Albert Lea
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Albert Lea clear sky chart from 2005-11-06 to 2024-01-10.

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
34%
24766
17%
74704
9%
24705
41%
24705
23%
50127

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%
950
12%
2647
4%
946
30%
946
18%
1943
January11th to 20thNight
23%
900
11%
2443
4%
900
28%
900
15%
1893
January21st to endNight
19%
990
12%
2574
3%
990
26%
990
15%
2024
February1st to 10thNight
21%
900
12%
2340
3%
900
27%
900
18%
1748
February11th to 20thNight
22%
879
16%
2274
5%
875
30%
875
23%
1596
February21st to endNight
23%
673
16%
1857
4%
673
33%
673
19%
1316
March1st to 10thNight
27%
580
15%
2020
8%
580
35%
580
19%
1331
March11th to 20thNight
29%
540
17%
1980
11%
540
39%
540
19%
1300
March21st to endNight
28%
594
12%
2169
9%
594
35%
594
15%
1530
April1st to 10thNight
25%
540
16%
1800
9%
540
36%
540
18%
1211
April11th to 20thNight
26%
533
16%
1775
12%
533
37%
533
18%
1194
April21st to endNight
30%
540
18%
1634
10%
540
40%
540
21%
1130
May1st to 10thNight
34%
540
15%
1574
10%
540
40%
540
24%
1060
May11th to 20thNight
36%
531
18%
1417
8%
531
43%
531
28%
952
May21st to endNight
40%
584
14%
1551
5%
582
44%
582
27%
1042
June1st to 10thNight
51%
540
18%
1440
7%
540
55%
540
37%
899
June11th to 20thNight
45%
540
16%
1440
7%
540
49%
540
33%
927
June21st to endNight
55%
540
19%
1440
9%
540
58%
540
41%
838
July1st to 10thNight
65%
525
18%
1400
9%
525
67%
525
47%
781
July11th to 20thNight
63%
522
21%
1392
11%
522
66%
522
47%
778
July21st to endNight
67%
591
24%
1578
17%
558
70%
558
48%
832
August1st to 10thNight
66%
537
23%
1601
21%
534
69%
534
37%
916
August11th to 20thNight
61%
534
24%
1600
23%
534
66%
534
35%
945
August21st to endNight
57%
594
23%
1908
22%
594
65%
594
39%
1020
September1st to 10thNight
55%
540
24%
1800
22%
540
62%
540
37%
959
September11th to 20thNight
48%
540
26%
1834
21%
540
59%
540
34%
1022
September21st to endNight
40%
602
23%
2042
13%
602
52%
602
30%
1152
October1st to 10thNight
38%
720
21%
2160
13%
720
44%
720
29%
1346
October11th to 20thNight
31%
720
21%
2160
9%
720
42%
720
25%
1371
October21st to endNight
30%
792
19%
2376
10%
792
39%
792
20%
1605
November1st to 10thNight
30%
816
23%
2464
10%
816
41%
816
25%
1537
November11th to 20thNight
23%
950
17%
2660
5%
950
33%
950
20%
1890
November21st to endNight
24%
950
17%
2660
7%
950
33%
950
22%
1819
December1st to 10thNight
23%
950
10%
2660
3%
950
28%
950
17%
1969
December11th to 20thNight
21%
949
11%
3201
3%
948
28%
948
13%
2340
December21st to endNight
16%
1040
8%
4833
4%
1026
25%
1026
7%
3911

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%8%47%6%35%5%5%7%36%
74684
Night
12%8%47%6%3445%7%39%
75022
TransparencyDay
46%7%14%21%11%1
74390
Night
44%6%13%22%13%2
74836
SeeingDay
17%10%30%27%13%4
14761
Night
16%10%34%29%10%1
24772

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
8%11%6%10%10%6%7%5%7%6%24%
1509
11th to 20thDay
9%14%7%12%10%47%46%7%20%
1516
21st to endDay
11%11%7%12%11%47%6%6%7%18%
1782
February1st to 10thDay
8%11%5%11%10%6%7%5%6%7%24%
1620
11th to 20thDay
10%11%5%9%7%48%5%6%7%28%
1574
21st to endDay
14%11%411%8%3445%6%30%
1399
March1st to 10thDay
13%11%6%10%6%45%5%5%6%29%
1956
11th to 20thDay
14%9%49%6%35%45%7%32%
1980
21st to endDay
19%12%47%6%345%5%6%28%
2186
April1st to 10thDay
18%11%48%6%2445%8%28%
2160
11th to 20thDay
18%11%46%5%34446%33%
2134
21st to endDay
22%11%47%5%35%5%5%5%30%
2323
May1st to 10thDay
17%10%37%6%3446%8%30%
2384
11th to 20thDay
17%8%35%5%45%6%6%7%35%
2479
21st to endDay
17%7%36%5%35%46%7%37%
2725
June1st to 10thDay
11%6%26%5%345%5%7%46%
2520
11th to 20thDay
13%6%25%5%35%6%6%9%41%
2520
21st to endDay
11%5%35%5%45%6%6%9%42%
2520
July1st to 10thDay
6%425%5%45%5%7%10%48%
2520
11th to 20thDay
7%425%5%445%5%9%51%
2520
21st to endDay
6%424436%6%6%10%49%
2644
August1st to 10thDay
8%7%36%6%45%6%7%9%42%
2328
11th to 20thDay
13%6%25%435%5%6%9%42%
2301
21st to endDay
8%4244445%6%8%50%
2447
September1st to 10thDay
13%5%35%43445%7%48%
2160
11th to 20thDay
10%6%26%43446%8%48%
2124
21st to endDay
12%7%26%5%345%6%7%43%
1900
October1st to 10thDay
16%6%35%4345%47%43%
1800
11th to 20thDay
16%8%35%43445%6%42%
1800
21st to endDay
17%11%47%5%2345%5%38%
1980
November1st to 10thDay
11%10%35%5%345%5%8%42%
1612
11th to 20thDay
12%10%7%11%7%35%446%31%
1520
21st to endDay
13%11%5%6%7%3345%8%36%
1520
December1st to 10thDay
12%10%411%10%5%6%5%6%6%25%
1520
11th to 20thDay
11%12%6%11%8%46%6%5%6%26%
1918
21st to endDay
19%15%7%16%6%34445%17%
2783
January1st to 10thNight
8%8%410%9%5%7%6%6%7%30%
2647
11th to 20thNight
10%11%5%11%9%47%5%6%8%23%
2443
21st to endNight
13%13%5%10%9%46%5%6%7%24%
2574
February1st to 10thNight
8%12%6%10%8%5%5%5%6%6%30%
2340
11th to 20thNight
8%10%47%6%45%5%7%7%37%
2273
21st to endNight
13%8%48%8%45%5%5%6%34%
1857
March1st to 10thNight
13%9%46%6%4345%7%38%
2020
11th to 20thNight
15%9%46%5%3445%7%37%
1980
21st to endNight
18%11%46%6%3445%7%31%
2169
April1st to 10thNight
14%11%46%6%35%445%38%
1800
11th to 20thNight
18%10%36%43445%6%36%
1775
21st to endNight
19%8%36%6%33446%37%
1634
May1st to 10thNight
17%6%36%5%35%35%7%40%
1574
11th to 20thNight
15%7%35%5%245%5%7%43%
1416
21st to endNight
16%6%36%4245%6%9%40%
1551
June1st to 10thNight
8%424425%5%7%9%50%
1440
11th to 20thNight
10%5%25%5%345%5%8%47%
1440
21st to endNight
10%42432345%9%54%
1440
July1st to 10thNight
5%32442345%10%58%
1440
11th to 20thNight
33234245%6%9%60%
1440
21st to endNight
431342346%8%61%
1671
August1st to 10thNight
6%3345%345%6%9%51%
1611
11th to 20thNight
10%42443445%9%52%
1600
21st to endNight
6%425%424446%60%
1908
September1st to 10thNight
9%41433345%7%57%
1800
11th to 20thNight
11%425%324347%54%
1834
21st to endNight
10%6%35%32335%6%53%
2042
October1st to 10thNight
13%7%25%433446%48%
2160
11th to 20thNight
15%8%246%34446%44%
2160
21st to endNight
16%9%47%5%34345%40%
2376
November1st to 10thNight
12%8%35%43445%6%46%
2464
11th to 20thNight
11%9%5%10%6%45%45%6%36%
2660
21st to endNight
13%10%46%6%34446%40%
2660
December1st to 10thNight
10%10%5%9%8%5%6%5%5%7%30%
2660
11th to 20thNight
12%10%49%8%5%6%5%5%6%28%
3279
21st to endNight
20%15%6%14%8%34445%18%
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
58%6%12%16%8%
1510
11th to 20thDay
63%6%10%13%8%
1516
21st to endDay
63%7%13%10%6%1
1782
February1st to 10thDay
58%7%13%14%8%1
1620
11th to 20thDay
54%6%12%19%7%2
1583
21st to endDay
56%5%11%17%10%1
1399
March1st to 10thDay
54%7%14%17%7%1
1956
11th to 20thDay
51%7%12%21%8%1
1980
21st to endDay
55%7%12%18%6%1
2186
April1st to 10thDay
54%6%13%18%8%1
2160
11th to 20thDay
51%6%12%17%12%1
2134
21st to endDay
55%7%12%18%8%1
2323
May1st to 10thDay
51%7%16%18%7%1
2384
11th to 20thDay
46%10%13%21%10%1
2483
21st to endDay
46%8%12%20%12%1
2725
June1st to 10thDay
35%8%15%28%13%1
2520
11th to 20thDay
37%9%15%20%18%1
2520
21st to endDay
37%9%18%24%11%1
2520
July1st to 10thDay
30%8%17%31%12%1
2451
11th to 20thDay
31%7%16%25%18%3
2445
21st to endDay
29%8%18%29%14%2
2497
August1st to 10thDay
37%9%14%27%10%3
2314
11th to 20thDay
37%10%14%27%11%1
2301
21st to endDay
31%7%14%28%18%1
2447
September1st to 10thDay
36%8%12%29%15%1
2160
11th to 20thDay
34%7%16%31%12%
2124
21st to endDay
39%7%12%28%14%1
1900
October1st to 10thDay
40%6%12%26%14%1
1800
11th to 20thDay
42%7%13%23%14%2
1800
21st to endDay
48%6%12%22%12%
1980
November1st to 10thDay
40%8%13%21%15%3
1612
11th to 20thDay
54%5%12%18%10%1
1520
21st to endDay
48%5%17%21%9%1
1520
December1st to 10thDay
57%8%15%11%8%1
1520
11th to 20thDay
57%6%17%13%6%
1915
21st to endDay
69%6%10%11%41
2783
January1st to 10thNight
53%6%13%18%10%1
2647
11th to 20thNight
58%6%14%14%8%
2443
21st to endNight
58%7%11%15%8%1
2574
February1st to 10thNight
54%6%11%20%9%1
2340
11th to 20thNight
45%6%14%22%10%2
2274
21st to endNight
49%6%11%19%12%2
1857
March1st to 10thNight
45%7%15%24%7%1
2020
11th to 20thNight
46%6%12%23%12%1
1980
21st to endNight
52%7%13%18%8%2
2169
April1st to 10thNight
48%6%11%21%14%1
1800
11th to 20thNight
47%6%12%18%15%2
1775
21st to endNight
47%6%10%22%13%2
1634
May1st to 10thNight
43%7%13%23%13%1
1574
11th to 20thNight
39%8%15%23%13%2
1417
21st to endNight
41%7%14%21%16%1
1552
June1st to 10thNight
30%9%14%30%15%2
1440
11th to 20thNight
34%8%14%22%18%3
1440
21st to endNight
26%7%18%30%17%3
1440
July1st to 10thNight
23%7%15%35%19%2
1400
11th to 20thNight
21%8%19%29%19%3
1392
21st to endNight
20%7%17%34%19%3
1578
August1st to 10thNight
28%8%16%29%17%3
1601
11th to 20thNight
30%8%16%28%18%2
1600
21st to endNight
26%7%14%29%20%4
1908
September1st to 10thNight
27%6%13%30%23%2
1800
11th to 20thNight
30%7%15%30%18%1
1834
21st to endNight
32%6%12%29%19%1
2042
October1st to 10thNight
37%6%10%27%17%2
2160
11th to 20thNight
39%6%13%24%16%2
2160
21st to endNight
47%5%11%23%13%1
2376
November1st to 10thNight
38%6%14%23%16%3
2464
11th to 20thNight
49%6%12%20%12%1
2660
21st to endNight
46%5%14%24%10%1
2660
December1st to 10thNight
53%7%15%17%7%1
2660
11th to 20thNight
54%6%15%18%5%
3281
21st to endNight
68%6%10%12%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
16%16%36%21%9%3
267
11th to 20thDay
20%9%43%22%5%1
240
21st to endDay
15%12%42%24%5%2
264
February1st to 10thDay
11%17%45%23%4
240
11th to 20thDay
18%14%39%23%5%1
240
21st to endDay
24%15%36%22%2
198
March1st to 10thDay
17%17%39%22%6%
240
11th to 20thDay
23%7%36%25%7%2
240
21st to endDay
31%11%30%19%8%1
272
April1st to 10thDay
28%12%33%21%5%
420
11th to 20thDay
27%13%26%24%9%1
412
21st to endDay
27%15%25%21%9%2
583
May1st to 10thDay
20%13%35%24%6%1
603
11th to 20thDay
23%12%27%24%11%4
625
21st to endDay
21%7%29%25%14%4
679
June1st to 10thDay
11%6%27%30%21%6%
630
11th to 20thDay
13%6%32%32%14%3
630
21st to endDay
12%7%31%29%16%5%
630
July1st to 10thDay
7%419%36%24%10%
621
11th to 20thDay
9%5%29%32%19%6%
618
21st to endDay
7%426%37%20%6%
684
August1st to 10thDay
10%420%32%27%7%
626
11th to 20thDay
13%5%21%31%25%6%
615
21st to endDay
12%5%24%36%17%6%
566
September1st to 10thDay
16%6%28%31%14%5%
450
11th to 20thDay
11%5%32%33%15%4
414
21st to endDay
19%10%31%25%11%4
270
October1st to 10thDay
21%11%26%27%12%3
270
11th to 20thDay
19%18%37%19%7%1
270
21st to endDay
25%18%33%17%6%1
297
November1st to 10thDay
16%18%34%24%6%2
270
11th to 20thDay
16%24%39%16%6%
270
21st to endDay
21%14%41%21%2
270
December1st to 10thDay
15%12%40%27%6%1
270
11th to 20thDay
16%15%40%23%6%1
270
21st to endDay
27%17%33%20%2
297
January1st to 10thNight
12%13%43%24%8%
950
11th to 20thNight
16%12%38%28%5%1
900
21st to endNight
19%14%36%24%6%
990
February1st to 10thNight
15%13%41%25%5%1
900
11th to 20thNight
14%15%42%23%6%1
879
21st to endNight
18%15%36%24%7%1
673
March1st to 10thNight
17%13%37%25%7%1
580
11th to 20thNight
19%9%38%26%8%
540
21st to endNight
23%10%33%24%7%2
594
April1st to 10thNight
18%16%36%27%4
540
11th to 20thNight
24%13%32%24%7%1
533
21st to endNight
23%10%32%25%8%2
540
May1st to 10thNight
18%11%32%30%8%1
540
11th to 20thNight
17%10%32%31%8%2
531
21st to endNight
19%7%27%32%14%1
584
June1st to 10thNight
9%5%29%41%15%1
540
11th to 20thNight
12%5%31%40%12%
540
21st to endNight
11%425%43%15%1
540
July1st to 10thNight
7%220%38%32%2
525
11th to 20thNight
4325%41%25%2
522
21st to endNight
5%220%50%21%3
591
August1st to 10thNight
7%217%46%25%3
537
11th to 20thNight
10%318%40%26%4
534
21st to endNight
7%226%41%22%3
594
September1st to 10thNight
11%426%38%18%3
540
11th to 20thNight
11%5%31%35%16%2
540
21st to endNight
12%9%35%30%13%1
602
October1st to 10thNight
16%9%31%29%13%1
720
11th to 20thNight
19%13%33%28%7%
720
21st to endNight
22%13%30%27%8%
792
November1st to 10thNight
16%13%38%27%6%1
816
11th to 20thNight
16%15%42%22%5%
950
21st to endNight
18%14%38%23%7%
950
December1st to 10thNight
15%13%39%26%7%
950
11th to 20thNight
20%11%40%23%6%
950
21st to endNight
24%13%37%22%4
1045
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