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 2017-04-28.

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%
14593
12%
45517
8%
14558
35%
14558
15%
33655

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
12%
859
4%
2643
1%
856
16%
856
6%
2273
January16th to endNight
19%
768
10%
2496
6%
768
24%
768
9%
2028
February1st to 15thNight
19%
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
38%
534
18%
1602
11%
534
44%
534
22%
1114
May1st to 15thNight
44%
432
17%
1422
16%
432
48%
432
22%
932
May16th to endNight
46%
342
14%
1369
12%
342
55%
342
23%
778
June1st to 15thNight
48%
330
12%
1229
14%
330
52%
330
19%
792
June16th to endNight
51%
330
12%
1155
13%
330
56%
330
25%
699
July1st to 15thNight
62%
310
17%
1085
22%
310
65%
310
34%
582
July16th to endNight
49%
423
12%
1368
12%
395
49%
395
26%
816
August1st to 15thNight
58%
494
17%
1474
14%
491
60%
491
30%
915
August16th to endNight
55%
550
17%
1600
10%
550
59%
550
30%
1009
September1st to 15thNight
48%
660
14%
1669
7%
660
50%
660
28%
1161
September16th to endNight
50%
657
19%
1829
13%
657
54%
657
26%
1233
October1st to 15thNight
30%
660
14%
1980
10%
660
37%
660
16%
1475
October16th to endNight
20%
704
10%
2121
5%
704
26%
704
10%
1699
November1st to 15thNight
27%
700
14%
2416
12%
700
32%
700
13%
1798
November16th to endNight
17%
720
7%
2520
4%
720
20%
720
7%
2057
December1st to 15thNight
11%
720
3%
2520
1%
720
13%
720
5%
2220
December16th to endNight
11%
876
6%
2796
2%
876
16%
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
17%9%36%5%3445%6%33%
46180
Night
19%11%47%5%24446%29%
45683
Cloud CoverDay
18%9%36%5%34446%32%
46190
Night
18%11%47%5%34446%30%
45688
TransparencyDay
50%6%11%19%9%
45865
Night
55%6%10%17%9%
45517
SeeingDay
21%9%27%25%12%4
5132
Night
24%9%27%25%11%1
14598

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%24434346%38%
2305
May1st to 15thDay
18%6%25%5%3435%7%38%
2199
16th to endDay
13%42433445%8%44%
2394
June1st to 15thDay
18%5%345%25%46%8%35%
2398
16th to endDay
14%6%3442446%9%38%
2475
July1st to 15thDay
11%42442446%8%46%
2475
16th to endDay
12%424425%46%8%43%
2387
August1st to 15thDay
12%5%25%43445%7%44%
2145
16th to endDay
14%4245%345%5%8%40%
2239
September1st to 15thDay
17%6%245%2345%7%39%
1960
16th to endDay
17%7%245%34346%39%
1800
October1st to 15thDay
27%7%35%423335%32%
1650
16th to endDay
33%9%27%5%2435%420%
1749
November1st to 15thDay
23%12%36%5%34347%23%
1440
16th to endDay
26%15%46%5%45%345%18%
1440
December1st to 15thDay
21%25%7%8%5%23235%14%
1440
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%424436%36%
1602
May1st to 15thNight
16%6%35%42346%7%37%
1422
16th to endNight
13%4145%2446%9%44%
1367
June1st to 15thNight
16%6%244345%6%8%38%
1229
16th to endNight
13%7%25%3245%6%11%38%
1155
July1st to 15thNight
9%42341445%7%52%
1155
16th to endNight
10%425%42446%9%43%
1469
August1st to 15thNight
12%425%334448%46%
1485
16th to endNight
13%5%2443446%6%45%
1600
September1st to 15thNight
14%5%245%3445%9%39%
1669
16th to endNight
17%5%145%2445%6%41%
1829
October1st to 15thNight
24%8%25%5%3345%430%
1980
16th to endNight
32%9%46%5%2334424%
2121
November1st to 15thNight
22%11%36%5%24446%27%
2416
16th to endNight
26%15%5%6%5%24345%18%
2520
December1st to 15thNight
22%24%7%8%6%2333412%
2520
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%
2305
May1st to 15thDay
18%6%345%3435%7%37%
2199
16th to endDay
13%425%4245%47%43%
2394
June1st to 15thDay
18%6%35%5%35%5%5%8%34%
2398
16th to endDay
15%6%345%3446%9%37%
2475
July1st to 15thDay
11%4244345%5%7%46%
2475
16th to endDay
12%4245%35%5%6%9%41%
2387
August1st to 15thDay
12%6%25%5%3445%7%43%
2145
16th to endDay
14%5%25%5%35%5%6%7%39%
2239
September1st to 15thDay
18%6%25%43436%7%38%
1960
16th to endDay
19%6%24434446%39%
1800
October1st to 15thDay
26%7%35%433435%32%
1650
16th to endDay
34%8%26%6%2444420%
1749
November1st to 15thDay
23%11%36%5%34447%23%
1440
16th to endDay
25%16%46%5%3444419%
1440
December1st to 15thDay
20%25%7%8%5%2323415%
1440
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%36%
1602
May1st to 15thNight
16%7%35%43445%8%37%
1422
16th to endNight
13%42442445%10%43%
1367
June1st to 15thNight
16%6%3433446%7%38%
1229
16th to endNight
14%5%25%42446%10%39%
1155
July1st to 15thNight
9%423434447%52%
1155
16th to endNight
9%5%15%5%25%45%10%43%
1469
August1st to 15thNight
11%5%24424448%46%
1485
16th to endNight
13%5%1443445%6%46%
1600
September1st to 15thNight
15%5%245%25%45%8%40%
1669
16th to endNight
17%42443445%6%42%
1829
October1st to 15thNight
24%7%25%5%345%45%31%
1980
16th to endNight
31%9%38%42334424%
2121
November1st to 15thNight
21%11%36%5%25%446%28%
2416
16th to endNight
26%14%47%5%24446%19%
2520
December1st to 15thNight
22%24%7%8%5%2333412%
2520
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
2305
May1st to 15thDay
45%5%10%23%13%1
2199
16th to endDay
37%8%12%25%13%2
2398
June1st to 15thDay
45%8%11%23%11%
2398
16th to endDay
41%7%15%21%12%
2475
July1st to 15thDay
31%7%15%28%14%1
2316
16th to endDay
38%7%13%27%11%
2226
August1st to 15thDay
37%8%16%23%13%
2132
16th to endDay
40%8%13%27%8%1
2239
September1st to 15thDay
43%8%15%24%8%
1960
16th to endDay
45%7%12%26%8%
1800
October1st to 15thDay
55%5%11%17%10%
1650
16th to endDay
66%6%10%10%5%
1749
November1st to 15thDay
60%6%13%13%6%
1440
16th to endDay
68%6%12%8%21
1440
December1st to 15thDay
75%6%9%6%2
1440
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
47%5%7%18%18%2
1602
May1st to 15thNight
44%5%9%20%15%3
1422
16th to endNight
35%7%14%23%17%1
1369
June1st to 15thNight
43%7%10%23%14%
1229
16th to endNight
39%5%12%26%15%
1155
July1st to 15thNight
28%6%12%30%19%2
1085
16th to endNight
37%5%15%25%14%
1368
August1st to 15thNight
35%7%16%25%14%1
1474
16th to endNight
36%7%15%26%13%
1600
September1st to 15thNight
40%8%16%23%9%
1669
16th to endNight
42%6%13%28%9%
1829
October1st to 15thNight
54%7%9%17%11%
1980
16th to endNight
64%6%9%14%5%
2121
November1st to 15thNight
56%6%12%16%6%
2416
16th to endNight
67%7%11%10%2
2520
December1st to 15thNight
77%6%9%5%2
2520
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
23%11%28%19%13%3
259
May1st to 15thDay
23%9%22%23%15%5%
228
16th to endDay
14%7%28%28%15%5%
267
June1st to 15thDay
19%10%27%28%11%2
343
16th to endDay
16%427%38%12%1
420
July1st to 15thDay
10%7%26%31%19%5%
400
16th to endDay
14%428%33%12%6%
275
August1st to 15thDay
15%322%35%13%10%
253
16th to endDay
20%218%28%19%9%
268
September1st to 15thDay
15%426%23%19%9%
255
16th to endDay
19%5%23%27%18%5%
254
October1st to 15thDay
27%8%27%22%9%3
255
16th to endDay
36%14%24%19%4
261
November1st to 15thDay
21%10%37%21%9%
66
16th to endDay
31%18%38%11%
60
December1st to 15thDay
31%23%28%13%3
60
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%
534
May1st to 15thNight
18%422%35%16%2
432
16th to endNight
13%429%34%19%
343
June1st to 15thNight
18%422%40%12%1
330
16th to endNight
17%320%37%20%
330
July1st to 15thNight
10%120%40%25%2
310
16th to endNight
11%227%30%25%1
423
August1st to 15thNight
13%317%38%23%4
494
16th to endNight
15%221%29%27%3
550
September1st to 15thNight
16%424%28%19%6%
660
16th to endNight
20%5%19%31%19%4
657
October1st to 15thNight
27%8%26%23%11%1
660
16th to endNight
36%14%24%20%4
704
November1st to 15thNight
29%11%26%20%11%
700
16th to endNight
35%11%29%18%4
720
December1st to 15thNight
35%18%29%13%3
720
16th to endNight
32%14%31%18%3
876
Page generated at 2017-04-29 09:45:07. Version ac04

Copyright 2017 A. Danko


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