Le Chat Qui Peche Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Le Chat Qui Peche Observatory clear sky chart from 2005-11-05 to 2017-12-02.

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
31%
15262
12%
47649
8%
15227
36%
15227
15%
35138

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
13%
859
4%
2643
1%
856
17%
856
6%
2273
January16th to endNight
19%
768
10%
2496
6%
768
24%
768
9%
2028
February1st to 15thNight
18%
702
8%
2287
3%
701
24%
701
8%
1846
February16th to endNight
25%
631
10%
2024
6%
631
31%
631
12%
1551
March1st to 15thNight
23%
720
13%
1992
6%
720
29%
720
16%
1493
March16th to endNight
35%
768
19%
2112
11%
768
41%
768
24%
1431
April1st to 15thNight
28%
703
14%
1808
6%
703
33%
703
20%
1336
April16th to endNight
37%
540
18%
1620
11%
540
43%
540
22%
1130
May1st to 15thNight
42%
471
16%
1551
15%
471
46%
471
21%
1032
May16th to endNight
44%
374
14%
1497
12%
374
53%
374
21%
873
June1st to 15thNight
48%
360
11%
1341
14%
360
52%
360
20%
851
June16th to endNight
51%
360
12%
1260
14%
360
56%
360
25%
763
July1st to 15thNight
60%
340
16%
1190
20%
340
63%
340
32%
659
July16th to endNight
51%
458
14%
1487
15%
430
52%
430
27%
880
August1st to 15thNight
59%
539
16%
1609
13%
536
61%
536
30%
1002
August16th to endNight
54%
600
18%
1746
11%
600
58%
600
29%
1101
September1st to 15thNight
49%
720
15%
1821
7%
720
52%
720
29%
1247
September16th to endNight
52%
717
20%
1996
14%
717
56%
717
27%
1332
October1st to 15thNight
31%
720
14%
2160
10%
720
37%
720
16%
1601
October16th to endNight
20%
768
11%
2314
5%
768
27%
768
10%
1851
November1st to 15thNight
25%
760
13%
2623
11%
760
30%
760
12%
1972
November16th to endNight
16%
780
7%
2730
4%
780
20%
780
7%
2223
December1st to 15thNight
10%
728
3%
2546
1%
728
12%
728
5%
2246
December16th to endNight
10%
876
6%
2796
2%
876
15%
876
6%
2417

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%9%36%5%3445%6%33%
48801
Night
18%11%47%5%24446%30%
47815
Cloud CoverDay
18%9%36%5%34446%33%
48811
Night
18%11%47%5%24446%30%
47820
TransparencyDay
50%6%12%19%9%
48486
Night
55%6%10%17%9%
47649
SeeingDay
21%9%27%25%12%4
5974
Night
24%9%27%25%11%1
15267

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
22%17%7%11%424345%17%
1292
16th to endDay
15%18%8%10%6%34335%19%
1728
February1st to 15thDay
14%16%6%12%7%25%34421%
1575
16th to endDay
16%16%7%9%5%3442325%
1446
March1st to 15thDay
15%11%46%5%34445%32%
1957
16th to endDay
13%7%3443446%6%40%
2112
April1st to 15thDay
21%10%35%424445%33%
2149
16th to endDay
20%7%24424346%38%
2340
May1st to 15thDay
19%6%25%5%3435%6%37%
2400
16th to endDay
13%5%2443446%8%42%
2618
June1st to 15thDay
18%5%245%25%46%8%36%
2616
16th to endDay
14%6%345%3446%9%37%
2700
July1st to 15thDay
12%42442446%8%46%
2700
16th to endDay
12%424425%46%8%43%
2576
August1st to 15thDay
12%425%43445%7%44%
2340
16th to endDay
15%4245%345%5%7%40%
2444
September1st to 15thDay
16%5%245%2345%7%40%
2138
16th to endDay
17%7%24424346%41%
1963
October1st to 15thDay
27%7%35%423435%32%
1800
16th to endDay
32%9%27%5%2435%421%
1908
November1st to 15thDay
24%12%37%5%34347%23%
1563
16th to endDay
26%15%46%5%45%335%18%
1560
December1st to 15thDay
21%25%7%8%5%23235%14%
1451
16th to endDay
21%21%7%10%6%2444413%
1425
January1st to 15thNight
23%16%7%11%8%3442414%
2643
16th to endNight
16%16%7%10%8%24345%20%
2496
February1st to 15thNight
14%17%7%10%8%34445%19%
2285
16th to endNight
17%12%6%9%6%34445%25%
2024
March1st to 15thNight
17%11%5%7%6%34335%30%
1980
16th to endNight
14%8%37%423345%41%
2112
April1st to 15thNight
23%9%35%422445%33%
1808
16th to endNight
18%8%26%5%24436%36%
1620
May1st to 15thNight
18%6%35%5%235%5%7%35%
1551
16th to endNight
14%4145%2446%9%42%
1495
June1st to 15thNight
16%5%244245%6%8%38%
1341
16th to endNight
13%6%25%3245%6%11%39%
1260
July1st to 15thNight
10%42442445%7%51%
1260
16th to endNight
10%425%42446%9%44%
1588
August1st to 15thNight
11%425%43445%8%46%
1620
16th to endNight
13%42443446%6%45%
1746
September1st to 15thNight
14%5%2443446%9%40%
1821
16th to endNight
16%5%145%25%45%6%42%
1996
October1st to 15thNight
24%8%25%5%3344431%
2160
16th to endNight
31%9%46%5%2334424%
2314
November1st to 15thNight
23%11%36%5%24446%26%
2623
16th to endNight
26%15%5%7%5%24346%18%
2730
December1st to 15thNight
22%25%7%8%6%2333412%
2546
16th to endNight
23%21%7%9%5%3333414%
2796

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
21%17%6%10%6%33345%17%
1292
16th to endDay
15%18%7%11%7%2434420%
1728
February1st to 15thDay
13%16%6%13%7%35%43420%
1575
16th to endDay
16%16%7%9%7%35%33323%
1446
March1st to 15thDay
16%11%47%5%34445%31%
1968
16th to endDay
13%7%35%4445%46%38%
2111
April1st to 15thDay
22%9%35%5%34445%32%
2149
16th to endDay
20%8%25%423445%37%
2340
May1st to 15thDay
19%6%25%5%34347%35%
2400
16th to endDay
14%425%5%245%5%7%42%
2618
June1st to 15thDay
18%6%35%5%35%45%8%35%
2616
16th to endDay
15%6%3443446%9%36%
2700
July1st to 15thDay
12%4244345%5%7%45%
2700
16th to endDay
13%5%245%245%6%9%41%
2576
August1st to 15thDay
11%6%25%5%3445%7%43%
2340
16th to endDay
14%5%25%5%35%5%5%7%39%
2444
September1st to 15thDay
17%6%25%43435%6%40%
2138
16th to endDay
19%6%24433446%40%
1963
October1st to 15thDay
26%7%35%433435%32%
1800
16th to endDay
33%8%26%6%2444421%
1908
November1st to 15thDay
24%11%36%5%34347%23%
1563
16th to endDay
25%16%46%6%3444419%
1560
December1st to 15thDay
20%25%7%8%5%2333415%
1451
16th to endDay
21%21%7%10%5%2343414%
1425
January1st to 15thNight
22%16%7%11%8%3333315%
2643
16th to endNight
15%17%7%11%7%24345%20%
2496
February1st to 15thNight
13%17%7%10%7%45%45%5%18%
2278
16th to endNight
17%13%6%9%6%34435%25%
2024
March1st to 15thNight
17%11%5%7%7%34435%30%
1992
16th to endNight
14%8%37%5%23345%41%
2112
April1st to 15thNight
22%11%36%423345%33%
1808
16th to endNight
17%9%36%5%34347%35%
1620
May1st to 15thNight
18%7%25%5%3445%7%35%
1551
16th to endNight
14%4245%2446%9%41%
1495
June1st to 15thNight
15%6%3433446%7%38%
1341
16th to endNight
14%5%25%42446%10%39%
1260
July1st to 15thNight
9%423434446%51%
1260
16th to endNight
10%5%15%5%25%45%10%43%
1588
August1st to 15thNight
11%425%5%3445%7%46%
1620
16th to endNight
12%5%1443445%6%46%
1746
September1st to 15thNight
14%5%235%25%46%8%41%
1821
16th to endNight
15%425%5%3445%6%43%
1996
October1st to 15thNight
23%7%25%5%345%45%31%
2160
16th to endNight
30%9%38%423345%24%
2314
November1st to 15thNight
22%11%36%5%25%446%27%
2623
16th to endNight
26%14%47%5%24446%19%
2730
December1st to 15thNight
21%24%7%8%5%2333412%
2546
16th to endNight
23%20%7%10%5%2333414%
2796

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
70%5%10%9%3
1293
16th to endDay
68%6%7%10%6%
1728
February1st to 15thDay
67%5%9%13%4
1577
16th to endDay
64%5%7%16%6%
1446
March1st to 15thDay
52%6%15%17%7%
1968
16th to endDay
42%6%10%22%15%2
2112
April1st to 15thDay
52%49%20%11%1
2149
16th to endDay
46%5%7%22%14%2
2340
May1st to 15thDay
47%5%10%22%12%1
2400
16th to endDay
38%8%13%24%13%1
2622
June1st to 15thDay
45%7%11%24%11%
2616
16th to endDay
42%7%16%20%12%
2700
July1st to 15thDay
32%7%15%27%14%1
2541
16th to endDay
39%7%12%28%11%
2415
August1st to 15thDay
37%8%16%23%12%
2327
16th to endDay
41%8%13%26%8%
2444
September1st to 15thDay
42%8%14%24%9%
2138
16th to endDay
44%7%11%28%8%
1963
October1st to 15thDay
54%5%10%18%10%
1800
16th to endDay
65%6%10%11%5%
1908
November1st to 15thDay
61%6%12%12%6%
1563
16th to endDay
68%6%13%8%21
1560
December1st to 15thDay
74%6%9%6%2
1451
16th to endDay
74%49%8%2
1425
January1st to 15thNight
74%5%8%7%3
2643
16th to endNight
67%5%7%12%6%
2496
February1st to 15thNight
67%5%10%12%3
2287
16th to endNight
60%5%11%15%6%
2024
March1st to 15thNight
56%412%17%7%
1992
16th to endNight
45%49%20%17%2
2112
April1st to 15thNight
52%47%19%13%1
1808
16th to endNight
48%5%7%18%18%2
1620
May1st to 15thNight
46%5%9%19%15%3
1551
16th to endNight
37%7%14%22%16%1
1497
June1st to 15thNight
42%7%10%25%13%
1341
16th to endNight
38%6%14%26%14%
1260
July1st to 15thNight
30%6%12%29%18%2
1190
16th to endNight
37%5%14%27%14%
1487
August1st to 15thNight
35%7%16%25%13%
1609
16th to endNight
35%8%15%27%12%
1746
September1st to 15thNight
39%8%15%24%11%
1821
16th to endNight
41%6%12%29%9%
1996
October1st to 15thNight
53%7%9%18%11%
2160
16th to endNight
64%6%9%14%5%
2314
November1st to 15thNight
57%6%12%15%6%
2623
16th to endNight
67%7%11%10%2
2730
December1st to 15thNight
77%6%9%5%2
2546
16th to endNight
74%5%7%7%4
2796

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
18%18%49%11%3
61
16th to endDay
41%11%28%12%6%
96
February1st to 15thDay
31%21%36%11%
90
16th to endDay
34%14%34%16%
81
March1st to 15thDay
23%12%32%24%6%
258
16th to endDay
20%9%35%21%11%2
288
April1st to 15thDay
25%10%31%20%9%2
270
16th to endDay
24%12%27%18%12%2
270
May1st to 15thDay
26%7%23%23%13%4
288
16th to endDay
15%8%31%26%12%4
331
June1st to 15thDay
20%10%26%28%12%2
411
16th to endDay
17%430%34%10%1
495
July1st to 15thDay
11%6%26%32%18%4
475
16th to endDay
16%426%32%13%6%
331
August1st to 15thDay
16%218%37%15%9%
313
16th to endDay
21%416%28%18%9%
332
September1st to 15thDay
14%425%23%22%10%
315
16th to endDay
18%5%20%26%22%5%
314
October1st to 15thDay
28%8%26%22%10%3
315
16th to endDay
35%16%25%18%3
324
November1st to 15thDay
28%13%38%14%6%
99
16th to endDay
32%20%37%10%
90
December1st to 15thDay
30%22%26%15%4
63
16th to endDay
39%32%25%3
64
January1st to 15thNight
30%17%30%17%4
861
16th to endNight
24%10%32%23%8%
768
February1st to 15thNight
23%13%34%23%5%
704
16th to endNight
22%10%33%24%8%
631
March1st to 15thNight
23%13%32%25%5%
720
16th to endNight
18%6%31%29%11%1
768
April1st to 15thNight
28%7%28%28%6%
703
16th to endNight
23%6%26%28%14%
540
May1st to 15thNight
20%422%35%15%2
471
16th to endNight
14%429%32%19%
375
June1st to 15thNight
17%422%40%13%1
360
16th to endNight
17%321%37%19%
360
July1st to 15thNight
10%220%39%24%2
340
16th to endNight
11%225%31%26%1
458
August1st to 15thNight
12%316%38%25%4
539
16th to endNight
15%322%28%27%3
600
September1st to 15thNight
15%5%24%27%20%7%
720
16th to endNight
18%5%18%30%21%5%
717
October1st to 15thNight
27%8%26%23%11%1
720
16th to endNight
36%14%24%20%4
768
November1st to 15thNight
30%11%26%20%10%
760
16th to endNight
36%12%29%18%3
780
December1st to 15thNight
35%18%28%13%3
728
16th to endNight
32%14%31%18%3
876
Page generated at 2017-12-03 11:16:44. Version ac04

Copyright 2017 A. Danko


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