Altoona
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Altoona 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
33%
23250
15%
74770
9%
23199
40%
23199
18%
51046

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
13%
757
14%
2591
4%
757
25%
757
10%
1842
January11th to 20thNight
15%
720
10%
2340
2%
720
24%
720
10%
1784
January21st to endNight
14%
792
12%
2574
4%
792
23%
792
10%
1915
February1st to 10thNight
15%
720
12%
2340
5%
720
24%
720
11%
1706
February11th to 20thNight
12%
703
12%
2275
3%
700
23%
700
10%
1644
February21st to endNight
15%
592
15%
1792
4%
592
28%
592
11%
1343
March1st to 10thNight
21%
720
18%
1980
7%
720
33%
720
19%
1330
March11th to 20thNight
21%
720
18%
1980
8%
720
30%
720
15%
1388
March21st to endNight
21%
792
17%
2178
6%
792
29%
792
18%
1520
April1st to 10thNight
20%
720
13%
1811
3%
720
26%
720
17%
1352
April11th to 20thNight
33%
711
16%
1775
7%
711
37%
711
24%
1227
April21st to endNight
31%
640
18%
1720
7%
640
37%
640
21%
1191
May1st to 10thNight
37%
540
15%
1620
8%
540
42%
540
18%
1143
May11th to 20thNight
39%
440
15%
1502
11%
440
45%
440
18%
1006
May21st to endNight
51%
388
17%
1551
15%
388
57%
388
21%
930
June1st to 10thNight
50%
360
17%
1440
17%
360
58%
360
22%
851
June11th to 20thNight
47%
360
14%
1440
15%
360
53%
360
20%
889
June21st to endNight
53%
360
16%
1440
17%
360
59%
360
25%
815
July1st to 10thNight
59%
350
15%
1400
17%
350
63%
350
22%
838
July11th to 20thNight
66%
429
18%
1473
19%
429
68%
429
33%
827
July21st to endNight
55%
591
16%
1672
12%
558
59%
558
28%
1062
August1st to 10thNight
62%
537
16%
1600
12%
534
65%
534
31%
986
August11th to 20thNight
61%
534
19%
1598
14%
534
64%
534
30%
1005
August21st to endNight
57%
774
19%
1962
11%
774
59%
774
32%
1286
September1st to 10thNight
53%
720
21%
1800
11%
720
57%
720
30%
1228
September11th to 20thNight
58%
720
27%
1848
18%
720
62%
720
38%
1127
September21st to endNight
45%
720
20%
2052
16%
720
51%
720
26%
1344
October1st to 10thNight
44%
720
16%
2160
14%
720
48%
720
24%
1400
October11th to 20thNight
34%
720
18%
2160
12%
720
44%
720
23%
1415
October21st to endNight
29%
792
20%
2376
11%
792
40%
792
19%
1611
November1st to 10thNight
37%
740
22%
2285
15%
740
48%
740
26%
1427
November11th to 20thNight
26%
760
17%
2626
11%
760
36%
760
16%
1748
November21st to endNight
25%
760
15%
2660
10%
760
34%
760
14%
1818
December1st to 10thNight
18%
760
8%
2660
4%
760
23%
760
10%
1989
December11th to 20thNight
20%
760
11%
3225
5%
759
28%
759
9%
2308
December21st to endNight
20%
828
7%
4864
6%
817
27%
817
5%
3751

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%8%47%6%45%5%6%7%32%
74628
Night
14%8%36%6%35%5%6%8%36%
75044
TransparencyDay
49%7%13%19%11%1
74338
Night
46%7%14%20%11%2
74853
SeeingDay
23%17%27%20%10%3
13623
Night
20%14%27%27%11%1
23262

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
11%11%6%11%8%45%5%6%6%27%
1560
11th to 20thDay
13%13%6%14%8%35%5%5%6%21%
1620
21st to endDay
12%15%7%12%10%46%5%45%21%
1782
February1st to 10thDay
14%15%5%10%8%46%45%6%23%
1620
11th to 20thDay
14%9%5%10%9%45%5%6%8%24%
1573
21st to endDay
16%10%6%10%7%445%46%28%
1461
March1st to 10thDay
12%8%38%7%46%6%5%6%34%
1980
11th to 20thDay
17%9%39%7%45%5%5%7%29%
1980
21st to endDay
18%10%47%6%4445%8%30%
2178
April1st to 10thDay
13%10%5%8%6%45%46%8%32%
2147
11th to 20thDay
14%10%37%7%35%5%5%6%34%
2134
21st to endDay
20%9%37%5%345%5%6%33%
2255
May1st to 10thDay
17%9%36%6%46%6%6%7%29%
2340
11th to 20thDay
20%7%46%5%5%5%5%6%7%32%
2388
21st to endDay
13%6%36%5%36%5%6%9%37%
2725
June1st to 10thDay
14%6%36%6%46%6%7%8%35%
2520
11th to 20thDay
12%7%36%7%47%6%7%9%33%
2520
21st to endDay
12%5%26%7%45%5%6%10%38%
2520
July1st to 10thDay
9%6%36%7%47%6%7%8%37%
2520
11th to 20thDay
8%6%35%6%46%7%8%8%39%
2434
21st to endDay
10%7%37%8%5%6%6%7%9%34%
2547
August1st to 10thDay
9%6%26%6%5%8%8%7%10%31%
2327
11th to 20thDay
13%6%27%6%46%7%7%8%34%
2303
21st to endDay
12%7%26%6%36%5%8%9%35%
2376
September1st to 10thDay
17%6%245%45%447%41%
2160
11th to 20thDay
14%5%24435%47%7%44%
2108
21st to endDay
18%8%25%5%35%5%6%7%35%
1908
October1st to 10thDay
15%8%27%7%445%6%6%36%
1800
11th to 20thDay
17%8%36%5%35%5%5%7%35%
1800
21st to endDay
17%9%46%5%345%5%7%34%
1980
November1st to 10thDay
11%6%46%5%345%6%7%42%
1791
11th to 20thDay
15%7%47%7%45%6%5%8%32%
1549
21st to endDay
14%10%5%7%7%47%6%5%6%29%
1520
December1st to 10thDay
16%12%6%9%8%46%6%5%7%21%
1520
11th to 20thDay
15%13%5%8%7%35%46%7%26%
1910
21st to endDay
20%16%7%10%8%45%45%5%16%
2772
January1st to 10thNight
12%9%5%8%8%36%6%6%9%28%
2591
11th to 20thNight
15%11%6%9%8%46%5%6%6%24%
2340
21st to endNight
12%10%410%8%46%6%7%6%26%
2574
February1st to 10thNight
15%9%5%9%6%46%5%6%8%29%
2340
11th to 20thNight
13%10%38%8%46%6%7%8%27%
2273
21st to endNight
15%11%48%7%45%6%5%5%28%
1792
March1st to 10thNight
11%7%35%6%45%6%7%8%38%
1980
11th to 20thNight
16%7%46%6%345%47%38%
1980
21st to endNight
15%9%46%5%34447%38%
2178
April1st to 10thNight
14%10%37%7%35%46%7%33%
1811
11th to 20thNight
13%7%35%5%46%5%6%8%39%
1775
21st to endNight
18%6%26%5%3445%8%38%
1720
May1st to 10thNight
16%8%36%6%36%5%5%8%34%
1620
11th to 20thNight
19%6%35%5%35%46%7%38%
1501
21st to endNight
11%6%35%5%25%5%6%10%42%
1550
June1st to 10thNight
11%5%35%6%35%46%9%44%
1440
11th to 20thNight
10%5%26%5%35%7%6%9%40%
1440
21st to endNight
9%425%436%6%6%10%46%
1440
July1st to 10thNight
9%5%35%5%36%6%6%9%45%
1440
11th to 20thNight
6%3244345%6%9%52%
1521
21st to endNight
7%5%26%5%46%6%8%10%40%
1771
August1st to 10thNight
6%5%25%5%35%5%7%11%45%
1611
11th to 20thNight
9%6%25%5%246%6%8%46%
1598
21st to endNight
12%5%345%345%7%8%45%
1962
September1st to 10thNight
15%6%245%345%5%5%45%
1800
11th to 20thNight
11%5%233335%5%9%51%
1848
21st to endNight
16%6%25%4345%5%7%43%
2052
October1st to 10thNight
15%7%35%5%345%48%43%
2160
11th to 20thNight
17%6%25%5%345%5%7%41%
2160
21st to endNight
19%9%25%435%45%7%37%
2376
November1st to 10thNight
9%6%36%6%3445%7%47%
2285
11th to 20thNight
14%7%46%6%36%5%6%7%35%
2626
21st to endNight
14%8%46%7%36%5%6%8%33%
2660
December1st to 10thNight
16%9%5%8%8%47%5%7%7%23%
2660
11th to 20thNight
15%8%49%7%5%6%6%6%7%28%
3285
21st to endNight
18%12%6%9%9%46%5%5%7%19%
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
55%7%14%17%6%1
1561
11th to 20thDay
63%6%13%13%5%
1620
21st to endDay
65%5%11%12%6%1
1782
February1st to 10thDay
62%5%14%12%6%1
1620
11th to 20thDay
57%7%13%16%6%
1582
21st to endDay
57%5%13%15%7%3
1461
March1st to 10thDay
50%6%14%21%8%1
1980
11th to 20thDay
54%6%11%18%8%2
1980
21st to endDay
53%5%11%19%10%2
2178
April1st to 10thDay
51%7%11%17%12%2
2147
11th to 20thDay
49%6%10%16%15%3
2134
21st to endDay
51%6%10%20%11%2
2255
May1st to 10thDay
52%8%10%18%11%1
2340
11th to 20thDay
51%7%12%15%13%2
2392
21st to endDay
43%9%17%20%10%2
2725
June1st to 10thDay
45%8%12%21%13%1
2520
11th to 20thDay
45%9%14%18%12%1
2520
21st to endDay
40%9%14%25%12%
2520
July1st to 10thDay
43%10%12%19%12%3
2450
11th to 20thDay
37%10%15%22%15%1
2359
21st to endDay
44%8%12%20%14%2
2405
August1st to 10thDay
42%11%17%20%9%
2314
11th to 20thDay
44%10%12%22%11%1
2303
21st to endDay
41%8%14%21%12%3
2376
September1st to 10thDay
43%8%11%20%15%4
2160
11th to 20thDay
37%5%12%27%17%2
2108
21st to endDay
46%7%13%18%15%1
1908
October1st to 10thDay
46%7%12%20%13%2
1800
11th to 20thDay
47%7%12%24%10%
1800
21st to endDay
48%7%14%19%11%1
1980
November1st to 10thDay
39%6%16%19%15%4
1791
11th to 20thDay
50%5%14%18%10%2
1549
21st to endDay
54%6%13%20%7%
1520
December1st to 10thDay
62%8%15%12%4
1520
11th to 20thDay
57%5%13%21%4
1906
21st to endDay
68%6%11%11%3
2772
January1st to 10thNight
53%6%15%18%7%1
2591
11th to 20thNight
60%6%14%14%5%1
2340
21st to endNight
56%7%14%16%7%1
2574
February1st to 10thNight
54%7%14%18%7%
2340
11th to 20thNight
54%7%13%18%9%
2275
21st to endNight
55%7%10%16%10%2
1792
March1st to 10thNight
41%7%15%23%12%1
1980
11th to 20thNight
47%6%13%21%11%2
1980
21st to endNight
48%5%12%18%14%3
2178
April1st to 10thNight
51%7%11%17%13%1
1811
11th to 20thNight
42%6%13%21%15%2
1775
21st to endNight
45%6%11%23%12%3
1720
May1st to 10thNight
47%8%10%20%11%4
1620
11th to 20thNight
46%8%13%17%14%2
1502
21st to endNight
36%10%16%24%12%2
1551
June1st to 10thNight
37%8%13%27%14%2
1440
11th to 20thNight
38%10%15%22%13%2
1440
21st to endNight
32%10%17%26%14%1
1440
July1st to 10thNight
36%11%14%22%15%3
1400
11th to 20thNight
29%8%17%25%19%2
1473
21st to endNight
34%12%17%20%15%2
1672
August1st to 10thNight
31%11%19%25%13%1
1600
11th to 20thNight
34%9%17%24%15%1
1598
21st to endNight
36%8%14%25%14%3
1962
September1st to 10thNight
41%6%11%22%17%3
1800
11th to 20thNight
31%6%14%28%19%2
1848
21st to endNight
41%6%12%23%17%1
2052
October1st to 10thNight
40%8%14%23%14%1
2160
11th to 20thNight
41%6%13%25%13%1
2160
21st to endNight
46%6%12%22%13%1
2376
November1st to 10thNight
38%6%14%21%17%3
2285
11th to 20thNight
46%7%13%21%11%3
2626
21st to endNight
49%6%15%20%8%1
2660
December1st to 10thNight
57%8%17%13%4
2660
11th to 20thNight
54%7%13%20%5%
3288
21st to endNight
64%7%15%12%3
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
32%29%26%10%2
201
11th to 20thDay
35%25%31%8%1
240
21st to endDay
28%30%33%6%3
264
February1st to 10thDay
35%31%26%7%1
240
11th to 20thDay
42%27%29%3
240
21st to endDay
38%26%25%11%
306
March1st to 10thDay
32%21%28%17%2
420
11th to 20thDay
31%24%27%13%41
420
21st to endDay
30%24%27%14%5%1
462
April1st to 10thDay
29%24%26%15%5%1
420
11th to 20thDay
26%17%26%18%9%3
412
21st to endDay
32%21%26%14%6%1
420
May1st to 10thDay
30%19%26%14%7%3
423
11th to 20thDay
26%17%30%16%9%3
447
21st to endDay
18%15%26%22%14%5%
485
June1st to 10thDay
18%17%29%22%12%2
450
11th to 20thDay
20%14%27%25%11%3
450
21st to endDay
14%13%31%27%13%2
450
July1st to 10thDay
11%8%29%27%18%9%
445
11th to 20thDay
6%9%30%32%16%7%
444
21st to endDay
12%10%29%28%16%5%
488
August1st to 10thDay
11%8%26%28%19%8%
446
11th to 20thDay
14%7%26%25%18%10%
439
21st to endDay
15%9%24%28%14%11%
495
September1st to 10thDay
20%8%20%26%18%9%
450
11th to 20thDay
16%6%22%28%20%8%
450
21st to endDay
24%15%23%19%13%6%
450
October1st to 10thDay
21%13%20%25%17%4
450
11th to 20thDay
26%17%26%22%8%1
450
21st to endDay
23%22%29%19%7%
495
November1st to 10thDay
21%15%29%20%13%2
424
11th to 20thDay
29%23%29%15%4
209
21st to endDay
27%26%33%11%3
180
December1st to 10thDay
32%32%23%9%31
180
11th to 20thDay
35%21%31%12%1
180
21st to endDay
32%23%26%16%3
198
January1st to 10thNight
24%24%35%15%2
760
11th to 20thNight
29%18%32%19%3
720
21st to endNight
21%24%33%19%2
792
February1st to 10thNight
28%20%31%19%3
720
11th to 20thNight
25%26%34%14%1
703
21st to endNight
27%20%33%18%2
592
March1st to 10thNight
24%21%32%22%2
720
11th to 20thNight
28%20%27%19%6%1
720
21st to endNight
21%20%33%20%5%
792
April1st to 10thNight
25%23%29%18%4
720
11th to 20thNight
20%17%27%28%7%1
711
21st to endNight
23%14%26%31%7%
640
May1st to 10thNight
22%12%24%31%11%1
540
11th to 20thNight
20%10%26%35%10%
440
21st to endNight
12%9%22%37%18%2
389
June1st to 10thNight
12%7%25%39%16%1
360
11th to 20thNight
13%7%26%37%17%1
360
21st to endNight
10%5%28%42%16%
360
July1st to 10thNight
10%318%43%22%3
350
11th to 20thNight
7%317%40%30%2
429
21st to endNight
9%422%41%23%1
591
August1st to 10thNight
8%218%42%29%1
537
11th to 20thNight
11%5%16%38%27%3
534
21st to endNight
14%318%37%24%3
774
September1st to 10thNight
18%417%35%23%3
720
11th to 20thNight
13%6%17%32%28%4
720
21st to endNight
20%7%22%29%19%4
720
October1st to 10thNight
18%8%23%31%18%2
720
11th to 20thNight
21%13%29%27%9%1
720
21st to endNight
26%16%26%26%7%1
792
November1st to 10thNight
15%13%31%31%10%1
740
11th to 20thNight
24%19%26%24%6%1
760
21st to endNight
23%20%28%24%5%1
760
December1st to 10thNight
27%19%31%19%4
760
11th to 20thNight
24%20%31%22%2
760
21st to endNight
23%22%29%25%1
836
Page generated at 2024-01-07 10:06:53. Version ac07

Copyright 2024 Attilla Danko


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