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 2005-11-06 to 2024-03-06.

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
32%
23731
10%
81124
8%
23636
36%
23636
12%
62709

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
11%
942
1%
4729
1%
926
13%
926
2%
4278
January11th to 20thNight
14%
947
2%
4438
1%
930
16%
930
2%
4171
January21st to endNight
19%
890
3%
4631
3%
878
22%
878
3%
4096
February1st to 10thNight
16%
760
7%
2470
3%
760
20%
760
7%
2049
February11th to 20thNight
23%
741
8%
2405
3%
740
29%
740
9%
1933
February21st to endNight
20%
628
9%
1903
3%
628
26%
628
11%
1491
March1st to 10thNight
28%
743
14%
2139
7%
743
35%
743
19%
1538
March11th to 20thNight
27%
720
16%
1980
7%
720
35%
720
20%
1446
March21st to endNight
35%
792
17%
2178
8%
792
41%
792
22%
1533
April1st to 10thNight
30%
681
14%
1873
6%
681
35%
681
20%
1354
April11th to 20thNight
39%
533
20%
1597
11%
533
45%
533
24%
1047
April21st to endNight
37%
540
15%
1620
9%
540
41%
540
19%
1158
May1st to 10thNight
48%
540
13%
1620
11%
540
50%
540
22%
1105
May11th to 20thNight
50%
444
17%
1506
17%
444
54%
444
22%
944
May21st to endNight
55%
388
14%
1495
17%
388
59%
388
24%
873
June1st to 10thNight
48%
360
14%
1260
14%
360
54%
360
23%
778
June11th to 20thNight
60%
360
15%
1260
16%
360
64%
360
29%
731
June21st to endNight
59%
360
12%
1260
14%
360
61%
360
24%
788
July1st to 10thNight
70%
350
19%
1225
22%
350
72%
350
36%
648
July11th to 20thNight
64%
392
18%
1262
20%
392
67%
392
32%
743
July21st to endNight
64%
591
16%
1594
15%
558
64%
558
33%
968
August1st to 10thNight
63%
537
17%
1600
14%
534
66%
534
34%
934
August11th to 20thNight
63%
534
18%
1598
14%
534
66%
534
31%
964
August21st to endNight
53%
594
17%
1782
12%
594
58%
594
27%
1150
September1st to 10thNight
54%
684
17%
1813
10%
684
57%
684
31%
1162
September11th to 20thNight
54%
720
20%
1980
14%
720
56%
720
30%
1286
September21st to endNight
47%
720
18%
1980
12%
720
49%
720
22%
1390
October1st to 10thNight
38%
720
14%
2114
11%
720
42%
720
17%
1546
October11th to 20thNight
28%
720
8%
2160
5%
720
32%
720
11%
1748
October21st to endNight
20%
792
9%
2492
5%
792
25%
792
8%
2072
November1st to 10thNight
27%
740
12%
2434
10%
740
31%
740
12%
1879
November11th to 20thNight
16%
760
6%
2660
6%
760
18%
760
6%
2232
November21st to endNight
14%
760
4%
2660
3%
760
15%
760
4%
2342
December1st to 10thNight
10%
760
2%
2660
1%
760
11%
760
3%
2436
December11th to 20thNight
8%
950
3%
3510
0%
949
10%
949
3%
3073
December21st to endNight
8%
1038
1%
5236
0%
1026
9%
1026
1%
4823

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%10%47%6%3445%7%33%
78210
Night
17%13%5%9%6%3445%6%27%
81331
TransparencyDay
50%8%12%19%9%1
77913
Night
59%8%10%14%8%1
81163
SeeingDay
18%8%24%30%17%3
14279
Night
21%10%27%26%13%2
23762

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 10thDay
18%21%13%13%5%2343413%
2220
11th to 20thDay
13%17%9%20%15%45%3446%
2530
21st to endDay
19%19%8%12%8%45%5%45%12%
3009
February1st to 10thDay
13%15%7%14%10%45%45%6%18%
1710
11th to 20thDay
12%13%6%11%9%46%5%6%6%24%
1663
21st to endDay
13%13%5%11%7%36%45%7%27%
1551
March1st to 10thDay
13%9%47%6%45%45%7%37%
1934
11th to 20thDay
12%9%48%6%45%5%5%5%36%
1980
21st to endDay
16%7%36%5%35%45%6%39%
2178
April1st to 10thDay
18%8%46%5%35%5%5%7%34%
2101
11th to 20thDay
19%6%35%5%35%446%41%
2312
21st to endDay
18%8%35%5%24448%38%
2340
May1st to 10thDay
18%6%35%5%3345%8%40%
2340
11th to 20thDay
16%6%345%3345%7%43%
2388
21st to endDay
11%5%25%5%445%5%8%45%
2778
June1st to 10thDay
12%6%35%6%36%5%6%8%41%
2700
11th to 20thDay
11%6%35%5%35%5%7%8%43%
2700
21st to endDay
13%7%25%5%35%5%5%8%41%
2700
July1st to 10thDay
6%5%35%435%5%5%9%51%
2700
11th to 20thDay
9%5%25%5%45%5%5%9%45%
2652
21st to endDay
8%425%4345%6%8%50%
2627
August1st to 10thDay
11%5%244345%6%9%49%
2327
11th to 20thDay
10%5%244345%6%8%50%
2303
21st to endDay
11%5%35%5%35%5%5%8%44%
2574
September1st to 10thDay
11%5%35%6%35%5%5%8%44%
2125
11th to 20thDay
12%5%245%2445%8%48%
1980
21st to endDay
17%6%36%5%345%5%7%38%
1980
October1st to 10thDay
18%9%36%5%445%6%7%33%
1846
11th to 20thDay
25%9%37%6%45%5%47%25%
1800
21st to endDay
26%14%47%6%3445%6%21%
1861
November1st to 10thDay
17%16%48%6%45%5%5%6%25%
1643
11th to 20thDay
18%17%6%9%7%35%5%5%7%19%
1520
21st to endDay
25%21%49%7%35%45%413%
1520
December1st to 10thDay
16%25%10%13%7%4334410%
1516
11th to 20thDay
20%21%9%13%7%3334313%
1671
21st to endDay
28%23%8%13%7%343335%
2431
January1st to 10thNight
17%23%11%14%7%3444311%
4734
11th to 20thNight
14%16%9%21%11%45%4449%
4440
21st to endNight
16%18%8%12%9%45%44416%
4648
February1st to 10thNight
12%17%7%14%9%4445%5%19%
2470
11th to 20thNight
12%14%6%11%8%45%5%6%6%23%
2403
21st to endNight
15%15%6%8%7%45%45%427%
1903
March1st to 10thNight
12%9%47%6%35%45%6%38%
2129
11th to 20thNight
13%11%48%6%3446%6%35%
1979
21st to endNight
15%9%37%6%245%5%7%38%
2178
April1st to 10thNight
22%8%35%5%25%46%6%34%
1873
11th to 20thNight
18%7%35%43446%8%39%
1597
21st to endNight
19%9%47%5%445%45%34%
1620
May1st to 10thNight
14%6%36%7%47%5%5%7%36%
1620
11th to 20thNight
15%7%36%6%345%6%6%40%
1505
21st to endNight
11%7%35%5%35%45%7%45%
1494
June1st to 10thNight
12%6%36%6%35%5%5%7%41%
1260
11th to 20thNight
9%5%24436%6%7%8%44%
1260
21st to endNight
11%6%37%5%35%5%6%9%41%
1260
July1st to 10thNight
7%415%435%45%8%55%
1260
11th to 20thNight
9%335%6%346%7%7%47%
1304
21st to endNight
9%326%44446%8%50%
1688
August1st to 10thNight
8%4245%25%5%6%9%49%
1611
11th to 20thNight
9%325%5%36%6%6%9%47%
1598
21st to endNight
11%5%26%5%345%7%7%44%
1782
September1st to 10thNight
12%435%5%445%5%7%47%
1813
11th to 20thNight
12%5%25%5%345%6%6%47%
1980
21st to endNight
19%7%25%5%445%6%7%38%
1980
October1st to 10thNight
22%9%36%6%44346%32%
2114
11th to 20thNight
27%11%47%5%445%5%6%23%
2160
21st to endNight
27%13%48%6%3445%5%20%
2492
November1st to 10thNight
20%17%47%5%3446%6%25%
2434
11th to 20thNight
19%18%6%10%7%445%46%17%
2660
21st to endNight
23%21%7%8%6%3445%5%13%
2660
December1st to 10thNight
22%23%10%11%7%343349%
2660
11th to 20thNight
19%21%7%13%7%4434414%
3526
21st to endNight
26%22%8%14%7%343347%
5236

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
78%10%9%3
2221
11th to 20thDay
87%5%421
2530
21st to endDay
75%12%8%41
3009
February1st to 10thDay
70%7%11%11%2
1710
11th to 20thDay
62%9%12%11%5%
1672
21st to endDay
58%8%13%17%4
1551
March1st to 10thDay
46%9%16%17%11%2
1937
11th to 20thDay
49%7%12%21%8%3
1980
21st to endDay
46%6%12%21%13%2
2178
April1st to 10thDay
50%6%14%19%10%1
2101
11th to 20thDay
44%6%9%25%14%2
2312
21st to endDay
44%7%14%19%13%3
2340
May1st to 10thDay
42%6%11%24%14%3
2340
11th to 20thDay
41%6%11%23%18%2
2392
21st to endDay
35%8%17%22%16%2
2778
June1st to 10thDay
39%8%13%25%14%1
2700
11th to 20thDay
36%7%11%28%17%1
2700
21st to endDay
39%9%13%25%13%2
2700
July1st to 10thDay
28%9%16%28%18%2
2626
11th to 20thDay
32%10%15%29%12%2
2571
21st to endDay
31%10%14%28%16%1
2481
August1st to 10thDay
30%10%19%28%13%1
2314
11th to 20thDay
30%9%19%29%12%
2303
21st to endDay
36%9%16%26%11%1
2574
September1st to 10thDay
38%9%14%27%11%1
2125
11th to 20thDay
35%8%17%31%9%
1980
21st to endDay
45%9%15%23%7%
1980
October1st to 10thDay
50%7%13%17%12%
1846
11th to 20thDay
60%9%14%13%4
1800
21st to endDay
65%8%11%11%4
1861
November1st to 10thDay
60%8%14%13%5%
1643
11th to 20thDay
66%10%10%9%4
1520
21st to endDay
75%8%10%5%1
1520
December1st to 10thDay
81%8%6%32
1516
11th to 20thDay
77%9%7%6%
1671
21st to endDay
84%10%5%2
2431
January1st to 10thNight
78%10%7%41
4734
11th to 20thNight
83%8%431
4440
21st to endNight
73%12%7%6%2
4648
February1st to 10thNight
70%6%9%11%3
2470
11th to 20thNight
64%9%10%13%5%
2405
21st to endNight
59%9%12%12%7%
1903
March1st to 10thNight
48%9%13%18%10%1
2139
11th to 20thNight
49%9%10%19%11%2
1980
21st to endNight
47%7%10%19%15%3
2178
April1st to 10thNight
51%6%10%19%12%2
1873
11th to 20thNight
42%6%9%22%18%2
1597
21st to endNight
51%6%9%16%15%3
1620
May1st to 10thNight
46%7%11%20%13%3
1620
11th to 20thNight
42%6%9%21%19%3
1506
21st to endNight
38%7%16%21%15%4
1495
June1st to 10thNight
40%7%11%22%18%2
1260
11th to 20thNight
33%8%16%22%20%2
1260
21st to endNight
40%7%15%22%14%2
1260
July1st to 10thNight
27%7%12%29%21%4
1225
11th to 20thNight
32%7%15%27%18%2
1262
21st to endNight
31%8%15%26%18%1
1594
August1st to 10thNight
30%9%18%28%14%2
1600
11th to 20thNight
32%9%18%27%13%1
1598
21st to endNight
38%8%16%23%12%2
1782
September1st to 10thNight
36%8%13%27%14%2
1813
11th to 20thNight
36%9%15%30%10%
1980
21st to endNight
46%8%14%24%8%
1980
October1st to 10thNight
53%7%10%20%11%
2114
11th to 20thNight
62%9%11%14%4
2160
21st to endNight
67%8%8%12%5%
2492
November1st to 10thNight
60%7%11%17%5%
2434
11th to 20thNight
69%9%11%8%31
2660
21st to endNight
74%9%10%6%1
2660
December1st to 10thNight
82%7%7%41
2660
11th to 20thNight
76%8%9%6%1
3525
21st to endNight
81%9%7%2
5236

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
23%17%32%22%8%
186
11th to 20thDay
24%11%36%23%7%
270
21st to endDay
26%10%26%28%9%
297
February1st to 10thDay
19%15%37%23%6%
270
11th to 20thDay
19%15%36%26%4
270
21st to endDay
20%23%36%19%1
225
March1st to 10thDay
18%9%38%26%8%1
342
11th to 20thDay
17%12%31%29%9%1
420
21st to endDay
24%8%27%31%8%2
462
April1st to 10thDay
20%7%33%29%10%1
420
11th to 20thDay
24%8%28%23%13%4
412
21st to endDay
21%8%29%29%12%1
420
May1st to 10thDay
22%325%35%13%2
423
11th to 20thDay
17%420%33%21%5%
447
21st to endDay
12%319%38%21%6%
538
June1st to 10thDay
13%221%40%21%2
630
11th to 20thDay
12%420%39%21%4
630
21st to endDay
16%318%39%21%3
630
July1st to 10thDay
7%215%44%28%4
621
11th to 20thDay
10%318%38%25%6%
618
21st to endDay
11%316%40%27%3
568
August1st to 10thDay
15%413%31%31%6%
446
11th to 20thDay
10%313%33%31%10%
439
21st to endDay
13%7%19%31%25%5%
495
September1st to 10thDay
14%422%28%26%6%
450
11th to 20thDay
11%5%22%27%29%6%
450
21st to endDay
19%8%20%26%21%6%
450
October1st to 10thDay
23%11%23%23%18%3
450
11th to 20thDay
25%15%29%25%5%1
450
21st to endDay
33%14%28%20%41
376
November1st to 10thDay
25%13%33%20%8%
256
11th to 20thDay
25%18%36%16%6%
180
21st to endDay
32%17%32%17%1
180
December1st to 10thDay
27%18%30%19%5%1
180
11th to 20thDay
29%22%31%15%3
180
21st to endDay
34%21%33%10%21
198
January1st to 10thNight
25%17%30%22%5%1
950
11th to 20thNight
25%16%30%23%5%1
950
21st to endNight
21%9%35%26%9%2
900
February1st to 10thNight
21%13%37%23%5%
760
11th to 20thNight
19%11%36%26%8%
743
21st to endNight
22%10%38%24%5%1
628
March1st to 10thNight
16%10%37%28%7%1
743
11th to 20thNight
17%10%36%25%10%2
720
21st to endNight
19%6%31%31%13%1
792
April1st to 10thNight
25%8%30%28%8%1
681
11th to 20thNight
21%9%25%29%13%3
533
21st to endNight
22%7%25%30%14%1
540
May1st to 10thNight
16%323%37%18%3
540
11th to 20thNight
16%320%37%20%2
444
21st to endNight
16%316%38%23%4
389
June1st to 10thNight
15%323%38%19%3
360
11th to 20thNight
11%418%41%23%4
360
21st to endNight
12%216%37%29%3
360
July1st to 10thNight
7%312%46%27%4
350
11th to 20thNight
10%216%37%27%8%
392
21st to endNight
9%215%42%28%4
591
August1st to 10thNight
10%316%36%29%6%
537
11th to 20thNight
12%314%31%32%9%
534
21st to endNight
13%420%32%26%5%
594
September1st to 10thNight
14%420%30%23%9%
684
11th to 20thNight
14%6%21%30%20%9%
720
21st to endNight
20%8%19%24%22%6%
720
October1st to 10thNight
25%8%22%25%18%3
720
11th to 20thNight
31%12%25%21%10%1
720
21st to endNight
34%13%26%23%41
792
November1st to 10thNight
28%13%26%24%8%1
740
11th to 20thNight
26%18%31%16%7%
760
21st to endNight
32%15%30%18%5%
760
December1st to 10thNight
34%18%28%14%6%
760
11th to 20thNight
29%19%34%14%41
950
21st to endNight
33%17%30%15%4
1045
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