Brantford
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Brantford clear sky chart from 2005-11-06 to 2024-01-31.

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
33%
23016
14%
74837
9%
22966
40%
22966
18%
52499

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
16%
757
10%
2607
4%
757
24%
757
9%
2030
January11th to 20thNight
15%
760
7%
2470
3%
760
19%
760
7%
2028
January21st to endNight
19%
835
11%
2711
4%
835
28%
835
11%
2097
February1st to 10thNight
15%
720
7%
2340
2%
720
22%
720
9%
1856
February11th to 20thNight
19%
700
10%
2275
3%
700
28%
700
12%
1699
February21st to endNight
17%
592
11%
1832
3%
592
26%
592
12%
1388
March1st to 10thNight
24%
720
16%
1990
7%
720
31%
720
18%
1446
March11th to 20thNight
24%
720
18%
1980
8%
720
33%
720
19%
1436
March21st to endNight
29%
792
18%
2178
9%
792
36%
792
20%
1553
April1st to 10thNight
28%
720
14%
1872
6%
720
33%
720
20%
1364
April11th to 20thNight
30%
623
19%
1687
8%
623
36%
623
22%
1179
April21st to endNight
34%
540
17%
1620
7%
540
41%
540
22%
1095
May1st to 10thNight
38%
540
15%
1620
9%
540
44%
540
23%
1092
May11th to 20thNight
43%
450
19%
1512
12%
450
53%
450
23%
955
May21st to endNight
50%
388
17%
1551
18%
388
58%
388
27%
836
June1st to 10thNight
45%
360
15%
1440
14%
360
56%
360
22%
841
June11th to 20thNight
46%
360
15%
1432
16%
360
55%
360
23%
820
June21st to endNight
51%
360
18%
1260
18%
360
60%
360
27%
735
July1st to 10thNight
63%
350
19%
1318
23%
350
69%
350
35%
667
July11th to 20thNight
58%
420
18%
1464
19%
420
63%
420
32%
811
July21st to endNight
60%
591
17%
1672
13%
558
63%
558
34%
988
August1st to 10thNight
63%
537
18%
1600
14%
534
66%
534
32%
971
August11th to 20thNight
66%
534
22%
1598
15%
534
70%
534
37%
923
August21st to endNight
58%
646
21%
1834
14%
646
61%
646
34%
1132
September1st to 10thNight
53%
720
19%
1800
10%
720
56%
720
32%
1204
September11th to 20thNight
59%
720
26%
1961
18%
720
63%
720
37%
1168
September21st to endNight
48%
720
20%
1982
14%
720
52%
720
27%
1318
October1st to 10thNight
42%
720
18%
2160
16%
720
47%
720
25%
1421
October11th to 20thNight
31%
720
16%
2160
10%
720
39%
720
20%
1494
October21st to endNight
25%
792
17%
2376
11%
792
33%
792
15%
1779
November1st to 10thNight
34%
740
19%
2421
14%
740
42%
740
21%
1552
November11th to 20thNight
23%
760
14%
2660
8%
760
33%
760
14%
1898
November21st to endNight
22%
760
10%
2660
6%
760
28%
760
12%
1956
December1st to 10thNight
16%
760
6%
2660
3%
760
20%
760
8%
2101
December11th to 20thNight
14%
760
8%
3252
2%
758
22%
758
7%
2441
December21st to endNight
13%
829
4%
4882
1%
817
19%
817
3%
4225

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
15%9%47%6%45%5%6%7%32%
75040
Night
16%9%47%6%35%5%5%7%34%
75058
TransparencyDay
50%8%13%19%10%1
74757
Night
49%7%12%19%11%1
74875
SeeingDay
19%12%28%23%12%5%
13626
Night
19%10%30%28%11%1
23030

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
17%13%6%8%8%45%6%47%21%
1555
11th to 20thDay
16%17%7%11%8%45%5%5%6%18%
1710
21st to endDay
15%15%8%12%8%45%6%45%17%
1872
February1st to 10thDay
17%14%6%11%8%46%45%6%18%
1620
11th to 20thDay
14%13%8%12%8%35%5%46%23%
1573
21st to endDay
18%13%410%7%45%445%24%
1422
March1st to 10thDay
15%11%6%8%7%45%45%7%28%
1966
11th to 20thDay
14%11%6%8%7%345%5%5%31%
1980
21st to endDay
18%11%48%6%35%45%5%31%
2178
April1st to 10thDay
17%11%5%7%7%35%45%6%29%
2088
11th to 20thDay
18%9%37%5%3445%7%35%
2237
21st to endDay
20%10%47%5%35%445%33%
2340
May1st to 10thDay
16%8%37%6%45%5%5%8%34%
2340
11th to 20thDay
16%7%36%6%45%45%7%38%
2379
21st to endDay
11%5%35%5%36%5%5%8%43%
2725
June1st to 10thDay
13%5%35%6%35%6%7%8%40%
2520
11th to 20thDay
11%6%25%6%35%6%6%9%39%
2520
21st to endDay
13%5%246%36%5%6%10%41%
2698
July1st to 10thDay
9%4245%45%5%7%10%45%
2590
11th to 20thDay
11%6%35%5%46%6%8%10%37%
2444
21st to endDay
9%426%6%46%7%7%10%38%
2547
August1st to 10thDay
9%5%26%6%46%7%8%10%39%
2327
11th to 20thDay
10%5%26%6%46%7%8%9%37%
2303
21st to endDay
11%7%35%5%45%6%6%10%40%
2502
September1st to 10thDay
13%6%35%6%35%6%6%9%38%
2160
11th to 20thDay
10%5%26%5%35%6%6%9%45%
1997
21st to endDay
14%6%27%6%446%6%9%36%
1977
October1st to 10thDay
18%7%47%6%445%5%6%35%
1800
11th to 20thDay
21%8%37%6%45%5%6%7%29%
1800
21st to endDay
24%10%37%7%45%5%5%6%24%
1980
November1st to 10thDay
14%9%37%7%46%5%6%7%34%
1652
11th to 20thDay
15%13%46%7%35%5%7%8%27%
1520
21st to endDay
20%14%5%8%6%35%46%6%23%
1520
December1st to 10thDay
15%16%5%10%9%46%5%46%21%
1520
11th to 20thDay
19%15%7%9%6%35%6%6%6%19%
1906
21st to endDay
29%18%7%9%6%35%44410%
2772
January1st to 10thNight
17%12%6%11%7%45%5%5%6%23%
2607
11th to 20thNight
19%15%7%10%7%35%5%5%6%18%
2470
21st to endNight
14%13%7%11%7%3445%6%24%
2711
February1st to 10thNight
18%14%5%9%8%45%5%5%6%21%
2340
11th to 20thNight
16%11%5%9%8%45%5%6%7%25%
2273
21st to endNight
16%12%6%10%6%45%45%6%25%
1832
March1st to 10thNight
14%9%46%8%45%5%6%5%34%
1980
11th to 20thNight
16%11%5%7%5%34448%33%
1979
21st to endNight
16%11%46%5%3445%5%37%
2178
April1st to 10thNight
18%8%46%6%45%45%7%34%
1872
11th to 20thNight
17%8%36%5%345%47%38%
1687
21st to endNight
15%7%36%6%35%5%6%8%36%
1620
May1st to 10thNight
16%7%36%5%3446%7%38%
1620
11th to 20thNight
15%5%26%5%35%5%5%7%41%
1511
21st to endNight
10%42443446%8%50%
1550
June1st to 10thNight
11%425%5%45%5%7%9%44%
1440
11th to 20thNight
10%5%35%436%6%6%8%44%
1432
21st to endNight
11%425%5%35%5%6%7%47%
1260
July1st to 10thNight
6%324434449%57%
1358
11th to 20thNight
9%4344345%5%9%50%
1512
21st to endNight
7%425%6%25%5%6%8%50%
1771
August1st to 10thNight
6%426%436%5%8%8%46%
1611
11th to 20thNight
7%424435%47%9%51%
1598
21st to endNight
9%426%436%46%8%48%
1834
September1st to 10thNight
11%5%36%7%3445%8%45%
1800
11th to 20thNight
10%32442445%6%53%
1961
21st to endNight
14%6%35%6%3445%7%42%
1982
October1st to 10thNight
16%7%35%5%3345%6%42%
2160
11th to 20thNight
18%9%35%6%345%5%7%35%
2160
21st to endNight
22%8%47%6%35%5%5%6%29%
2376
November1st to 10thNight
15%8%35%5%35%5%6%7%39%
2421
11th to 20thNight
16%10%37%6%46%5%6%7%30%
2660
21st to endNight
20%10%47%6%35%5%6%8%27%
2660
December1st to 10thNight
20%14%6%8%6%26%5%6%7%20%
2660
11th to 20thNight
16%17%5%9%6%45%45%7%25%
3288
21st to endNight
29%18%6%9%7%3444412%
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
62%7%10%13%8%
1556
11th to 20thDay
68%6%11%10%5%
1710
21st to endDay
69%7%8%10%6%1
1872
February1st to 10thDay
68%7%11%11%3
1620
11th to 20thDay
63%5%10%14%7%1
1582
21st to endDay
63%6%10%14%6%1
1422
March1st to 10thDay
56%7%14%17%7%1
1969
11th to 20thDay
55%6%10%18%9%3
1980
21st to endDay
55%5%9%17%11%2
2178
April1st to 10thDay
55%6%11%15%12%
2088
11th to 20thDay
49%6%11%20%12%1
2237
21st to endDay
52%6%11%18%10%3
2340
May1st to 10thDay
48%7%12%21%12%1
2340
11th to 20thDay
46%7%11%22%12%2
2383
21st to endDay
38%8%15%23%14%2
2725
June1st to 10thDay
40%8%13%23%14%2
2520
11th to 20thDay
39%9%14%22%15%1
2520
21st to endDay
38%8%14%24%16%
2698
July1st to 10thDay
32%9%14%24%17%3
2520
11th to 20thDay
38%10%16%24%12%1
2369
21st to endDay
37%10%15%23%13%2
2405
August1st to 10thDay
37%10%15%25%11%1
2314
11th to 20thDay
39%10%17%24%9%1
2303
21st to endDay
38%9%14%25%12%1
2502
September1st to 10thDay
41%8%15%23%11%1
2160
11th to 20thDay
35%8%14%29%15%
1997
21st to endDay
43%9%15%23%9%1
1977
October1st to 10thDay
49%8%14%18%11%1
1800
11th to 20thDay
52%7%15%17%8%1
1800
21st to endDay
60%7%12%15%6%1
1980
November1st to 10thDay
48%8%13%22%8%1
1652
11th to 20thDay
52%9%16%14%8%
1520
21st to endDay
59%8%16%13%4
1520
December1st to 10thDay
64%8%13%11%4
1520
11th to 20thDay
64%9%13%10%4
1906
21st to endDay
77%7%8%6%2
2772
January1st to 10thNight
63%6%11%12%8%
2607
11th to 20thNight
67%7%11%9%5%1
2470
21st to endNight
60%7%10%15%6%1
2711
February1st to 10thNight
63%7%11%14%5%1
2340
11th to 20thNight
57%7%13%15%8%
2275
21st to endNight
59%6%11%16%8%
1832
March1st to 10thNight
49%8%13%20%9%2
1990
11th to 20thNight
50%6%10%21%11%2
1980
21st to endNight
50%6%8%20%14%3
2178
April1st to 10thNight
49%7%12%19%13%1
1872
11th to 20thNight
46%6%9%20%16%3
1687
21st to endNight
45%7%11%19%15%3
1620
May1st to 10thNight
44%7%10%22%15%3
1620
11th to 20thNight
41%6%13%24%12%4
1512
21st to endNight
31%7%15%25%19%3
1551
June1st to 10thNight
37%8%11%25%17%2
1440
11th to 20thNight
35%8%12%25%17%2
1432
21st to endNight
35%7%15%24%18%1
1260
July1st to 10thNight
27%6%11%27%26%3
1318
11th to 20thNight
30%7%14%29%17%3
1464
21st to endNight
31%8%16%26%16%3
1672
August1st to 10thNight
30%11%15%30%12%2
1600
11th to 20thNight
28%9%19%30%13%2
1598
21st to endNight
32%9%14%29%15%2
1834
September1st to 10thNight
38%7%14%25%15%2
1800
11th to 20thNight
30%7%13%31%18%1
1961
21st to endNight
41%7%13%26%12%1
1982
October1st to 10thNight
42%7%12%24%15%1
2160
11th to 20thNight
47%7%13%23%10%
2160
21st to endNight
54%8%10%17%11%1
2376
November1st to 10thNight
41%8%14%23%13%1
2421
11th to 20thNight
51%8%14%17%9%1
2660
21st to endNight
55%8%17%15%5%
2660
December1st to 10thNight
63%9%13%12%4
2660
11th to 20thNight
59%7%14%15%5%
3288
21st to endNight
75%8%9%6%2
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
26%21%28%16%9%1
198
11th to 20thDay
26%20%37%11%41
270
21st to endDay
26%18%33%18%41
294
February1st to 10thDay
28%23%39%9%2
240
11th to 20thDay
26%24%36%14%
240
21st to endDay
36%26%26%11%
198
March1st to 10thDay
24%13%35%20%7%
409
11th to 20thDay
24%13%37%20%5%1
420
21st to endDay
31%13%30%17%8%
462
April1st to 10thDay
20%19%33%20%7%1
420
11th to 20thDay
25%15%26%20%10%3
412
21st to endDay
25%12%30%21%8%3
420
May1st to 10thDay
24%13%25%23%9%6%
423
11th to 20thDay
18%11%27%25%15%4
447
21st to endDay
13%8%24%30%18%8%
485
June1st to 10thDay
13%12%32%28%12%3
450
11th to 20thDay
14%10%27%28%16%5%
450
21st to endDay
14%8%30%33%11%4
628
July1st to 10thDay
8%6%22%29%25%10%
515
11th to 20thDay
13%5%24%27%20%11%
444
21st to endDay
8%328%35%20%6%
488
August1st to 10thDay
9%421%29%24%13%
446
11th to 20thDay
12%421%28%22%14%
439
21st to endDay
11%6%23%28%20%12%
495
September1st to 10thDay
12%9%20%28%18%12%
450
11th to 20thDay
9%6%19%26%26%14%
450
21st to endDay
14%12%26%24%16%8%
450
October1st to 10thDay
21%11%26%21%14%6%
450
11th to 20thDay
21%16%35%20%6%2
450
21st to endDay
28%14%31%19%7%1
495
November1st to 10thDay
22%21%31%17%7%2
270
11th to 20thDay
27%22%28%15%6%2
180
21st to endDay
29%18%33%17%21
180
December1st to 10thDay
27%22%35%12%41
180
11th to 20thDay
26%26%31%14%3
180
21st to endDay
30%20%37%11%3
198
January1st to 10thNight
23%19%35%18%6%1
760
11th to 20thNight
29%15%32%20%3
760
21st to endNight
20%13%35%25%6%
835
February1st to 10thNight
25%17%36%20%2
720
11th to 20thNight
23%14%36%21%5%
703
21st to endNight
24%17%35%21%3
592
March1st to 10thNight
18%13%36%24%7%
720
11th to 20thNight
22%13%34%24%6%1
720
21st to endNight
20%11%32%26%10%1
792
April1st to 10thNight
22%13%31%29%5%
720
11th to 20thNight
20%12%32%25%10%1
623
21st to endNight
17%9%33%31%10%
540
May1st to 10thNight
18%6%31%28%14%2
540
11th to 20thNight
14%5%30%38%11%1
450
21st to endNight
13%429%34%19%1
389
June1st to 10thNight
11%434%39%12%1
360
11th to 20thNight
12%5%31%39%13%1
360
21st to endNight
11%5%26%43%15%
360
July1st to 10thNight
7%124%45%22%2
350
11th to 20thNight
10%224%40%21%2
420
21st to endNight
10%319%47%20%2
591
August1st to 10thNight
7%218%43%27%3
537
11th to 20thNight
8%117%38%32%2
534
21st to endNight
10%322%35%29%2
646
September1st to 10thNight
12%5%21%34%22%5%
720
11th to 20thNight
11%5%18%34%28%4
720
21st to endNight
16%7%22%29%21%5%
720
October1st to 10thNight
17%8%27%27%18%3
720
11th to 20thNight
22%11%30%27%9%1
720
21st to endNight
27%11%31%27%4
792
November1st to 10thNight
19%11%30%27%10%2
740
11th to 20thNight
20%16%33%21%8%1
760
21st to endNight
25%12%34%22%6%
760
December1st to 10thNight
28%17%31%19%6%
760
11th to 20thNight
23%18%36%18%4
760
21st to endNight
31%12%34%20%3
836
Page generated at 2024-01-28 05:26:38. Version ac07

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