Otter Lake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Otter Lake clear sky chart from 2005-11-06 to 2024-01-13.

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
27%
22522
13%
74750
8%
22480
34%
22480
15%
53865

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%
2194
January11th to 20thNight
16%
732
9%
2560
4%
732
22%
732
8%
2041
January21st to endNight
19%
792
13%
2688
7%
792
28%
792
12%
1987
February1st to 10thNight
14%
720
9%
2340
2%
720
22%
720
9%
1827
February11th to 20thNight
14%
702
13%
2275
4%
700
27%
700
12%
1702
February21st to endNight
18%
592
14%
1803
5%
592
29%
592
13%
1354
March1st to 10thNight
18%
720
14%
2134
8%
720
27%
720
13%
1605
March11th to 20thNight
19%
720
16%
1979
5%
720
30%
720
17%
1452
March21st to endNight
22%
792
20%
2081
6%
792
32%
792
19%
1464
April1st to 10thNight
20%
720
14%
1800
4%
720
26%
720
18%
1353
April11th to 20thNight
24%
711
17%
1775
6%
711
30%
711
20%
1278
April21st to endNight
24%
579
15%
1659
7%
579
31%
579
16%
1228
May1st to 10thNight
28%
360
18%
1440
14%
360
39%
360
17%
924
May11th to 20thNight
31%
354
20%
1416
16%
354
45%
354
17%
889
May21st to endNight
33%
389
14%
1551
10%
388
48%
388
21%
932
June1st to 10thNight
33%
360
9%
1440
8%
360
41%
360
17%
923
June11th to 20thNight
40%
360
12%
1440
15%
360
48%
360
20%
864
June21st to endNight
41%
360
10%
1440
13%
360
47%
360
18%
947
July1st to 10thNight
49%
350
14%
1400
18%
350
57%
350
25%
794
July11th to 20thNight
49%
348
15%
1392
20%
348
55%
348
24%
822
July21st to endNight
52%
394
15%
1486
16%
372
57%
372
24%
852
August1st to 10thNight
50%
408
14%
1472
13%
406
56%
406
22%
913
August11th to 20thNight
53%
534
17%
1598
13%
534
57%
534
30%
1010
August21st to endNight
44%
765
18%
1953
7%
765
49%
765
31%
1292
September1st to 10thNight
43%
720
17%
1800
7%
720
47%
720
31%
1209
September11th to 20thNight
47%
720
21%
1800
11%
720
51%
720
34%
1168
September21st to endNight
38%
720
20%
2047
14%
720
43%
720
25%
1364
October1st to 10thNight
33%
720
18%
2160
11%
720
42%
720
20%
1474
October11th to 20thNight
24%
720
12%
2160
7%
720
32%
720
15%
1617
October21st to endNight
22%
792
12%
2503
6%
792
30%
792
12%
1911
November1st to 10thNight
25%
740
15%
2445
10%
740
33%
740
15%
1715
November11th to 20thNight
20%
760
13%
2660
8%
760
28%
760
11%
1989
November21st to endNight
18%
760
8%
2660
3%
760
24%
760
8%
2103
December1st to 10thNight
15%
760
7%
2660
3%
760
20%
760
6%
2205
December11th to 20thNight
16%
760
10%
3242
4%
759
24%
759
7%
2486
December21st to endNight
12%
828
6%
4842
2%
817
19%
817
4%
3977

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%6%35%45%6%32%
74730
Night
17%11%48%6%34446%31%
75010
TransparencyDay
53%6%11%19%10%1
74435
Night
54%6%11%19%10%1
74839
SeeingDay
23%17%31%19%8%2
13298
Night
23%14%30%23%9%1
22531

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
16%17%7%13%8%4443420%
1517
11th to 20thDay
18%16%6%9%8%4445%422%
1462
21st to endDay
13%16%7%10%8%35%45%5%25%
1665
February1st to 10thDay
13%17%6%11%9%45%45%5%21%
1620
11th to 20thDay
12%16%7%10%6%34446%27%
1573
21st to endDay
17%15%6%9%6%45%35%5%25%
1453
March1st to 10thDay
14%15%6%8%8%44446%28%
1822
11th to 20thDay
13%14%6%9%8%45%345%29%
1980
21st to endDay
18%10%47%5%34345%37%
2274
April1st to 10thDay
22%12%46%6%44345%30%
2160
11th to 20thDay
22%8%46%5%33445%35%
2134
21st to endDay
23%11%47%6%34345%31%
2313
May1st to 10thDay
21%8%37%5%24446%34%
2520
11th to 20thDay
18%8%37%6%43445%38%
2478
21st to endDay
17%6%36%6%36%5%5%6%37%
2725
June1st to 10thDay
22%7%37%6%35%5%5%6%30%
2520
11th to 20thDay
16%6%35%5%345%5%9%39%
2520
21st to endDay
19%7%36%5%45%5%7%7%32%
2520
July1st to 10thDay
13%6%25%6%46%6%7%8%38%
2520
11th to 20thDay
13%6%35%6%35%6%7%9%36%
2520
21st to endDay
13%5%36%6%35%6%7%9%38%
2744
August1st to 10thDay
12%6%37%5%46%5%6%8%38%
2453
11th to 20thDay
14%6%35%6%37%5%6%7%38%
2303
21st to endDay
15%6%26%5%35%6%7%8%38%
2383
September1st to 10thDay
15%6%35%435%5%5%8%42%
2160
11th to 20thDay
14%6%26%5%3445%7%43%
2160
21st to endDay
20%6%25%5%3446%7%37%
1909
October1st to 10thDay
21%8%26%5%346%5%6%34%
1800
11th to 20thDay
25%12%36%7%3445%5%26%
1800
21st to endDay
29%9%38%6%24445%26%
1851
November1st to 10thDay
15%11%37%6%36%5%5%7%33%
1633
11th to 20thDay
20%13%6%9%7%4445%5%24%
1520
21st to endDay
21%17%6%10%8%34435%18%
1520
December1st to 10thDay
22%18%7%10%8%34445%16%
1520
11th to 20thDay
20%14%5%10%7%345%46%22%
1906
21st to endDay
25%21%7%12%5%2322318%
2772
January1st to 10thNight
17%17%7%12%8%46%44417%
2649
11th to 20thNight
17%15%7%10%8%45%435%21%
2560
21st to endNight
11%14%6%9%8%46%445%29%
2688
February1st to 10thNight
13%13%8%12%10%45%45%6%21%
2340
11th to 20thNight
13%14%5%10%7%36%445%27%
2273
21st to endNight
14%14%7%8%7%46%5%3428%
1803
March1st to 10thNight
15%14%6%7%7%45%445%29%
2124
11th to 20thNight
15%12%5%8%6%35%45%6%32%
1979
21st to endNight
15%10%48%5%33345%40%
2081
April1st to 10thNight
21%10%46%6%35%35%6%31%
1800
11th to 20thNight
19%9%35%5%345%5%6%36%
1775
21st to endNight
21%10%5%6%7%34346%31%
1659
May1st to 10thNight
21%8%35%5%235%47%37%
1440
11th to 20thNight
19%7%35%5%3445%6%39%
1415
21st to endNight
13%6%36%5%3445%8%42%
1550
June1st to 10thNight
19%5%25%6%35%5%7%9%34%
1440
11th to 20thNight
15%6%25%5%3446%7%42%
1440
21st to endNight
17%7%25%5%45%5%6%8%37%
1440
July1st to 10thNight
11%5%25%5%45%6%6%8%45%
1440
11th to 20thNight
13%5%25%5%25%5%6%7%44%
1440
21st to endNight
9%425%5%36%5%8%9%44%
1574
August1st to 10thNight
9%5%35%6%45%6%7%7%41%
1482
11th to 20thNight
10%5%36%6%346%6%8%44%
1598
21st to endNight
12%6%26%6%245%5%7%45%
1953
September1st to 10thNight
13%5%35%5%445%5%7%45%
1800
11th to 20thNight
16%5%35%423349%47%
1800
21st to endNight
18%7%36%433345%43%
2047
October1st to 10thNight
20%8%25%433446%40%
2160
11th to 20thNight
22%10%36%6%35%447%29%
2160
21st to endNight
24%11%37%6%45%445%27%
2503
November1st to 10thNight
17%11%37%5%35%45%7%32%
2445
11th to 20thNight
19%11%5%9%6%45%445%27%
2660
21st to endNight
21%14%5%9%7%35%5%45%22%
2660
December1st to 10thNight
20%19%6%10%7%44445%17%
2660
11th to 20thNight
21%16%6%8%6%3344425%
3288
21st to endNight
26%20%6%10%6%3333417%
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%5%8%10%10%1
1462
21st to endDay
62%5%9%14%10%1
1665
February1st to 10thDay
64%410%15%5%1
1620
11th to 20thDay
60%411%13%10%1
1582
21st to endDay
62%5%9%13%10%1
1453
March1st to 10thDay
59%49%17%10%1
1825
11th to 20thDay
57%5%10%14%10%3
1980
21st to endDay
51%48%20%13%5%
2274
April1st to 10thDay
58%47%17%12%3
2160
11th to 20thDay
52%47%20%15%2
2134
21st to endDay
57%47%15%13%4
2313
May1st to 10thDay
52%49%18%13%3
2520
11th to 20thDay
49%48%20%17%2
2482
21st to endDay
47%7%11%19%14%2
2725
June1st to 10thDay
53%6%11%18%11%1
2520
11th to 20thDay
43%8%11%24%12%3
2520
21st to endDay
49%8%13%20%10%1
2520
July1st to 10thDay
40%9%12%26%13%1
2450
11th to 20thDay
40%9%16%24%11%
2445
21st to endDay
42%9%15%25%9%
2591
August1st to 10thDay
43%10%15%23%9%
2439
11th to 20thDay
43%9%16%24%8%1
2303
21st to endDay
41%8%15%25%11%1
2383
September1st to 10thDay
40%7%14%28%11%
2160
11th to 20thDay
40%7%12%29%11%1
2160
21st to endDay
46%7%14%25%8%
1909
October1st to 10thDay
50%7%12%20%10%1
1800
11th to 20thDay
60%7%14%15%41
1800
21st to endDay
61%6%12%15%6%1
1851
November1st to 10thDay
50%7%14%23%6%1
1633
11th to 20thDay
61%7%12%12%7%1
1520
21st to endDay
69%6%10%8%6%1
1520
December1st to 10thDay
72%5%10%8%4
1520
11th to 20thDay
63%8%10%12%7%
1906
21st to endDay
74%36%13%3
2772
January1st to 10thNight
72%5%9%10%4
2649
11th to 20thNight
67%5%9%11%7%1
2560
21st to endNight
58%5%8%16%12%1
2688
February1st to 10thNight
64%5%9%14%7%1
2340
11th to 20thNight
60%410%18%7%1
2275
21st to endNight
58%5%9%18%10%1
1803
March1st to 10thNight
58%5%9%17%9%2
2134
11th to 20thNight
53%5%10%17%12%2
1980
21st to endNight
47%5%8%20%15%5%
2081
April1st to 10thNight
55%410%17%13%2
1800
11th to 20thNight
48%5%9%21%14%2
1775
21st to endNight
54%5%7%15%15%3
1659
May1st to 10thNight
47%5%8%20%16%4
1440
11th to 20thNight
46%5%8%22%16%4
1416
21st to endNight
40%6%13%22%17%3
1551
June1st to 10thNight
45%7%15%24%8%1
1440
11th to 20thNight
40%7%12%25%14%2
1440
21st to endNight
44%9%13%21%12%1
1440
July1st to 10thNight
33%8%15%25%17%1
1400
11th to 20thNight
38%7%13%29%13%
1392
21st to endNight
34%9%18%28%12%
1486
August1st to 10thNight
38%10%18%23%12%
1472
11th to 20thNight
36%8%18%27%11%
1598
21st to endNight
38%6%17%28%10%
1953
September1st to 10thNight
38%7%12%28%14%1
1800
11th to 20thNight
36%5%16%32%10%1
1800
21st to endNight
43%5%14%29%9%
2047
October1st to 10thNight
47%6%11%23%13%
2160
11th to 20thNight
54%7%13%18%7%1
2160
21st to endNight
60%6%12%15%7%
2503
November1st to 10thNight
51%7%15%19%9%
2445
11th to 20thNight
59%6%12%15%7%1
2660
21st to endNight
64%6%12%14%3
2660
December1st to 10thNight
70%6%9%11%3
2660
11th to 20thNight
64%5%9%14%8%
3288
21st to endNight
74%47%12%4
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
22%23%34%18%21
180
11th to 20thDay
25%18%36%16%5%
166
21st to endDay
19%25%33%17%6%
212
February1st to 10thDay
32%27%30%10%1
240
11th to 20thDay
28%29%35%7%1
240
21st to endDay
32%24%30%12%2
319
March1st to 10thDay
25%21%35%13%5%
420
11th to 20thDay
26%24%32%15%41
420
21st to endDay
30%21%28%15%5%1
462
April1st to 10thDay
32%20%27%15%5%1
420
11th to 20thDay
34%19%22%15%9%1
412
21st to endDay
30%20%32%12%5%1
420
May1st to 10thDay
28%17%32%15%6%3
423
11th to 20thDay
22%17%33%18%7%3
447
21st to endDay
21%18%33%19%7%1
485
June1st to 10thDay
25%13%36%19%6%2
450
11th to 20thDay
18%15%31%24%10%3
450
21st to endDay
18%14%32%24%10%2
450
July1st to 10thDay
12%8%33%36%10%2
445
11th to 20thDay
14%11%34%27%11%3
444
21st to endDay
13%9%35%30%11%2
488
August1st to 10thDay
15%8%31%28%14%4
446
11th to 20thDay
16%8%26%32%13%7%
439
21st to endDay
17%13%31%21%13%5%
495
September1st to 10thDay
17%11%32%21%13%6%
450
11th to 20thDay
16%11%28%22%16%7%
450
21st to endDay
21%14%28%18%12%6%
450
October1st to 10thDay
24%17%25%20%11%3
450
11th to 20thDay
29%21%29%14%6%1
450
21st to endDay
32%17%31%16%5%
430
November1st to 10thDay
25%19%31%19%41
327
11th to 20thDay
26%28%31%11%41
180
21st to endDay
28%26%30%11%41
180
December1st to 10thDay
31%14%41%12%2
180
11th to 20thDay
32%27%32%7%11
180
21st to endDay
34%19%33%12%21
198
January1st to 10thNight
27%16%36%16%4
760
11th to 20thNight
28%17%29%20%5%
732
21st to endNight
18%15%38%23%6%1
792
February1st to 10thNight
19%22%36%18%5%
720
11th to 20thNight
23%18%40%16%3
703
21st to endNight
22%22%32%21%4
592
March1st to 10thNight
23%18%34%20%4
720
11th to 20thNight
23%18%35%17%5%1
720
21st to endNight
22%17%34%19%8%
792
April1st to 10thNight
28%15%30%22%5%
720
11th to 20thNight
24%20%28%20%7%1
711
21st to endNight
26%17%28%23%5%1
579
May1st to 10thNight
25%10%31%24%9%1
360
11th to 20thNight
25%11%28%29%8%
354
21st to endNight
16%10%37%26%10%
389
June1st to 10thNight
19%9%33%32%7%
360
11th to 20thNight
18%9%28%31%14%1
360
21st to endNight
17%7%30%32%14%1
360
July1st to 10thNight
9%7%29%40%15%1
350
11th to 20thNight
14%5%25%37%18%
348
21st to endNight
9%6%28%41%15%1
394
August1st to 10thNight
11%6%23%39%21%
408
11th to 20thNight
12%321%39%22%3
534
21st to endNight
14%8%28%30%18%2
765
September1st to 10thNight
14%8%29%30%17%2
720
11th to 20thNight
17%7%26%31%17%3
720
21st to endNight
21%11%25%24%16%2
720
October1st to 10thNight
24%13%26%22%14%1
720
11th to 20thNight
26%14%31%21%6%1
720
21st to endNight
29%16%28%23%4
792
November1st to 10thNight
24%17%29%23%6%1
740
11th to 20thNight
26%19%30%16%9%
760
21st to endNight
31%18%26%20%5%
760
December1st to 10thNight
30%20%29%18%3
760
11th to 20thNight
27%19%31%18%5%1
760
21st to endNight
33%17%30%16%31
836
Page generated at 2024-01-10 19:35:21. Version ac07

Copyright 2024 Attilla Danko


Otter Lake Clear Sky Chart |Charts Home