Lake Monticello
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Lake Monticello clear sky chart from 2005-11-05 to 2018-01-12.

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
42%
15883
22%
48427
13%
15847
52%
15847
26%
30463

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
27%
761
23%
2472
10%
761
44%
761
23%
1535
January16th to endNight
23%
768
24%
2496
10%
768
41%
768
23%
1538
February1st to 15thNight
26%
701
22%
2287
10%
701
42%
701
24%
1372
February16th to endNight
23%
631
26%
1908
9%
631
42%
631
25%
1197
March1st to 15thNight
29%
720
23%
1980
10%
720
41%
720
27%
1266
March16th to endNight
31%
768
20%
2112
10%
768
40%
768
25%
1413
April1st to 15thNight
29%
718
21%
1813
5%
718
39%
718
31%
1165
April16th to endNight
41%
720
21%
1800
9%
720
46%
720
32%
1186
May1st to 15thNight
40%
546
16%
1626
8%
546
47%
546
24%
1091
May16th to endNight
55%
465
16%
1587
14%
465
58%
465
24%
1008
June1st to 15thNight
65%
360
20%
1440
22%
360
71%
360
25%
823
June16th to endNight
63%
360
18%
1440
21%
360
69%
360
25%
836
July1st to 15thNight
63%
456
13%
1476
12%
456
64%
456
25%
955
July16th to endNight
73%
564
17%
1595
13%
531
75%
531
33%
952
August1st to 15thNight
67%
539
18%
1609
15%
536
68%
536
28%
1054
August16th to endNight
61%
729
18%
1875
11%
729
62%
729
28%
1288
September1st to 15thNight
60%
720
24%
1800
17%
720
62%
720
33%
1193
September16th to endNight
52%
717
21%
2003
18%
717
55%
717
27%
1351
October1st to 15thNight
51%
720
24%
2160
23%
720
57%
720
27%
1362
October16th to endNight
44%
768
31%
2304
21%
768
58%
768
34%
1338
November1st to 15thNight
41%
760
26%
2317
17%
760
53%
760
29%
1417
November16th to endNight
38%
780
25%
2701
16%
780
52%
780
27%
1546
December1st to 15thNight
31%
780
20%
2730
11%
780
43%
780
20%
1735
December16th to endNight
33%
832
23%
2896
13%
832
47%
832
21%
1842

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
13%5%244345%5%7%42%
48888
Night
14%5%2442445%7%44%
48621
Cloud CoverDay
14%5%2443445%7%42%
48898
Night
14%5%2442445%7%44%
48625
TransparencyDay
39%6%11%22%16%3
48599
Night
38%5%10%22%18%4
48428
SeeingDay
17%7%23%26%17%8%
6019
Night
16%6%26%31%15%1
15892

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
16%5%25%41445%5%44%
1710
16th to endDay
15%5%24425%445%44%
1728
February1st to 15thDay
12%7%25%5%25%446%42%
1575
16th to endDay
14%6%245%3445%7%41%
1563
March1st to 15thDay
15%425%433445%46%
1969
16th to endDay
17%6%35%5%3435%5%40%
2112
April1st to 15thDay
11%5%2432335%7%49%
2134
16th to endDay
16%5%245%235%46%43%
2165
May1st to 15thDay
17%6%245%345%48%36%
2331
16th to endDay
13%4244345%6%7%40%
2524
June1st to 15thDay
11%324435%5%7%9%42%
2520
16th to endDay
7%3245%45%6%7%10%41%
2520
July1st to 15thDay
10%5%25%5%36%6%7%9%35%
2391
16th to endDay
6%325%6%47%7%7%11%36%
2465
August1st to 15thDay
11%5%26%7%46%6%6%9%33%
2340
16th to endDay
11%4246%45%7%7%8%36%
2312
September1st to 15thDay
11%425%5%35%46%7%44%
2160
16th to endDay
17%6%25%425%5%5%7%37%
1953
October1st to 15thDay
18%424423245%47%
1800
16th to endDay
13%424423235%52%
1920
November1st to 15thDay
14%5%13423346%49%
1871
16th to endDay
15%31332345%5%50%
1588
December1st to 15thDay
16%5%24324446%44%
1560
16th to endDay
19%6%35%423345%41%
1677
January1st to 15thNight
15%6%24423346%45%
2472
16th to endNight
15%6%24434346%45%
2496
February1st to 15thNight
14%6%23434446%46%
2285
16th to endNight
13%6%25%424346%46%
1908
March1st to 15thNight
16%42332445%7%45%
1968
16th to endNight
17%6%245%24436%43%
2112
April1st to 15thNight
12%5%2443435%8%46%
1813
16th to endNight
14%5%23424447%46%
1800
May1st to 15thNight
17%5%25%5%245%5%7%38%
1626
16th to endNight
12%4245%35%5%6%8%41%
1586
June1st to 15thNight
8%3235%35%6%7%9%44%
1440
16th to endNight
7%424436%5%5%10%44%
1440
July1st to 15thNight
10%5%25%436%5%6%8%41%
1566
16th to endNight
5%4136%36%5%9%11%42%
1703
August1st to 15thNight
9%425%5%35%7%6%9%40%
1620
16th to endNight
9%6%36%7%46%6%6%8%36%
1875
September1st to 15thNight
11%425%5%345%5%7%44%
1800
16th to endNight
17%5%25%325%45%6%40%
2003
October1st to 15thNight
18%414413446%45%
2160
16th to endNight
13%313323445%53%
2304
November1st to 15thNight
14%5%24423335%50%
2317
16th to endNight
14%31342445%5%50%
2701
December1st to 15thNight
16%7%25%434345%41%
2730
16th to endNight
16%6%2442446%6%41%
2896

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
16%5%2442345%5%44%
1710
16th to endDay
16%5%24325%446%43%
1728
February1st to 15thDay
13%7%245%3435%6%42%
1575
16th to endDay
14%5%35%5%3445%7%41%
1563
March1st to 15thDay
15%415%42345%6%46%
1980
16th to endDay
17%5%35%5%3435%6%39%
2111
April1st to 15thDay
12%424423347%50%
2134
16th to endDay
17%5%245%24436%43%
2165
May1st to 15thDay
17%5%34425%45%8%36%
2331
16th to endDay
13%425%435%5%6%8%40%
2524
June1st to 15thDay
11%324435%5%7%9%42%
2520
16th to endDay
8%415%5%35%5%8%10%41%
2520
July1st to 15thDay
11%5%245%36%6%8%9%35%
2391
16th to endDay
6%3246%47%6%7%11%36%
2465
August1st to 15thDay
11%6%26%6%46%5%7%9%34%
2340
16th to endDay
11%4146%46%6%6%9%37%
2312
September1st to 15thDay
11%425%435%5%6%6%45%
2160
16th to endDay
18%5%35%4345%5%7%37%
1953
October1st to 15thDay
18%414323236%47%
1800
16th to endDay
14%414423235%53%
1920
November1st to 15thDay
15%423423336%49%
1871
16th to endDay
15%313323446%51%
1588
December1st to 15thDay
16%5%2333445%6%44%
1560
16th to endDay
20%7%25%423345%41%
1677
January1st to 15thNight
16%5%33424346%45%
2472
16th to endNight
16%5%24434345%45%
2496
February1st to 15thNight
15%6%13424446%46%
2278
16th to endNight
13%5%24424346%46%
1908
March1st to 15thNight
16%42332345%7%45%
1980
16th to endNight
17%6%14424346%43%
2112
April1st to 15thNight
13%41442445%7%46%
1813
16th to endNight
15%424424347%46%
1800
May1st to 15thNight
17%5%245%2445%7%38%
1625
16th to endNight
12%4246%35%5%5%8%42%
1586
June1st to 15thNight
8%3235%35%6%6%9%44%
1440
16th to endNight
7%4145%36%5%6%9%45%
1440
July1st to 15thNight
10%5%24435%5%5%9%42%
1566
16th to endNight
5%3136%37%5%8%11%42%
1703
August1st to 15thNight
9%5%15%5%25%6%6%9%40%
1620
16th to endNight
10%5%26%5%46%6%6%8%36%
1875
September1st to 15thNight
11%5%15%4335%6%7%44%
1800
16th to endNight
18%6%244345%46%40%
2003
October1st to 15thNight
18%424423337%45%
2160
16th to endNight
13%313324345%53%
2304
November1st to 15thNight
15%5%24423325%50%
2317
16th to endNight
14%413424445%50%
2701
December1st to 15thNight
16%6%35%5%24345%41%
2730
16th to endNight
17%6%2442445%5%41%
2896

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
40%5%11%20%17%4
1711
16th to endDay
40%49%23%16%4
1728
February1st to 15thDay
42%48%23%18%3
1577
16th to endDay
41%410%21%18%3
1563
March1st to 15thDay
38%5%10%22%16%6%
1980
16th to endDay
44%5%9%20%15%4
2112
April1st to 15thDay
34%311%24%19%6%
2134
16th to endDay
41%5%9%18%18%6%
2165
May1st to 15thDay
45%7%13%18%14%1
2331
16th to endDay
38%9%13%25%12%
2528
June1st to 15thDay
34%8%16%23%15%1
2520
16th to endDay
34%9%16%21%15%2
2520
July1st to 15thDay
40%8%13%18%13%4
2252
16th to endDay
36%8%14%23%14%1
2310
August1st to 15thDay
44%8%12%21%12%1
2327
16th to endDay
40%8%14%22%11%1
2312
September1st to 15thDay
37%6%12%18%21%3
2160
16th to endDay
45%5%8%20%19%1
1953
October1st to 15thDay
38%48%26%18%4
1800
16th to endDay
34%26%28%22%5%
1920
November1st to 15thDay
36%49%20%22%6%
1871
16th to endDay
33%49%24%23%4
1588
December1st to 15thDay
40%5%10%22%16%5%
1560
16th to endDay
45%39%23%15%1
1677
January1st to 15thNight
40%49%18%19%8%
2472
16th to endNight
40%49%24%17%3
2496
February1st to 15thNight
38%38%24%19%5%
2287
16th to endNight
38%48%24%20%4
1908
March1st to 15thNight
38%5%10%26%16%3
1980
16th to endNight
41%5%9%21%17%3
2112
April1st to 15thNight
35%5%10%20%21%6%
1813
16th to endNight
37%5%11%19%19%7%
1800
May1st to 15thNight
44%6%12%20%13%2
1626
16th to endNight
39%8%13%24%11%2
1588
June1st to 15thNight
34%8%13%26%15%2
1440
16th to endNight
33%9%15%20%18%3
1440
July1st to 15thNight
39%9%15%17%14%4
1476
16th to endNight
30%8%18%26%15%1
1595
August1st to 15thNight
37%9%15%21%15%1
1609
16th to endNight
41%8%13%23%11%2
1875
September1st to 15thNight
36%7%12%20%17%4
1800
16th to endNight
43%5%9%19%18%2
2003
October1st to 15thNight
39%5%8%23%19%4
2160
16th to endNight
33%47%25%24%5%
2304
November1st to 15thNight
38%36%19%23%8%
2317
16th to endNight
35%47%22%24%5%
2701
December1st to 15thNight
44%48%21%17%3
2730
16th to endNight
43%5%10%21%15%3
2896

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
20%22%35%16%4
123
16th to endDay
29%25%36%7%2
96
February1st to 15thDay
22%26%36%12%2
90
16th to endDay
19%16%30%31%2
183
March1st to 15thDay
18%11%33%28%7%
270
16th to endDay
19%11%35%23%9%1
288
April1st to 15thDay
17%13%26%23%15%3
270
16th to endDay
23%427%23%13%7%
270
May1st to 15thDay
25%10%28%18%11%5%
288
16th to endDay
19%224%25%19%7%
331
June1st to 15thDay
12%420%29%20%11%
315
16th to endDay
12%224%33%20%6%
315
July1st to 15thDay
15%119%33%24%5%
305
16th to endDay
7%112%31%29%17%
326
August1st to 15thDay
15%115%24%28%14%
313
16th to endDay
14%110%30%25%18%
332
September1st to 15thDay
12%416%23%22%20%
315
16th to endDay
27%114%26%17%12%
314
October1st to 15thDay
22%219%25%21%8%
315
16th to endDay
14%8%28%26%17%4
336
November1st to 15thDay
19%7%19%32%16%3
317
16th to endDay
16%11%29%27%11%3
118
December1st to 15thDay
21%11%37%15%12%2
90
16th to endDay
33%18%26%20%2
99
January1st to 15thNight
18%12%36%26%5%
765
16th to endNight
19%11%40%25%2
768
February1st to 15thNight
19%10%38%30%1
704
16th to endNight
18%13%39%25%2
631
March1st to 15thNight
20%11%35%27%4
720
16th to endNight
19%9%33%28%7%
768
April1st to 15thNight
14%12%40%24%7%
718
16th to endNight
17%7%28%32%13%
720
May1st to 15thNight
20%425%33%14%1
546
16th to endNight
14%117%39%23%2
467
June1st to 15thNight
8%17%41%30%1
360
16th to endNight
8%119%46%24%
360
July1st to 15thNight
12%115%36%32%2
456
16th to endNight
6%110%40%34%6%
564
August1st to 15thNight
12%8%40%34%3
539
16th to endNight
13%110%33%36%3
729
September1st to 15thNight
13%115%31%33%4
720
16th to endNight
20%215%30%27%3
717
October1st to 15thNight
22%5%16%30%23%3
720
16th to endNight
15%6%30%30%16%1
768
November1st to 15thNight
17%7%25%32%14%1
760
16th to endNight
16%9%31%30%12%
780
December1st to 15thNight
19%8%33%28%9%
780
16th to endNight
19%9%31%35%3
832
Page generated at 2018-01-12 22:01:37. Version ac04

Copyright 2018 A. Danko


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