Barry's Bay
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Barry's Bay clear sky chart from 2005-11-06 to 2024-01-12.

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
26%
22570
13%
74782
7%
22529
33%
22529
15%
54417

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
11%
760
7%
2649
2%
757
18%
757
6%
2201
January11th to 20thNight
16%
727
8%
2541
4%
727
22%
727
7%
2070
January21st to endNight
19%
792
13%
2610
7%
792
27%
792
11%
1990
February1st to 10thNight
12%
720
8%
2340
2%
720
18%
720
8%
1875
February11th to 20thNight
14%
701
13%
2275
3%
700
26%
700
12%
1684
February21st to endNight
18%
592
14%
1852
5%
592
29%
592
12%
1398
March1st to 10thNight
17%
720
14%
2062
7%
720
25%
720
14%
1550
March11th to 20thNight
20%
720
15%
1979
5%
720
30%
720
16%
1454
March21st to endNight
24%
792
19%
2133
7%
792
33%
792
21%
1499
April1st to 10thNight
19%
720
14%
1800
4%
720
23%
720
18%
1362
April11th to 20thNight
24%
711
18%
1775
7%
711
31%
711
21%
1293
April21st to endNight
29%
550
15%
1630
7%
550
35%
550
17%
1194
May1st to 10thNight
34%
396
17%
1476
14%
396
42%
396
18%
955
May11th to 20thNight
29%
354
20%
1416
14%
354
46%
354
19%
874
May21st to endNight
34%
389
14%
1551
12%
388
45%
388
22%
914
June1st to 10thNight
32%
360
10%
1440
9%
360
41%
360
16%
932
June11th to 20thNight
38%
360
14%
1440
14%
360
47%
360
22%
852
June21st to endNight
38%
360
10%
1440
12%
360
45%
360
17%
923
July1st to 10thNight
45%
350
14%
1400
15%
350
56%
350
26%
784
July11th to 20thNight
46%
348
15%
1392
18%
348
53%
348
23%
807
July21st to endNight
44%
394
16%
1486
14%
372
53%
372
25%
851
August1st to 10thNight
48%
501
15%
1565
11%
499
53%
499
27%
983
August11th to 20thNight
56%
534
18%
1598
12%
534
61%
534
32%
981
August21st to endNight
42%
719
17%
1907
8%
719
48%
719
30%
1262
September1st to 10thNight
43%
720
17%
1800
7%
720
47%
720
32%
1183
September11th to 20thNight
45%
720
21%
1800
12%
720
48%
720
32%
1195
September21st to endNight
41%
720
19%
2074
15%
720
45%
720
24%
1403
October1st to 10thNight
31%
720
17%
2160
11%
720
39%
720
20%
1492
October11th to 20thNight
22%
720
11%
2160
5%
720
29%
720
14%
1625
October21st to endNight
19%
792
12%
2438
6%
792
27%
792
11%
1911
November1st to 10thNight
24%
740
14%
2502
9%
740
32%
740
14%
1794
November11th to 20thNight
17%
760
12%
2660
7%
760
25%
760
10%
2042
November21st to endNight
17%
760
8%
2660
4%
760
21%
760
7%
2164
December1st to 10thNight
11%
760
7%
2660
3%
760
17%
760
5%
2242
December11th to 20thNight
15%
760
9%
3259
4%
759
23%
759
7%
2554
December21st to endNight
11%
828
5%
4852
1%
817
16%
817
3%
4124

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
16%11%48%6%35%45%6%31%
74692
Night
16%12%5%8%6%3445%6%31%
75015
TransparencyDay
54%6%10%19%10%1
74397
Night
54%6%11%18%10%1
74844
SeeingDay
23%18%31%19%8%2
13252
Night
22%15%31%23%8%1
22580

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
13%18%7%14%9%34445%18%
1517
11th to 20thDay
16%14%7%13%8%35%45%5%20%
1448
21st to endDay
11%13%6%13%9%5%6%44423%
1742
February1st to 10thDay
11%15%6%14%11%45%5%4420%
1620
11th to 20thDay
12%14%7%11%7%5%5%5%5%6%25%
1573
21st to endDay
16%16%5%9%8%45%5%5%5%22%
1404
March1st to 10thDay
13%14%6%10%8%45%445%28%
1893
11th to 20thDay
13%13%6%11%8%46%5%5%427%
1980
21st to endDay
17%11%5%7%5%34435%36%
2222
April1st to 10thDay
20%14%47%6%35%445%28%
2160
11th to 20thDay
21%10%46%5%34345%36%
2140
21st to endDay
22%10%36%6%25%445%33%
2340
May1st to 10thDay
18%10%36%5%34446%36%
2482
11th to 20thDay
17%9%46%5%3445%6%36%
2478
21st to endDay
14%6%37%6%45%45%7%39%
2725
June1st to 10thDay
20%9%46%6%45%45%7%31%
2520
11th to 20thDay
16%6%25%5%35%5%6%8%38%
2520
21st to endDay
16%7%36%6%46%6%5%8%34%
2520
July1st to 10thDay
12%6%35%6%36%5%6%9%38%
2520
11th to 20thDay
12%6%35%6%46%6%6%8%38%
2520
21st to endDay
12%5%37%6%46%6%6%10%36%
2744
August1st to 10thDay
13%6%37%7%45%6%6%8%36%
2360
11th to 20thDay
14%6%35%6%46%6%5%8%35%
2303
21st to endDay
14%6%36%6%46%6%6%9%34%
2430
September1st to 10thDay
15%7%35%5%345%6%8%40%
2160
11th to 20thDay
15%7%35%6%3335%7%43%
2160
21st to endDay
18%8%37%5%35%45%7%35%
1883
October1st to 10thDay
20%10%37%5%345%46%33%
1800
11th to 20thDay
23%13%5%8%6%35%445%24%
1800
21st to endDay
27%14%47%6%44445%21%
1918
November1st to 10thDay
15%12%5%8%5%35%447%32%
1572
11th to 20thDay
16%15%7%8%8%3445%5%25%
1520
21st to endDay
20%18%6%10%8%35%345%15%
1520
December1st to 10thDay
19%19%9%11%9%4434415%
1520
11th to 20thDay
17%17%6%10%8%35%45%420%
1906
21st to endDay
23%21%7%13%7%2223417%
2772
January1st to 10thNight
15%15%7%12%9%5%6%5%45%16%
2649
11th to 20thNight
13%16%7%11%9%5%6%5%5%5%19%
2541
21st to endNight
10%14%7%11%9%45%5%5%5%26%
2610
February1st to 10thNight
12%15%7%12%9%5%5%45%7%18%
2340
11th to 20thNight
12%14%7%9%6%46%45%5%28%
2273
21st to endNight
12%15%6%10%6%35%5%5%6%27%
1852
March1st to 10thNight
14%12%6%10%7%34345%31%
2052
11th to 20thNight
12%13%5%9%6%35%46%6%31%
1979
21st to endNight
13%10%48%7%2445%6%38%
2133
April1st to 10thNight
19%13%5%7%6%34435%31%
1800
11th to 20thNight
18%11%46%434346%37%
1775
21st to endNight
19%10%48%6%345%45%32%
1630
May1st to 10thNight
19%7%36%43445%6%38%
1476
11th to 20thNight
17%7%36%5%2445%8%40%
1415
21st to endNight
11%5%36%5%246%6%8%45%
1550
June1st to 10thNight
17%6%36%6%35%6%5%7%36%
1440
11th to 20thNight
15%5%36%425%45%8%43%
1440
21st to endNight
15%7%36%5%45%47%8%37%
1440
July1st to 10thNight
9%6%245%445%6%8%48%
1440
11th to 20thNight
12%6%245%345%5%8%45%
1440
21st to endNight
9%5%25%5%345%7%10%46%
1574
August1st to 10thNight
10%426%6%5%46%5%8%44%
1575
11th to 20thNight
9%5%25%5%345%6%8%48%
1598
21st to endNight
13%5%36%5%35%5%5%8%44%
1907
September1st to 10thNight
13%5%345%345%47%47%
1800
11th to 20thNight
15%6%24433447%48%
1800
21st to endNight
16%8%35%5%345%5%6%41%
2074
October1st to 10thNight
21%8%36%424446%39%
2160
11th to 20thNight
21%11%47%6%345%46%28%
2160
21st to endNight
23%14%48%7%3345%5%24%
2438
November1st to 10thNight
17%13%47%6%3445%6%31%
2502
11th to 20thNight
16%13%6%10%8%44446%24%
2660
21st to endNight
18%16%6%11%8%45%345%19%
2660
December1st to 10thNight
18%20%8%12%7%45%445%14%
2660
11th to 20thNight
17%18%7%10%6%34435%22%
3288
21st to endNight
25%20%6%12%8%3433413%
4884

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
69%5%8%13%5%
1518
11th to 20thDay
66%6%6%10%10%1
1448
21st to endDay
64%5%8%11%10%2
1742
February1st to 10thDay
68%48%14%5%1
1620
11th to 20thDay
60%5%11%13%9%2
1582
21st to endDay
63%5%8%13%10%1
1404
March1st to 10thDay
59%5%10%15%10%2
1896
11th to 20thDay
60%49%15%9%2
1980
21st to endDay
51%5%7%18%14%6%
2222
April1st to 10thDay
58%5%7%18%10%3
2160
11th to 20thDay
52%47%23%13%2
2140
21st to endDay
54%5%7%17%14%3
2340
May1st to 10thDay
49%5%9%20%12%4
2482
11th to 20thDay
49%6%8%21%15%2
2482
21st to endDay
45%7%11%20%14%3
2725
June1st to 10thDay
52%6%10%19%11%1
2520
11th to 20thDay
43%7%11%23%13%3
2520
21st to endDay
47%8%12%20%12%1
2520
July1st to 10thDay
40%7%12%26%14%1
2450
11th to 20thDay
41%8%14%24%12%1
2445
21st to endDay
43%9%13%26%9%
2591
August1st to 10thDay
46%9%14%21%10%1
2346
11th to 20thDay
44%9%14%24%8%1
2303
21st to endDay
44%10%13%23%10%1
2430
September1st to 10thDay
41%7%13%26%12%1
2160
11th to 20thDay
41%6%11%30%11%
2160
21st to endDay
49%6%12%24%9%
1883
October1st to 10thDay
52%6%10%20%11%1
1800
11th to 20thDay
62%6%10%15%5%1
1800
21st to endDay
65%7%10%12%5%1
1918
November1st to 10thDay
52%6%14%20%7%1
1572
11th to 20thDay
61%7%11%12%7%1
1520
21st to endDay
71%5%10%9%5%1
1520
December1st to 10thDay
74%5%7%9%4
1520
11th to 20thDay
66%7%8%10%8%1
1906
21st to endDay
75%35%14%3
2772
January1st to 10thNight
70%6%9%10%5%
2649
11th to 20thNight
67%6%8%10%7%1
2541
21st to endNight
60%6%8%15%11%1
2610
February1st to 10thNight
65%6%9%12%6%1
2340
11th to 20thNight
58%5%12%17%7%1
2275
21st to endNight
57%6%9%18%9%1
1852
March1st to 10thNight
57%5%10%16%10%2
2062
11th to 20thNight
53%5%11%18%12%1
1980
21st to endNight
47%6%8%21%15%3
2133
April1st to 10thNight
56%49%18%11%2
1800
11th to 20thNight
50%5%7%24%13%2
1775
21st to endNight
54%6%7%16%16%2
1630
May1st to 10thNight
46%6%10%19%16%4
1476
11th to 20thNight
42%6%10%23%16%2
1416
21st to endNight
37%8%15%21%17%3
1551
June1st to 10thNight
45%8%12%22%12%1
1440
11th to 20thNight
39%6%11%27%15%2
1440
21st to endNight
45%7%15%20%13%1
1440
July1st to 10thNight
32%9%14%25%19%2
1400
11th to 20thNight
38%6%14%29%13%1
1392
21st to endNight
33%9%16%31%10%1
1486
August1st to 10thNight
36%9%18%25%12%1
1565
11th to 20thNight
34%8%18%29%10%1
1598
21st to endNight
37%8%16%28%10%1
1907
September1st to 10thNight
37%7%14%28%13%1
1800
11th to 20thNight
38%6%13%32%11%
1800
21st to endNight
44%6%12%30%8%
2074
October1st to 10thNight
47%7%12%20%14%
2160
11th to 20thNight
56%7%13%17%7%
2160
21st to endNight
61%7%10%14%8%
2438
November1st to 10thNight
54%6%14%18%7%
2502
11th to 20thNight
61%6%10%15%7%1
2660
21st to endNight
67%7%10%12%3
2660
December1st to 10thNight
72%6%8%10%4
2660
11th to 20thNight
65%5%9%13%7%1
3288
21st to endNight
77%36%10%3
4884

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
21%26%34%16%31
180
11th to 20thDay
27%14%37%17%41
162
21st to endDay
23%20%35%17%4
246
February1st to 10thDay
28%32%33%6%2
240
11th to 20thDay
26%28%41%5%
240
21st to endDay
32%24%30%13%1
270
March1st to 10thDay
24%25%34%15%2
420
11th to 20thDay
26%19%33%17%5%1
420
21st to endDay
30%22%31%12%5%1
462
April1st to 10thDay
29%22%30%13%5%1
420
11th to 20thDay
33%21%21%14%8%3
412
21st to endDay
29%19%32%12%7%1
420
May1st to 10thDay
27%17%29%17%8%2
423
11th to 20thDay
21%19%30%19%8%3
447
21st to endDay
17%19%32%20%9%2
485
June1st to 10thDay
23%14%37%18%7%
450
11th to 20thDay
19%15%31%22%11%3
450
21st to endDay
18%14%33%22%10%2
450
July1st to 10thDay
11%9%32%36%9%2
445
11th to 20thDay
14%12%35%24%13%2
444
21st to endDay
13%10%36%29%9%2
488
August1st to 10thDay
15%9%33%28%11%5%
446
11th to 20thDay
14%9%29%26%17%5%
439
21st to endDay
16%13%31%25%10%6%
495
September1st to 10thDay
15%14%29%22%13%6%
450
11th to 20thDay
16%13%25%23%17%6%
450
21st to endDay
19%16%26%22%12%5%
450
October1st to 10thDay
26%17%24%17%12%4
450
11th to 20thDay
28%26%26%14%5%1
450
21st to endDay
35%17%29%16%3
464
November1st to 10thDay
26%20%32%16%6%
266
11th to 20thDay
29%24%31%10%6%1
180
21st to endDay
32%22%36%7%21
180
December1st to 10thDay
32%16%36%13%2
180
11th to 20thDay
32%30%24%11%21
180
21st to endDay
32%25%27%11%41
198
January1st to 10thNight
23%20%37%16%41
760
11th to 20thNight
26%18%30%20%5%1
727
21st to endNight
17%16%37%23%7%1
792
February1st to 10thNight
20%21%41%15%3
720
11th to 20thNight
21%19%40%16%4
703
21st to endNight
23%21%32%21%3
592
March1st to 10thNight
22%21%34%19%3
720
11th to 20thNight
23%19%32%19%5%1
720
21st to endNight
19%17%35%21%8%
792
April1st to 10thNight
28%17%31%21%3
720
11th to 20thNight
25%18%30%19%8%
711
21st to endNight
22%16%27%26%9%
550
May1st to 10thNight
20%12%28%29%11%1
396
11th to 20thNight
21%11%34%27%7%
354
21st to endNight
12%10%37%29%12%
389
June1st to 10thNight
17%8%37%33%5%1
360
11th to 20thNight
20%8%30%31%11%1
360
21st to endNight
18%11%29%30%12%
360
July1st to 10thNight
9%6%36%33%14%1
350
11th to 20thNight
14%6%27%38%15%1
348
21st to endNight
9%8%35%37%11%1
394
August1st to 10thNight
11%7%25%35%21%1
501
11th to 20thNight
10%424%39%20%3
534
21st to endNight
13%8%30%30%17%2
719
September1st to 10thNight
17%7%29%28%18%2
720
11th to 20thNight
18%8%26%27%19%3
720
21st to endNight
19%13%23%27%17%2
720
October1st to 10thNight
25%12%29%21%11%2
720
11th to 20thNight
26%17%31%17%8%1
720
21st to endNight
31%18%27%20%5%
792
November1st to 10thNight
26%16%29%22%5%1
740
11th to 20thNight
22%23%30%15%8%1
760
21st to endNight
29%19%28%20%4
760
December1st to 10thNight
29%19%33%14%5%
760
11th to 20thNight
26%20%31%19%31
760
21st to endNight
33%18%28%18%31
836
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