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 2017-09-16.

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%
14703
12%
46522
8%
14669
35%
14669
15%
34011

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
11%
719
6%
2506
2%
716
16%
716
5%
2128
January16th to endNight
19%
768
10%
2511
5%
768
25%
768
9%
2019
February1st to 15thNight
14%
702
8%
2287
2%
701
20%
701
8%
1861
February16th to endNight
19%
631
11%
2039
5%
631
27%
631
11%
1572
March1st to 15thNight
18%
720
12%
1980
4%
720
25%
720
14%
1493
March16th to endNight
30%
768
19%
2112
11%
768
37%
768
23%
1446
April1st to 15thNight
23%
718
14%
1808
5%
718
28%
718
19%
1375
April16th to endNight
31%
552
18%
1632
9%
552
38%
552
21%
1129
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
47%
658
20%
1843
14%
658
52%
658
28%
1205
October1st to 15thNight
31%
660
15%
1980
10%
660
38%
660
18%
1425
October16th to endNight
18%
704
10%
2112
4%
704
25%
704
10%
1689
November1st to 15thNight
28%
700
15%
2423
13%
700
34%
700
15%
1728
November16th to endNight
19%
720
9%
2520
6%
720
24%
720
9%
2016
December1st to 15thNight
11%
720
4%
2520
2%
720
13%
720
5%
2163
December16th to endNight
10%
768
7%
2688
3%
768
16%
768
6%
2290

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%36%5%34446%30%
48228
Night
18%11%47%5%34445%30%
46691
Cloud CoverDay
18%10%46%5%34446%30%
48238
Night
18%11%47%5%34445%31%
46696
TransparencyDay
53%5%11%18%9%
47916
Night
54%5%11%18%9%
46522
SeeingDay
23%12%28%21%9%4
5652
Night
23%11%28%24%10%1
14707

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%3334418%
1432
16th to endDay
14%18%8%11%6%34345%19%
1711
February1st to 15thDay
14%16%7%13%8%4433418%
1575
16th to endDay
16%19%6%9%7%4433420%
1434
March1st to 15thDay
16%12%5%6%7%35%445%27%
1969
16th to endDay
13%9%46%5%44445%36%
2112
April1st to 15thDay
23%11%35%434345%31%
2140
16th to endDay
21%9%24423335%37%
2340
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%8%245%24446%38%
1788
October1st to 15thDay
25%6%36%6%23435%31%
1650
16th to endDay
34%9%26%6%23345%20%
1760
November1st to 15thDay
21%11%37%5%25%5%46%25%
1434
16th to endDay
23%17%5%7%7%2435%417%
1440
December1st to 15thDay
22%22%6%11%5%2323314%
1440
16th to endDay
20%21%8%10%5%3433315%
1536
January1st to 15thNight
21%17%8%12%6%4433315%
2506
16th to endNight
15%15%7%11%7%34345%19%
2511
February1st to 15thNight
12%16%7%12%8%5%45%4418%
2285
16th to endNight
17%14%7%8%7%3434424%
2039
March1st to 15thNight
17%11%48%7%3443430%
1968
16th to endNight
15%7%37%5%2444440%
2112
April1st to 15thNight
23%11%35%423345%32%
1808
16th to endNight
18%8%35%5%24446%36%
1632
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
16%5%34433345%44%
1843
October1st to 15thNight
20%7%26%5%25%346%33%
1980
16th to endNight
28%10%47%6%2333424%
2112
November1st to 15thNight
20%11%36%424445%31%
2423
16th to endNight
25%14%5%6%5%24445%19%
2520
December1st to 15thNight
22%22%7%9%5%2434413%
2520
16th to endNight
23%20%8%10%5%2433314%
2688

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
21%17%8%9%6%3424418%
1432
16th to endDay
14%18%8%11%7%3334419%
1711
February1st to 15thDay
14%17%8%12%9%4432418%
1575
16th to endDay
16%19%6%9%7%4422420%
1434
March1st to 15thDay
16%12%47%7%44445%27%
1980
16th to endDay
13%9%46%6%34445%37%
2111
April1st to 15thDay
24%10%35%433345%31%
2140
16th to endDay
21%9%24423345%37%
2340
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
19%6%25%5%24346%38%
1788
October1st to 15thDay
24%8%26%5%34435%31%
1650
16th to endDay
34%8%35%6%24336%20%
1760
November1st to 15thDay
21%10%46%6%35%446%26%
1434
16th to endDay
23%17%5%8%7%24345%17%
1440
December1st to 15thDay
22%23%7%10%5%2333415%
1440
16th to endDay
21%22%8%9%5%2424316%
1536
January1st to 15thNight
21%17%8%11%7%3433315%
2506
16th to endNight
15%16%7%10%8%34335%20%
2511
February1st to 15thNight
13%16%7%12%8%35%44419%
2278
16th to endNight
17%14%6%8%6%34345%24%
2039
March1st to 15thNight
18%11%47%7%3433430%
1980
16th to endNight
15%7%37%5%23345%39%
2112
April1st to 15thNight
23%11%35%5%2333432%
1808
16th to endNight
18%8%35%5%3335%5%37%
1632
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
17%5%245%33336%45%
1843
October1st to 15thNight
21%8%35%5%34346%34%
1980
16th to endNight
29%10%36%6%33435%23%
2112
November1st to 15thNight
20%11%44434345%32%
2423
16th to endNight
25%14%47%5%34445%20%
2520
December1st to 15thNight
22%22%6%9%5%2433413%
2520
16th to endNight
23%19%8%9%5%2433415%
2688

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%9%5%
1433
16th to endDay
68%46%9%8%1
1711
February1st to 15thDay
71%47%12%3
1577
16th to endDay
68%26%13%8%
1434
March1st to 15thDay
59%413%15%6%
1980
16th to endDay
49%49%17%15%3
2112
April1st to 15thDay
55%48%18%11%1
2140
16th to endDay
49%47%22%14%1
2340
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
47%6%10%26%8%
1788
October1st to 15thDay
55%5%10%18%9%
1650
16th to endDay
66%5%10%10%5%
1760
November1st to 15thDay
57%8%12%15%5%
1434
16th to endDay
69%410%10%31
1440
December1st to 15thDay
73%49%8%2
1440
16th to endDay
75%45%10%4
1536
January1st to 15thNight
74%47%8%4
2506
16th to endNight
66%5%7%12%7%
2511
February1st to 15thNight
68%5%9%11%4
2287
16th to endNight
62%410%15%7%
2039
March1st to 15thNight
57%412%16%8%
1980
16th to endNight
46%49%20%16%2
2112
April1st to 15thNight
55%37%19%11%1
1808
16th to endNight
48%47%19%17%2
1632
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
40%5%13%30%10%
1843
October1st to 15thNight
51%6%11%19%10%
1980
16th to endNight
63%5%11%12%6%
2112
November1st to 15thNight
53%6%12%19%7%1
2423
16th to endNight
65%6%10%13%3
2520
December1st to 15thNight
74%6%9%7%2
2520
16th to endNight
74%47%7%5%
2688

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
25%20%38%15%1
60
16th to endDay
36%11%34%12%4
93
February1st to 15thDay
31%31%32%5%
90
16th to endDay
37%18%36%6%
87
March1st to 15thDay
22%17%32%22%4
270
16th to endDay
21%12%35%18%10%1
288
April1st to 15thDay
27%17%25%19%8%1
270
16th to endDay
26%14%28%14%11%4
270
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
20%8%25%24%14%6%
254
October1st to 15thDay
23%11%28%22%9%4
255
16th to endDay
37%15%26%17%3
272
November1st to 15thDay
24%14%33%21%5%
74
16th to endDay
41%13%30%13%1
60
December1st to 15thDay
38%15%28%16%1
60
16th to endDay
39%42%14%31
64
January1st to 15thNight
31%19%29%15%4
720
16th to endNight
23%12%33%22%7%
768
February1st to 15thNight
21%19%33%20%4
704
16th to endNight
26%15%32%18%6%
631
March1st to 15thNight
24%19%32%20%3
720
16th to endNight
20%12%30%24%10%
768
April1st to 15thNight
28%14%29%21%5%
718
16th to endNight
23%11%29%23%10%
552
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
19%5%21%31%18%3
658
October1st to 15thNight
24%9%28%25%11%1
660
16th to endNight
34%14%27%18%5%
704
November1st to 15thNight
24%12%29%23%8%1
700
16th to endNight
33%13%25%20%5%
720
December1st to 15thNight
34%19%28%14%2
720
16th to endNight
32%15%31%16%3
768
Page generated at 2017-09-16 17:07:02. Version ac04

Copyright 2017 A. Danko


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