5%8%6%37%5%7%7%24%
1605
16th to endDay
5%13%5%8%7%49%6%6%7%25%
1546
December1st to 15thDay
38%6%7%8%46%7%8%8%31%
1365
16th to endDay
6%13%6%10%6%45%5%6%6%26%
1566
January1st to 15thNight
6%11%7%11%9%45%5%5%8%23%
2716
16th to endNight
6%10%5%10%8%36%6%5%8%27%
2912
February1st to 15thNight
6%12%48%7%5%6%6%6%6%30%
2552
16th to endNight
49%5%8%6%36%7%7%7%32%
2124
March1st to 15thNight
6%11%5%7%6%46%6%6%8%28%
2338
16th to endNight
6%10%48%8%47%6%6%6%29%
2063
April1st to 15thNight
6%9%46%7%5%7%5%6%6%33%
1799
16th to endNight
5%8%345%26%5%6%8%41%
1603
May1st to 15thNight
5%7%235%3445%8%48%
1439
16th to endNight
11%5%245%245%7%12%36%
1496
June1st to 15thNight
11%5%25%6%35%5%6%6%41%
1308
16th to endNight
6%5%23325%5%6%7%48%
1136
July1st to 15thNight
411331445%6%62%
1350
16th to endNight
31222336%7%66%
1512
August1st to 15thNight
2312324447%63%
1440
16th to endNight
32123235%48%61%
1800
September1st to 15thNight
4212324446%63%
1800
16th to endNight
7%5%143245%5%8%50%
1941
October1st to 15thNight
8%6%25%6%35%5%5%5%44%
2160
16th to endNight
10%8%26%5%45%6%6%7%35%
2460
November1st to 15thNight
8%11%48%7%5%6%5%6%7%28%
2583
16th to endNight
413%5%9%7%5%8%6%5%6%26%
2730
December1st to 15thNight
411%7%9%7%46%6%5%6%29%
2924
16th to endNight
5%14%7%11%8%36%5%5%5%26%
3019

Percentage Cloud Cover SW (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 15thDay
6%15%8%14%6%35%5%5%5%23%
1552
16th to endDay
8%17%8%9%5%3335%7%26%
1664
February1st to 15thDay
7%14%6%7%6%35%5%6%7%28%
1627
16th to endDay
5%11%48%7%46%8%6%9%28%
1635
March1st to 15thDay
9%13%36%6%48%7%6%8%26%
1950
16th to endDay
7%12%5%8%8%47%6%7%9%23%
2284
April1st to 15thDay
8%10%38%7%47%6%7%9%26%
2149
16th to endDay
8%7%36%7%35%6%6%9%34%
2354
May1st to 15thDay
7%6%26%7%45%5%6%8%38%
2511
16th to endDay
12%7%37%7%36%6%6%8%31%
2615
June1st to 15thDay
15%6%26%6%36%46%7%33%
2646
16th to endDay
10%5%36%6%46%5%6%7%37%
2819
July1st to 15thDay
4314435%45%6%54%
2607
16th to endDay
42133245%5%7%58%
2657
August1st to 15thDay
33134245%5%7%56%
2520
16th to endDay
5%2134245%6%7%55%
2400
September1st to 15thDay
4214423346%62%
2160
16th to endDay
7%5%235%25%5%6%7%47%
2015
October1st to 15thDay
9%5%25%5%35%5%5%7%43%
1800
16th to endDay
14%12%36%4235%5%7%33%
1764
November1st to 15thDay
10%15%46%6%346%6%9%25%
1605
16th to endDay
8%13%7%11%6%35%45%7%26%
1546
December1st to 15thDay
5%13%6%9%7%45%6%5%8%26%
1365
16th to endDay
8%16%8%10%6%35%45%6%24%
1566
January1st to 15thNight
8%16%8%14%7%4345%6%21%
2716
16th to endNight
7%17%8%12%7%34446%22%
2912
February1st to 15thNight
8%14%6%10%43446%7%28%
2552
16th to endNight
5%9%38%7%35%6%7%8%34%
2124
March1st to 15thNight
8%11%47%6%36%5%6%7%30%
2338
16th to endNight
6%8%37%7%47%6%6%8%31%
2067
April1st to 15thNight
7%7%36%6%35%6%7%7%38%
1799
16th to endNight
5%6%25%5%25%5%7%9%44%
1603
May1st to 15thNight
5%41443445%8%51%
1439
16th to endNight
11%324347%46%10%42%
1496
June1st to 15thNight
9%5%24435%6%5%8%44%
1308
16th to endNight
5%3244246%6%9%51%
1136
July1st to 15thNight
321221345%7%65%
1350
16th to endNight
21211335%8%69%
1512
August1st to 15thNight
12322335%7%65%
1440
16th to endNight
311232345%7%65%
1800
September1st to 15thNight
322323345%68%
1800
16th to endNight
6%31432345%8%55%
1941
October1st to 15thNight
10%5%235%345%5%6%46%
2160
16th to endNight
12%7%25%5%35%5%6%8%37%
2460
November1st to 15thNight
11%14%45%5%36%5%5%8%28%
2583
16th to endNight
8%16%8%9%6%3445%6%24%
2730
December1st to 15thNight
7%14%7%10%8%445%36%26%
2924
16th to endNight
8%18%8%12%7%33335%23%
3019

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 15thDay
61%7%14%11%4
1552
16th to endDay
57%6%14%15%41
1664
February1st to 15thDay
52%8%18%15%4
1627
16th to endDay
48%7%19%16%7%
1635
March1st to 15thDay
50%7%19%17%4
1950
16th to endDay
53%5%19%16%4
2284
April1st to 15thDay
51%6%16%18%7%
2149
16th to endDay
44%6%16%25%6%
2354
May1st to 15thDay
41%317%24%11%1
2511
16th to endDay
47%417%23%5%
2619
June1st to 15thDay
47%314%22%8%2
2646
16th to endDay
43%313%25%13%1
2819
July1st to 15thDay
28%39%25%22%8%
2455
16th to endDay
23%49%28%27%6%
2490
August1st to 15thDay
24%411%34%20%5%
2503
16th to endDay
25%313%33%20%3
2400
September1st to 15thDay
22%213%29%27%3
2160
16th to endDay
32%5%17%26%15%2
2015
October1st to 15thDay
37%420%26%11%
1800
16th to endDay
49%5%17%21%5%
1764
November1st to 15thDay
52%9%16%15%41
1605
16th to endDay
56%6%14%15%5%
1546
December1st to 15thDay
55%6%17%17%2
1365
16th to endDay
60%5%12%15%5%
1566
January1st to 15thNight
62%415%14%3
2716
16th to endNight
62%415%12%4
2912
February1st to 15thNight
53%6%18%14%5%
2564
16th to endNight
45%6%20%22%6%
2124
March1st to 15thNight
49%6%19%19%4
2338
16th to endNight
47%5%19%21%5%
2067
April1st to 15thNight
41%6%18%24%8%1
1799
16th to endNight
34%420%31%8%
1603
May1st to 15thNight
30%218%30%16%1
1440
16th to endNight
36%423%29%5%
1496
June1st to 15thNight
35%415%31%10%2
1308
16th to endNight
27%419%29%17%1
1136
July1st to 15thNight
18%314%30%23%9%
1273
16th to endNight
13%310%32%31%8%
1416
August1st to 15thNight
17%312%35%25%6%
1432
16th to endNight
16%214%36%25%4
1800
September1st to 15thNight
17%214%32%27%5%
1800
16th to endNight
26%316%32%17%3
1941
October1st to 15thNight
36%318%27%13%
2160
16th to endNight
43%5%19%26%4
2460
November1st to 15thNight
53%7%17%14%41
2583
16th to endNight
60%414%14%6%
2730
December1st to 15thNight
59%6%15%16%2
2924
16th to endNight
63%410%13%6%
3019

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 15thDay
7%6%25%31%20%8%
90
16th to endDay
30%14%25%22%43
96
February1st to 15thDay
12%24%40%18%2
197
16th to endDay
11%21%36%22%5%
273
March1st to 15thDay
20%31%29%13%4
330
16th to endDay
15%36%28%16%2
311
April1st to 15thDay
20%33%24%16%41
269
16th to endDay
12%36%28%15%42
270
May1st to 15thDay
13%30%30%18%6%1
288
16th to endDay
13%22%25%22%11%4
330
June1st to 15thDay
13%24%26%26%8%
441
16th to endDay
9%24%36%22%6%
614
July1st to 15thDay
422%33%30%7%1
389
16th to endDay
423%30%29%9%1
327
August1st to 15thDay
6%16%30%32%11%3
315
16th to endDay
7%20%33%27%7%3
332
September1st to 15thDay
7%18%33%26%10%3
315
16th to endDay
10%25%32%20%9%1
315
October1st to 15thDay
13%27%32%18%6%
315
16th to endDay
25%12%29%20%10%1
180
November1st to 15thDay
19%12%45%17%3
109
16th to endDay
15%18%25%26%10%3
90
December1st to 15thDay
16%6%32%30%11%3
90
16th to endDay
11%9%44%30%4
96
January1st to 15thNight
12%21%28%23%12%1
780
16th to endNight
13%20%28%24%11%1
832
February1st to 15thNight
11%21%28%26%10%1
764
16th to endNight
7%20%29%27%12%1
684
March1st to 15thNight
13%22%27%25%9%1
780
16th to endNight
9%21%32%26%8%
792
April1st to 15thNight
9%21%28%28%11%1
719
16th to endNight
6%25%31%27%8%1
523
May1st to 15thNight
6%23%30%25%12%
360
16th to endNight
10%21%20%33%13%
375
June1st to 15thNight
8%24%23%30%12%
360
16th to endNight
6%19%33%30%10%
360
July1st to 15thNight
416%24%36%17%1
340
16th to endNight
120%24%34%17%
376
August1st to 15thNight
113%19%41%21%1
360
16th to endNight
312%28%32%20%1
654
September1st to 15thNight
315%23%29%24%3
720
16th to endNight
8%12%24%31%20%3
716
October1st to 15thNight
13%15%28%24%15%1
720
16th to endNight
15%12%26%31%11%2
768
November1st to 15thNight
18%19%30%24%6%
760
16th to endNight
16%24%29%18%9%2
780
December1st to 15thNight
14%21%32%22%7%
974
16th to endNight
15%22%33%23%5%
939
Page generated at 2018-03-22 08:34:23. Version ac04

Copyright 2018 A. Danko


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