Bracebridge
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Bracebridge clear sky chart from 2005-11-05 to 2018-04-23.

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
29%
15569
12%
49239
8%
15535
34%
15535
15%
36045

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%
779
6%
2716
2%
776
17%
776
5%
2285
January16th to endNight
19%
832
10%
2720
5%
832
24%
832
9%
2191
February1st to 15thNight
14%
762
9%
2482
2%
761
20%
761
8%
2015
February16th to endNight
19%
683
10%
2208
5%
683
26%
683
11%
1709
March1st to 15thNight
18%
780
11%
2145
4%
780
25%
780
14%
1620
March16th to endNight
30%
832
20%
2288
10%
832
38%
832
23%
1551
April1st to 15thNight
22%
778
14%
1959
5%
778
27%
778
18%
1500
April16th to endNight
31%
571
19%
1685
9%
571
38%
571
21%
1162
May1st to 15thNight
37%
450
15%
1530
12%
450
44%
450
21%
998
May16th to endNight
39%
374
14%
1497
11%
374
49%
374
21%
883
June1st to 15thNight
38%
360
9%
1398
10%
360
43%
360
17%
905
June16th to endNight
46%
360
11%
1260
11%
360
51%
360
22%
803
July1st to 15thNight
58%
340
16%
1232
19%
340
62%
340
31%
676
July16th to endNight
50%
435
14%
1472
14%
408
53%
408
26%
885
August1st to 15thNight
59%
539
15%
1609
13%
536
62%
536
30%
1002
August16th to endNight
53%
617
19%
1763
10%
617
59%
617
32%
1103
September1st to 15thNight
47%
720
14%
1800
7%
720
49%
720
30%
1217
September16th to endNight
49%
717
22%
2008
15%
717
54%
717
29%
1292
October1st to 15thNight
32%
720
15%
2160
10%
720
39%
720
18%
1545
October16th to endNight
18%
768
11%
2304
5%
768
26%
768
11%
1828
November1st to 15thNight
28%
760
14%
2631
12%
760
34%
760
14%
1890
November16th to endNight
18%
780
9%
2730
6%
780
24%
780
8%
2182
December1st to 15thNight
11%
780
4%
2730
2%
780
14%
780
5%
2340
December16th to endNight
10%
832
8%
2912
3%
832
16%
832
6%
2463

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%10%46%5%34446%30%
50287
Night
18%11%47%5%34445%30%
49408
Cloud CoverDay
18%10%46%5%34446%30%
50297
Night
18%11%47%5%34445%30%
49413
TransparencyDay
54%5%10%18%9%
49975
Night
55%5%10%17%9%
49239
SeeingDay
24%12%28%20%9%3
6324
Night
23%11%28%24%10%1
15573

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
20%16%7%11%6%3324418%
1552
16th to endDay
15%18%8%11%6%34345%18%
1854
February1st to 15thDay
13%17%7%14%7%4433418%
1710
16th to endDay
17%18%6%9%7%4433420%
1551
March1st to 15thDay
15%13%5%6%7%34445%27%
2134
16th to endDay
13%9%46%5%345%45%37%
2288
April1st to 15thDay
23%11%35%5%34335%30%
2319
16th to endDay
21%9%24423335%38%
2402
May1st to 15thDay
20%9%25%5%345%47%32%
2420
16th to endDay
15%5%25%435%448%38%
2618
June1st to 15thDay
20%7%25%42446%8%31%
2559
16th to endDay
17%6%25%5%35%45%8%34%
2700
July1st to 15thDay
12%6%24435%5%5%9%39%
2652
16th to endDay
13%6%35%5%25%5%6%8%36%
2592
August1st to 15thDay
13%6%26%5%345%5%7%38%
2340
16th to endDay
14%5%25%5%35%5%5%7%37%
2426
September1st to 15thDay
18%6%25%6%15%45%6%37%
2160
16th to endDay
17%7%245%24446%39%
1950
October1st to 15thDay
26%6%36%6%23435%31%
1800
16th to endDay
33%9%26%6%23345%21%
1920
November1st to 15thDay
21%11%37%5%25%5%46%25%
1556
16th to endDay
22%18%5%7%7%2435%418%
1560
December1st to 15thDay
20%23%6%11%5%2333314%
1560
16th to endDay
20%20%8%10%5%3433316%
1664
January1st to 15thNight
21%16%8%11%6%4433316%
2716
16th to endNight
15%15%7%11%7%34345%19%
2720
February1st to 15thNight
11%16%7%12%8%5%45%3419%
2480
16th to endNight
17%14%7%8%7%3434424%
2208
March1st to 15thNight
16%13%48%7%3433430%
2133
16th to endNight
15%7%36%5%24445%40%
2288
April1st to 15thNight
22%11%46%5%23345%31%
1959
16th to endNight
18%7%345%24446%37%
1685
May1st to 15thNight
19%8%34424447%36%
1530
16th to endNight
14%5%23435%5%5%8%42%
1495
June1st to 15thNight
15%7%35%5%345%6%7%35%
1398
16th to endNight
14%6%35%5%245%47%39%
1260
July1st to 15thNight
8%42443445%5%51%
1305
16th to endNight
12%5%25%435%45%7%44%
1573
August1st to 15thNight
9%5%235%35%5%5%8%45%
1620
16th to endNight
11%424435%45%6%47%
1763
September1st to 15thNight
15%5%2442345%7%42%
1800
16th to endNight
15%5%23433345%45%
2008
October1st to 15thNight
20%7%26%5%25%346%34%
2160
16th to endNight
28%11%47%6%23335%24%
2304
November1st to 15thNight
20%11%36%424446%30%
2631
16th to endNight
25%14%5%6%5%24445%19%
2730
December1st to 15thNight
21%23%7%9%5%2433413%
2730
16th to endNight
21%20%8%10%6%3333315%
2912

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
20%17%8%9%6%3423418%
1552
16th to endDay
14%19%8%11%7%33345%18%
1854
February1st to 15thDay
14%17%9%12%8%3432418%
1710
16th to endDay
17%18%6%9%7%44225%20%
1551
March1st to 15thDay
16%13%5%7%6%44445%27%
2145
16th to endDay
13%9%45%6%345%45%37%
2287
April1st to 15thDay
24%10%35%433345%30%
2319
16th to endDay
21%9%24413335%38%
2402
May1st to 15thDay
20%8%345%245%47%32%
2420
16th to endDay
16%6%245%245%5%7%38%
2618
June1st to 15thDay
22%6%25%4245%5%8%31%
2559
16th to endDay
18%5%25%5%35%6%5%7%34%
2700
July1st to 15thDay
13%5%35%4345%6%8%39%
2652
16th to endDay
13%6%35%5%35%5%6%8%36%
2592
August1st to 15thDay
14%6%35%5%3445%8%38%
2340
16th to endDay
14%5%26%5%35%5%5%8%37%
2426
September1st to 15thDay
18%7%25%5%24446%37%
2160
16th to endDay
18%6%25%5%24346%40%
1950
October1st to 15thDay
25%8%26%5%33335%31%
1800
16th to endDay
33%8%35%6%24336%21%
1920
November1st to 15thDay
22%11%37%6%34436%25%
1556
16th to endDay
22%17%5%8%7%24345%17%
1560
December1st to 15thDay
20%23%7%10%6%2333315%
1560
16th to endDay
20%21%7%9%5%2433317%
1664
January1st to 15thNight
21%17%7%11%7%3433316%
2716
16th to endNight
15%16%6%10%8%34335%19%
2720
February1st to 15thNight
12%16%7%12%9%35%43419%
2473
16th to endNight
17%14%6%8%7%35%345%24%
2208
March1st to 15thNight
17%12%47%7%3433430%
2145
16th to endNight
15%7%37%5%23346%40%
2288
April1st to 15thNight
23%11%35%5%2233431%
1959
16th to endNight
18%8%245%33345%37%
1685
May1st to 15thNight
20%6%34414448%36%
1530
16th to endNight
13%5%234245%6%7%42%
1495
June1st to 15thNight
17%7%25%5%245%6%6%36%
1398
16th to endNight
13%5%36%5%345%47%39%
1260
July1st to 15thNight
8%425%4235%46%51%
1305
16th to endNight
12%5%2443445%8%45%
1573
August1st to 15thNight
10%4245%3446%7%46%
1620
16th to endNight
10%4245%3445%6%48%
1763
September1st to 15thNight
16%5%2443345%8%42%
1800
16th to endNight
16%5%245%33336%46%
2008
October1st to 15thNight
20%8%35%5%34346%34%
2160
16th to endNight
28%10%36%5%33435%24%
2304
November1st to 15thNight
21%11%44434345%31%
2631
16th to endNight
24%14%47%5%34445%20%
2730
December1st to 15thNight
21%22%6%9%6%2434413%
2730
16th to endNight
22%19%8%10%6%2423415%
2912

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
71%39%10%5%
1553
16th to endDay
69%46%9%8%1
1854
February1st to 15thDay
71%47%12%4
1712
16th to endDay
69%37%12%7%
1551
March1st to 15thDay
59%412%14%7%
2145
16th to endDay
48%5%8%18%15%3
2288
April1st to 15thDay
56%47%18%11%1
2319
16th to endDay
48%37%22%14%2
2402
May1st to 15thDay
50%5%10%19%12%1
2420
16th to endDay
43%6%12%21%13%1
2622
June1st to 15thDay
49%7%10%22%10%
2559
16th to endDay
47%6%14%19%11%
2700
July1st to 15thDay
38%8%12%26%13%1
2497
16th to endDay
44%6%13%24%10%
2430
August1st to 15thDay
43%7%15%20%11%
2327
16th to endDay
43%8%14%25%7%
2426
September1st to 15thDay
46%6%13%23%9%
2160
16th to endDay
45%6%10%28%8%
1950
October1st to 15thDay
55%5%10%18%9%
1800
16th to endDay
65%5%11%11%5%
1920
November1st to 15thDay
58%8%11%14%6%
1556
16th to endDay
68%5%10%10%31
1560
December1st to 15thDay
73%49%8%3
1560
16th to endDay
73%45%10%4
1664
January1st to 15thNight
73%47%8%5%1
2716
16th to endNight
66%5%7%12%7%
2720
February1st to 15thNight
68%5%9%12%4
2482
16th to endNight
62%49%15%7%
2208
March1st to 15thNight
58%311%15%8%1
2145
16th to endNight
45%49%22%16%2
2288
April1st to 15thNight
56%37%18%11%1
1959
16th to endNight
48%47%19%18%2
1685
May1st to 15thNight
46%412%19%15%2
1530
16th to endNight
37%8%14%23%15%1
1497
June1st to 15thNight
45%7%11%21%13%
1398
16th to endNight
43%5%14%23%13%
1260
July1st to 15thNight
30%6%12%29%19%1
1232
16th to endNight
37%6%12%28%13%
1472
August1st to 15thNight
34%8%17%26%12%
1609
16th to endNight
34%7%15%29%11%
1763
September1st to 15thNight
40%5%17%24%11%
1800
16th to endNight
39%5%13%31%10%
2008
October1st to 15thNight
50%6%11%20%11%
2160
16th to endNight
62%5%11%13%5%
2304
November1st to 15thNight
53%6%12%18%7%1
2631
16th to endNight
65%6%10%13%3
2730
December1st to 15thNight
73%6%8%7%3
2730
16th to endNight
73%47%8%5%
2912

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
22%24%38%13%1
90
16th to endDay
37%15%33%10%3
140
February1st to 15thDay
31%28%34%5%
135
16th to endDay
36%24%33%5%
126
March1st to 15thDay
25%16%32%20%4
330
16th to endDay
21%14%33%20%8%1
352
April1st to 15thDay
29%17%26%17%7%
330
16th to endDay
26%15%27%15%11%3
289
May1st to 15thDay
32%7%27%17%7%5%
288
16th to endDay
20%16%30%19%10%2
331
June1st to 15thDay
24%13%25%25%8%1
354
16th to endDay
19%11%34%23%9%2
495
July1st to 15thDay
15%8%32%25%12%5%
431
16th to endDay
15%8%26%29%11%7%
326
August1st to 15thDay
14%327%30%13%10%
313
16th to endDay
19%5%20%25%18%10%
332
September1st to 15thDay
17%6%24%25%15%11%
315
16th to endDay
18%8%23%24%18%7%
314
October1st to 15thDay
27%10%26%20%10%3
315
16th to endDay
36%17%25%17%3
336
November1st to 15thDay
30%16%31%17%3
106
16th to endDay
40%20%28%8%2
90
December1st to 15thDay
33%17%33%13%2
90
16th to endDay
32%31%28%6%11
96
January1st to 15thNight
30%18%29%15%5%
780
16th to endNight
23%13%33%21%7%
832
February1st to 15thNight
21%19%34%20%4
764
16th to endNight
27%15%31%18%5%
683
March1st to 15thNight
24%19%30%20%3
780
16th to endNight
20%12%31%25%9%
832
April1st to 15thNight
28%14%29%22%5%
778
16th to endNight
24%11%29%23%10%
571
May1st to 15thNight
25%5%24%29%13%2
450
16th to endNight
14%6%32%33%13%
375
June1st to 15thNight
20%8%26%34%10%
360
16th to endNight
17%424%41%11%
360
July1st to 15thNight
10%322%45%18%
340
16th to endNight
14%325%36%19%
435
August1st to 15thNight
12%217%39%25%3
539
16th to endNight
12%424%29%25%2
617
September1st to 15thNight
17%5%24%28%19%4
720
16th to endNight
18%5%20%31%20%3
717
October1st to 15thNight
23%9%29%25%11%1
720
16th to endNight
33%13%28%18%5%
768
November1st to 15thNight
25%12%28%24%8%1
760
16th to endNight
33%14%25%19%5%
780
December1st to 15thNight
34%18%28%15%2
780
16th to endNight
31%15%32%16%3
832
Page generated at 2018-04-24 10:02:59. Version ac04

Copyright 2018 A. Danko


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