Bonaventure
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Bonaventure 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
32%
15015
13%
47727
7%
14979
39%
14979
17%
33560

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
15%
750
10%
2685
2%
746
25%
746
9%
2023
January16th to endNight
21%
779
18%
2696
6%
779
36%
779
15%
1810
February1st to 15thNight
29%
703
14%
2286
5%
701
40%
701
17%
1561
February16th to endNight
23%
631
12%
2036
5%
631
32%
631
12%
1513
March1st to 15thNight
29%
720
18%
2025
9%
720
37%
720
18%
1466
March16th to endNight
33%
768
18%
2112
8%
768
41%
768
22%
1470
April1st to 15thNight
34%
566
16%
1745
9%
566
40%
566
18%
1246
April16th to endNight
35%
540
18%
1620
10%
540
42%
540
21%
1126
May1st to 15thNight
37%
540
11%
1500
7%
540
41%
540
21%
1078
May16th to endNight
33%
471
10%
1405
5%
470
38%
470
18%
1006
June1st to 15thNight
42%
360
5%
1260
5%
360
44%
360
16%
881
June16th to endNight
43%
360
5%
1260
3%
360
46%
360
16%
887
July1st to 15thNight
52%
340
8%
1190
7%
340
54%
340
22%
762
July16th to endNight
51%
415
10%
1287
10%
390
53%
390
23%
841
August1st to 15thNight
53%
539
9%
1608
7%
535
55%
535
24%
1052
August16th to endNight
49%
573
15%
1719
10%
573
53%
573
26%
1106
September1st to 15thNight
41%
567
15%
1826
9%
567
48%
567
26%
1135
September16th to endNight
44%
717
21%
1989
13%
717
51%
717
30%
1246
October1st to 15thNight
32%
720
18%
2160
7%
720
42%
720
23%
1435
October16th to endNight
27%
768
14%
2380
7%
768
35%
768
17%
1700
November1st to 15thNight
28%
804
15%
2660
8%
804
37%
804
15%
1877
November16th to endNight
24%
825
11%
2730
4%
825
31%
825
11%
2060
December1st to 15thNight
17%
759
8%
2668
2%
759
25%
759
9%
2040
December16th to endNight
17%
800
9%
2880
3%
800
25%
800
8%
2239

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%35%5%3445%7%33%
48747
Night
18%9%36%5%3445%6%32%
47882
TransparencyDay
49%414%21%9%
48420
Night
51%412%20%9%
47728
SeeingDay
22%9%22%26%15%4
7199
Night
22%10%25%28%11%1
15016

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
14%12%48%7%45%5%5%7%24%
1253
16th to endDay
14%9%35%5%3447%9%32%
1527
February1st to 15thDay
8%12%45%6%46%5%6%7%32%
1575
16th to endDay
13%15%47%5%35%46%6%27%
1437
March1st to 15thDay
16%8%35%435%5%6%7%32%
1924
16th to endDay
13%9%36%5%34445%38%
2112
April1st to 15thDay
19%8%25%5%35%5%5%7%32%
2203
16th to endDay
22%8%35%423346%33%
2340
May1st to 15thDay
22%7%36%5%245%5%431%
2451
16th to endDay
23%6%36%5%25%45%6%29%
2719
June1st to 15thDay
23%7%36%423347%32%
2700
16th to endDay
21%7%35%5%345%5%7%29%
2700
July1st to 15thDay
15%5%25%435%5%7%10%33%
2700
16th to endDay
17%6%34425%5%6%9%35%
2780
August1st to 15thDay
15%5%16%5%3446%8%36%
2340
16th to endDay
13%5%25%5%345%6%8%38%
2483
September1st to 15thDay
17%6%25%6%3345%6%39%
2133
16th to endDay
16%6%25%422446%43%
1971
October1st to 15thDay
15%6%35%5%4445%6%37%
1800
16th to endDay
24%7%26%5%24446%30%
1842
November1st to 15thDay
22%5%25%5%345%5%6%32%
1526
16th to endDay
20%11%47%5%2446%6%26%
1560
December1st to 15thDay
22%12%37%5%345%5%7%22%
1327
16th to endDay
19%12%46%5%25%5%6%8%23%
1344
January1st to 15thNight
16%12%47%6%345%6%6%24%
2685
16th to endNight
14%9%37%5%35%5%6%9%29%
2696
February1st to 15thNight
8%12%5%6%5%45%6%6%8%29%
2285
16th to endNight
16%14%47%5%36%45%5%26%
2036
March1st to 15thNight
16%8%47%5%36%5%5%5%30%
2013
16th to endNight
14%10%46%5%245%4438%
2112
April1st to 15thNight
23%8%35%424445%31%
1745
16th to endNight
23%7%34434345%36%
1620
May1st to 15thNight
21%6%37%5%34435%34%
1500
16th to endNight
22%6%35%44446%6%30%
1404
June1st to 15thNight
24%6%25%4345%6%6%30%
1260
16th to endNight
24%5%25%5%35%446%30%
1260
July1st to 15thNight
16%6%245%35%5%6%6%38%
1260
16th to endNight
16%5%244345%6%8%37%
1374
August1st to 15thNight
16%5%26%4345%5%8%38%
1620
16th to endNight
14%425%5%35%45%7%41%
1719
September1st to 15thNight
16%5%24424346%44%
1826
16th to endNight
18%323323446%47%
1989
October1st to 15thNight
19%6%26%324446%40%
2160
16th to endNight
25%7%245%33446%32%
2380
November1st to 15thNight
22%7%245%35%5%45%33%
2660
16th to endNight
20%11%47%434446%27%
2730
December1st to 15thNight
20%14%46%435%47%5%24%
2668
16th to endNight
18%14%48%5%35%5%6%5%21%
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
59%411%15%7%
1254
16th to endDay
47%310%27%10%
1527
February1st to 15thDay
49%315%23%7%1
1578
16th to endDay
55%39%21%9%
1437
March1st to 15thDay
48%311%21%12%2
1935
16th to endDay
45%39%24%14%1
2112
April1st to 15thDay
49%48%20%14%2
2203
16th to endDay
50%39%19%15%2
2340
May1st to 15thDay
53%311%18%11%1
2451
16th to endDay
53%413%18%8%
2723
June1st to 15thDay
50%413%19%11%1
2700
16th to endDay
51%6%15%18%7%
2700
July1st to 15thDay
41%5%20%25%7%
2541
16th to endDay
44%418%22%9%
2606
August1st to 15thDay
43%420%25%5%
2327
16th to endDay
40%5%22%24%7%
2483
September1st to 15thDay
43%417%27%7%
2133
16th to endDay
40%414%28%12%
1971
October1st to 15thDay
45%317%23%8%1
1800
16th to endDay
51%5%13%21%7%
1842
November1st to 15thDay
51%5%15%19%7%
1526
16th to endDay
58%315%17%4
1560
December1st to 15thDay
62%5%12%13%4
1327
16th to endDay
60%412%17%5%
1344
January1st to 15thNight
60%5%12%16%5%
2685
16th to endNight
49%411%23%11%
2696
February1st to 15thNight
49%413%22%9%1
2286
16th to endNight
59%38%16%10%1
2036
March1st to 15thNight
53%38%20%12%1
2025
16th to endNight
49%29%18%16%2
2112
April1st to 15thNight
53%38%18%13%2
1745
16th to endNight
50%37%17%18%2
1620
May1st to 15thNight
52%310%21%10%1
1500
16th to endNight
51%6%12%20%8%1
1406
June1st to 15thNight
52%6%12%15%12%1
1260
16th to endNight
53%415%17%8%
1260
July1st to 15thNight
43%5%16%26%7%
1190
16th to endNight
43%6%18%21%9%
1287
August1st to 15thNight
43%5%22%23%5%
1608
16th to endNight
42%420%25%7%
1719
September1st to 15thNight
41%314%30%9%
1826
16th to endNight
37%415%29%12%1
1989
October1st to 15thNight
45%314%25%10%1
2160
16th to endNight
53%313%22%7%
2380
November1st to 15thNight
53%314%19%7%
2660
16th to endNight
59%5%13%16%4
2730
December1st to 15thNight
61%412%16%3
2668
16th to endNight
64%410%16%5%
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
26%26%26%15%31
60
16th to endDay
17%11%29%27%11%
118
February1st to 15thDay
14%16%25%29%11%2
236
16th to endDay
20%18%25%20%12%2
215
March1st to 15thDay
22%10%27%24%11%2
270
16th to endDay
18%10%27%22%14%6%
288
April1st to 15thDay
23%10%27%22%11%4
270
16th to endDay
23%9%22%25%11%7%
270
May1st to 15thDay
27%7%20%23%15%4
407
16th to endDay
27%5%23%24%15%3
519
June1st to 15thDay
29%5%17%30%14%2
495
16th to endDay
24%5%20%26%20%2
495
July1st to 15thDay
18%5%20%29%19%6%
475
16th to endDay
20%317%32%20%4
502
August1st to 15thDay
16%220%27%26%7%
313
16th to endDay
16%318%30%20%9%
332
September1st to 15thDay
18%6%26%30%12%6%
315
16th to endDay
19%12%22%27%12%6%
312
October1st to 15thDay
17%16%26%20%14%4
270
16th to endDay
28%18%24%17%9%2
288
November1st to 15thDay
25%15%19%26%12%2
280
16th to endDay
27%14%26%22%8%1
285
December1st to 15thDay
35%9%19%30%5%
120
16th to endDay
26%18%32%20%1
64
January1st to 15thNight
21%18%30%23%6%
750
16th to endNight
18%16%31%25%6%
779
February1st to 15thNight
15%12%30%30%9%
704
16th to endNight
26%12%26%23%8%2
631
March1st to 15thNight
18%11%29%30%9%
720
16th to endNight
18%11%25%30%11%1
768
April1st to 15thNight
27%6%23%32%9%
566
16th to endNight
29%5%23%29%10%1
540
May1st to 15thNight
24%423%31%13%1
540
16th to endNight
24%6%27%29%10%1
471
June1st to 15thNight
29%315%37%13%1
360
16th to endNight
26%216%37%15%1
360
July1st to 15thNight
19%217%39%18%2
340
16th to endNight
18%216%40%21%1
415
August1st to 15thNight
17%315%40%20%1
539
16th to endNight
15%419%39%19%2
573
September1st to 15thNight
18%7%25%31%17%
567
16th to endNight
19%8%23%34%13%1
717
October1st to 15thNight
23%8%30%25%11%1
720
16th to endNight
30%11%24%24%9%
768
November1st to 15thNight
26%11%26%24%8%2
804
16th to endNight
24%17%25%22%8%2
825
December1st to 15thNight
27%16%30%19%5%
759
16th to endNight
29%16%27%19%5%1
800
Page generated at 2017-12-03 11:16:36. Version ac04

Copyright 2017 A. Danko


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