Lake of Bays
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lake of Bays clear sky chart from 2005-11-05 to 2018-10-08.

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%
16003
12%
50695
8%
15971
34%
15971
15%
37236

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
5%
2716
2%
776
16%
776
6%
2275
January16th to endNight
19%
832
10%
2736
5%
832
24%
832
9%
2216
February1st to 15thNight
15%
762
9%
2482
3%
761
22%
761
8%
2020
February16th to endNight
18%
683
10%
2207
4%
683
26%
683
10%
1717
March1st to 15thNight
18%
780
11%
2150
5%
780
24%
780
14%
1646
March16th to endNight
31%
832
20%
2288
10%
832
39%
832
24%
1561
April1st to 15thNight
22%
778
14%
1950
5%
778
27%
778
18%
1496
April16th to endNight
31%
599
17%
1755
10%
599
37%
599
21%
1224
May1st to 15thNight
38%
472
17%
1642
14%
472
46%
472
21%
1060
May16th to endNight
40%
406
13%
1625
11%
406
50%
406
21%
952
June1st to 15thNight
38%
390
10%
1522
10%
390
44%
390
17%
981
June16th to endNight
46%
390
11%
1365
11%
390
50%
390
21%
880
July1st to 15thNight
56%
370
17%
1349
22%
370
60%
370
31%
743
July16th to endNight
52%
453
14%
1588
15%
428
56%
428
25%
935
August1st to 15thNight
56%
575
15%
1715
13%
572
59%
572
28%
1101
August16th to endNight
52%
673
17%
1915
9%
673
56%
673
30%
1217
September1st to 15thNight
45%
780
16%
1950
8%
780
49%
780
30%
1318
September16th to endNight
45%
777
20%
2171
14%
777
50%
777
28%
1419
October1st to 15thNight
29%
752
15%
2255
9%
752
37%
752
18%
1623
October16th to endNight
19%
768
10%
2304
4%
768
25%
768
10%
1871
November1st to 15thNight
26%
760
14%
2638
11%
760
32%
760
13%
1930
November16th to endNight
18%
780
9%
2730
5%
780
24%
780
8%
2215
December1st to 15thNight
12%
780
5%
2730
2%
780
16%
780
5%
2367
December16th to endNight
11%
832
8%
2912
3%
832
16%
832
5%
2469

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%47%5%34446%30%
52439
Night
17%11%47%5%24445%30%
50863
Cloud CoverDay
18%10%47%5%34446%30%
52449
Night
17%12%47%5%34445%30%
50868
TransparencyDay
54%6%10%17%9%1
52125
Night
55%5%10%17%9%
50695
SeeingDay
24%13%29%20%9%3
6997
Night
24%11%28%24%10%1
16007

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%17%9%10%7%23235%17%
1552
16th to endDay
14%20%8%10%7%43435%17%
1836
February1st to 15thDay
12%18%8%14%8%33335%17%
1710
16th to endDay
16%17%7%11%6%3433421%
1552
March1st to 15thDay
15%13%5%8%6%45%45%5%25%
2127
16th to endDay
13%9%47%5%35%445%37%
2288
April1st to 15thDay
23%11%45%424345%29%
2327
16th to endDay
20%9%25%423335%38%
2490
May1st to 15thDay
19%8%35%434447%33%
2637
16th to endDay
15%7%25%5%245%5%7%38%
2842
June1st to 15thDay
22%7%35%5%2445%7%31%
2763
16th to endDay
18%6%25%5%35%5%5%8%33%
2925
July1st to 15thDay
14%5%25%5%35%45%8%40%
2863
16th to endDay
13%6%26%6%35%5%6%9%34%
2831
August1st to 15thDay
14%5%37%6%36%5%47%35%
2487
16th to endDay
16%5%25%5%35%5%5%7%35%
2624
September1st to 15thDay
19%6%26%43435%6%36%
2340
16th to endDay
19%6%25%324445%40%
2116
October1st to 15thDay
26%8%36%5%23335%30%
1875
16th to endDay
33%10%27%6%23345%20%
1920
November1st to 15thDay
21%11%47%7%24436%25%
1550
16th to endDay
23%17%6%9%5%3434416%
1560
December1st to 15thDay
20%24%7%10%5%2323414%
1560
16th to endDay
19%23%6%10%5%2334415%
1664
January1st to 15thNight
20%19%7%11%7%2334415%
2716
16th to endNight
14%17%8%11%7%34435%19%
2736
February1st to 15thNight
11%18%7%12%8%4444419%
2480
16th to endNight
17%14%8%9%6%3444423%
2207
March1st to 15thNight
17%12%5%7%6%3434429%
2138
16th to endNight
14%9%45%42345%5%40%
2288
April1st to 15thNight
22%11%5%5%5%24345%30%
1950
16th to endNight
19%9%345%24447%35%
1755
May1st to 15thNight
18%7%25%42446%8%37%
1642
16th to endNight
12%5%2443446%8%42%
1623
June1st to 15thNight
16%8%35%5%2445%7%36%
1522
16th to endNight
14%6%15%5%345%6%7%39%
1365
July1st to 15thNight
10%41442345%6%52%
1423
16th to endNight
11%5%24425%5%5%9%44%
1687
August1st to 15thNight
11%425%4245%47%45%
1726
16th to endNight
11%5%25%425%46%7%45%
1915
September1st to 15thNight
15%5%2442346%7%42%
1950
16th to endNight
16%5%25%423336%45%
2171
October1st to 15thNight
22%8%35%433446%33%
2255
16th to endNight
28%12%37%5%2343423%
2304
November1st to 15thNight
22%12%35%423446%30%
2638
16th to endNight
23%16%5%7%6%3443419%
2730
December1st to 15thNight
21%22%7%9%5%3433412%
2730
16th to endNight
21%19%8%10%6%2333414%
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%11%6%2233417%
1552
16th to endDay
14%19%8%11%7%4434417%
1836
February1st to 15thDay
12%18%8%15%9%23335%17%
1710
16th to endDay
16%17%8%10%7%3433420%
1552
March1st to 15thDay
16%12%5%8%7%45%35%5%24%
2138
16th to endDay
12%9%46%6%35%445%37%
2287
April1st to 15thDay
24%11%35%434345%29%
2327
16th to endDay
20%10%25%423245%39%
2490
May1st to 15thDay
18%9%36%5%34347%33%
2637
16th to endDay
15%7%25%5%345%5%7%38%
2842
June1st to 15thDay
21%8%36%42445%7%31%
2763
16th to endDay
18%6%35%435%5%5%8%33%
2925
July1st to 15thDay
13%5%25%5%3445%8%40%
2863
16th to endDay
14%5%36%6%35%46%9%34%
2831
August1st to 15thDay
14%6%27%6%45%5%5%6%34%
2487
16th to endDay
15%6%25%6%45%5%6%8%34%
2624
September1st to 15thDay
19%7%25%5%3435%6%36%
2340
16th to endDay
19%6%25%433446%39%
2116
October1st to 15thDay
26%8%36%6%23335%29%
1875
16th to endDay
32%11%26%6%23445%19%
1920
November1st to 15thDay
21%12%38%6%3335%5%25%
1550
16th to endDay
24%18%7%8%5%33345%16%
1560
December1st to 15thDay
20%22%8%11%6%2324413%
1560
16th to endDay
19%23%7%10%5%3333415%
1664
January1st to 15thNight
20%18%8%11%7%3433415%
2716
16th to endNight
14%17%8%10%7%44345%20%
2736
February1st to 15thNight
11%17%7%12%9%35%35%418%
2473
16th to endNight
17%15%7%10%6%3443423%
2207
March1st to 15thNight
17%13%5%8%6%3424429%
2150
16th to endNight
13%9%46%413445%40%
2288
April1st to 15thNight
22%12%5%5%5%33335%30%
1950
16th to endNight
20%8%25%434346%35%
1755
May1st to 15thNight
18%7%25%42445%8%37%
1642
16th to endNight
13%5%24425%46%8%41%
1623
June1st to 15thNight
16%7%35%5%345%6%6%36%
1522
16th to endNight
14%6%15%5%35%5%6%7%38%
1365
July1st to 15thNight
9%42442345%6%51%
1423
16th to endNight
10%5%25%43445%8%44%
1687
August1st to 15thNight
11%425%4245%6%7%45%
1726
16th to endNight
11%5%245%2446%6%45%
1915
September1st to 15thNight
15%6%1442345%8%42%
1950
16th to endNight
16%5%24423346%45%
2171
October1st to 15thNight
21%9%35%424346%33%
2255
16th to endNight
27%13%46%5%2343423%
2304
November1st to 15thNight
21%11%35%42435%6%30%
2638
16th to endNight
24%16%5%6%6%3433419%
2730
December1st to 15thNight
21%22%7%9%5%3443413%
2730
16th to endNight
21%19%8%11%7%2323414%
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
70%38%10%6%
1553
16th to endDay
69%47%9%7%1
1836
February1st to 15thDay
71%47%11%4
1712
16th to endDay
67%37%11%8%
1552
March1st to 15thDay
59%6%11%13%7%
2138
16th to endDay
48%49%18%14%3
2288
April1st to 15thDay
57%5%8%16%11%1
2327
16th to endDay
48%47%21%15%2
2490
May1st to 15thDay
50%5%9%20%12%1
2637
16th to endDay
43%7%12%21%13%2
2846
June1st to 15thDay
52%6%10%19%11%
2763
16th to endDay
47%7%13%18%10%1
2925
July1st to 15thDay
39%7%11%26%13%1
2708
16th to endDay
45%7%13%23%9%
2667
August1st to 15thDay
47%8%14%19%9%
2474
16th to endDay
45%8%12%24%7%
2624
September1st to 15thDay
47%5%12%22%10%
2340
16th to endDay
45%7%11%27%8%
2116
October1st to 15thDay
57%410%17%9%
1875
16th to endDay
65%6%9%11%5%
1920
November1st to 15thDay
59%8%11%13%6%
1550
16th to endDay
71%5%8%9%31
1560
December1st to 15thDay
74%5%8%7%3
1560
16th to endDay
73%46%9%5%
1664
January1st to 15thNight
73%48%7%41
2716
16th to endNight
66%5%6%11%8%
2736
February1st to 15thNight
68%5%9%12%5%
2482
16th to endNight
64%49%15%6%
2207
March1st to 15thNight
59%311%15%8%1
2150
16th to endNight
44%5%9%21%16%2
2288
April1st to 15thNight
57%37%17%11%1
1950
16th to endNight
48%5%8%18%17%2
1755
May1st to 15thNight
44%5%12%19%15%2
1642
16th to endNight
38%6%15%22%14%1
1625
June1st to 15thNight
45%7%12%20%13%1
1522
16th to endNight
42%7%12%23%12%
1365
July1st to 15thNight
30%6%11%29%20%1
1349
16th to endNight
36%6%14%27%14%
1588
August1st to 15thNight
36%8%16%25%11%
1715
16th to endNight
36%7%17%26%11%
1915
September1st to 15thNight
38%7%17%23%12%
1950
16th to endNight
40%5%14%29%9%
2171
October1st to 15thNight
51%6%10%19%11%
2255
16th to endNight
65%6%9%13%5%
2304
November1st to 15thNight
54%7%12%17%6%
2638
16th to endNight
67%6%9%12%3
2730
December1st to 15thNight
75%6%7%8%3
2730
16th to endNight
74%46%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
26%24%37%10%1
90
16th to endDay
39%14%31%9%4
136
February1st to 15thDay
29%28%34%6%
135
16th to endDay
39%18%33%8%
133
March1st to 15thDay
25%19%32%18%31
330
16th to endDay
20%16%32%21%7%1
352
April1st to 15thDay
27%18%26%17%8%1
330
16th to endDay
27%15%26%17%9%4
319
May1st to 15thDay
29%10%27%20%7%4
348
16th to endDay
21%12%35%17%10%2
395
June1st to 15thDay
23%12%31%23%8%
408
16th to endDay
19%11%35%23%7%2
570
July1st to 15thDay
15%9%30%29%11%3
492
16th to endDay
15%10%28%28%11%5%
390
August1st to 15thDay
18%425%30%12%8%
358
16th to endDay
23%7%19%23%17%8%
396
September1st to 15thDay
19%6%25%23%17%8%
375
16th to endDay
20%8%28%21%15%5%
374
October1st to 15thDay
29%13%26%18%9%2
345
16th to endDay
39%14%25%15%3
336
November1st to 15thDay
30%17%30%17%4
109
16th to endDay
41%20%30%6%2
90
December1st to 15thDay
32%22%31%12%2
90
16th to endDay
26%33%31%6%21
96
January1st to 15thNight
30%18%29%16%4
780
16th to endNight
24%13%35%18%7%
832
February1st to 15thNight
21%19%33%20%4
764
16th to endNight
26%18%30%19%5%
683
March1st to 15thNight
24%19%31%20%3
780
16th to endNight
19%12%31%25%9%1
832
April1st to 15thNight
27%14%30%21%5%
778
16th to endNight
24%10%28%24%11%
599
May1st to 15thNight
24%5%26%29%13%1
472
16th to endNight
14%6%34%34%9%
407
June1st to 15thNight
20%7%28%32%10%
390
16th to endNight
17%5%23%40%12%
390
July1st to 15thNight
10%322%44%18%
370
16th to endNight
12%226%37%20%
453
August1st to 15thNight
13%317%37%24%3
575
16th to endNight
13%5%23%31%22%2
673
September1st to 15thNight
18%427%26%18%5%
780
16th to endNight
19%6%23%27%20%2
777
October1st to 15thNight
26%9%29%22%10%1
752
16th to endNight
35%12%29%17%5%
768
November1st to 15thNight
28%13%26%21%9%
760
16th to endNight
34%13%27%17%6%
780
December1st to 15thNight
32%19%29%14%3
780
16th to endNight
31%17%30%17%3
832
Page generated at 2018-10-09 10:39:18. Version ac04

Copyright 2018 A. Danko


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