Lake Katherine Nature Center
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lake Katherine Nature Center clear sky chart from 2005-11-05 to 2017-09-24.

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
37%
15982
17%
46917
11%
15940
43%
15940
23%
31567

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
19%
900
13%
2506
4%
895
27%
895
16%
1841
January16th to endNight
20%
960
12%
2664
4%
960
27%
960
15%
2032
February1st to 15thNight
22%
779
14%
2190
4%
779
30%
779
18%
1571
February16th to endNight
25%
631
18%
1893
7%
631
35%
631
17%
1339
March1st to 15thNight
25%
720
13%
2160
8%
720
29%
720
17%
1546
March16th to endNight
30%
637
15%
2017
10%
637
37%
637
18%
1420
April1st to 15thNight
31%
539
15%
1797
10%
539
39%
539
20%
1203
April16th to endNight
32%
540
18%
1728
11%
540
42%
540
21%
1165
May1st to 15thNight
37%
540
16%
1617
9%
540
43%
540
22%
1119
May16th to endNight
51%
562
17%
1498
10%
561
55%
561
32%
981
June1st to 15thNight
52%
540
16%
1440
11%
540
56%
540
35%
891
June16th to endNight
50%
540
17%
1440
9%
540
55%
540
32%
948
July1st to 15thNight
62%
510
17%
1360
11%
510
65%
510
39%
823
July16th to endNight
69%
564
22%
1417
17%
531
72%
531
43%
827
August1st to 15thNight
77%
539
22%
1580
22%
536
78%
536
41%
889
August16th to endNight
67%
573
21%
1910
21%
573
71%
573
33%
1085
September1st to 15thNight
62%
553
27%
1813
27%
553
67%
553
35%
1011
September16th to endNight
60%
693
27%
1914
21%
693
63%
693
35%
1163
October1st to 15thNight
48%
660
26%
1884
19%
660
54%
660
32%
1140
October16th to endNight
28%
704
17%
2247
11%
704
37%
704
21%
1475
November1st to 15thNight
30%
700
23%
2276
15%
700
41%
700
24%
1411
November16th to endNight
26%
738
17%
2358
10%
738
34%
738
19%
1589
December1st to 15thNight
18%
900
12%
2520
4%
900
25%
900
16%
1892
December16th to endNight
14%
960
10%
2688
2%
960
22%
960
10%
2206

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
14%7%36%5%3445%7%36%
48022
Night
14%8%35%424446%40%
47085
Cloud CoverDay
13%8%36%5%35%45%7%36%
48031
Night
14%8%35%424446%39%
47090
TransparencyDay
46%6%12%21%11%1
47708
Night
44%5%12%22%13%1
46917
SeeingDay
14%8%29%27%15%5%
5989
Night
18%9%29%28%12%1
15986

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
15%14%47%7%35%45%7%24%
1432
16th to endDay
13%15%7%9%6%34345%25%
1560
February1st to 15thDay
16%12%5%8%7%34435%27%
1670
16th to endDay
16%11%47%6%2345%6%31%
1580
March1st to 15thDay
16%13%5%7%5%35%445%29%
1790
16th to endDay
18%9%46%5%3445%7%30%
2217
April1st to 15thDay
19%9%37%5%24345%32%
2151
16th to endDay
20%7%25%5%24446%35%
2232
May1st to 15thDay
18%9%35%6%3445%7%29%
2331
16th to endDay
13%5%36%5%25%45%8%39%
2617
June1st to 15thDay
11%4345%245%5%7%44%
2520
16th to endDay
10%4346%36%6%7%9%36%
2520
July1st to 15thDay
8%426%5%35%5%6%9%43%
2520
16th to endDay
7%425%5%36%6%7%9%40%
2655
August1st to 15thDay
7%425%6%35%6%6%8%43%
2370
16th to endDay
10%4245%35%5%5%9%42%
2292
September1st to 15thDay
13%424424447%48%
2134
16th to endDay
9%6%24436%46%9%43%
1905
October1st to 15thDay
14%6%25%5%2435%5%44%
1744
16th to endDay
18%7%36%5%33346%35%
1625
November1st to 15thDay
14%7%3442345%6%43%
1582
16th to endDay
18%8%38%324336%36%
1599
December1st to 15thDay
18%12%48%6%35%345%27%
1440
16th to endDay
21%16%5%8%5%3433423%
1536
January1st to 15thNight
17%12%46%5%33345%33%
2506
16th to endNight
14%12%7%8%5%25%45%5%29%
2664
February1st to 15thNight
16%12%5%5%5%24345%34%
2188
16th to endNight
16%10%5%6%5%24346%33%
1893
March1st to 15thNight
17%11%46%5%2434435%
2147
16th to endNight
16%8%35%445%5%5%7%34%
2017
April1st to 15thNight
16%8%46%5%2345%6%36%
1797
16th to endNight
19%7%25%5%2435%5%38%
1728
May1st to 15thNight
18%6%245%335%6%7%35%
1617
16th to endNight
11%325%5%3446%9%44%
1496
June1st to 15thNight
9%5%25%434447%50%
1440
16th to endNight
10%424426%5%6%10%41%
1440
July1st to 15thNight
6%4135%25%5%6%7%51%
1440
16th to endNight
441442447%10%50%
1513
August1st to 15thNight
4214435%45%9%54%
1589
16th to endNight
9%31442345%7%53%
1910
September1st to 15thNight
11%31442335%7%54%
1813
16th to endNight
8%435%32446%6%49%
1914
October1st to 15thNight
13%5%24423337%49%
1884
16th to endNight
20%8%34323335%40%
2247
November1st to 15thNight
13%8%35%423345%46%
2276
16th to endNight
19%7%36%423346%37%
2358
December1st to 15thNight
20%9%48%5%33435%31%
2520
16th to endNight
24%15%5%7%6%3443422%
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
15%14%47%6%35%5%5%6%25%
1432
16th to endDay
13%16%8%8%6%34345%25%
1560
February1st to 15thDay
15%13%6%8%6%35%445%27%
1670
16th to endDay
15%11%47%6%25%446%30%
1580
March1st to 15thDay
16%13%48%435%45%5%28%
1800
16th to endDay
18%9%47%5%35%45%6%30%
2216
April1st to 15thDay
18%10%47%5%34345%32%
2151
16th to endDay
19%7%25%5%3445%6%35%
2232
May1st to 15thDay
17%9%37%5%35%45%7%29%
2331
16th to endDay
12%5%35%5%345%5%8%38%
2617
June1st to 15thDay
10%5%345%35%45%7%43%
2520
16th to endDay
9%5%25%7%35%7%7%9%36%
2520
July1st to 15thDay
7%426%5%36%46%9%43%
2520
16th to endDay
6%425%5%46%7%7%9%40%
2655
August1st to 15thDay
5%426%6%35%6%6%9%42%
2370
16th to endDay
9%4245%35%5%6%9%41%
2292
September1st to 15thDay
12%324434447%47%
2134
16th to endDay
8%6%245%25%5%7%8%42%
1905
October1st to 15thDay
13%7%26%424446%43%
1744
16th to endDay
17%9%35%5%33346%35%
1625
November1st to 15thDay
14%7%35%5%22447%42%
1582
16th to endDay
18%9%37%425%336%35%
1599
December1st to 15thDay
17%12%5%7%7%35%345%27%
1440
16th to endDay
22%14%6%7%6%2443422%
1536
January1st to 15thNight
17%12%47%5%24345%33%
2506
16th to endNight
14%12%7%8%5%34445%28%
2664
February1st to 15thNight
15%11%5%5%5%34345%34%
2181
16th to endNight
16%11%46%6%2435%5%33%
1893
March1st to 15thNight
17%11%5%6%5%2433435%
2160
16th to endNight
16%8%36%435%45%7%34%
2017
April1st to 15thNight
16%8%46%5%2445%6%36%
1797
16th to endNight
19%7%35%433445%38%
1728
May1st to 15thNight
19%6%25%6%246%5%7%34%
1616
16th to endNight
10%3245%4445%9%43%
1496
June1st to 15thNight
9%5%25%5%24347%50%
1440
16th to endNight
10%424435%5%6%11%40%
1440
July1st to 15thNight
6%313435%6%6%8%50%
1440
16th to endNight
44244245%7%10%50%
1513
August1st to 15thNight
33133445%5%9%54%
1589
16th to endNight
9%31342445%8%51%
1910
September1st to 15thNight
10%314423347%53%
1813
16th to endNight
8%5%25%42445%7%49%
1914
October1st to 15thNight
12%5%2442325%7%48%
1884
16th to endNight
20%7%35%323346%39%
2247
November1st to 15thNight
12%9%25%5%23335%45%
2276
16th to endNight
18%7%46%423346%36%
2358
December1st to 15thNight
20%9%48%424345%30%
2520
16th to endNight
23%15%47%6%3433422%
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
57%6%13%12%9%
1433
16th to endDay
60%5%11%14%6%
1560
February1st to 15thDay
58%5%10%15%8%1
1672
16th to endDay
54%5%12%20%5%1
1580
March1st to 15thDay
56%6%11%18%7%1
1800
16th to endDay
53%6%14%20%5%
2217
April1st to 15thDay
52%5%8%20%11%
2151
16th to endDay
48%6%13%16%11%3
2232
May1st to 15thDay
52%6%12%21%6%
2331
16th to endDay
42%7%12%20%15%1
2621
June1st to 15thDay
37%6%10%24%18%1
2520
16th to endDay
40%9%13%20%14%2
2520
July1st to 15thDay
36%7%12%25%15%2
2371
16th to endDay
34%9%16%22%14%2
2488
August1st to 15thDay
35%7%14%25%14%2
2355
16th to endDay
35%8%12%24%15%2
2292
September1st to 15thDay
35%5%11%25%19%3
2134
16th to endDay
35%6%11%28%15%1
1905
October1st to 15thDay
41%5%11%25%14%1
1744
16th to endDay
49%413%22%9%1
1625
November1st to 15thDay
41%5%13%22%14%2
1582
16th to endDay
50%5%12%23%7%
1599
December1st to 15thDay
59%5%11%18%5%
1440
16th to endDay
64%5%10%11%6%
1536
January1st to 15thNight
53%413%18%9%
2506
16th to endNight
56%6%13%16%7%
2664
February1st to 15thNight
52%412%20%9%1
2190
16th to endNight
52%411%21%9%1
1893
March1st to 15thNight
52%5%11%18%9%1
2160
16th to endNight
49%7%12%20%8%1
2017
April1st to 15thNight
47%410%21%14%1
1797
16th to endNight
47%5%9%20%13%3
1728
May1st to 15thNight
46%6%11%23%11%
1617
16th to endNight
36%7%14%20%17%3
1498
June1st to 15thNight
33%5%12%26%19%2
1440
16th to endNight
36%7%13%22%18%1
1440
July1st to 15thNight
29%6%13%26%19%2
1360
16th to endNight
25%7%17%27%18%4
1417
August1st to 15thNight
25%7%17%27%19%2
1580
16th to endNight
29%8%12%26%18%4
1910
September1st to 15thNight
30%410%26%24%3
1813
16th to endNight
32%6%9%29%19%2
1914
October1st to 15thNight
34%410%27%20%1
1884
16th to endNight
46%313%23%12%1
2247
November1st to 15thNight
41%49%23%17%3
2276
16th to endNight
47%414%23%9%
2358
December1st to 15thNight
55%5%11%18%8%
2520
16th to endNight
66%48%13%41
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
24%13%34%22%5%
90
16th to endDay
17%13%39%22%6%
96
February1st to 15thDay
18%18%51%11%
90
16th to endDay
18%14%37%18%7%3
81
March1st to 15thDay
27%20%33%16%2
90
16th to endDay
27%8%31%20%9%1
252
April1st to 15thDay
23%12%28%24%10%
270
16th to endDay
22%11%31%19%12%3
270
May1st to 15thDay
20%12%31%21%9%3
288
16th to endDay
14%9%33%26%11%3
517
June1st to 15thDay
11%6%32%31%13%4
495
16th to endDay
11%7%38%27%10%4
495
July1st to 15thDay
9%429%30%17%8%
475
16th to endDay
7%326%32%20%8%
515
August1st to 15thDay
6%217%35%23%14%
385
16th to endDay
9%316%32%25%12%
332
September1st to 15thDay
12%318%31%26%8%
315
16th to endDay
9%417%29%29%9%
287
October1st to 15thDay
16%7%25%27%16%5%
184
16th to endDay
21%11%39%26%1
96
November1st to 15thDay
5%11%27%34%15%5%
90
16th to endDay
23%21%35%14%5%
90
December1st to 15thDay
18%16%44%16%3
90
16th to endDay
26%25%41%5%2
96
January1st to 15thNight
22%15%36%20%4
900
16th to endNight
19%15%35%26%3
960
February1st to 15thNight
21%11%39%23%4
782
16th to endNight
22%14%32%25%5%
631
March1st to 15thNight
22%12%35%22%6%
720
16th to endNight
18%11%33%27%8%1
637
April1st to 15thNight
20%13%30%27%7%
539
16th to endNight
22%7%32%25%10%1
540
May1st to 15thNight
22%430%29%12%
540
16th to endNight
13%425%38%18%1
563
June1st to 15thNight
11%324%45%14%
540
16th to endNight
12%128%35%20%1
540
July1st to 15thNight
7%121%40%25%2
510
16th to endNight
6%115%46%26%3
564
August1st to 15thNight
5%10%49%29%5%
539
16th to endNight
10%214%36%31%4
573
September1st to 15thNight
11%415%34%27%5%
553
16th to endNight
9%5%17%34%29%3
693
October1st to 15thNight
15%7%24%32%18%1
660
16th to endNight
24%13%30%23%7%
704
November1st to 15thNight
17%13%35%21%9%2
700
16th to endNight
22%14%32%22%6%
738
December1st to 15thNight
25%14%36%19%4
900
16th to endNight
30%14%33%18%2
960
Page generated at 2017-09-25 08:02:28. Version ac04

Copyright 2017 A. Danko


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