Bonaventure
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Bonaventure clear sky chart from 2005-11-06 to 2024-02-10.

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
30%
23175
9%
80671
4%
23072
35%
23072
9%
63199

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 10thNight
14%
839
10%
4668
0%
817
19%
817
3%
3289
January11th to 20thNight
18%
843
10%
4695
2%
820
25%
820
3%
3770
January21st to endNight
23%
822
9%
4663
5%
815
34%
815
6%
2939
February1st to 10thNight
24%
759
10%
2464
4%
759
32%
759
9%
1970
February11th to 20thNight
19%
702
7%
2276
1%
700
27%
700
6%
1884
February21st to endNight
27%
592
11%
1901
4%
592
35%
592
9%
1535
March1st to 10thNight
26%
720
12%
2047
5%
720
33%
720
10%
1670
March11th to 20thNight
27%
720
11%
1980
5%
720
33%
720
11%
1621
March21st to endNight
31%
792
12%
2178
4%
792
37%
792
11%
1755
April1st to 10thNight
27%
581
8%
1813
5%
581
30%
581
8%
1503
April11th to 20thNight
34%
534
14%
1598
8%
534
38%
534
13%
1241
April21st to endNight
33%
540
12%
1620
6%
540
39%
540
12%
1283
May1st to 10thNight
31%
540
8%
1531
6%
540
35%
540
11%
1245
May11th to 20thNight
37%
532
11%
1417
6%
532
40%
532
14%
1129
May21st to endNight
33%
451
9%
1418
4%
450
38%
450
12%
1106
June1st to 10thNight
40%
360
5%
1260
4%
360
41%
360
9%
1009
June11th to 20thNight
47%
360
7%
1260
5%
360
48%
360
11%
977
June21st to endNight
42%
360
3%
1260
2%
360
43%
360
7%
1048
July1st to 10thNight
47%
350
6%
1225
4%
350
49%
350
11%
949
July11th to 20thNight
53%
348
7%
1218
7%
348
55%
348
12%
956
July21st to endNight
51%
452
8%
1370
8%
427
52%
427
12%
1072
August1st to 10thNight
52%
538
6%
1600
4%
534
54%
534
14%
1235
August11th to 20thNight
52%
532
9%
1596
7%
532
54%
532
14%
1249
August21st to endNight
51%
594
12%
1782
8%
594
54%
594
15%
1328
September1st to 10thNight
41%
540
9%
1798
4%
540
46%
540
13%
1346
September11th to 20thNight
44%
669
14%
1929
9%
669
50%
669
16%
1439
September21st to endNight
42%
720
14%
1993
8%
720
47%
720
15%
1530
October1st to 10thNight
33%
720
13%
2160
5%
720
40%
720
14%
1670
October11th to 20thNight
30%
720
10%
2160
5%
720
34%
720
10%
1730
October21st to endNight
27%
792
11%
2489
5%
792
33%
792
10%
1980
November1st to 10thNight
27%
828
9%
2589
4%
828
32%
828
9%
2066
November11th to 20thNight
23%
850
10%
2660
4%
850
30%
850
8%
2211
November21st to endNight
21%
850
6%
2660
2%
850
25%
850
6%
2247
December1st to 10thNight
20%
850
5%
2759
1%
850
25%
850
5%
2401
December11th to 20thNight
14%
850
6%
3486
2%
849
19%
849
3%
2987
December21st to endNight
17%
925
4%
5148
1%
907
21%
907
3%
3829

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%8%36%6%35%5%6%7%34%
77793
Night
17%9%47%6%35%5%6%6%32%
81188
TransparencyDay
34%35%9%15%7%1
77482
Night
37%33%9%14%6%1
81035
SeeingDay
22%11%26%25%13%3
15389
Night
23%11%27%28%10%1
23219

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 10thDay
14%10%48%8%5%45%47%32%
2207
11th to 20thDay
13%11%47%10%47%8%8%6%22%
2210
21st to endDay
7%8%35%5%35%6%9%9%40%
2892
February1st to 10thDay
11%11%5%6%6%5%6%6%6%7%32%
1701
11th to 20thDay
12%14%6%7%6%5%5%5%5%6%29%
1573
21st to endDay
8%13%35%5%46%5%7%8%35%
1354
March1st to 10thDay
13%12%46%5%35%5%6%7%33%
1908
11th to 20thDay
14%8%37%6%5%7%5%6%6%33%
1980
21st to endDay
15%12%47%5%34446%37%
2178
April1st to 10thDay
20%9%36%6%36%5%5%7%30%
2145
11th to 20thDay
18%8%35%4345%6%7%37%
2312
21st to endDay
23%9%36%6%35%45%6%30%
2340
May1st to 10thDay
22%10%46%5%345%5%6%31%
2427
11th to 20thDay
21%6%36%6%35%5%5%6%33%
2478
21st to endDay
20%6%26%5%35%5%5%7%36%
2871
June1st to 10thDay
24%8%36%6%2445%7%31%
2700
11th to 20thDay
18%6%26%5%345%5%8%37%
2700
21st to endDay
22%9%35%5%35%5%5%7%31%
2700
July1st to 10thDay
15%6%26%6%36%6%8%9%32%
2700
11th to 20thDay
13%5%35%5%46%6%7%10%38%
2700
21st to endDay
17%7%345%3447%8%37%
2847
August1st to 10thDay
15%6%26%6%45%5%6%9%36%
2327
11th to 20thDay
16%6%26%5%346%6%7%38%
2304
21st to endDay
12%5%25%5%46%5%7%8%40%
2574
September1st to 10thDay
16%6%25%6%445%6%7%41%
2161
11th to 20thDay
17%6%35%5%34445%44%
2030
21st to endDay
17%7%36%4335%5%7%39%
1967
October1st to 10thDay
15%7%36%5%4446%5%40%
1800
11th to 20thDay
20%8%37%6%445%5%7%31%
1800
21st to endDay
23%8%37%5%35%45%7%31%
1864
November1st to 10thDay
20%6%35%7%45%6%5%6%33%
1487
11th to 20thDay
20%8%48%5%45%5%7%6%28%
1520
21st to endDay
20%13%48%6%4445%7%26%
1520
December1st to 10thDay
20%12%37%7%46%6%5%7%24%
1417
11th to 20thDay
18%13%47%8%46%5%6%7%22%
1668
21st to endDay
16%11%37%6%35%446%35%
2431
January1st to 10thNight
10%10%5%9%8%46%7%8%9%26%
4748
11th to 20thNight
17%11%48%11%5%5%5%5%5%23%
4760
21st to endNight
7%10%5%7%5%35%5%7%9%37%
4747
February1st to 10thNight
9%13%5%8%6%45%6%6%7%31%
2464
11th to 20thNight
15%13%48%6%445%6%6%29%
2273
21st to endNight
13%12%5%7%6%36%6%6%6%32%
1901
March1st to 10thNight
13%10%5%8%6%35%5%5%6%33%
2038
11th to 20thNight
15%10%47%5%46%6%6%5%31%
1979
21st to endNight
15%11%47%6%345%45%36%
2178
April1st to 10thNight
23%11%46%6%34445%29%
1813
11th to 20thNight
19%8%35%5%35%45%6%36%
1598
21st to endNight
25%8%45%5%34446%33%
1620
May1st to 10thNight
23%7%28%5%35%5%46%33%
1531
11th to 20thNight
18%8%46%6%4445%6%36%
1416
21st to endNight
19%6%445%45%47%8%36%
1418
June1st to 10thNight
24%7%36%4345%5%7%31%
1260
11th to 20thNight
21%6%35%5%35%5%5%7%35%
1260
21st to endNight
26%5%36%5%36%46%6%30%
1260
July1st to 10thNight
17%6%25%6%26%5%7%8%37%
1260
11th to 20thNight
15%7%35%6%445%6%7%40%
1260
21st to endNight
16%7%25%5%445%7%9%36%
1450
August1st to 10thNight
14%6%36%5%446%6%8%39%
1612
11th to 20thNight
17%5%27%5%35%5%6%8%36%
1596
21st to endNight
13%5%345%35%5%5%8%44%
1782
September1st to 10thNight
17%6%25%4245%5%6%44%
1798
11th to 20thNight
17%7%24334446%46%
1929
21st to endNight
20%32442345%6%47%
1993
October1st to 10thNight
19%7%36%434446%41%
2160
11th to 20thNight
21%8%36%5%4446%6%34%
2160
21st to endNight
24%7%35%6%4445%7%32%
2489
November1st to 10thNight
21%7%35%6%36%5%5%6%33%
2589
11th to 20thNight
20%10%5%7%6%35%5%5%6%28%
2660
21st to endNight
21%11%47%6%45%5%5%7%25%
2660
December1st to 10thNight
20%11%48%6%46%5%7%5%24%
2759
11th to 20thNight
23%12%47%7%45%5%6%5%22%
3531
21st to endNight
16%14%48%6%35%5%5%5%29%
5236

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 10thDay
43%24%9%15%10%
2208
11th to 20thDay
49%24%7%14%7%
2210
21st to endDay
30%23%13%21%12%1
2892
February1st to 10thDay
36%34%10%12%8%
1701
11th to 20thDay
39%36%6%12%6%1
1581
21st to endDay
32%36%8%17%6%2
1354
March1st to 10thDay
34%35%8%15%6%1
1912
11th to 20thDay
32%35%8%15%9%1
1980
21st to endDay
34%35%6%14%9%1
2178
April1st to 10thDay
37%35%7%12%8%1
2145
11th to 20thDay
31%35%7%17%11%
2312
21st to endDay
34%35%6%13%10%2
2340
May1st to 10thDay
37%35%7%12%8%1
2427
11th to 20thDay
34%36%7%13%9%1
2482
21st to endDay
32%36%9%14%9%1
2871
June1st to 10thDay
36%35%8%12%7%1
2700
11th to 20thDay
29%36%10%16%9%1
2700
21st to endDay
37%37%10%11%5%
2700
July1st to 10thDay
29%38%14%15%4
2625
11th to 20thDay
28%37%12%16%7%
2619
21st to endDay
31%37%12%16%4
2688
August1st to 10thDay
31%35%11%18%5%
2314
11th to 20thDay
29%35%16%16%3
2304
21st to endDay
28%36%12%18%5%
2574
September1st to 10thDay
28%36%11%18%6%
2161
11th to 20thDay
28%35%8%19%9%
2030
21st to endDay
31%36%8%18%6%
1967
October1st to 10thDay
30%35%12%17%5%1
1800
11th to 20thDay
36%36%10%15%3
1800
21st to endDay
33%37%9%14%6%
1864
November1st to 10thDay
29%41%9%15%6%
1487
11th to 20thDay
34%40%9%13%4
1520
21st to endDay
39%40%8%10%3
1520
December1st to 10thDay
41%41%6%9%3
1417
11th to 20thDay
45%32%9%9%6%
1668
21st to endDay
40%24%12%14%7%3
2431
January1st to 10thNight
42%24%13%17%3
4748
11th to 20thNight
51%25%6%11%7%
4760
21st to endNight
35%22%12%18%14%1
4747
February1st to 10thNight
36%35%7%13%8%2
2464
11th to 20thNight
39%36%7%11%6%1
2276
21st to endNight
37%35%7%13%8%
1901
March1st to 10thNight
36%35%6%15%6%
2047
11th to 20thNight
35%36%6%13%8%1
1980
21st to endNight
35%35%7%12%10%2
2178
April1st to 10thNight
39%36%7%10%8%1
1813
11th to 20thNight
32%35%5%16%10%2
1598
21st to endNight
33%35%6%12%13%1
1620
May1st to 10thNight
36%35%7%11%10%1
1531
11th to 20thNight
32%35%6%19%7%
1417
21st to endNight
30%38%9%14%9%1
1419
June1st to 10thNight
36%36%9%11%8%
1260
11th to 20thNight
32%37%10%12%8%1
1260
21st to endNight
40%37%9%8%5%1
1260
July1st to 10thNight
31%37%10%17%4
1225
11th to 20thNight
32%37%11%15%5%1
1218
21st to endNight
29%39%12%16%4
1370
August1st to 10thNight
30%36%13%16%5%
1600
11th to 20thNight
31%36%14%16%3
1596
21st to endNight
27%35%12%20%5%
1782
September1st to 10thNight
28%36%11%18%6%
1798
11th to 20thNight
25%36%8%22%9%1
1929
21st to endNight
27%36%8%19%9%
1993
October1st to 10thNight
30%35%10%17%7%1
2160
11th to 20thNight
36%35%11%15%4
2160
21st to endNight
33%37%9%17%5%
2489
November1st to 10thNight
31%40%10%13%5%1
2589
11th to 20thNight
36%39%8%12%4
2660
21st to endNight
37%40%9%10%3
2660
December1st to 10thNight
41%40%7%9%2
2759
11th to 20thNight
48%32%6%10%3
3532
21st to endNight
46%24%11%12%43
5236

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 10thDay
29%17%27%17%9%1
180
11th to 20thDay
29%21%23%19%7%2
180
21st to endDay
15%14%31%27%11%1
283
February1st to 10thDay
20%17%29%23%7%5%
367
11th to 20thDay
20%20%29%23%7%1
336
21st to endDay
13%18%34%23%10%2
290
March1st to 10thDay
23%11%31%24%8%2
420
11th to 20thDay
19%14%28%27%11%2
420
21st to endDay
23%13%28%21%10%3
462
April1st to 10thDay
26%15%28%22%6%2
420
11th to 20thDay
24%8%28%26%10%3
412
21st to endDay
27%12%26%23%8%4
420
May1st to 10thDay
27%9%26%24%10%4
510
11th to 20thDay
25%8%25%20%18%4
624
21st to endDay
23%9%29%25%11%3
680
June1st to 10thDay
28%7%24%27%12%2
630
11th to 20thDay
23%6%25%28%15%3
630
21st to endDay
24%7%21%28%18%3
630
July1st to 10thDay
18%7%25%30%15%5%
620
11th to 20thDay
15%5%22%35%21%2
618
21st to endDay
20%418%32%22%5%
667
August1st to 10thDay
15%424%29%23%5%
446
11th to 20thDay
19%5%19%32%19%6%
439
21st to endDay
15%6%21%31%21%6%
495
September1st to 10thDay
17%7%28%27%15%6%
450
11th to 20thDay
24%10%26%24%11%5%
450
21st to endDay
21%13%25%24%13%4
444
October1st to 10thDay
17%13%27%24%16%3
360
11th to 20thDay
25%14%27%18%13%4
360
21st to endDay
29%17%24%18%9%3
396
November1st to 10thDay
25%15%27%24%8%1
365
11th to 20thDay
28%15%23%24%8%1
370
21st to endDay
27%18%29%20%6%1
370
December1st to 10thDay
30%9%27%26%7%1
267
11th to 20thDay
24%22%29%19%41
180
21st to endDay
25%20%28%22%5%
198
January1st to 10thNight
21%15%32%25%7%1
850
11th to 20thNight
23%15%32%24%6%
850
21st to endNight
16%16%32%26%9%1
837
February1st to 10thNight
16%15%33%26%9%1
759
11th to 20thNight
24%15%31%23%5%2
703
21st to endNight
21%10%31%28%9%1
592
March1st to 10thNight
20%11%32%30%8%
720
11th to 20thNight
20%12%30%28%10%1
720
21st to endNight
21%11%26%32%9%1
792
April1st to 10thNight
31%8%25%29%7%
581
11th to 20thNight
25%5%29%28%11%1
534
21st to endNight
31%7%21%31%9%2
540
May1st to 10thNight
27%6%26%29%12%1
540
11th to 20thNight
23%5%27%29%14%2
532
21st to endNight
20%7%31%32%9%1
451
June1st to 10thNight
28%419%38%10%1
360
11th to 20thNight
23%318%36%20%1
360
21st to endNight
28%416%38%13%1
360
July1st to 10thNight
19%320%39%17%2
350
11th to 20thNight
18%218%47%13%2
348
21st to endNight
18%416%37%23%2
452
August1st to 10thNight
16%418%42%19%1
538
11th to 20thNight
17%414%40%23%2
532
21st to endNight
15%5%19%38%21%2
594
September1st to 10thNight
19%6%26%32%15%1
540
11th to 20thNight
20%8%21%35%15%1
669
21st to endNight
20%9%23%33%13%1
720
October1st to 10thNight
24%7%29%27%12%1
720
11th to 20thNight
26%10%26%25%12%1
720
21st to endNight
29%12%25%25%9%
792
November1st to 10thNight
26%13%28%25%7%1
828
11th to 20thNight
27%16%28%20%8%2
850
21st to endNight
26%17%28%22%6%1
850
December1st to 10thNight
28%12%30%22%8%1
850
11th to 20thNight
28%20%31%15%5%1
850
21st to endNight
28%16%29%22%41
935
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