This page made possible by the sponsorship of: Klaus Peltsch
and the
Algoma Area Astronomers.

Sault Ste. Marie
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Sault Ste. Marie clear sky chart from 2005-11-05 to 2017-10-06.

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
34%
15614
12%
47026
8%
15571
38%
15571
17%
33998

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
21%
900
7%
2550
2%
895
25%
895
9%
2123
January16th to endNight
23%
960
8%
2688
4%
960
26%
960
10%
2212
February1st to 15thNight
24%
751
7%
2336
5%
750
27%
750
10%
1864
February16th to endNight
27%
631
11%
1896
5%
631
32%
631
14%
1453
March1st to 15thNight
30%
720
15%
2112
9%
720
36%
720
22%
1466
March16th to endNight
38%
759
19%
2103
12%
759
44%
759
26%
1405
April1st to 15thNight
36%
539
15%
1749
10%
539
41%
539
21%
1171
April16th to endNight
38%
540
19%
1620
10%
540
46%
540
25%
1060
May1st to 15thNight
38%
540
12%
1618
9%
540
41%
540
19%
1131
May16th to endNight
44%
445
15%
1381
11%
444
51%
444
26%
868
June1st to 15thNight
45%
360
11%
1260
10%
360
49%
360
23%
768
June16th to endNight
48%
360
11%
1260
10%
360
52%
360
26%
766
July1st to 15thNight
53%
387
13%
1237
11%
387
55%
387
29%
741
July16th to endNight
62%
564
14%
1417
11%
531
64%
531
34%
900
August1st to 15thNight
61%
539
17%
1555
14%
536
65%
536
37%
904
August16th to endNight
58%
573
17%
1721
14%
573
60%
573
29%
1065
September1st to 15thNight
50%
624
14%
1884
10%
624
52%
624
27%
1192
September16th to endNight
47%
717
17%
1980
13%
717
49%
717
26%
1336
October1st to 15thNight
39%
684
16%
1963
11%
684
45%
684
21%
1365
October16th to endNight
26%
704
8%
2280
4%
704
31%
704
10%
1827
November1st to 15thNight
24%
700
13%
2279
9%
700
29%
700
12%
1728
November16th to endNight
19%
757
7%
2557
4%
757
23%
757
8%
2076
December1st to 15thNight
19%
900
6%
2700
3%
900
21%
900
10%
2174
December16th to endNight
18%
960
7%
2880
2%
960
22%
960
8%
2403

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%8%36%5%3445%7%33%
48183
Night
16%10%47%6%3445%6%30%
47188
Cloud CoverDay
15%8%36%5%3445%7%34%
48192
Night
16%10%47%6%3445%6%30%
47193
TransparencyDay
49%413%22%9%
47863
Night
54%412%19%8%
47026
SeeingDay
19%9%27%24%13%4
6083
Night
21%8%26%30%12%1
15617

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
15%15%6%11%9%46%445%14%
1385
16th to endDay
13%15%7%9%9%345%45%21%
1536
February1st to 15thDay
10%13%5%12%10%47%5%5%6%18%
1524
16th to endDay
12%11%49%8%45%5%5%5%27%
1577
March1st to 15thDay
15%8%46%424347%35%
1838
16th to endDay
14%8%35%5%24346%40%
2131
April1st to 15thDay
19%9%35%423447%35%
2199
16th to endDay
18%8%25%43446%6%36%
2340
May1st to 15thDay
18%8%245%3345%6%36%
2331
16th to endDay
15%5%2442445%8%41%
2733
June1st to 15thDay
15%6%24335%47%8%37%
2700
16th to endDay
13%6%35%5%25%5%6%9%36%
2700
July1st to 15thDay
11%5%244245%6%8%44%
2646
16th to endDay
11%5%2432445%9%45%
2655
August1st to 15thDay
12%4244245%6%8%45%
2394
16th to endDay
14%5%25%43345%8%41%
2480
September1st to 15thDay
14%5%25%5%3445%7%39%
2064
16th to endDay
16%6%35%5%3445%8%36%
1980
October1st to 15thDay
19%7%37%7%3445%6%29%
1795
16th to endDay
27%9%37%8%45%5%3418%
1592
November1st to 15thDay
21%11%47%6%35%45%7%22%
1578
16th to endDay
20%16%6%9%6%33337%19%
1401
December1st to 15thDay
16%15%5%9%8%46%44420%
1260
16th to endDay
22%16%5%9%7%25%235%17%
1344
January1st to 15thNight
17%15%7%10%7%45%35%6%17%
2550
16th to endNight
15%14%5%12%8%5%5%44418%
2688
February1st to 15thNight
10%14%6%11%9%45%5%6%6%18%
2334
16th to endNight
12%12%6%10%8%45%45%6%23%
1896
March1st to 15thNight
15%8%46%5%3345%6%36%
2099
16th to endNight
12%8%36%425%45%6%41%
2103
April1st to 15thNight
18%7%46%42345%7%35%
1749
16th to endNight
16%6%25%5%23447%40%
1620
May1st to 15thNight
17%7%46%5%345%6%5%32%
1618
16th to endNight
14%7%25%32445%7%41%
1379
June1st to 15thNight
13%7%245%3445%8%40%
1260
16th to endNight
11%5%25%435%6%6%10%39%
1260
July1st to 15thNight
12%5%244246%5%6%45%
1311
16th to endNight
9%4234345%7%9%44%
1513
August1st to 15thNight
9%42433445%7%50%
1564
16th to endNight
11%425%5%34446%46%
1721
September1st to 15thNight
14%4245%3445%5%44%
1884
16th to endNight
17%6%25%5%2445%7%39%
1980
October1st to 15thNight
18%7%25%3235%6%7%35%
1963
16th to endNight
26%11%37%5%345%5%5%20%
2280
November1st to 15thNight
21%13%45%6%35%445%25%
2279
16th to endNight
21%14%6%7%6%3445%6%19%
2557
December1st to 15thNight
19%15%6%8%7%34446%20%
2700
16th to endNight
20%18%6%9%7%33335%17%
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
14%16%5%13%8%5%6%445%15%
1385
16th to endDay
14%13%7%10%9%35%44421%
1536
February1st to 15thDay
10%13%6%12%9%47%5%5%5%18%
1524
16th to endDay
12%11%48%8%5%5%5%5%428%
1577
March1st to 15thDay
15%9%46%424447%36%
1848
16th to endDay
14%7%35%424346%41%
2130
April1st to 15thDay
18%9%35%42335%6%36%
2199
16th to endDay
18%7%25%5%3445%6%36%
2340
May1st to 15thDay
17%8%345%3345%6%37%
2331
16th to endDay
15%6%235%2445%8%41%
2733
June1st to 15thDay
15%5%244345%7%8%38%
2700
16th to endDay
13%5%25%5%345%6%9%37%
2700
July1st to 15thDay
10%5%244245%5%9%44%
2646
16th to endDay
11%5%2432445%9%46%
2655
August1st to 15thDay
11%4144245%5%8%46%
2394
16th to endDay
14%5%245%3345%8%42%
2480
September1st to 15thDay
14%5%25%6%445%5%7%39%
2064
16th to endDay
16%6%25%5%35%448%36%
1980
October1st to 15thDay
19%7%37%6%44446%30%
1795
16th to endDay
26%10%47%8%45%44419%
1592
November1st to 15thDay
21%12%46%6%35%35%7%22%
1578
16th to endDay
20%15%6%9%6%34336%18%
1401
December1st to 15thDay
15%15%6%9%7%5%5%44321%
1260
16th to endDay
21%17%6%8%8%35%235%17%
1344
January1st to 15thNight
17%16%7%9%8%45%35%5%17%
2550
16th to endNight
15%14%6%12%8%46%44418%
2688
February1st to 15thNight
10%14%7%11%8%46%5%5%7%18%
2327
16th to endNight
12%12%6%10%7%46%45%6%23%
1896
March1st to 15thNight
15%7%46%5%3435%6%36%
2112
16th to endNight
12%8%35%5%25%45%6%40%
2103
April1st to 15thNight
17%8%36%5%2445%7%35%
1749
16th to endNight
16%6%25%5%2445%7%40%
1620
May1st to 15thNight
16%8%46%5%3446%6%32%
1617
16th to endNight
14%6%25%425%46%6%42%
1379
June1st to 15thNight
14%6%245%2445%8%40%
1260
16th to endNight
11%5%25%435%6%5%11%38%
1260
July1st to 15thNight
12%5%24425%5%5%6%45%
1311
16th to endNight
9%5%234345%6%9%44%
1513
August1st to 15thNight
9%4244235%5%7%50%
1564
16th to endNight
11%425%5%35%347%46%
1721
September1st to 15thNight
14%5%24435%45%6%43%
1884
16th to endNight
16%6%25%5%3345%7%39%
1980
October1st to 15thNight
18%8%26%3235%6%7%35%
1963
16th to endNight
26%10%47%5%345%5%5%20%
2280
November1st to 15thNight
21%12%46%7%25%445%25%
2279
16th to endNight
20%14%6%8%6%34446%19%
2557
December1st to 15thNight
19%15%5%8%6%34345%20%
2700
16th to endNight
20%18%6%9%7%34345%17%
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
72%411%9%2
1386
16th to endDay
66%38%14%6%
1536
February1st to 15thDay
64%6%13%10%5%
1526
16th to endDay
56%413%18%7%
1577
March1st to 15thDay
48%314%20%10%1
1848
16th to endDay
44%314%25%9%3
2131
April1st to 15thDay
49%311%22%11%1
2199
16th to endDay
47%39%21%14%3
2340
May1st to 15thDay
46%410%21%13%3
2331
16th to endDay
40%5%14%25%13%1
2737
June1st to 15thDay
42%313%25%13%1
2700
16th to endDay
42%5%14%26%10%
2700
July1st to 15thDay
35%413%31%13%
2491
16th to endDay
36%314%29%14%
2488
August1st to 15thDay
35%417%30%11%
2379
16th to endDay
40%416%28%9%
2480
September1st to 15thDay
43%417%26%8%
2064
16th to endDay
45%418%25%6%
1980
October1st to 15thDay
55%312%21%6%
1795
16th to endDay
68%410%10%5%
1592
November1st to 15thDay
61%411%15%5%
1578
16th to endDay
69%5%11%8%5%
1401
December1st to 15thDay
68%413%10%2
1260
16th to endDay
71%311%10%3
1344
January1st to 15thNight
69%411%9%4
2550
16th to endNight
68%38%13%5%
2688
February1st to 15thNight
65%413%11%3
2336
16th to endNight
62%212%15%6%
1896
March1st to 15thNight
49%314%20%10%
2112
16th to endNight
44%311%24%12%2
2103
April1st to 15thNight
49%310%23%12%
1749
16th to endNight
44%311%21%16%2
1620
May1st to 15thNight
51%411%17%12%3
1618
16th to endNight
41%412%25%14%1
1381
June1st to 15thNight
41%413%23%15%1
1260
16th to endNight
38%5%14%29%10%1
1260
July1st to 15thNight
36%5%11%30%14%1
1237
16th to endNight
35%6%14%29%12%
1417
August1st to 15thNight
33%316%34%10%2
1555
16th to endNight
38%416%29%9%
1721
September1st to 15thNight
41%417%27%8%
1884
16th to endNight
44%414%28%7%
1980
October1st to 15thNight
48%5%14%23%7%
1963
16th to endNight
65%5%11%12%4
2280
November1st to 15thNight
60%411%17%5%
2279
16th to endNight
68%411%10%4
2557
December1st to 15thNight
66%415%11%1
2700
16th to endNight
71%310%10%3
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
19%6%36%24%10%2
82
16th to endDay
23%7%14%35%16%2
96
February1st to 15thDay
26%11%40%15%6%
90
16th to endDay
24%16%34%22%2
81
March1st to 15thDay
23%16%26%20%11%1
138
16th to endDay
23%5%27%24%15%3
288
April1st to 15thDay
21%12%21%30%11%2
270
16th to endDay
23%11%26%18%12%7%
270
May1st to 15thDay
25%10%25%20%12%6%
288
16th to endDay
20%11%30%23%11%3
517
June1st to 15thDay
20%11%32%21%10%2
495
16th to endDay
15%10%30%28%10%4
495
July1st to 15thDay
13%8%34%25%13%5%
475
16th to endDay
12%7%30%28%14%5%
515
August1st to 15thDay
16%419%30%21%8%
367
16th to endDay
20%6%17%24%22%8%
332
September1st to 15thDay
16%220%25%26%7%
315
16th to endDay
20%8%21%30%14%4
314
October1st to 15thDay
17%12%28%26%13%1
278
16th to endDay
29%14%36%15%3
104
November1st to 15thDay
22%11%40%16%8%
89
16th to endDay
31%18%26%15%8%
60
December1st to 15thDay
28%15%25%16%11%3
60
16th to endDay
39%10%42%6%1
64
January1st to 15thNight
24%12%28%25%8%
900
16th to endNight
20%9%28%30%9%1
960
February1st to 15thNight
18%10%31%33%6%
753
16th to endNight
19%8%31%30%9%
631
March1st to 15thNight
19%9%32%26%10%
720
16th to endNight
16%8%28%33%10%1
759
April1st to 15thNight
20%7%26%37%7%
539
16th to endNight
19%8%27%29%13%1
540
May1st to 15thNight
20%6%25%34%12%
540
16th to endNight
17%5%26%37%12%1
446
June1st to 15thNight
17%5%26%37%13%
360
16th to endNight
15%228%36%15%1
360
July1st to 15thNight
16%221%39%18%1
387
16th to endNight
12%215%44%21%2
564
August1st to 15thNight
12%217%38%27%2
539
16th to endNight
15%216%38%25%1
573
September1st to 15thNight
16%421%30%20%5%
624
16th to endNight
20%6%20%31%17%4
717
October1st to 15thNight
23%9%24%29%12%1
684
16th to endNight
33%9%25%24%6%
704
November1st to 15thNight
30%11%27%22%7%
700
16th to endNight
27%12%28%24%6%
757
December1st to 15thNight
27%12%33%20%6%
900
16th to endNight
28%9%30%21%8%1
960
Page generated at 2017-10-07 14:07:49. Version ac04

Copyright 2017 A. Danko


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