Canmore
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Canmore clear sky chart from 2005-11-05 to 2017-08-12.

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
25%
14975
11%
46444
4%
14942
32%
14942
17%
31821

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
9%
900
8%
2685
2%
895
16%
895
11%
2021
January16th to endNight
11%
780
13%
2700
5%
780
22%
780
12%
1837
February1st to 15thNight
20%
700
8%
2449
5%
697
26%
697
13%
1710
February16th to endNight
21%
632
11%
1941
4%
632
30%
632
17%
1374
March1st to 15thNight
16%
720
11%
2145
3%
720
26%
720
16%
1477
March16th to endNight
23%
768
11%
2046
2%
767
30%
767
17%
1491
April1st to 15thNight
25%
656
8%
1736
2%
656
28%
656
14%
1326
April16th to endNight
29%
540
10%
1620
7%
540
33%
540
14%
1178
May1st to 15thNight
39%
379
8%
1415
10%
379
42%
379
17%
928
May16th to endNight
39%
374
4%
1309
3%
374
40%
374
15%
939
June1st to 15thNight
33%
360
0%
1260
0%
360
33%
360
13%
908
June16th to endNight
38%
360
0%
1260
0%
360
38%
360
17%
828
July1st to 15thNight
49%
340
2%
1190
0%
340
49%
340
24%
730
July16th to endNight
53%
376
9%
1320
9%
354
57%
354
28%
737
August1st to 15thNight
61%
357
14%
1405
17%
355
68%
355
26%
791
August16th to endNight
48%
525
17%
1575
12%
525
51%
525
34%
881
September1st to 15thNight
46%
644
16%
1670
8%
644
49%
644
32%
1048
September16th to endNight
35%
656
18%
1815
9%
656
43%
656
27%
1129
October1st to 15thNight
26%
660
14%
1952
6%
660
34%
660
18%
1378
October16th to endNight
21%
704
15%
2288
4%
704
34%
704
15%
1561
November1st to 15thNight
10%
784
11%
2383
2%
784
19%
784
15%
1627
November16th to endNight
14%
900
10%
2700
3%
900
21%
900
14%
1931
December1st to 15thNight
15%
900
11%
2700
4%
900
22%
900
13%
1935
December16th to endNight
11%
960
12%
2880
1%
960
22%
960
14%
2056

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
8%8%48%7%46%5%7%8%29%
47559
Night
46%37%6%46%6%7%10%35%
46600
TransparencyDay
48%13%16%15%5%
47217
Night
39%14%19%18%6%
46447
SeeingDay
18%21%32%19%6%1
5839
Night
10%19%39%21%8%
14981

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
1427%6%5%6%6%10%13%33%
1253
16th to endDay
15%48%6%5%6%6%8%12%35%
1533
February1st to 15thDay
25%28%9%5%7%6%9%10%32%
1416
16th to endDay
7%413%8%48%7%6%11%25%
1530
March1st to 15thDay
5%49%8%5%8%6%8%13%29%
1815
16th to endDay
213%7%11%8%5%8%7%7%9%18%
2171
April1st to 15thDay
5%16%7%12%7%47%6%5%6%18%
2212
16th to endDay
7%17%6%12%7%45%5%46%21%
2340
May1st to 15thDay
8%14%5%9%6%346%6%8%26%
2535
16th to endDay
22%12%38%7%36%46%5%18%
2802
June1st to 15thDay
21%12%48%8%46%445%17%
2700
16th to endDay
16%8%47%9%46%5%6%6%23%
2700
July1st to 15thDay
11%6%38%8%46%6%6%7%30%
2700
16th to endDay
8%425%7%46%5%7%8%39%
2757
August1st to 15thDay
11%5%37%7%46%6%7%8%31%
2462
16th to endDay
11%5%25%6%45%46%8%39%
2275
September1st to 15thDay
12%8%25%7%3335%6%41%
1958
16th to endDay
8%5%25%6%446%6%9%39%
1815
October1st to 15thDay
7%9%47%6%47%6%8%9%29%
1675
16th to endDay
37%47%7%36%6%8%10%35%
1584
November1st to 15thDay
16%36%446%6%9%14%36%
1462
16th to endDay
15%36%6%35%6%9%12%39%
1260
December1st to 15thDay
15%38%8%47%5%8%11%35%
1260
16th to endDay
6%48%6%37%6%8%11%36%
1344
January1st to 15thNight
16%38%9%5%9%8%8%14%24%
2685
16th to endNight
16%38%7%46%7%9%11%32%
2700
February1st to 15thNight
16%38%7%48%8%8%11%31%
2437
16th to endNight
6%5%8%9%5%8%7%7%10%31%
1941
March1st to 15thNight
426%7%38%7%11%13%33%
2145
16th to endNight
17%410%7%35%6%7%11%33%
2046
April1st to 15thNight
411%7%11%5%35%46%9%31%
1736
16th to endNight
412%6%8%6%35%45%9%32%
1620
May1st to 15thNight
5%11%5%6%6%35%45%7%37%
1414
16th to endNight
19%7%26%6%35%5%5%7%29%
1309
June1st to 15thNight
17%7%36%6%35%5%5%6%32%
1260
16th to endNight
13%5%246%35%5%6%8%38%
1260
July1st to 15thNight
8%5%2443446%10%46%
1260
16th to endNight
6%3134247%6%8%50%
1411
August1st to 15thNight
9%6%144235%49%48%
1413
16th to endNight
8%31232346%8%54%
1575
September1st to 15thNight
9%7%1432345%7%50%
1670
16th to endNight
8%5%2232346%8%50%
1815
October1st to 15thNight
6%10%36%5%345%7%9%35%
1952
16th to endNight
26%37%6%35%7%9%11%36%
2288
November1st to 15thNight
17%346%5%7%7%9%12%35%
2383
16th to endNight
6%5%8%7%46%6%8%14%31%
2700
December1st to 15thNight
15%49%8%46%7%9%13%29%
2700
16th to endNight
449%8%5%8%8%7%11%30%
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
36%19%21%14%41
1253
16th to endDay
39%15%20%15%6%2
1533
February1st to 15thDay
41%14%19%15%5%2
1416
16th to endDay
50%14%15%13%5%
1530
March1st to 15thDay
42%19%21%12%3
1815
16th to endDay
56%16%15%8%2
2172
April1st to 15thDay
60%13%14%9%2
2212
16th to endDay
61%10%13%10%2
2340
May1st to 15thDay
53%10%17%14%4
2535
16th to endDay
65%10%11%8%3
2807
June1st to 15thDay
67%9%9%10%2
2700
16th to endDay
56%11%13%13%4
2700
July1st to 15thDay
50%10%15%15%8%
2541
16th to endDay
40%11%14%21%11%
2585
August1st to 15thDay
46%12%15%19%5%1
2445
16th to endDay
39%10%16%25%7%1
2275
September1st to 15thDay
42%8%15%21%11%1
1958
16th to endDay
37%12%18%22%7%
1815
October1st to 15thDay
46%15%15%15%6%
1675
16th to endDay
40%13%22%18%5%
1584
November1st to 15thDay
34%18%24%16%5%
1462
16th to endDay
34%16%23%15%7%1
1260
December1st to 15thDay
39%17%22%14%5%
1260
16th to endDay
36%14%23%17%8%
1344
January1st to 15thNight
41%20%18%12%41
2685
16th to endNight
39%15%19%15%7%3
2700
February1st to 15thNight
40%16%20%14%6%1
2449
16th to endNight
43%12%15%17%8%1
1941
March1st to 15thNight
35%17%26%15%5%
2145
16th to endNight
43%13%19%18%5%
2049
April1st to 15thNight
49%11%18%14%5%
1736
16th to endNight
49%9%18%16%41
1620
May1st to 15thNight
44%8%19%22%5%
1415
16th to endNight
52%8%18%16%3
1309
June1st to 15thNight
51%9%16%16%6%
1260
16th to endNight
40%11%17%22%6%
1260
July1st to 15thNight
34%9%19%25%9%1
1190
16th to endNight
28%10%19%28%13%
1320
August1st to 15thNight
32%7%20%30%7%
1405
16th to endNight
25%8%21%34%8%
1575
September1st to 15thNight
31%8%20%26%12%
1670
16th to endNight
29%10%19%27%10%
1815
October1st to 15thNight
41%13%17%19%7%
1952
16th to endNight
34%18%19%21%5%
2288
November1st to 15thNight
35%17%22%18%5%
2383
16th to endNight
37%19%21%13%6%2
2700
December1st to 15thNight
40%17%21%14%6%
2700
16th to endNight
40%16%19%16%6%
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
38%40%30%11%6%
60
16th to endDay
428%35%18%7%4
64
February1st to 15thDay
15%20%47%9%6%
63
16th to endDay
8%24%39%21%41
189
March1st to 15thDay
13%41%35%9%
270
16th to endDay
15%29%38%15%
288
April1st to 15thDay
21%30%32%14%1
269
16th to endDay
26%25%28%13%5%1
270
May1st to 15thDay
21%18%30%21%7%
333
16th to endDay
29%11%20%24%11%3
517
June1st to 15thDay
26%16%27%19%9%
495
16th to endDay
18%16%35%19%7%1
495
July1st to 15thDay
15%14%29%24%13%2
475
16th to endDay
11%22%37%19%9%
426
August1st to 15thDay
16%13%37%24%7%1
300
16th to endDay
20%23%32%20%2
268
September1st to 15thDay
23%21%31%16%6%1
255
16th to endDay
16%34%30%16%1
255
October1st to 15thDay
19%29%31%16%2
181
16th to endDay
7%12%44%23%10%1
96
November1st to 15thDay
8%30%50%8%21
86
16th to endDay
5%18%41%13%10%11%
60
December1st to 15thDay
6%26%25%25%13%3
60
16th to endDay
7%26%40%18%6%
64
January1st to 15thNight
10%28%47%10%2
900
16th to endNight
7%29%43%14%3
780
February1st to 15thNight
5%22%43%20%7%
704
16th to endNight
5%14%51%21%7%
632
March1st to 15thNight
5%25%49%16%3
720
16th to endNight
7%17%44%22%7%
768
April1st to 15thNight
12%16%35%28%5%
656
16th to endNight
12%14%37%26%8%
540
May1st to 15thNight
12%10%31%32%11%
380
16th to endNight
21%7%24%23%21%1
375
June1st to 15thNight
20%10%30%21%16%
360
16th to endNight
15%11%28%29%14%
360
July1st to 15thNight
12%7%26%37%16%
340
16th to endNight
8%8%25%41%16%
376
August1st to 15thNight
15%414%36%26%2
357
16th to endNight
12%10%27%33%15%
525
September1st to 15thNight
16%8%26%26%17%5%
644
16th to endNight
11%17%32%25%10%1
656
October1st to 15thNight
14%13%39%24%6%
660
16th to endNight
10%20%44%20%3
704
November1st to 15thNight
10%28%47%9%2
784
16th to endNight
7%28%45%14%31
900
December1st to 15thNight
6%28%43%15%6%
900
16th to endNight
426%49%13%4
960
Page generated at 2017-08-13 12:16:17. Version ac04

Copyright 2017 A. Danko


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