MAS LaGrange site
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the MAS LaGrange site clear sky chart from 2005-11-06 to 2024-01-15.

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
45%
24015
23%
74525
16%
23957
53%
23957
28%
45347

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
22%
949
22%
2625
8%
946
32%
946
22%
1759
January11th to 20thNight
21%
921
22%
2393
7%
921
32%
921
20%
1714
January21st to endNight
23%
976
26%
2560
8%
976
36%
976
27%
1678
February1st to 10thNight
22%
720
19%
2160
7%
720
32%
720
19%
1471
February11th to 20thNight
20%
703
19%
2099
9%
700
28%
700
20%
1417
February21st to endNight
21%
592
21%
1776
8%
592
30%
592
18%
1219
March1st to 10thNight
29%
720
21%
2160
10%
720
38%
720
25%
1370
March11th to 20thNight
28%
595
17%
2035
10%
595
36%
595
19%
1340
March21st to endNight
32%
594
20%
2016
12%
594
42%
594
21%
1287
April1st to 10thNight
35%
540
25%
1800
14%
540
48%
540
27%
1051
April11th to 20thNight
35%
533
27%
1775
16%
533
52%
533
29%
1021
April21st to endNight
38%
540
24%
1800
16%
540
52%
540
27%
1069
May1st to 10thNight
45%
540
20%
1799
17%
540
53%
540
30%
1049
May11th to 20thNight
50%
531
21%
1592
16%
531
54%
531
29%
991
May21st to endNight
59%
583
21%
1688
17%
582
63%
582
32%
1037
June1st to 10thNight
67%
540
22%
1440
18%
540
69%
540
33%
926
June11th to 20thNight
76%
540
27%
1440
21%
540
78%
540
50%
782
June21st to endNight
74%
540
26%
1440
21%
540
76%
540
45%
817
July1st to 10thNight
73%
525
19%
1400
17%
525
75%
525
35%
886
July11th to 20thNight
72%
522
20%
1419
18%
522
74%
522
40%
831
July21st to endNight
78%
591
23%
1711
25%
558
79%
558
39%
963
August1st to 10thNight
80%
537
21%
1778
26%
534
81%
534
38%
938
August11th to 20thNight
76%
534
21%
1776
24%
534
76%
534
32%
1023
August21st to endNight
74%
594
23%
1980
26%
594
75%
594
33%
1118
September1st to 10thNight
72%
540
27%
1800
31%
540
73%
540
34%
1012
September11th to 20thNight
66%
607
27%
1867
26%
607
67%
607
34%
1094
September21st to endNight
64%
720
32%
1980
24%
720
68%
720
43%
1116
October1st to 10thNight
63%
720
31%
2029
25%
720
67%
720
45%
1102
October11th to 20thNight
47%
720
31%
2160
21%
720
57%
720
36%
1226
October21st to endNight
42%
792
30%
2376
21%
792
51%
792
30%
1435
November1st to 10thNight
51%
740
31%
2404
27%
740
59%
740
36%
1294
November11th to 20thNight
39%
760
28%
2470
19%
760
53%
760
33%
1365
November21st to endNight
35%
760
26%
2470
17%
760
47%
760
26%
1479
December1st to 10thNight
30%
760
23%
2470
13%
760
43%
760
21%
1588
December11th to 20thNight
30%
896
25%
3077
12%
895
42%
895
22%
1875
December21st to endNight
24%
1040
12%
4760
8%
1026
35%
1026
13%
3004

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
12%6%35%5%35%5%5%7%43%
74782
Night
12%6%25%43445%7%47%
74998
TransparencyDay
39%7%11%21%18%4
74499
Night
36%6%11%22%20%5%
74802
SeeingDay
16%10%23%25%19%7%
14141
Night
15%10%25%29%18%3
24023

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 10thDay
18%9%45%423335%43%
1536
11th to 20thDay
19%10%36%5%34445%37%
1656
21st to endDay
14%8%35%433446%47%
1793
February1st to 10thDay
20%11%45%5%23336%39%
1800
11th to 20thDay
20%9%45%43445%5%38%
1748
21st to endDay
24%10%36%423346%36%
1480
March1st to 10thDay
16%9%37%434445%41%
1800
11th to 20thDay
20%8%47%6%25%436%35%
1939
21st to endDay
17%8%35%5%345%5%7%36%
2340
April1st to 10thDay
12%6%25%5%44447%45%
2160
11th to 20thDay
17%7%2443435%6%45%
2134
21st to endDay
12%7%36%6%345%5%7%42%
2160
May1st to 10thDay
14%6%26%4345%6%7%42%
2160
11th to 20thDay
11%5%36%5%45%46%7%43%
2301
21st to endDay
8%6%26%6%46%6%7%10%38%
2582
June1st to 10thDay
9%5%26%6%46%6%6%9%41%
2520
11th to 20thDay
4425%6%45%7%7%10%48%
2520
21st to endDay
5%425%6%46%7%7%10%46%
2520
July1st to 10thDay
7%5%36%7%46%7%9%11%34%
2520
11th to 20thDay
7%5%25%7%47%7%7%12%39%
2488
21st to endDay
7%425%6%47%7%8%11%39%
2505
August1st to 10thDay
6%5%25%7%46%7%8%12%38%
2148
11th to 20thDay
9%5%25%6%46%6%7%9%41%
2125
21st to endDay
10%5%25%5%45%6%7%10%41%
2376
September1st to 10thDay
9%426%6%35%6%7%8%44%
2160
11th to 20thDay
11%5%26%5%4446%7%46%
2073
21st to endDay
10%5%25%433447%53%
1980
October1st to 10thDay
8%425%334447%57%
1927
11th to 20thDay
11%424423447%55%
1800
21st to endDay
18%6%1432343351%
1980
November1st to 10thDay
12%423323345%59%
1672
11th to 20thDay
14%5%2342345%6%52%
1710
21st to endDay
18%8%24424446%43%
1710
December1st to 10thDay
20%9%36%5%24346%38%
1710
11th to 20thDay
14%9%36%5%34345%44%
1966
21st to endDay
12%12%47%6%345%5%6%35%
2783
January1st to 10thNight
19%8%36%423435%44%
2625
11th to 20thNight
18%10%46%5%33445%38%
2393
21st to endNight
17%7%35%423346%46%
2560
February1st to 10thNight
20%9%47%5%23335%40%
2160
11th to 20thNight
19%8%36%5%2433442%
2098
21st to endNight
20%8%35%5%35%445%39%
1776
March1st to 10thNight
16%6%3443445%6%46%
2160
11th to 20thNight
19%7%36%5%34446%39%
2035
21st to endNight
15%7%26%5%445%6%7%40%
2016
April1st to 10thNight
12%5%35%42446%8%47%
1800
11th to 20thNight
16%5%2442345%7%49%
1775
21st to endNight
11%6%245%3445%7%48%
1800
May1st to 10thNight
13%6%24323449%49%
1799
11th to 20thNight
10%6%245%3447%8%46%
1592
21st to endNight
5%5%25%7%35%6%7%12%44%
1688
June1st to 10thNight
7%5%36%436%6%5%11%45%
1440
11th to 20thNight
23233245%6%9%61%
1440
21st to endNight
3313335%47%11%56%
1440
July1st to 10thNight
4425%6%46%7%7%11%45%
1440
11th to 20thNight
6%415%42446%13%49%
1467
21st to endNight
4414435%6%7%10%53%
1812
August1st to 10thNight
33135%46%6%8%9%52%
1790
11th to 20thNight
6%3245%45%6%7%11%46%
1776
21st to endNight
7%4245%35%5%6%11%49%
1980
September1st to 10thNight
7%5%25%5%25%5%6%6%52%
1800
11th to 20thNight
8%6%3442445%8%51%
1867
21st to endNight
9%424423346%59%
1980
October1st to 10thNight
7%423323347%61%
2029
11th to 20thNight
12%5%24333436%56%
2160
21st to endNight
16%6%25%423335%51%
2376
November1st to 10thNight
10%313424346%58%
2404
11th to 20thNight
11%5%2432446%6%52%
2470
21st to endNight
15%6%15%424446%49%
2470
December1st to 10thNight
21%8%34423437%42%
2470
11th to 20thNight
16%7%345%2335%5%47%
3226
21st to endNight
14%9%37%6%45%5%6%7%34%
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
45%48%21%18%5%
1537
11th to 20thDay
50%49%19%17%2
1656
21st to endDay
39%49%23%23%3
1793
February1st to 10thDay
49%47%21%17%3
1800
11th to 20thDay
50%5%6%19%16%4
1758
21st to endDay
51%48%14%16%7%
1480
March1st to 10thDay
46%5%7%16%18%9%
1800
11th to 20thDay
52%5%7%16%16%3
1939
21st to endDay
46%7%10%22%15%
2340
April1st to 10thDay
39%6%8%24%19%4
2160
11th to 20thDay
41%49%20%21%5%
2134
21st to endDay
41%6%9%24%19%1
2160
May1st to 10thDay
41%7%11%21%18%2
2160
11th to 20thDay
39%7%15%22%15%2
2305
21st to endDay
39%10%15%24%11%2
2582
June1st to 10thDay
37%10%12%21%18%2
2520
11th to 20thDay
28%9%15%28%17%3
2520
21st to endDay
32%9%14%24%17%4
2520
July1st to 10thDay
36%12%18%19%12%3
2451
11th to 20thDay
35%11%19%21%10%4
2413
21st to endDay
34%12%15%27%11%1
2366
August1st to 10thDay
35%10%19%24%11%1
2136
11th to 20thDay
37%11%13%22%15%2
2125
21st to endDay
36%9%14%23%14%3
2376
September1st to 10thDay
35%10%12%23%17%4
2160
11th to 20thDay
35%8%11%17%22%5%
2073
21st to endDay
31%5%10%23%24%7%
1980
October1st to 10thDay
28%5%10%23%26%7%
1927
11th to 20thDay
29%5%8%21%29%8%
1800
21st to endDay
38%45%20%25%7%
1980
November1st to 10thDay
29%5%7%23%27%8%
1672
11th to 20thDay
33%48%20%26%9%
1710
21st to endDay
43%47%17%24%5%
1710
December1st to 10thDay
49%5%6%19%17%4
1710
11th to 20thDay
44%47%20%22%3
1963
21st to endDay
47%7%11%21%13%2
2783
January1st to 10thNight
44%47%19%21%4
2625
11th to 20thNight
50%47%20%16%4
2393
21st to endNight
41%48%23%22%3
2560
February1st to 10thNight
49%49%17%18%3
2160
11th to 20thNight
47%47%20%17%5%
2099
21st to endNight
49%47%16%17%6%
1776
March1st to 10thNight
40%5%9%16%21%10%
2160
11th to 20thNight
46%6%9%18%17%3
2035
21st to endNight
43%6%10%21%18%3
2016
April1st to 10thNight
35%5%11%23%20%5%
1800
11th to 20thNight
35%49%22%23%8%
1775
21st to endNight
36%6%9%26%20%3
1800
May1st to 10thNight
33%7%12%24%21%4
1799
11th to 20thNight
35%9%14%23%18%2
1593
21st to endNight
31%10%15%27%14%2
1689
June1st to 10thNight
32%10%12%22%21%2
1440
11th to 20thNight
19%8%16%30%23%4
1440
21st to endNight
22%9%16%28%20%5%
1440
July1st to 10thNight
28%12%19%23%14%3
1400
11th to 20thNight
25%10%22%24%15%5%
1419
21st to endNight
24%10%19%30%15%1
1711
August1st to 10thNight
23%10%19%32%16%1
1778
11th to 20thNight
28%11%18%25%15%3
1776
21st to endNight
28%9%17%25%16%6%
1980
September1st to 10thNight
30%7%11%22%23%7%
1800
11th to 20thNight
31%7%12%18%27%5%
1867
21st to endNight
27%5%10%26%24%8%
1980
October1st to 10thNight
25%5%10%24%25%12%
2029
11th to 20thNight
31%48%19%29%10%
2160
21st to endNight
37%37%20%25%8%
2376
November1st to 10thNight
28%5%7%23%29%8%
2404
11th to 20thNight
30%5%8%21%25%10%
2470
21st to endNight
38%47%20%24%6%
2470
December1st to 10thNight
44%48%20%18%4
2470
11th to 20thNight
39%47%22%24%4
3228
21st to endNight
44%7%12%20%13%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
26%24%32%14%3
270
11th to 20thDay
32%21%34%10%21
252
21st to endDay
27%28%33%9%3
264
February1st to 10thDay
29%25%32%12%21
240
11th to 20thDay
38%23%31%7%1
240
21st to endDay
37%26%27%7%2
198
March1st to 10thDay
26%21%37%13%3
240
11th to 20thDay
26%29%32%13%
240
21st to endDay
26%18%33%15%7%
426
April1st to 10thDay
21%17%34%21%7%1
420
11th to 20thDay
20%17%32%22%8%1
412
21st to endDay
22%15%29%23%10%1
420
May1st to 10thDay
20%15%28%26%9%3
423
11th to 20thDay
13%8%28%29%17%6%
447
21st to endDay
9%6%25%31%19%10%
536
June1st to 10thDay
12%418%28%26%11%
630
11th to 20thDay
4317%38%27%12%
630
21st to endDay
6%421%34%23%12%
630
July1st to 10thDay
7%314%31%31%16%
621
11th to 20thDay
7%211%25%37%17%
618
21st to endDay
7%210%31%33%17%
643
August1st to 10thDay
6%312%30%37%12%
446
11th to 20thDay
10%313%31%33%10%
439
21st to endDay
13%19%23%35%18%
495
September1st to 10thDay
8%411%31%38%9%
450
11th to 20thDay
10%314%26%33%14%
450
21st to endDay
15%6%14%31%22%11%
450
October1st to 10thDay
11%324%30%28%5%
397
11th to 20thDay
12%13%40%26%7%2
270
21st to endDay
25%15%31%21%8%1
297
November1st to 10thDay
18%10%27%33%10%1
270
11th to 20thDay
11%20%37%26%6%
270
21st to endDay
26%15%29%17%11%1
270
December1st to 10thDay
29%21%28%18%31
270
11th to 20thDay
26%19%31%18%6%
270
21st to endDay
25%21%39%12%3
297
January1st to 10thNight
23%18%33%22%4
950
11th to 20thNight
24%18%33%21%4
921
21st to endNight
21%17%36%24%2
976
February1st to 10thNight
23%18%34%22%3
720
11th to 20thNight
24%21%33%21%2
703
21st to endNight
24%22%31%20%3
592
March1st to 10thNight
20%15%33%29%4
720
11th to 20thNight
23%12%34%26%41
595
21st to endNight
20%13%32%24%11%
594
April1st to 10thNight
14%15%35%28%8%1
540
11th to 20thNight
17%10%33%28%11%1
533
21st to endNight
14%11%34%30%10%1
540
May1st to 10thNight
16%7%27%35%13%2
540
11th to 20thNight
13%5%26%33%18%4
531
21st to endNight
8%122%36%28%5%
584
June1st to 10thNight
8%314%37%31%7%
540
11th to 20thNight
3114%37%42%3
540
21st to endNight
4114%38%36%6%
540
July1st to 10thNight
4211%27%46%10%
525
11th to 20thNight
6%211%28%40%13%
522
21st to endNight
4110%29%45%12%
591
August1st to 10thNight
417%31%49%9%
537
11th to 20thNight
6%25%39%42%5%
534
21st to endNight
8%19%28%44%9%
594
September1st to 10thNight
7%27%38%41%5%
540
11th to 20thNight
10%214%31%35%7%
607
21st to endNight
11%316%36%30%4
720
October1st to 10thNight
9%418%33%32%4
720
11th to 20thNight
14%7%27%33%17%2
720
21st to endNight
21%9%25%30%15%1
792
November1st to 10thNight
11%9%24%36%18%1
740
11th to 20thNight
13%11%34%30%12%
760
21st to endNight
20%10%32%26%11%1
760
December1st to 10thNight
24%12%30%27%6%
760
11th to 20thNight
23%14%31%27%6%
897
21st to endNight
23%17%32%24%4
1045
Page generated at 2024-01-11 21:33:45. Version ac07

Copyright 2024 Attilla Danko


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