Grieser Field
Clear Sky Chart
History

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

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%
23975
18%
74807
12%
23925
44%
23925
21%
50741

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
16%
760
14%
2459
6%
757
25%
757
10%
1899
January11th to 20thNight
16%
724
10%
2352
4%
724
24%
724
10%
1817
January21st to endNight
17%
792
14%
2574
7%
792
26%
792
11%
1952
February1st to 10thNight
20%
720
12%
2340
6%
720
27%
720
12%
1773
February11th to 20thNight
16%
700
14%
2173
5%
700
25%
700
11%
1639
February21st to endNight
14%
592
15%
1776
5%
592
25%
592
12%
1360
March1st to 10thNight
22%
720
20%
2026
9%
720
31%
720
19%
1405
March11th to 20thNight
25%
720
18%
1980
9%
720
33%
720
19%
1392
March21st to endNight
23%
792
18%
2178
8%
792
32%
792
19%
1538
April1st to 10thNight
26%
720
17%
1973
8%
720
34%
720
24%
1337
April11th to 20thNight
31%
591
22%
1655
10%
591
41%
591
25%
1093
April21st to endNight
29%
540
21%
1620
8%
540
38%
540
23%
1064
May1st to 10thNight
32%
540
14%
1620
7%
540
38%
540
20%
1124
May11th to 20thNight
40%
531
16%
1593
10%
531
46%
531
22%
1106
May21st to endNight
55%
582
17%
1745
12%
582
60%
582
32%
1071
June1st to 10thNight
53%
540
17%
1620
14%
540
57%
540
30%
978
June11th to 20thNight
55%
540
18%
1620
14%
540
60%
540
31%
984
June21st to endNight
57%
540
17%
1620
15%
540
61%
540
34%
974
July1st to 10thNight
59%
525
16%
1575
14%
525
62%
525
31%
974
July11th to 20thNight
66%
522
19%
1566
14%
522
70%
522
36%
920
July21st to endNight
59%
591
18%
1672
15%
558
62%
558
30%
1032
August1st to 10thNight
68%
537
20%
1600
15%
534
70%
534
34%
941
August11th to 20thNight
61%
534
22%
1598
18%
534
63%
534
31%
996
August21st to endNight
63%
623
26%
1811
21%
623
65%
623
39%
1018
September1st to 10thNight
60%
720
25%
1935
16%
720
63%
720
38%
1178
September11th to 20thNight
65%
720
30%
1980
22%
720
70%
720
42%
1140
September21st to endNight
48%
720
25%
1980
19%
720
55%
720
30%
1275
October1st to 10thNight
52%
720
24%
2078
20%
720
57%
720
32%
1259
October11th to 20thNight
38%
720
24%
2160
16%
720
49%
720
26%
1368
October21st to endNight
34%
792
23%
2376
18%
792
42%
792
21%
1602
November1st to 10thNight
41%
740
25%
2378
19%
740
51%
740
29%
1398
November11th to 20thNight
28%
760
21%
2470
11%
760
41%
760
18%
1659
November21st to endNight
30%
760
19%
2478
13%
760
38%
760
17%
1730
December1st to 10thNight
19%
760
11%
2660
6%
760
26%
760
11%
2015
December11th to 20thNight
25%
759
12%
3075
8%
759
33%
759
11%
2215
December21st to endNight
19%
828
8%
4491
6%
817
27%
817
6%
3515

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
16%9%47%6%35%5%5%7%33%
74587
Night
16%9%46%6%3445%7%36%
75096
TransparencyDay
50%311%22%12%2
74309
Night
49%310%22%13%2
74893
SeeingDay
23%12%27%21%12%5%
13695
Night
22%10%25%28%14%2
23989

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
19%14%7%9%8%45%445%22%
1706
11th to 20thDay
19%19%8%9%7%34345%21%
1620
21st to endDay
18%18%7%10%7%34345%20%
1782
February1st to 10thDay
24%14%5%9%7%34345%23%
1620
11th to 20thDay
18%14%7%11%5%24447%24%
1671
21st to endDay
18%14%5%8%5%33345%31%
1480
March1st to 10thDay
18%10%5%7%6%2445%6%34%
1932
11th to 20thDay
18%11%48%5%34446%30%
1980
21st to endDay
21%10%46%6%34446%31%
2178
April1st to 10thDay
14%11%47%6%4446%6%33%
1986
11th to 20thDay
17%9%46%6%35%5%5%6%36%
2269
21st to endDay
18%8%37%5%35%5%5%8%33%
2340
May1st to 10thDay
19%8%47%7%45%45%7%30%
2340
11th to 20thDay
21%8%36%6%45%45%7%31%
2301
21st to endDay
9%5%35%5%46%6%8%10%37%
2531
June1st to 10thDay
12%6%35%6%36%6%7%9%36%
2340
11th to 20thDay
12%6%36%7%45%6%7%10%35%
2340
21st to endDay
12%5%26%6%46%6%8%11%35%
2340
July1st to 10thDay
11%6%36%5%5%6%6%6%10%35%
2340
11th to 20thDay
11%6%36%6%45%6%7%9%38%
2340
21st to endDay
11%6%36%6%36%7%7%10%35%
2547
August1st to 10thDay
9%5%35%7%46%6%8%11%35%
2327
11th to 20thDay
11%5%35%6%46%7%8%10%34%
2303
21st to endDay
9%5%25%6%45%6%6%9%43%
2525
September1st to 10thDay
15%5%2443446%8%45%
2021
11th to 20thDay
10%5%25%435%5%6%8%47%
1980
21st to endDay
17%7%36%5%23446%42%
1980
October1st to 10thDay
14%6%25%5%35%46%8%41%
1882
11th to 20thDay
16%6%36%5%345%5%7%40%
1800
21st to endDay
22%10%25%5%34446%36%
1980
November1st to 10thDay
11%7%36%434446%48%
1695
11th to 20thDay
17%12%46%5%3435%6%35%
1710
21st to endDay
18%11%5%7%6%35%446%32%
1691
December1st to 10thDay
22%15%6%10%5%3444422%
1520
11th to 20thDay
19%15%5%11%5%3435%6%24%
2066
21st to endDay
22%20%5%9%6%35%5%5%5%14%
3124
January1st to 10thNight
18%13%7%10%8%5%4445%23%
2459
11th to 20thNight
20%14%6%9%7%35%44422%
2352
21st to endNight
18%14%6%11%6%44445%25%
2574
February1st to 10thNight
23%12%49%5%44445%26%
2340
11th to 20thNight
21%12%5%9%7%45%45%5%25%
2171
21st to endNight
20%15%5%8%6%3444427%
1776
March1st to 10thNight
17%9%47%5%345%45%36%
2026
11th to 20thNight
19%9%45%6%3445%7%34%
1980
21st to endNight
21%9%37%5%33346%35%
2178
April1st to 10thNight
16%9%35%5%35%46%7%38%
1973
11th to 20thNight
15%7%35%5%35%5%7%8%38%
1655
21st to endNight
15%9%35%4445%7%8%36%
1620
May1st to 10thNight
17%8%37%7%45%5%5%6%33%
1620
11th to 20thNight
16%8%36%7%35%5%5%6%36%
1592
21st to endNight
8%5%26%6%26%5%7%10%43%
1744
June1st to 10thNight
9%5%35%5%35%5%6%7%46%
1620
11th to 20thNight
10%6%345%35%5%7%11%42%
1620
21st to endNight
12%5%24435%6%6%9%45%
1620
July1st to 10thNight
9%6%25%6%345%6%9%45%
1620
11th to 20thNight
7%5%145%36%6%7%10%46%
1620
21st to endNight
8%5%35%6%45%5%6%9%44%
1771
August1st to 10thNight
6%426%5%36%5%7%11%44%
1611
11th to 20thNight
8%7%26%5%36%5%6%8%44%
1598
21st to endNight
8%425%5%245%7%9%50%
1811
September1st to 10thNight
12%4245%3345%7%51%
1935
11th to 20thNight
9%4144235%6%7%53%
1980
21st to endNight
15%6%36%43435%6%45%
1980
October1st to 10thNight
11%6%35%4345%5%7%47%
2078
11th to 20thNight
15%7%25%5%245%5%7%41%
2160
21st to endNight
21%8%35%5%3445%6%38%
2376
November1st to 10thNight
13%7%35%423336%49%
2378
11th to 20thNight
17%8%36%6%45%45%6%35%
2470
21st to endNight
19%10%47%6%3445%6%32%
2478
December1st to 10thNight
22%14%6%8%6%3445%424%
2660
11th to 20thNight
18%14%7%7%6%35%45%6%27%
3118
21st to endNight
21%19%6%9%7%44446%17%
4532

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
65%38%16%7%1
1707
11th to 20thDay
68%211%15%4
1620
21st to endDay
68%28%16%6%1
1782
February1st to 10thDay
65%210%15%8%1
1620
11th to 20thDay
61%29%18%9%
1680
21st to endDay
58%110%20%9%2
1480
March1st to 10thDay
52%29%25%11%1
1932
11th to 20thDay
55%39%20%11%2
1980
21st to endDay
56%39%20%11%1
2178
April1st to 10thDay
52%210%21%13%3
1986
11th to 20thDay
48%311%17%17%3
2269
21st to endDay
51%39%23%12%2
2340
May1st to 10thDay
54%311%21%9%2
2340
11th to 20thDay
54%411%19%11%2
2305
21st to endDay
39%7%15%26%11%2
2531
June1st to 10thDay
42%412%25%15%2
2340
11th to 20thDay
44%415%22%14%1
2340
21st to endDay
41%415%22%15%2
2340
July1st to 10thDay
45%413%21%16%1
2275
11th to 20thDay
41%411%27%15%1
2271
21st to endDay
42%312%27%13%2
2405
August1st to 10thDay
40%413%28%13%1
2314
11th to 20thDay
41%414%28%12%1
2303
21st to endDay
37%412%26%16%5%
2525
September1st to 10thDay
38%311%23%21%4
2021
11th to 20thDay
35%311%29%20%2
1980
21st to endDay
44%38%24%20%1
1980
October1st to 10thDay
41%49%26%19%1
1882
11th to 20thDay
44%310%25%16%1
1800
21st to endDay
51%29%23%13%2
1980
November1st to 10thDay
38%39%30%16%3
1695
11th to 20thDay
52%28%22%14%3
1710
21st to endDay
54%38%22%12%1
1691
December1st to 10thDay
67%29%17%4
1520
11th to 20thDay
63%19%20%7%
2063
21st to endDay
73%111%11%4
3124
January1st to 10thNight
65%37%17%8%1
2459
11th to 20thNight
65%212%15%5%
2352
21st to endNight
63%28%19%7%1
2574
February1st to 10thNight
62%310%19%7%1
2340
11th to 20thNight
62%27%19%9%1
2173
21st to endNight
62%28%17%8%2
1776
March1st to 10thNight
51%28%25%14%1
2026
11th to 20thNight
50%310%24%11%2
1980
21st to endNight
52%28%22%14%3
2178
April1st to 10thNight
47%310%23%16%3
1973
11th to 20thNight
44%310%20%19%4
1655
21st to endNight
45%410%24%16%2
1620
May1st to 10thNight
51%312%20%10%4
1620
11th to 20thNight
49%410%21%14%3
1593
21st to endNight
36%5%16%27%13%2
1745
June1st to 10thNight
37%412%26%19%2
1620
11th to 20thNight
37%414%25%17%3
1620
21st to endNight
35%5%14%27%18%3
1620
July1st to 10thNight
37%5%11%24%19%3
1575
11th to 20thNight
32%5%15%26%19%2
1566
21st to endNight
37%6%14%25%17%2
1672
August1st to 10thNight
34%5%15%29%16%1
1600
11th to 20thNight
38%5%12%25%18%2
1598
21st to endNight
31%214%29%18%5%
1811
September1st to 10thNight
34%311%23%21%7%
1935
11th to 20thNight
30%311%28%25%3
1980
21st to endNight
41%39%23%23%2
1980
October1st to 10thNight
37%310%27%21%2
2078
11th to 20thNight
42%38%26%19%2
2160
21st to endNight
48%37%25%15%2
2376
November1st to 10thNight
39%210%26%20%4
2378
11th to 20thNight
50%27%22%16%2
2470
21st to endNight
54%211%22%10%1
2478
December1st to 10thNight
64%29%19%6%1
2660
11th to 20thNight
59%211%21%7%
3120
21st to endNight
70%19%15%4
4532

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
32%20%33%10%4
270
11th to 20thDay
32%23%35%8%1
240
21st to endDay
34%25%30%9%2
264
February1st to 10thDay
38%20%31%9%2
240
11th to 20thDay
41%24%30%4
240
21st to endDay
34%23%35%8%
198
March1st to 10thDay
30%20%31%16%3
372
11th to 20thDay
30%18%32%13%5%1
420
21st to endDay
34%15%32%14%5%
462
April1st to 10thDay
26%16%35%14%8%2
420
11th to 20thDay
30%13%29%17%8%3
412
21st to endDay
24%19%32%18%6%2
420
May1st to 10thDay
28%15%30%17%8%3
423
11th to 20thDay
25%11%29%20%10%5%
447
21st to endDay
14%8%26%28%16%7%
485
June1st to 10thDay
17%5%30%27%17%5%
450
11th to 20thDay
18%9%22%30%14%7%
450
21st to endDay
14%7%28%29%15%6%
450
July1st to 10thDay
16%318%24%23%17%
445
11th to 20thDay
15%322%29%20%11%
444
21st to endDay
15%5%19%30%20%11%
488
August1st to 10thDay
12%5%16%32%22%12%
446
11th to 20thDay
15%320%32%18%12%
439
21st to endDay
12%321%27%24%12%
495
September1st to 10thDay
16%318%27%23%12%
450
11th to 20thDay
10%317%26%29%14%
450
21st to endDay
24%8%22%24%18%4
450
October1st to 10thDay
15%8%28%28%17%6%
450
11th to 20thDay
19%11%31%25%12%2
450
21st to endDay
29%13%30%19%7%1
495
November1st to 10thDay
18%16%35%20%8%3
293
11th to 20thDay
31%14%30%17%6%2
270
21st to endDay
23%20%36%18%3
261
December1st to 10thDay
32%14%37%11%5%2
180
11th to 20thDay
27%23%37%10%3
229
21st to endDay
36%19%27%14%4
297
January1st to 10thNight
29%18%30%19%3
760
11th to 20thNight
32%16%28%21%4
724
21st to endNight
27%19%31%20%2
792
February1st to 10thNight
33%14%28%23%2
720
11th to 20thNight
33%18%31%18%1
703
21st to endNight
31%18%31%18%2
592
March1st to 10thNight
25%15%32%23%4
720
11th to 20thNight
27%17%27%22%7%1
720
21st to endNight
27%14%30%22%7%
792
April1st to 10thNight
23%14%32%23%7%
720
11th to 20thNight
20%12%34%23%10%1
591
21st to endNight
21%9%35%27%7%1
540
May1st to 10thNight
22%8%28%28%12%1
540
11th to 20thNight
21%6%25%32%15%1
531
21st to endNight
12%321%33%27%4
584
June1st to 10thNight
10%423%40%22%1
540
11th to 20thNight
13%321%36%24%2
540
21st to endNight
14%318%39%24%2
540
July1st to 10thNight
12%115%35%30%7%
525
11th to 20thNight
9%214%39%31%5%
522
21st to endNight
12%117%32%35%3
591
August1st to 10thNight
8%210%39%35%5%
537
11th to 20thNight
11%314%34%32%6%
534
21st to endNight
10%217%30%34%7%
623
September1st to 10thNight
14%217%31%31%5%
720
11th to 20thNight
12%313%32%35%5%
720
21st to endNight
18%5%20%31%22%4
720
October1st to 10thNight
16%421%32%24%3
720
11th to 20thNight
20%9%27%30%13%1
720
21st to endNight
26%10%25%29%9%1
792
November1st to 10thNight
19%9%26%29%16%1
740
11th to 20thNight
25%13%28%26%8%1
760
21st to endNight
26%10%27%29%6%1
760
December1st to 10thNight
32%14%29%20%5%
760
11th to 20thNight
28%15%27%25%5%
760
21st to endNight
31%14%27%25%2
836
Page generated at 2024-01-08 11:14:18. Version ac07

Copyright 2024 Attilla Danko


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