Waldo Lake
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Waldo Lake clear sky chart from 2005-11-06 to 2024-03-06.

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
43%
22979
15%
80695
15%
22877
47%
22877
18%
56105

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
23%
755
5%
4396
5%
736
27%
736
5%
3607
January11th to 20thNight
33%
756
9%
4405
11%
740
38%
740
8%
3407
January21st to endNight
33%
836
10%
4538
14%
814
40%
814
8%
3670
February1st to 10thNight
29%
760
10%
2470
7%
760
33%
760
12%
1906
February11th to 20thNight
30%
743
10%
2404
8%
740
35%
740
12%
1857
February21st to endNight
25%
628
12%
1906
8%
628
30%
628
11%
1503
March1st to 10thNight
27%
742
9%
2158
7%
742
30%
742
11%
1727
March11th to 20thNight
35%
720
11%
1980
9%
720
37%
720
15%
1545
March21st to endNight
27%
792
6%
2113
4%
792
27%
792
11%
1775
April1st to 10thNight
30%
720
10%
1800
5%
720
32%
720
13%
1477
April11th to 20thNight
31%
711
12%
1779
5%
711
34%
711
16%
1420
April21st to endNight
34%
630
9%
1710
5%
630
36%
630
16%
1336
May1st to 10thNight
41%
415
15%
1495
13%
415
45%
415
19%
996
May11th to 20thNight
45%
354
14%
1416
16%
354
47%
354
14%
976
May21st to endNight
44%
389
10%
1552
14%
388
47%
388
13%
1089
June1st to 10thNight
53%
360
10%
1440
15%
360
54%
360
16%
958
June11th to 20thNight
51%
360
13%
1440
19%
360
54%
360
21%
868
June21st to endNight
67%
360
21%
1440
34%
360
70%
360
35%
693
July1st to 10thNight
76%
350
22%
1400
36%
350
79%
350
46%
577
July11th to 20thNight
77%
348
32%
1392
45%
348
83%
348
55%
521
July21st to endNight
84%
397
37%
1491
49%
375
87%
375
65%
498
August1st to 10thNight
83%
537
32%
1602
30%
534
83%
534
59%
711
August11th to 20thNight
81%
534
35%
1602
28%
534
84%
534
60%
721
August21st to endNight
70%
778
37%
1966
23%
778
72%
778
63%
992
September1st to 10thNight
70%
720
36%
1800
22%
720
72%
720
65%
892
September11th to 20thNight
65%
720
31%
1800
21%
720
67%
720
44%
1073
September21st to endNight
60%
720
26%
2046
24%
720
62%
720
36%
1211
October1st to 10thNight
50%
720
18%
2160
16%
720
57%
720
31%
1316
October11th to 20thNight
53%
720
22%
2160
22%
720
57%
720
28%
1379
October21st to endNight
41%
792
19%
2412
17%
792
45%
792
20%
1671
November1st to 10thNight
34%
740
14%
2409
14%
740
36%
740
14%
1829
November11th to 20thNight
32%
760
10%
2660
9%
760
36%
760
12%
2026
November21st to endNight
34%
760
11%
2660
10%
760
38%
760
15%
1887
December1st to 10thNight
36%
760
12%
2660
9%
760
40%
760
15%
1913
December11th to 20thNight
29%
759
10%
3213
8%
759
32%
759
8%
2567
December21st to endNight
21%
833
7%
4820
9%
817
26%
817
6%
3511

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
9%14%5%7%5%34445%40%
78523
Night
8%15%6%9%6%3445%5%34%
81021
TransparencyDay
44%7%10%18%15%6%
78227
Night
48%8%10%15%14%5%
80838
SeeingDay
19%18%27%22%12%2
13785
Night
15%15%20%31%17%2
22993

By Month

Percentage Cloud Cover SW (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
7%22%11%16%9%45%34416%
2539
11th to 20thDay
14%20%9%12%6%3333422%
2540
21st to endDay
15%24%6%8%6%35%445%21%
3114
February1st to 10thDay
9%19%7%10%6%45%5%6%6%22%
1710
11th to 20thDay
9%18%9%11%6%3435%5%25%
1665
21st to endDay
7%21%11%11%7%345%45%21%
1546
March1st to 10thDay
8%19%10%12%7%46%45%422%
1913
11th to 20thDay
8%22%7%9%6%35%447%24%
1980
21st to endDay
11%26%9%10%6%34446%18%
2242
April1st to 10thDay
11%23%9%10%7%445%4419%
2160
11th to 20thDay
10%19%7%8%7%3445%5%27%
2129
21st to endDay
7%20%5%7%6%4445%7%31%
2245
May1st to 10thDay
11%15%46%5%2445%6%38%
2463
11th to 20thDay
13%14%5%8%5%345%5%6%32%
2477
21st to endDay
16%16%46%6%34447%30%
2723
June1st to 10thDay
15%13%46%6%3445%6%36%
2520
11th to 20thDay
9%14%36%6%345%46%41%
2520
21st to endDay
7%5%23323446%63%
2520
July1st to 10thDay
321332333474%
2520
11th to 20thDay
431332323473%
2520
21st to endDay
221221223379%
2736
August1st to 10thDay
321222345%6%71%
2328
11th to 20thDay
3312323335%72%
2298
21st to endDay
4312212336%73%
2389
September1st to 10thDay
3312323335%72%
2160
11th to 20thDay
7%6%35%5%34446%55%
2160
21st to endDay
8%7%245%3445%5%52%
1910
October1st to 10thDay
10%12%26%42434448%
1800
11th to 20thDay
12%11%445%345%5%6%42%
1800
21st to endDay
11%11%47%6%3446%6%39%
1944
November1st to 10thDay
14%19%5%8%6%4445%5%26%
1670
11th to 20thDay
12%19%5%8%6%46%45%7%25%
1520
21st to endDay
9%18%7%8%7%5%445%5%29%
1520
December1st to 10thDay
9%16%6%8%6%345%6%5%31%
1520
11th to 20thDay
12%18%7%9%7%45%6%6%7%19%
1928
21st to endDay
10%20%8%12%7%46%5%5%6%18%
2794
January1st to 10thNight
8%24%10%15%8%445%5%413%
4406
11th to 20thNight
9%21%10%14%7%3445%5%19%
4420
21st to endNight
16%22%7%10%7%3444420%
4551
February1st to 10thNight
7%16%8%10%8%5%6%5%6%6%23%
2470
11th to 20thNight
8%15%9%11%7%46%5%45%25%
2402
21st to endNight
6%18%8%13%8%5%45%45%23%
1906
March1st to 10thNight
7%18%8%12%8%5%6%5%5%5%20%
2158
11th to 20thNight
7%20%7%8%7%46%5%6%6%23%
1980
21st to endNight
8%22%9%13%7%5%5%5%5%5%17%
2113
April1st to 10thNight
10%21%9%11%7%34445%22%
1800
11th to 20thNight
9%17%8%11%6%35%36%5%26%
1779
21st to endNight
9%19%7%9%7%345%5%6%26%
1710
May1st to 10thNight
10%15%6%6%5%336%5%5%37%
1495
11th to 20thNight
9%12%6%7%7%46%6%5%8%30%
1416
21st to endNight
12%15%5%8%5%45%5%7%8%28%
1552
June1st to 10thNight
13%14%46%5%35%45%6%35%
1440
11th to 20thNight
7%13%5%6%5%245%5%7%41%
1440
21st to endNight
6%424424347%60%
1440
July1st to 10thNight
3323323345%68%
1440
11th to 20thNight
221321333475%
1440
21st to endNight
1212212335%79%
1579
August1st to 10thNight
1214322347%71%
1611
11th to 20thNight
3413213245%72%
1602
21st to endNight
221332334472%
1966
September1st to 10thNight
3313212245%73%
1800
11th to 20thNight
5%6%25%5%345%46%56%
1800
21st to endNight
8%7%35%5%3445%6%51%
2046
October1st to 10thNight
7%10%36%5%34346%50%
2160
11th to 20thNight
11%10%45%5%24446%46%
2160
21st to endNight
10%14%48%7%35%435%39%
2412
November1st to 10thNight
12%18%6%10%7%335%5%6%25%
2409
11th to 20thNight
12%18%6%8%7%45%5%5%5%25%
2660
21st to endNight
7%15%6%10%7%45%5%5%6%30%
2660
December1st to 10thNight
10%13%6%9%7%35%5%6%6%29%
2660
11th to 20thNight
10%21%7%11%7%45%5%5%6%19%
3276
21st to endNight
9%18%7%11%8%45%6%5%5%22%
4862

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
63%13%11%9%41
2539
11th to 20thDay
63%8%8%12%5%4
2540
21st to endDay
62%10%8%12%7%2
3114
February1st to 10thDay
59%8%11%14%8%1
1710
11th to 20thDay
58%8%9%13%8%3
1674
21st to endDay
63%8%10%11%7%2
1546
March1st to 10thDay
62%9%10%12%7%1
1913
11th to 20thDay
57%8%10%16%7%1
1980
21st to endDay
66%8%11%11%4
2242
April1st to 10thDay
65%8%9%10%7%1
2160
11th to 20thDay
56%8%12%12%9%3
2132
21st to endDay
50%9%13%16%10%1
2245
May1st to 10thDay
43%8%14%23%12%
2463
11th to 20thDay
50%7%13%21%8%1
2480
21st to endDay
51%8%15%18%7%
2724
June1st to 10thDay
47%7%15%22%9%
2520
11th to 20thDay
39%8%14%26%11%2
2520
21st to endDay
23%5%11%32%22%7%
2520
July1st to 10thDay
15%410%23%28%20%
2451
11th to 20thDay
16%37%17%33%25%
2445
21st to endDay
11%3417%41%24%
2584
August1st to 10thDay
13%410%31%27%14%
2312
11th to 20thDay
15%38%25%35%14%
2298
21st to endDay
13%37%26%38%13%
2389
September1st to 10thDay
16%36%24%32%19%
2160
11th to 20thDay
30%410%23%23%10%
2160
21st to endDay
32%5%10%23%21%10%
1910
October1st to 10thDay
39%5%8%16%22%9%
1800
11th to 20thDay
40%6%12%16%21%5%
1800
21st to endDay
43%9%11%13%20%5%
1944
November1st to 10thDay
57%7%9%13%12%2
1670
11th to 20thDay
57%8%10%12%9%3
1520
21st to endDay
55%6%8%12%13%5%
1520
December1st to 10thDay
51%9%9%18%10%2
1520
11th to 20thDay
60%9%11%11%8%1
1928
21st to endDay
61%10%11%11%5%2
2794
January1st to 10thNight
62%15%10%7%41
4406
11th to 20thNight
62%8%8%11%5%5%
4420
21st to endNight
66%8%7%8%8%2
4551
February1st to 10thNight
56%11%11%12%9%1
2470
11th to 20thNight
58%9%9%12%8%3
2404
21st to endNight
60%9%8%12%9%2
1906
March1st to 10thNight
61%9%9%12%7%1
2158
11th to 20thNight
57%9%11%16%7%
1980
21st to endNight
65%9%10%12%4
2113
April1st to 10thNight
61%9%11%11%8%
1800
11th to 20thNight
57%9%11%12%8%3
1779
21st to endNight
54%11%12%14%8%1
1710
May1st to 10thNight
45%8%13%23%10%1
1495
11th to 20thNight
47%11%12%19%8%1
1416
21st to endNight
50%11%14%19%6%
1552
June1st to 10thNight
47%8%12%24%8%
1440
11th to 20thNight
39%8%14%27%10%2
1440
21st to endNight
25%6%11%30%21%7%
1440
July1st to 10thNight
16%6%11%21%28%18%
1400
11th to 20thNight
13%47%20%32%24%
1392
21st to endNight
9%26%17%45%21%
1491
August1st to 10thNight
14%39%30%32%12%
1602
11th to 20thNight
14%37%26%36%12%
1602
21st to endNight
14%48%25%35%13%
1966
September1st to 10thNight
14%38%23%34%19%
1800
11th to 20thNight
27%6%9%20%27%12%
1800
21st to endNight
32%6%10%20%20%13%
2046
October1st to 10thNight
36%5%9%17%23%10%
2160
11th to 20thNight
38%7%11%16%19%9%
2160
21st to endNight
46%8%9%11%19%7%
2412
November1st to 10thNight
57%8%9%10%12%3
2409
11th to 20thNight
58%8%10%11%9%3
2660
21st to endNight
52%7%9%11%13%8%
2660
December1st to 10thNight
51%9%10%15%13%2
2660
11th to 20thNight
60%11%8%10%10%1
3276
21st to endNight
57%11%11%12%7%1
4862

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
36%21%23%13%6%1
180
11th to 20thDay
35%17%21%18%5%3
180
21st to endDay
27%20%20%21%10%2
388
February1st to 10thDay
24%24%27%15%10%
370
11th to 20thDay
27%30%21%16%5%1
365
21st to endDay
30%21%26%18%4
370
March1st to 10thDay
27%25%27%17%3
441
11th to 20thDay
24%22%25%23%5%
420
21st to endDay
34%23%25%14%4
462
April1st to 10thDay
31%23%22%18%5%2
420
11th to 20thDay
32%21%26%14%6%1
412
21st to endDay
24%26%27%15%8%1
420
May1st to 10thDay
22%22%28%19%8%1
423
11th to 20thDay
30%17%24%17%9%3
448
21st to endDay
23%16%27%19%12%3
485
June1st to 10thDay
19%18%28%19%12%4
450
11th to 20thDay
19%23%27%22%7%2
450
21st to endDay
8%14%29%30%17%2
450
July1st to 10thDay
5%11%40%27%14%3
446
11th to 20thDay
214%36%28%16%4
444
21st to endDay
210%38%26%18%5%
487
August1st to 10thDay
311%35%28%18%6%
447
11th to 20thDay
310%27%32%19%8%
437
21st to endDay
8%11%32%28%17%5%
495
September1st to 10thDay
5%13%31%27%21%3
450
11th to 20thDay
13%12%29%29%15%2
450
21st to endDay
13%18%26%26%16%1
450
October1st to 10thDay
18%16%26%22%16%2
450
11th to 20thDay
21%14%22%22%20%1
450
21st to endDay
22%21%22%19%13%3
459
November1st to 10thDay
22%18%25%25%9%1
268
11th to 20thDay
21%19%24%23%12%2
180
21st to endDay
23%21%19%27%9%1
180
December1st to 10thDay
21%22%25%19%11%2
180
11th to 20thDay
26%24%24%18%7%1
180
21st to endDay
28%23%22%18%9%1
198
January1st to 10thNight
23%20%26%21%9%1
760
11th to 20thNight
24%17%21%25%12%2
760
21st to endNight
19%17%21%30%11%2
836
February1st to 10thNight
17%19%28%28%9%1
760
11th to 20thNight
18%19%26%27%9%1
744
21st to endNight
18%20%29%27%6%
628
March1st to 10thNight
19%24%23%24%9%1
742
11th to 20thNight
18%17%22%31%11%1
720
21st to endNight
21%21%25%24%9%
792
April1st to 10thNight
22%19%21%25%12%1
720
11th to 20thNight
15%25%23%22%14%2
711
21st to endNight
17%19%24%26%13%1
630
May1st to 10thNight
17%15%20%31%16%2
415
11th to 20thNight
17%9%21%30%22%1
354
21st to endNight
16%13%19%30%22%1
389
June1st to 10thNight
18%10%16%31%24%1
360
11th to 20thNight
11%13%20%32%23%1
360
21st to endNight
10%315%43%28%1
360
July1st to 10thNight
3312%47%32%2
350
11th to 20thNight
2114%54%28%1
348
21st to endNight
119%48%41%1
397
August1st to 10thNight
218%38%46%5%
537
11th to 20thNight
417%40%42%6%
534
21st to endNight
4419%43%30%1
778
September1st to 10thNight
5%417%41%29%3
720
11th to 20thNight
8%5%13%38%32%3
720
21st to endNight
11%7%16%38%25%3
720
October1st to 10thNight
12%9%23%32%22%3
720
11th to 20thNight
15%12%15%34%22%2
720
21st to endNight
19%15%19%27%18%4
792
November1st to 10thNight
20%17%22%29%11%1
740
11th to 20thNight
21%20%21%26%11%
760
21st to endNight
15%19%25%28%12%1
760
December1st to 10thNight
21%16%22%28%12%1
760
11th to 20thNight
22%21%21%25%10%1
760
21st to endNight
22%25%25%21%6%1
836
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