Lake Hamilton
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lake Hamilton 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
47%
16513
25%
49682
17%
16467
55%
16467
31%
29452

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
31%
974
26%
2522
10%
970
43%
970
28%
1631
January16th to endNight
29%
1040
29%
2704
10%
1040
41%
1040
32%
1707
February1st to 15thNight
26%
955
21%
2483
7%
951
34%
951
27%
1636
February16th to endNight
25%
618
26%
1984
10%
618
39%
618
23%
1214
March1st to 15thNight
31%
585
22%
2145
14%
585
43%
585
22%
1318
March16th to endNight
33%
624
20%
2288
14%
624
43%
624
22%
1402
April1st to 15thNight
32%
584
26%
1973
14%
584
50%
584
30%
1094
April16th to endNight
37%
558
26%
1858
17%
558
52%
558
31%
1054
May1st to 15thNight
45%
540
20%
1730
16%
540
54%
540
27%
1071
May16th to endNight
50%
563
22%
1685
18%
561
57%
561
30%
1031
June1st to 15thNight
76%
540
22%
1620
22%
540
79%
540
43%
870
June16th to endNight
73%
540
24%
1620
24%
540
76%
540
43%
866
July1st to 15thNight
74%
510
17%
1530
18%
510
76%
510
35%
891
July16th to endNight
84%
564
26%
1594
30%
531
84%
531
42%
868
August1st to 15thNight
79%
539
26%
1640
30%
536
81%
536
44%
850
August16th to endNight
74%
573
23%
1910
29%
573
74%
573
31%
1122
September1st to 15thNight
68%
540
25%
1800
27%
540
71%
540
33%
1018
September16th to endNight
68%
576
33%
1995
33%
576
72%
576
37%
1047
October1st to 15thNight
58%
720
30%
2160
23%
720
63%
720
38%
1208
October16th to endNight
50%
768
37%
2304
23%
768
62%
768
42%
1229
November1st to 15thNight
49%
760
29%
2280
20%
760
56%
760
33%
1298
November16th to endNight
40%
827
31%
2449
18%
827
52%
827
31%
1466
December1st to 15thNight
35%
975
22%
2704
12%
975
43%
975
28%
1737
December16th to endNight
30%
1040
23%
2704
10%
1040
39%
1040
25%
1824

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%5%2443445%6%43%
49822
Night
12%5%24423346%50%
49877
TransparencyDay
40%6%10%20%18%4
49522
Night
34%410%22%21%6%
49682
SeeingDay
14%6%21%26%22%7%
6350
Night
15%7%24%30%19%2
16514

By Month

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
18%7%23422335%46%
1746
16th to endDay
18%6%2332223449%
1872
February1st to 15thDay
19%6%24325%34443%
1710
16th to endDay
22%8%25%5%2333339%
1785
March1st to 15thDay
19%7%24322345%43%
2145
16th to endDay
17%8%36%5%24345%38%
2286
April1st to 15thDay
16%5%25%423346%46%
2303
16th to endDay
16%5%36%423345%42%
2216
May1st to 15thDay
18%6%25%5%35%446%36%
2218
16th to endDay
11%5%36%6%46%6%6%7%35%
2430
June1st to 15thDay
6%425%5%5%6%5%6%7%42%
2340
16th to endDay
6%425%5%46%6%7%10%39%
2340
July1st to 15thDay
8%426%7%5%6%6%7%10%34%
2340
16th to endDay
6%415%447%8%8%10%38%
2466
August1st to 15thDay
7%3145%46%7%8%10%39%
2310
16th to endDay
8%5%25%6%36%6%7%9%37%
2292
September1st to 15thDay
15%5%135%25%447%44%
2160
16th to endDay
10%4134245%47%51%
1950
October1st to 15thDay
13%5%2343235%5%49%
1800
16th to endDay
15%22212235%59%
1920
November1st to 15thDay
13%5%23212336%53%
1908
16th to endDay
18%6%23312235%49%
1833
December1st to 15thDay
16%6%335%23435%44%
1580
16th to endDay
20%7%25%43334442%
1872
January1st to 15thNight
18%6%23313235%49%
2522
16th to endNight
16%6%23322235%52%
2704
February1st to 15thNight
18%6%25%313335%46%
2473
16th to endNight
18%5%24323335%48%
1984
March1st to 15thNight
18%5%24322345%45%
2145
16th to endNight
15%6%34424345%46%
2288
April1st to 15thNight
11%42341335%8%50%
1973
16th to endNight
11%42432335%6%51%
1858
May1st to 15thNight
14%324435%446%46%
1729
16th to endNight
8%5%346%4445%9%45%
1683
June1st to 15thNight
42133245%5%8%58%
1620
16th to endNight
5%31332346%9%56%
1620
July1st to 15thNight
33245%35%5%8%13%44%
1620
16th to endNight
3124345%7%14%51%
1702
August1st to 15thNight
421431345%13%54%
1650
16th to endNight
6%424435%6%7%9%44%
1910
September1st to 15thNight
8%42442345%7%51%
1800
16th to endNight
7%41432445%5%56%
1995
October1st to 15thNight
10%414313335%56%
2160
16th to endNight
11%31331122463%
2304
November1st to 15thNight
10%413323345%55%
2280
16th to endNight
16%6%2331222453%
2449
December1st to 15thNight
17%6%24323345%46%
2704
16th to endNight
19%7%34313346%42%
2704

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
42%36%22%19%5%
1747
16th to endDay
40%3422%24%5%
1872
February1st to 15thDay
43%38%22%17%4
1711
16th to endDay
49%45%16%18%5%
1785
March1st to 15thDay
43%49%18%16%8%
2145
16th to endDay
47%48%22%14%1
2288
April1st to 15thDay
39%39%22%18%6%
2303
16th to endDay
43%49%19%19%3
2216
May1st to 15thDay
48%6%7%15%17%4
2218
16th to endDay
43%8%14%20%11%1
2434
June1st to 15thDay
38%7%12%23%16%1
2340
16th to endDay
36%8%13%21%16%2
2340
July1st to 15thDay
39%9%14%23%11%1
2201
16th to endDay
34%11%16%23%13%1
2311
August1st to 15thDay
34%9%15%22%14%2
2296
16th to endDay
40%9%13%20%12%3
2292
September1st to 15thDay
40%6%11%16%17%7%
2160
16th to endDay
32%6%10%21%22%7%
1950
October1st to 15thDay
35%5%9%18%21%9%
1800
16th to endDay
28%35%20%29%12%
1920
November1st to 15thDay
32%38%23%24%7%
1908
16th to endDay
39%26%17%26%6%
1833
December1st to 15thDay
42%5%9%18%17%7%
1580
16th to endDay
46%38%19%17%4
1872
January1st to 15thNight
39%36%20%26%4
2522
16th to endNight
37%26%19%25%7%
2704
February1st to 15thNight
41%28%21%19%5%
2483
16th to endNight
39%37%22%19%7%
1984
March1st to 15thNight
41%48%14%19%10%
2145
16th to endNight
41%48%22%20%2
2288
April1st to 15thNight
31%411%22%20%9%
1973
16th to endNight
32%49%24%22%5%
1858
May1st to 15thNight
39%5%9%20%18%7%
1730
16th to endNight
36%6%16%25%14%1
1685
June1st to 15thNight
24%6%12%31%22%2
1620
16th to endNight
25%5%13%27%24%4
1620
July1st to 15thNight
26%10%20%25%15%1
1530
16th to endNight
21%9%17%31%18%2
1594
August1st to 15thNight
23%5%17%31%19%2
1640
16th to endNight
32%8%14%25%16%3
1910
September1st to 15thNight
29%7%11%22%20%8%
1800
16th to endNight
28%49%21%26%9%
1995
October1st to 15thNight
29%410%18%23%13%
2160
16th to endNight
26%3418%33%14%
2304
November1st to 15thNight
31%48%20%25%10%
2280
16th to endNight
36%36%16%29%7%
2449
December1st to 15thNight
40%48%19%19%7%
2704
16th to endNight
44%38%21%17%5%
2704

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
23%8%42%20%4
135
16th to endDay
18%24%34%16%41
144
February1st to 15thDay
22%17%37%18%21
135
16th to endDay
28%20%35%13%2
120
March1st to 15thDay
26%14%41%14%2
135
16th to endDay
15%28%34%19%2
144
April1st to 15thDay
22%15%33%18%9%
302
16th to endDay
23%7%31%20%13%2
289
May1st to 15thDay
19%9%29%27%12%2
355
16th to endDay
14%6%29%30%14%5%
517
June1st to 15thDay
10%114%33%29%10%
495
16th to endDay
7%216%36%28%8%
495
July1st to 15thDay
8%115%34%31%8%
475
16th to endDay
7%6%24%44%17%
515
August1st to 15thDay
10%17%32%33%15%
463
16th to endDay
17%6%23%37%14%
332
September1st to 15thDay
12%10%21%39%15%
315
16th to endDay
7%111%39%29%10%
156
October1st to 15thDay
6%5%26%34%21%5%
135
16th to endDay
19%430%29%13%2
144
November1st to 15thDay
24%6%27%20%18%2
135
16th to endDay
27%10%27%22%9%2
135
December1st to 15thDay
15%17%36%19%9%2
135
16th to endDay
29%15%34%15%3
144
January1st to 15thNight
23%14%27%28%5%
975
16th to endNight
19%12%35%27%3
1040
February1st to 15thNight
22%13%34%25%3
955
16th to endNight
22%15%34%24%4
618
March1st to 15thNight
24%10%31%29%4
585
16th to endNight
18%12%32%29%7%
624
April1st to 15thNight
14%15%35%24%9%
584
16th to endNight
13%6%38%27%13%
558
May1st to 15thNight
15%5%26%37%12%1
540
16th to endNight
10%326%35%20%3
563
June1st to 15thNight
3211%42%36%3
540
16th to endNight
6%111%36%37%7%
540
July1st to 15thNight
310%34%44%6%
510
16th to endNight
3427%51%12%
564
August1st to 15thNight
7%5%30%45%11%
539
16th to endNight
9%5%31%44%7%
573
September1st to 15thNight
10%112%28%40%6%
540
16th to endNight
10%112%31%37%6%
576
October1st to 15thNight
12%321%28%31%3
720
16th to endNight
13%5%26%31%20%1
768
November1st to 15thNight
12%9%24%34%18%1
760
16th to endNight
19%10%25%28%14%
827
December1st to 15thNight
23%8%28%31%8%
975
16th to endNight
23%10%31%27%6%
1040
Page generated at 2018-04-24 09:02:59. Version ac04

Copyright 2018 A. Danko


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