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 2017-12-20.

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%
15516
11%
48050
5%
15483
32%
15483
17%
32774

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%
378
8%
1414
10%
378
43%
378
17%
927
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%
1321
9%
354
57%
354
28%
738
August1st to 15thNight
62%
366
14%
1438
17%
364
69%
364
27%
802
August16th to endNight
50%
573
20%
1719
15%
573
54%
573
36%
945
September1st to 15thNight
46%
704
16%
1823
8%
704
49%
704
33%
1140
September16th to endNight
37%
716
19%
1980
10%
716
45%
716
27%
1234
October1st to 15thNight
28%
720
13%
2130
5%
720
36%
720
19%
1479
October16th to endNight
20%
768
16%
2496
5%
768
34%
768
15%
1676
November1st to 15thNight
12%
851
11%
2587
3%
851
21%
851
14%
1789
November16th to endNight
13%
975
10%
2925
2%
975
21%
975
15%
2058
December1st to 15thNight
18%
975
11%
2925
4%
975
25%
975
15%
2056
December16th to endNight
12%
984
12%
2951
1%
984
22%
984
14%
2111

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%30%
48823
Night
46%37%6%36%6%7%10%36%
48206
TransparencyDay
48%13%16%15%5%
48481
Night
38%14%19%19%7%
48053
SeeingDay
17%21%32%19%7%1
6250
Night
10%19%39%21%8%
15522

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%5%8%12%35%
1534
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%
1814
16th to endDay
213%7%11%8%5%8%7%7%9%18%
2172
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%32%
2514
16th to endDay
10%5%25%6%4446%8%41%
2483
September1st to 15thDay
11%8%35%6%3335%6%41%
2135
16th to endDay
8%5%25%6%45%6%7%9%39%
1980
October1st to 15thDay
7%10%47%6%37%6%7%8%29%
1827
16th to endDay
37%37%6%35%6%8%10%36%
1728
November1st to 15thDay
16%37%5%46%6%9%14%35%
1589
16th to endDay
1436%6%35%6%8%12%40%
1365
December1st to 15thDay
1438%8%47%5%8%11%37%
1365
16th to endDay
6%48%6%37%6%8%11%36%
1372
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%
1413
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%
1412
August1st to 15thNight
9%6%14423449%49%
1446
16th to endNight
7%31332346%8%56%
1719
September1st to 15thNight
9%7%2432345%7%50%
1823
16th to endNight
8%5%2233346%8%49%
1980
October1st to 15thNight
5%10%36%5%345%7%9%37%
2130
16th to endNight
26%36%5%35%7%9%11%37%
2496
November1st to 15thNight
17%35%6%5%7%7%9%12%34%
2587
16th to endNight
6%5%7%7%46%6%8%14%33%
2925
December1st to 15thNight
449%7%46%7%9%13%31%
2925
16th to endNight
5%49%8%5%8%8%7%11%29%
2951

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
1534
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
1814
16th to endDay
56%16%15%8%2
2173
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%11%15%19%5%1
2497
16th to endDay
37%10%16%25%8%1
2483
September1st to 15thDay
41%8%15%21%11%1
2135
16th to endDay
37%13%18%21%8%
1980
October1st to 15thDay
46%14%15%15%7%
1827
16th to endDay
38%14%23%17%6%
1728
November1st to 15thDay
36%17%24%15%5%
1589
16th to endDay
33%16%25%15%6%1
1365
December1st to 15thDay
37%17%23%15%6%1
1365
16th to endDay
36%14%22%17%8%
1372
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%
1414
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%
1321
August1st to 15thNight
32%7%20%30%7%
1438
16th to endNight
24%8%21%35%9%
1719
September1st to 15thNight
31%7%20%26%12%1
1823
16th to endNight
30%10%20%27%10%
1980
October1st to 15thNight
40%13%18%19%9%
2130
16th to endNight
33%18%20%21%5%
2496
November1st to 15thNight
36%17%22%17%5%
2587
16th to endNight
36%18%22%14%6%2
2925
December1st to 15thNight
37%17%20%16%6%
2925
16th to endNight
40%16%19%16%6%
2951

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
15%13%36%24%7%
315
16th to endDay
16%21%33%22%5%
332
September1st to 15thDay
22%22%31%14%6%1
315
16th to endDay
16%29%29%20%4
315
October1st to 15thDay
19%28%28%17%5%1
234
16th to endDay
9%19%45%18%6%
144
November1st to 15thDay
7%24%43%16%6%1
129
16th to endDay
5%28%42%8%6%7%
90
December1st to 15thDay
421%34%25%12%2
90
16th to endDay
6%26%43%18%5%
72
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%
379
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%413%37%27%2
366
16th to endNight
11%9%26%34%17%
573
September1st to 15thNight
16%8%25%27%16%4
704
16th to endNight
12%17%30%26%12%1
716
October1st to 15thNight
14%13%38%25%7%
720
16th to endNight
10%20%44%20%3
768
November1st to 15thNight
10%27%46%11%3
851
16th to endNight
6%29%46%13%2
975
December1st to 15thNight
5%25%43%18%6%
975
16th to endNight
5%25%49%14%4
984
Page generated at 2017-12-21 05:04:56. Version ac04

Copyright 2017 A. Danko


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