Gatineau Gliding Club
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Gatineau Gliding Club clear sky chart from 2005-11-05 to 2019-06-19.

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
36%
16860
14%
53970
10%
16829
42%
16829
18%
38466

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
23%
840
8%
2926
5%
836
28%
836
9%
2336
January16th to endNight
26%
896
10%
3111
7%
896
32%
896
12%
2345
February1st to 15thNight
25%
823
11%
2677
6%
821
31%
821
12%
2071
February16th to endNight
31%
735
14%
2247
9%
735
39%
735
16%
1662
March1st to 15thNight
29%
840
13%
2481
10%
840
33%
840
15%
1890
March16th to endNight
38%
896
21%
2352
11%
896
45%
896
26%
1634
April1st to 15thNight
30%
838
15%
2096
7%
838
33%
838
21%
1560
April16th to endNight
34%
745
16%
1991
8%
745
39%
745
24%
1415
May1st to 15thNight
36%
420
19%
1680
17%
420
44%
420
17%
1097
May16th to endNight
40%
439
13%
1753
12%
438
50%
438
19%
1116
June1st to 15thNight
42%
420
10%
1680
13%
420
48%
420
16%
1145
June16th to endNight
48%
398
9%
1592
14%
398
51%
398
20%
997
July1st to 15thNight
61%
370
15%
1480
23%
370
66%
370
27%
806
July16th to endNight
61%
408
14%
1546
19%
386
64%
386
24%
899
August1st to 15thNight
59%
437
14%
1578
15%
435
61%
435
22%
998
August16th to endNight
59%
790
19%
2032
11%
790
62%
790
37%
1275
September1st to 15thNight
55%
780
17%
1950
10%
780
57%
780
30%
1340
September16th to endNight
54%
777
22%
2111
15%
777
57%
777
32%
1356
October1st to 15thNight
39%
780
17%
2340
12%
780
46%
780
22%
1623
October16th to endNight
31%
832
12%
2625
8%
832
38%
832
15%
1955
November1st to 15thNight
34%
820
17%
2706
14%
820
41%
820
17%
1924
November16th to endNight
27%
840
10%
2940
8%
840
31%
840
11%
2249
December1st to 15thNight
24%
840
9%
2940
5%
840
29%
840
10%
2295
December16th to endNight
21%
896
10%
3136
5%
896
27%
896
10%
2478

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
18%8%36%5%3445%6%33%
54761
Night
18%9%36%5%34445%32%
54139
Cloud CoverDay
18%8%36%5%3445%6%33%
54770
Night
18%9%36%5%34445%32%
54145
TransparencyDay
50%5%12%19%10%1
54448
Night
52%5%11%19%10%1
53970
SeeingDay
22%7%24%26%14%4
7647
Night
23%5%25%32%12%
16861

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
21%15%5%9%6%2433421%
1672
16th to endDay
14%15%5%9%6%346%46%23%
1814
February1st to 15thDay
15%13%5%10%7%36%445%24%
1845
16th to endDay
19%11%5%8%6%34345%26%
1797
March1st to 15thDay
18%11%49%7%35%43427%
2128
16th to endDay
17%7%345%34345%40%
2576
April1st to 15thDay
22%10%46%423435%32%
2512
16th to endDay
22%8%35%5%33335%34%
2584
May1st to 15thDay
20%7%35%5%34446%34%
2931
16th to endDay
19%6%245%3445%7%35%
3066
June1st to 15thDay
22%6%25%5%35%46%6%31%
2940
16th to endDay
17%6%26%335%6%6%8%33%
2776
July1st to 15thDay
12%4145%345%6%8%40%
2730
16th to endDay
12%5%245%35%6%7%9%36%
2878
August1st to 15thDay
12%6%26%6%45%5%6%8%36%
2622
16th to endDay
10%4245%35%5%5%8%45%
2509
September1st to 15thDay
16%4234245%5%7%42%
2340
16th to endDay
15%5%13323446%47%
2177
October1st to 15thDay
21%9%35%5%24346%34%
1950
16th to endDay
24%9%37%6%44445%26%
1950
November1st to 15thDay
18%8%36%5%35%45%7%31%
1812
16th to endDay
24%11%47%6%23336%25%
1680
December1st to 15thDay
22%14%5%7%6%34445%20%
1680
16th to endDay
23%15%5%8%6%24435%21%
1792
January1st to 15thNight
20%14%6%10%5%3433421%
2926
16th to endNight
15%15%5%7%6%34445%25%
3111
February1st to 15thNight
14%11%6%10%7%46%445%23%
2675
16th to endNight
17%10%5%7%5%345%45%29%
2247
March1st to 15thNight
19%12%48%7%3434427%
2468
16th to endNight
15%9%36%42333442%
2352
April1st to 15thNight
25%9%24433345%33%
2096
16th to endNight
21%8%25%423335%37%
1991
May1st to 15thNight
21%7%25%423445%36%
1680
16th to endNight
17%6%3443445%6%38%
1751
June1st to 15thNight
19%6%36%5%345%6%8%31%
1680
16th to endNight
17%5%145%2447%7%38%
1592
July1st to 15thNight
9%314335%47%7%48%
1560
16th to endNight
9%5%245%35%5%5%8%44%
1642
August1st to 15thNight
10%5%25%6%345%7%9%38%
1588
16th to endNight
10%32442445%7%49%
2032
September1st to 15thNight
14%5%15%5%345%5%6%41%
1950
16th to endNight
16%414423346%48%
2111
October1st to 15thNight
19%7%25%334447%35%
2340
16th to endNight
23%9%36%6%3445%5%28%
2625
November1st to 15thNight
22%8%36%5%24345%32%
2706
16th to endNight
22%11%47%6%35%345%25%
2940
December1st to 15thNight
21%14%5%7%5%34445%22%
2940
16th to endNight
23%15%5%7%6%2344422%
3136

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
22%14%6%9%6%24345%21%
1672
16th to endDay
14%15%5%8%6%35%446%24%
1814
February1st to 15thDay
15%13%410%7%34445%25%
1845
16th to endDay
18%12%5%6%6%44446%25%
1797
March1st to 15thDay
18%12%5%7%6%3444426%
2138
16th to endDay
17%6%35%5%24445%40%
2575
April1st to 15thDay
22%9%46%424335%32%
2512
16th to endDay
22%7%36%5%23335%34%
2584
May1st to 15thDay
21%6%35%5%35%446%34%
2931
16th to endDay
19%6%25%5%345%5%6%35%
3066
June1st to 15thDay
21%6%25%5%3445%6%31%
2940
16th to endDay
18%425%436%6%6%7%33%
2776
July1st to 15thDay
12%5%246%245%7%8%40%
2730
16th to endDay
12%5%25%5%25%6%7%8%37%
2878
August1st to 15thDay
12%6%26%6%35%5%6%8%36%
2622
16th to endDay
10%5%245%25%45%7%45%
2509
September1st to 15thDay
16%5%2433346%7%43%
2340
16th to endDay
16%5%24323346%47%
2177
October1st to 15thDay
21%8%35%424346%34%
1950
16th to endDay
23%9%37%6%44445%26%
1950
November1st to 15thDay
18%7%46%5%35%45%6%31%
1812
16th to endDay
23%12%47%5%24345%26%
1680
December1st to 15thDay
22%14%38%6%35%5%45%19%
1680
16th to endDay
23%15%5%7%6%3344421%
1792
January1st to 15thNight
21%15%5%10%6%3444321%
2926
16th to endNight
15%15%5%8%6%35%345%25%
3111
February1st to 15thNight
15%12%5%11%7%35%5%4423%
2668
16th to endNight
17%10%48%5%35%44429%
2247
March1st to 15thNight
19%12%5%7%6%3433427%
2481
16th to endNight
16%8%26%43334442%
2352
April1st to 15thNight
26%8%245%24336%32%
2096
16th to endNight
22%7%25%5%23335%38%
1991
May1st to 15thNight
22%7%25%42345%437%
1680
16th to endNight
16%7%35%435%35%6%39%
1751
June1st to 15thNight
20%6%35%5%3446%8%31%
1680
16th to endNight
16%5%245%145%7%9%37%
1592
July1st to 15thNight
10%3234245%6%9%46%
1560
16th to endNight
10%425%435%46%8%44%
1642
August1st to 15thNight
10%5%26%5%346%7%9%38%
1588
16th to endNight
10%42442446%7%48%
2032
September1st to 15thNight
14%5%15%6%25%447%41%
1950
16th to endNight
16%4245%23345%48%
2111
October1st to 15thNight
20%7%35%42445%6%36%
2340
16th to endNight
23%8%36%6%33445%29%
2625
November1st to 15thNight
22%8%35%5%24345%33%
2706
16th to endNight
22%11%48%5%34445%25%
2940
December1st to 15thNight
21%14%5%7%6%34445%22%
2940
16th to endNight
23%16%5%7%5%3444421%
3136

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
66%47%13%7%
1673
16th to endDay
60%412%14%7%
1814
February1st to 15thDay
60%411%17%4
1847
16th to endDay
59%410%14%9%1
1797
March1st to 15thDay
60%411%14%8%
2138
16th to endDay
45%5%9%18%16%4
2576
April1st to 15thDay
54%47%18%12%2
2512
16th to endDay
52%38%17%14%3
2584
May1st to 15thDay
51%5%7%20%14%1
2931
16th to endDay
47%7%12%19%11%1
3070
June1st to 15thDay
51%5%10%20%10%1
2940
16th to endDay
46%7%13%19%11%1
2776
July1st to 15thDay
37%6%16%26%13%
2581
16th to endDay
41%8%17%22%10%
2711
August1st to 15thDay
44%8%16%21%8%
2608
16th to endDay
35%7%16%28%11%
2509
September1st to 15thDay
38%6%14%26%13%
2340
16th to endDay
37%5%13%31%10%
2177
October1st to 15thDay
51%411%21%9%
1950
16th to endDay
59%5%13%15%5%
1950
November1st to 15thDay
51%6%15%17%8%1
1812
16th to endDay
60%412%14%7%
1680
December1st to 15thDay
65%6%12%12%2
1680
16th to endDay
66%49%12%6%
1792
January1st to 15thNight
66%5%9%11%5%
2926
16th to endNight
60%410%15%8%
3111
February1st to 15thNight
62%5%10%17%4
2677
16th to endNight
55%5%8%19%10%
2247
March1st to 15thNight
60%39%17%7%1
2481
16th to endNight
46%48%19%16%4
2352
April1st to 15thNight
53%48%17%14%1
2096
16th to endNight
49%48%17%17%3
1991
May1st to 15thNight
48%47%18%15%4
1680
16th to endNight
44%6%12%19%15%1
1753
June1st to 15thNight
50%6%12%18%11%1
1680
16th to endNight
42%7%13%20%16%
1592
July1st to 15thNight
31%7%14%28%16%1
1480
16th to endNight
36%6%15%24%15%
1546
August1st to 15thNight
38%9%18%22%9%
1578
16th to endNight
32%6%17%31%11%
2032
September1st to 15thNight
41%5%12%26%13%
1950
16th to endNight
37%5%12%32%11%
2111
October1st to 15thNight
48%5%10%23%11%
2340
16th to endNight
57%5%13%17%6%
2625
November1st to 15thNight
53%413%17%9%1
2706
16th to endNight
61%6%11%15%4
2940
December1st to 15thNight
64%5%12%14%4
2940
16th to endNight
65%5%9%12%6%
3136

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
30%8%25%26%7%1
120
16th to endDay
28%8%34%25%21
135
February1st to 15thDay
32%14%35%17%1
180
16th to endDay
29%10%27%30%3
300
March1st to 15thDay
25%10%28%26%9%
390
16th to endDay
20%8%28%25%11%4
416
April1st to 15thDay
28%11%28%17%11%1
390
16th to endDay
26%8%25%20%15%3
379
May1st to 15thDay
27%5%25%27%9%4
408
16th to endDay
21%8%32%22%12%2
459
June1st to 15thDay
24%6%22%30%11%4
435
16th to endDay
18%5%21%33%18%2
388
July1st to 15thDay
12%419%32%23%7%
365
16th to endDay
15%217%32%26%5%
390
August1st to 15thDay
15%314%33%25%7%
358
16th to endDay
13%414%31%23%13%
396
September1st to 15thDay
17%319%18%22%17%
375
16th to endDay
18%5%20%19%21%14%
374
October1st to 15thDay
28%6%24%22%16%2
375
16th to endDay
28%11%24%25%10%
360
November1st to 15thDay
24%10%21%29%13%1
286
16th to endDay
30%13%25%21%9%
120
December1st to 15thDay
23%7%34%25%9%
120
16th to endDay
30%9%35%21%3
128
January1st to 15thNight
29%7%27%29%5%
840
16th to endNight
23%7%29%31%7%
896
February1st to 15thNight
20%6%34%30%7%
824
16th to endNight
24%5%30%32%6%
735
March1st to 15thNight
26%8%27%31%6%
840
16th to endNight
20%427%34%11%
896
April1st to 15thNight
29%7%27%30%5%
838
16th to endNight
25%6%27%29%10%
745
May1st to 15thNight
27%324%32%9%1
420
16th to endNight
19%5%28%32%13%
439
June1st to 15thNight
20%423%41%9%
420
16th to endNight
17%123%39%16%1
398
July1st to 15thNight
9%220%45%20%
370
16th to endNight
12%116%45%23%
408
August1st to 15thNight
15%211%42%26%2
437
16th to endNight
12%217%40%25%2
790
September1st to 15thNight
17%315%38%22%1
780
16th to endNight
18%418%31%25%2
777
October1st to 15thNight
23%5%24%32%14%
780
16th to endNight
27%7%25%30%8%
832
November1st to 15thNight
26%6%23%29%12%
820
16th to endNight
27%8%27%24%10%
840
December1st to 15thNight
30%7%27%28%6%
840
16th to endNight
32%7%28%24%5%1
896
Page generated at 2019-06-20 08:02:30. Version ac04

Copyright 2019 A. Danko


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