Redmond
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Redmond clear sky chart from 2005-11-06 to 2024-03-08.

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
54%
22895
18%
80644
18%
22810
58%
22810
26%
49655

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
34%
748
8%
4365
9%
736
38%
736
9%
3111
January11th to 20thNight
40%
754
10%
4402
12%
740
46%
740
9%
3322
January21st to endNight
44%
833
11%
4631
16%
814
51%
814
11%
3282
February1st to 10thNight
36%
760
13%
2470
9%
760
42%
760
18%
1700
February11th to 20thNight
45%
742
14%
2395
12%
740
50%
740
22%
1566
February21st to endNight
39%
628
16%
1884
13%
628
44%
628
19%
1334
March1st to 10thNight
40%
750
14%
2236
11%
750
44%
750
20%
1558
March11th to 20thNight
48%
720
16%
1980
13%
720
51%
720
25%
1362
March21st to endNight
41%
792
12%
2076
6%
792
45%
792
20%
1548
April1st to 10thNight
45%
720
14%
1800
7%
720
46%
720
25%
1271
April11th to 20thNight
45%
711
16%
1779
9%
711
47%
711
27%
1247
April21st to endNight
48%
662
15%
1742
8%
662
51%
662
29%
1159
May1st to 10thNight
62%
360
21%
1440
23%
360
67%
360
29%
739
May11th to 20thNight
64%
354
18%
1416
24%
354
67%
354
26%
800
May21st to endNight
61%
388
14%
1552
19%
388
64%
388
24%
905
June1st to 10thNight
57%
360
14%
1440
19%
360
63%
360
25%
824
June11th to 20thNight
63%
360
19%
1440
28%
360
70%
360
37%
681
June21st to endNight
75%
360
24%
1440
40%
360
78%
360
47%
596
July1st to 10thNight
84%
350
24%
1400
37%
350
89%
350
59%
499
July11th to 20thNight
79%
348
32%
1392
45%
348
88%
348
67%
463
July21st to endNight
85%
394
39%
1488
53%
372
90%
372
68%
494
August1st to 10thNight
86%
458
34%
1524
36%
456
87%
456
63%
607
August11th to 20thNight
89%
549
36%
1617
30%
549
91%
549
68%
701
August21st to endNight
75%
792
39%
1980
25%
792
76%
792
69%
958
September1st to 10thNight
78%
720
39%
1800
23%
720
80%
720
73%
851
September11th to 20thNight
73%
720
35%
1800
24%
720
74%
720
52%
1005
September21st to endNight
70%
720
31%
2025
28%
720
72%
720
48%
1072
October1st to 10thNight
65%
720
23%
2160
23%
720
69%
720
40%
1204
October11th to 20thNight
61%
720
26%
2160
25%
720
66%
720
39%
1210
October21st to endNight
52%
792
21%
2466
20%
792
56%
792
28%
1522
November1st to 10thNight
49%
740
19%
2405
19%
740
53%
740
22%
1604
November11th to 20thNight
41%
760
14%
2632
11%
760
46%
760
18%
1767
November21st to endNight
50%
760
16%
2660
13%
760
55%
760
25%
1612
December1st to 10thNight
46%
760
15%
2660
13%
760
51%
760
21%
1723
December11th to 20thNight
38%
760
13%
3206
11%
759
44%
759
14%
2256
December21st to endNight
31%
830
8%
4781
9%
817
35%
817
9%
3102

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
8%8%36%5%345%5%7%47%
78504
Night
8%9%36%5%35%5%5%7%43%
81077
TransparencyDay
38%311%23%18%8%
78207
Night
42%313%23%15%4
80895
SeeingDay
12%11%23%26%20%8%
13696
Night
12%6%21%38%21%2
22925

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
13%11%49%8%5%7%7%6%7%23%
2539
11th to 20thDay
18%17%47%8%46%5%5%5%21%
2540
21st to endDay
13%15%5%9%6%35%5%5%7%27%
2989
February1st to 10thDay
8%12%47%6%5%6%6%6%7%33%
1710
11th to 20thDay
9%11%47%6%45%5%7%9%34%
1674
21st to endDay
7%12%49%7%36%6%7%9%30%
1570
March1st to 10thDay
9%12%5%9%7%5%6%6%7%8%28%
1879
11th to 20thDay
8%12%48%7%45%6%6%8%32%
1980
21st to endDay
9%12%5%10%7%47%6%6%6%29%
2278
April1st to 10thDay
9%11%49%7%46%5%5%7%31%
2160
11th to 20thDay
10%10%47%7%35%6%5%6%38%
2129
21st to endDay
7%7%35%5%345%7%8%45%
2213
May1st to 10thDay
7%7%36%5%35%5%5%7%48%
2520
11th to 20thDay
10%7%36%5%45%5%6%8%42%
2477
21st to endDay
11%7%36%5%35%5%5%7%42%
2723
June1st to 10thDay
10%7%35%6%45%45%7%43%
2520
11th to 20thDay
6%424435%46%7%55%
2520
21st to endDay
4313423446%67%
2520
July1st to 10thDay
2212223345%76%
2520
11th to 20thDay
2113222335%76%
2520
21st to endDay
121111223481%
2741
August1st to 10thDay
211222345%6%72%
2404
11th to 20thDay
2112322236%76%
2281
21st to endDay
3212212235%77%
2376
September1st to 10thDay
2212212235%78%
2160
11th to 20thDay
43143335%6%6%61%
2160
21st to endDay
7%6%14323446%58%
1931
October1st to 10thDay
9%6%26%5%335%45%52%
1800
11th to 20thDay
9%6%25%5%3445%9%48%
1800
21st to endDay
11%8%36%6%35%45%5%45%
1890
November1st to 10thDay
12%9%37%6%36%5%6%8%36%
1674
11th to 20thDay
11%10%47%7%46%6%7%8%30%
1544
21st to endDay
9%9%38%6%35%7%6%8%36%
1520
December1st to 10thDay
9%8%47%6%45%5%6%9%37%
1520
11th to 20thDay
10%11%48%7%45%7%6%9%27%
1928
21st to endDay
8%14%6%9%8%45%5%7%7%28%
2794
January1st to 10thNight
10%13%5%9%9%5%7%6%7%7%21%
4406
11th to 20thNight
16%15%5%8%8%5%6%5%5%6%20%
4420
21st to endNight
13%15%5%9%7%36%6%6%6%25%
4672
February1st to 10thNight
9%12%48%7%36%5%6%7%31%
2470
11th to 20thNight
9%11%47%5%35%5%5%7%37%
2393
21st to endNight
7%12%5%8%6%46%6%6%8%30%
1884
March1st to 10thNight
9%12%48%6%36%5%6%9%31%
2236
11th to 20thNight
7%11%37%5%46%7%7%9%33%
1980
21st to endNight
7%10%5%9%8%48%7%7%8%28%
2076
April1st to 10thNight
11%12%46%5%35%5%6%7%36%
1800
11th to 20thNight
9%13%37%5%25%5%5%6%38%
1779
21st to endNight
9%8%35%5%36%5%6%9%40%
1742
May1st to 10thNight
7%7%344245%6%9%49%
1440
11th to 20thNight
7%6%25%7%35%46%7%47%
1416
21st to endNight
9%7%35%7%45%36%9%43%
1552
June1st to 10thNight
12%7%25%5%3345%7%47%
1440
11th to 20thNight
6%5%2432345%9%58%
1440
21st to endNight
4313223446%69%
1440
July1st to 10thNight
212212346%76%
1440
11th to 20thNight
2111112235%82%
1440
21st to endNight
111221222483%
1576
August1st to 10thNight
1213212246%75%
1532
11th to 20thNight
112223345%77%
1617
21st to endNight
121321223479%
1980
September1st to 10thNight
2211212345%79%
1800
11th to 20thNight
4424434346%64%
1800
21st to endNight
7%413323446%61%
2025
October1st to 10thNight
8%6%34423446%56%
2160
11th to 20thNight
8%5%25%42445%7%54%
2160
21st to endNight
11%7%35%5%445%5%5%46%
2466
November1st to 10thNight
12%9%47%7%36%6%5%6%36%
2405
11th to 20thNight
12%9%48%7%46%6%6%7%32%
2632
21st to endNight
9%8%36%5%35%6%6%8%40%
2660
December1st to 10thNight
10%11%47%5%3445%8%37%
2660
11th to 20thNight
10%12%5%10%8%47%7%6%7%26%
3276
21st to endNight
9%14%5%9%7%45%5%5%7%30%
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
59%315%18%5%
2539
11th to 20thDay
64%312%14%43
2540
21st to endDay
55%315%20%6%1
2989
February1st to 10thDay
49%415%24%8%
1710
11th to 20thDay
45%415%23%11%2
1683
21st to endDay
50%5%16%18%10%1
1570
March1st to 10thDay
53%312%19%12%1
1879
11th to 20thDay
50%312%26%9%
1980
21st to endDay
55%413%21%7%1
2278
April1st to 10thDay
52%311%20%13%2
2160
11th to 20thDay
48%312%20%14%4
2132
21st to endDay
38%313%29%14%3
2213
May1st to 10thDay
37%211%29%20%1
2520
11th to 20thDay
42%210%29%15%3
2480
21st to endDay
42%314%26%15%1
2724
June1st to 10thDay
41%310%30%15%1
2520
11th to 20thDay
31%310%33%20%3
2520
21st to endDay
21%28%30%29%10%
2520
July1st to 10thDay
14%27%23%28%26%
2451
11th to 20thDay
14%25%14%33%32%
2445
21st to endDay
11%1214%39%33%
2589
August1st to 10thDay
14%25%25%35%19%
2387
11th to 20thDay
14%15%23%34%23%
2281
21st to endDay
13%1424%39%18%
2376
September1st to 10thDay
13%1426%33%23%
2160
11th to 20thDay
24%38%26%27%13%
2160
21st to endDay
28%28%26%24%11%
1931
October1st to 10thDay
36%29%21%23%9%
1800
11th to 20thDay
35%213%24%20%5%
1800
21st to endDay
42%211%23%19%3
1890
November1st to 10thDay
46%312%25%12%1
1674
11th to 20thDay
49%419%20%9%
1544
21st to endDay
43%5%16%20%15%1
1520
December1st to 10thDay
44%5%15%27%9%1
1520
11th to 20thDay
53%319%20%5%
1928
21st to endDay
55%314%23%41
2794
January1st to 10thNight
60%416%16%5%
4406
11th to 20thNight
65%311%14%5%3
4420
21st to endNight
59%214%17%7%1
4672
February1st to 10thNight
52%417%18%9%
2470
11th to 20thNight
45%5%17%22%10%1
2395
21st to endNight
51%5%13%22%8%1
1884
March1st to 10thNight
50%5%13%21%11%1
2236
11th to 20thNight
45%5%16%26%7%
1980
21st to endNight
53%6%16%20%6%
2076
April1st to 10thNight
49%416%20%10%1
1800
11th to 20thNight
47%314%21%13%2
1779
21st to endNight
41%6%14%25%11%2
1742
May1st to 10thNight
33%315%33%16%
1440
11th to 20thNight
37%5%16%30%10%3
1416
21st to endNight
41%317%28%11%
1552
June1st to 10thNight
38%412%32%12%1
1440
11th to 20thNight
26%314%39%15%2
1440
21st to endNight
20%211%35%25%7%
1440
July1st to 10thNight
12%29%29%28%20%
1400
11th to 20thNight
9%27%21%33%29%
1392
21st to endNight
9%1218%43%26%
1488
August1st to 10thNight
13%26%30%36%13%
1524
11th to 20thNight
12%16%27%36%17%
1617
21st to endNight
12%25%27%40%13%
1980
September1st to 10thNight
11%26%29%35%18%
1800
11th to 20thNight
24%38%25%27%13%
1800
21st to endNight
26%18%28%25%12%
2025
October1st to 10thNight
30%310%26%25%6%
2160
11th to 20thNight
31%315%25%22%5%
2160
21st to endNight
41%313%21%19%3
2466
November1st to 10thNight
48%411%22%13%2
2405
11th to 20thNight
49%5%15%24%7%
2632
21st to endNight
41%416%22%16%1
2660
December1st to 10thNight
45%5%17%23%9%1
2660
11th to 20thNight
55%315%20%7%
3276
21st to endNight
54%314%23%6%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
23%12%32%21%11%1
180
11th to 20thDay
21%11%27%24%13%4
180
21st to endDay
17%12%26%26%17%2
315
February1st to 10thDay
20%15%22%29%13%1
370
11th to 20thDay
17%18%28%22%12%2
369
21st to endDay
20%14%27%26%11%2
382
March1st to 10thDay
19%18%23%30%9%1
449
11th to 20thDay
16%15%24%27%14%3
420
21st to endDay
19%18%23%25%13%2
462
April1st to 10thDay
21%15%25%21%12%6%
420
11th to 20thDay
17%19%24%23%11%6%
412
21st to endDay
12%19%25%23%15%6%
420
May1st to 10thDay
11%13%27%24%17%8%
423
11th to 20thDay
19%12%21%22%17%8%
448
21st to endDay
13%9%21%25%21%13%
485
June1st to 10thDay
12%11%20%23%20%13%
450
11th to 20thDay
10%15%24%26%20%6%
450
21st to endDay
5%7%20%28%27%13%
450
July1st to 10thDay
36%25%31%26%10%
446
11th to 20thDay
27%26%24%28%13%
444
21st to endDay
2425%28%27%15%
487
August1st to 10thDay
2421%30%26%17%
447
11th to 20thDay
3416%31%27%20%
437
21st to endDay
5%6%20%27%28%15%
495
September1st to 10thDay
3323%27%28%16%
450
11th to 20thDay
6%7%17%31%29%10%
450
21st to endDay
11%8%20%27%29%7%
450
October1st to 10thDay
12%10%19%27%23%9%
450
11th to 20thDay
15%9%20%25%25%7%
450
21st to endDay
17%9%24%23%21%6%
405
November1st to 10thDay
17%9%25%33%14%2
270
11th to 20thDay
19%14%19%27%17%5%
192
21st to endDay
18%10%23%30%17%2
180
December1st to 10thDay
12%16%22%30%12%8%
180
11th to 20thDay
18%13%34%30%5%
180
21st to endDay
18%12%28%30%10%2
198
January1st to 10thNight
17%8%30%29%13%2
760
11th to 20thNight
18%9%24%29%18%3
760
21st to endNight
15%7%22%38%16%2
836
February1st to 10thNight
15%9%27%35%13%1
760
11th to 20thNight
15%6%25%39%14%1
744
21st to endNight
14%10%28%36%11%
628
March1st to 10thNight
16%12%23%36%11%1
750
11th to 20thNight
13%8%23%39%15%2
720
21st to endNight
14%9%26%35%15%2
792
April1st to 10thNight
18%8%21%33%19%1
720
11th to 20thNight
16%7%26%31%18%3
711
21st to endNight
13%8%25%34%19%1
662
May1st to 10thNight
12%5%16%42%22%2
360
11th to 20thNight
10%5%14%44%27%1
354
21st to endNight
12%5%14%40%26%3
389
June1st to 10thNight
14%5%16%42%21%1
360
11th to 20thNight
8%321%46%20%1
360
21st to endNight
6%114%51%27%1
360
July1st to 10thNight
229%55%32%1
350
11th to 20thNight
2114%59%23%1
348
21st to endNight
111%54%32%2
394
August1st to 10thNight
216%47%41%3
458
11th to 20thNight
26%40%44%8%
549
21st to endNight
3216%45%32%3
792
September1st to 10thNight
3115%44%32%5%
720
11th to 20thNight
6%112%39%35%7%
720
21st to endNight
8%413%42%27%5%
720
October1st to 10thNight
11%414%41%27%3
720
11th to 20thNight
11%419%38%24%5%
720
21st to endNight
15%5%22%35%18%5%
792
November1st to 10thNight
16%6%21%41%15%1
740
11th to 20thNight
18%8%26%32%15%2
760
21st to endNight
13%8%23%36%17%3
760
December1st to 10thNight
16%8%21%35%18%2
760
11th to 20thNight
17%8%27%32%14%1
760
21st to endNight
20%10%31%28%10%1
836
Page generated at 2024-03-05 04:24:04. Version ac07

Copyright © 2024 Attilla Danko.


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