Chi'Cheemaun 1/3rd Point
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Chi'Cheemaun 1/3rd Point clear sky chart from 2005-11-05 to 2017-09-16.

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
33%
15259
10%
46753
8%
15218
36%
15218
14%
35537

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
10%
898
1%
2616
0%
895
11%
895
3%
2438
January16th to endNight
17%
869
5%
2597
2%
869
20%
869
5%
2322
February1st to 15thNight
15%
702
5%
2287
2%
701
18%
701
7%
1944
February16th to endNight
26%
631
8%
1964
4%
631
31%
631
10%
1586
March1st to 15thNight
26%
720
12%
2042
6%
720
31%
720
17%
1520
March16th to endNight
40%
768
19%
2112
11%
768
46%
768
24%
1463
April1st to 15thNight
32%
632
16%
1785
7%
632
38%
632
22%
1247
April16th to endNight
40%
540
18%
1620
10%
540
45%
540
22%
1098
May1st to 15thNight
50%
539
13%
1619
13%
539
52%
539
21%
1126
May16th to endNight
53%
375
14%
1459
16%
374
57%
374
22%
846
June1st to 15thNight
50%
360
13%
1260
14%
360
55%
360
24%
783
June16th to endNight
64%
360
11%
1260
13%
360
66%
360
26%
766
July1st to 15thNight
68%
340
16%
1190
19%
340
70%
340
33%
651
July16th to endNight
65%
535
15%
1458
16%
502
64%
502
32%
887
August1st to 15thNight
63%
539
17%
1609
15%
536
66%
536
32%
963
August16th to endNight
61%
573
18%
1719
13%
573
64%
573
30%
1063
September1st to 15thNight
53%
696
14%
1869
10%
696
55%
696
28%
1251
September16th to endNight
51%
658
17%
1818
12%
658
53%
658
26%
1228
October1st to 15thNight
35%
660
12%
1952
10%
660
39%
660
16%
1472
October16th to endNight
22%
704
7%
2183
4%
704
26%
704
9%
1795
November1st to 15thNight
24%
700
12%
2354
11%
700
28%
700
11%
1861
November16th to endNight
17%
720
5%
2520
4%
720
18%
720
5%
2187
December1st to 15thNight
7%
780
1%
2580
0%
780
8%
780
2%
2382
December16th to endNight
8%
960
2%
2880
0%
960
10%
960
3%
2658

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
15%9%36%5%3445%7%35%
47993
Night
17%11%48%6%34445%29%
46919
Cloud CoverDay
15%9%36%5%3445%6%35%
48003
Night
17%12%48%6%34445%28%
46923
TransparencyDay
49%7%12%19%9%
47677
Night
58%6%10%15%8%
46753
SeeingDay
18%421%31%18%4
5859
Night
23%8%25%25%13%2
15263

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 15thDay
20%15%8%12%8%45%5%4410%
1320
16th to endDay
15%17%7%10%9%5%6%43413%
1626
February1st to 15thDay
12%15%7%12%8%35%45%5%18%
1575
16th to endDay
13%12%5%10%7%25%35%6%25%
1509
March1st to 15thDay
13%8%46%5%35%446%36%
1906
16th to endDay
13%6%36%5%3445%6%40%
2112
April1st to 15thDay
20%6%35%5%24446%37%
2172
16th to endDay
17%7%24424347%41%
2340
May1st to 15thDay
18%7%24433347%39%
2331
16th to endDay
12%5%244345%5%8%45%
2654
June1st to 15thDay
12%5%25%6%25%46%8%40%
2700
16th to endDay
11%6%25%5%35%5%6%9%38%
2700
July1st to 15thDay
7%4244345%5%8%50%
2700
16th to endDay
8%3243345%5%10%48%
2604
August1st to 15thDay
10%41333445%8%49%
2340
16th to endDay
10%5%245%3445%8%45%
2483
September1st to 15thDay
12%435%5%2435%7%45%
2076
16th to endDay
16%5%244245%5%8%41%
1815
October1st to 15thDay
21%9%35%5%3445%5%31%
1678
16th to endDay
28%12%47%6%35%335%20%
1687
November1st to 15thDay
19%13%46%6%36%445%24%
1504
16th to endDay
25%20%5%8%7%3433412%
1440
December1st to 15thDay
20%24%9%13%7%423338%
1377
16th to endDay
21%22%8%11%7%333438%
1344
January1st to 15thNight
20%19%7%13%8%35%4439%
2616
16th to endNight
15%17%8%12%9%35%33316%
2597
February1st to 15thNight
13%16%7%13%8%34345%17%
2285
16th to endNight
14%14%6%8%7%45%5%5%423%
1964
March1st to 15thNight
16%10%47%435%45%6%33%
2030
16th to endNight
13%7%26%6%23446%41%
2112
April1st to 15thNight
22%7%35%41335%6%37%
1785
16th to endNight
17%8%35%433446%37%
1620
May1st to 15thNight
16%6%36%6%36%446%35%
1619
16th to endNight
11%7%245%2435%7%43%
1457
June1st to 15thNight
12%6%36%5%35%5%5%7%39%
1260
16th to endNight
8%426%5%36%5%6%8%41%
1260
July1st to 15thNight
8%32442445%7%52%
1260
16th to endNight
8%315%43445%7%49%
1559
August1st to 15thNight
8%314435%5%5%7%49%
1620
16th to endNight
10%415%5%3445%8%46%
1719
September1st to 15thNight
14%4245%335%5%6%43%
1869
16th to endNight
17%5%2443345%6%41%
1818
October1st to 15thNight
24%9%37%5%33345%28%
1952
16th to endNight
29%11%36%5%23446%21%
2183
November1st to 15thNight
20%15%47%5%3446%6%22%
2354
16th to endNight
26%18%6%8%6%24335%14%
2520
December1st to 15thNight
24%21%9%12%7%232338%
2580
16th to endNight
24%21%7%12%6%333338%
2880

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 15thDay
19%19%7%12%8%5%5%5%438%
1320
16th to endDay
15%17%7%11%10%5%6%43411%
1626
February1st to 15thDay
13%15%8%12%10%45%5%4417%
1575
16th to endDay
13%12%7%10%7%25%35%6%24%
1509
March1st to 15thDay
14%8%46%5%35%45%6%35%
1917
16th to endDay
12%7%37%5%345%5%6%39%
2111
April1st to 15thDay
20%6%25%5%34446%36%
2172
16th to endDay
17%6%24423348%41%
2340
May1st to 15thDay
17%7%2443335%6%40%
2331
16th to endDay
11%5%2432445%8%46%
2654
June1st to 15thDay
12%5%245%25%5%6%8%40%
2700
16th to endDay
11%5%25%5%25%5%6%9%39%
2700
July1st to 15thDay
6%42442445%8%51%
2700
16th to endDay
7%42432446%9%49%
2604
August1st to 15thDay
10%41443335%8%50%
2340
16th to endDay
9%5%25%5%245%48%45%
2483
September1st to 15thDay
13%5%25%42445%6%46%
2076
16th to endDay
16%6%2442445%7%41%
1815
October1st to 15thDay
22%8%36%5%24446%31%
1678
16th to endDay
27%12%48%6%3444420%
1687
November1st to 15thDay
19%14%47%6%35%445%23%
1504
16th to endDay
23%22%6%8%6%3433413%
1440
December1st to 15thDay
20%24%10%12%9%232328%
1377
16th to endDay
21%21%9%13%7%342437%
1344
January1st to 15thNight
20%20%7%13%10%443338%
2616
16th to endNight
15%16%9%12%9%46%33414%
2597
February1st to 15thNight
14%16%8%13%9%3444416%
2278
16th to endNight
13%15%6%9%7%45%6%4422%
1964
March1st to 15thNight
16%10%37%6%24446%32%
2042
16th to endNight
13%7%37%5%33346%40%
2112
April1st to 15thNight
22%7%2441335%6%37%
1785
16th to endNight
17%8%35%5%24446%37%
1620
May1st to 15thNight
16%6%35%6%35%5%36%36%
1618
16th to endNight
11%6%35%5%24447%44%
1457
June1st to 15thNight
12%6%35%5%2447%8%38%
1260
16th to endNight
8%5%25%5%46%5%6%8%42%
1260
July1st to 15thNight
7%3245%35%35%8%51%
1260
16th to endNight
8%324425%5%6%7%49%
1559
August1st to 15thNight
8%3245%245%6%7%49%
1620
16th to endNight
10%426%5%335%5%8%46%
1719
September1st to 15thNight
15%415%5%2445%7%42%
1869
16th to endNight
16%7%1443345%6%41%
1818
October1st to 15thNight
25%9%46%6%33335%28%
1952
16th to endNight
29%12%46%5%34335%21%
2183
November1st to 15thNight
20%16%47%6%2445%6%22%
2354
16th to endNight
25%19%6%9%6%3333414%
2520
December1st to 15thNight
25%21%9%14%7%222237%
2580
16th to endNight
24%22%7%12%7%332337%
2880

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
80%7%7%3
1321
16th to endDay
77%7%8%41
1626
February1st to 15thDay
71%5%10%9%1
1577
16th to endDay
62%6%12%13%4
1509
March1st to 15thDay
48%7%14%19%8%
1917
16th to endDay
44%6%14%20%12%2
2112
April1st to 15thDay
48%5%10%21%11%1
2172
16th to endDay
41%5%12%23%14%2
2340
May1st to 15thDay
45%410%21%14%2
2331
16th to endDay
35%6%16%22%16%1
2658
June1st to 15thDay
40%7%12%27%11%
2700
16th to endDay
39%9%12%25%12%
2700
July1st to 15thDay
30%7%14%29%16%1
2541
16th to endDay
30%10%15%28%14%
2442
August1st to 15thDay
31%8%18%27%13%
2327
16th to endDay
36%8%17%26%10%
2483
September1st to 15thDay
38%6%16%28%8%
2076
16th to endDay
42%7%15%25%8%
1815
October1st to 15thDay
54%5%11%17%11%
1678
16th to endDay
67%7%12%9%3
1687
November1st to 15thDay
61%7%12%12%5%
1504
16th to endDay
75%6%8%6%2
1440
December1st to 15thDay
83%6%421
1377
16th to endDay
84%5%6%3
1344
January1st to 15thNight
83%6%431
2616
16th to endNight
77%7%6%6%2
2597
February1st to 15thNight
73%48%10%2
2287
16th to endNight
64%7%10%10%6%
1964
March1st to 15thNight
52%7%13%18%6%
2042
16th to endNight
45%6%9%20%15%2
2112
April1st to 15thNight
48%49%22%13%1
1785
16th to endNight
46%5%8%18%18%2
1620
May1st to 15thNight
48%5%9%20%13%2
1619
16th to endNight
39%5%14%21%17%2
1459
June1st to 15thNight
41%5%11%23%16%1
1260
16th to endNight
37%7%17%22%14%
1260
July1st to 15thNight
30%6%13%28%19%2
1190
16th to endNight
32%7%14%25%18%
1458
August1st to 15thNight
32%7%16%27%13%1
1609
16th to endNight
35%7%17%26%11%1
1719
September1st to 15thNight
40%7%14%25%10%1
1869
16th to endNight
42%6%14%26%9%
1818
October1st to 15thNight
57%5%9%17%9%
1952
16th to endNight
66%7%10%11%3
2183
November1st to 15thNight
63%6%10%14%4
2354
16th to endNight
74%7%10%6%1
2520
December1st to 15thNight
85%45%31
2580
16th to endNight
83%5%6%31
2880

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
22%14%33%26%2
71
16th to endDay
42%223%21%8%1
96
February1st to 15thDay
32%11%30%25%1
90
16th to endDay
24%12%32%27%3
81
March1st to 15thDay
19%10%33%28%7%
207
16th to endDay
22%5%25%30%12%3
288
April1st to 15thDay
23%327%32%10%2
270
16th to endDay
22%230%26%12%5%
270
May1st to 15thDay
23%222%29%18%3
288
16th to endDay
15%217%37%21%4
367
June1st to 15thDay
16%119%38%20%4
495
16th to endDay
14%117%37%23%4
495
July1st to 15thDay
8%115%43%23%6%
475
16th to endDay
11%20%33%29%4
437
August1st to 15thDay
13%114%32%31%7%
313
16th to endDay
16%315%31%25%7%
332
September1st to 15thDay
14%416%26%26%13%
315
16th to endDay
17%323%28%19%7%
254
October1st to 15thDay
26%8%21%27%12%3
255
16th to endDay
33%11%27%19%6%1
199
November1st to 15thDay
12%10%35%32%9%
77
16th to endDay
28%16%38%16%
60
December1st to 15thDay
31%23%30%10%5%
60
16th to endDay
37%28%31%3
64
January1st to 15thNight
28%16%31%18%3
900
16th to endNight
22%11%32%24%7%1
869
February1st to 15thNight
23%11%35%22%6%
704
16th to endNight
22%7%32%27%9%
631
March1st to 15thNight
22%9%34%24%7%1
720
16th to endNight
16%429%31%15%2
768
April1st to 15thNight
24%6%30%28%8%1
632
16th to endNight
22%5%26%27%16%2
540
May1st to 15thNight
18%318%34%21%3
539
16th to endNight
15%317%36%23%3
375
June1st to 15thNight
14%319%38%21%2
360
16th to endNight
11%113%39%29%4
360
July1st to 15thNight
7%214%41%26%6%
340
16th to endNight
8%115%37%32%4
535
August1st to 15thNight
11%116%34%29%7%
539
16th to endNight
13%215%31%31%6%
573
September1st to 15thNight
18%318%27%19%12%
696
16th to endNight
19%418%27%19%9%
658
October1st to 15thNight
28%5%22%24%15%2
660
16th to endNight
35%10%24%22%5%
704
November1st to 15thNight
27%13%28%20%9%1
700
16th to endNight
35%13%25%17%7%
720
December1st to 15thNight
34%17%31%12%4
780
16th to endNight
34%16%30%13%4
960
Page generated at 2017-09-16 17:06:59. Version ac04

Copyright 2017 A. Danko


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