Poulsbo Deep Space Observatory
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Poulsbo Deep Space Observatory clear sky chart from 2005-11-06 to 2024-01-12.

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%
22536
7%
74645
6%
22486
44%
22486
9%
61140

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
26%
850
2%
2836
2%
846
26%
846
3%
2580
January11th to 20thNight
32%
746
4%
2588
4%
746
34%
746
5%
2280
January21st to endNight
34%
792
5%
2714
4%
792
36%
792
6%
2336
February1st to 10thNight
28%
720
3%
2340
2%
720
30%
720
6%
2031
February11th to 20thNight
33%
702
5%
2274
5%
700
35%
700
8%
1908
February21st to endNight
32%
592
6%
1879
4%
592
35%
592
7%
1603
March1st to 10thNight
37%
720
6%
2102
5%
720
38%
720
9%
1774
March11th to 20thNight
34%
720
7%
1980
4%
720
37%
720
7%
1704
March21st to endNight
31%
792
4%
2116
2%
792
33%
792
7%
1850
April1st to 10thNight
37%
720
4%
1800
1%
720
38%
720
8%
1591
April11th to 20thNight
40%
668
8%
1736
4%
668
42%
668
11%
1447
April21st to endNight
40%
509
7%
1589
5%
509
41%
509
9%
1324
May1st to 10thNight
48%
360
8%
1440
10%
360
51%
360
8%
1137
May11th to 20thNight
55%
354
8%
1416
12%
354
58%
354
10%
1066
May21st to endNight
50%
388
4%
1552
6%
388
51%
388
6%
1292
June1st to 10thNight
46%
360
2%
1350
3%
360
47%
360
7%
1103
June11th to 20thNight
43%
360
2%
1260
2%
360
44%
360
7%
1060
June21st to endNight
60%
360
7%
1260
6%
360
63%
360
15%
905
July1st to 10thNight
66%
350
10%
1225
13%
350
66%
350
16%
862
July11th to 20thNight
70%
348
12%
1290
18%
348
72%
348
19%
848
July21st to endNight
77%
394
14%
1488
24%
372
79%
372
18%
957
August1st to 10thNight
73%
407
11%
1473
15%
405
74%
405
17%
1002
August11th to 20thNight
78%
534
18%
1602
17%
534
79%
534
24%
1071
August21st to endNight
65%
685
13%
1873
10%
685
66%
685
19%
1376
September1st to 10thNight
69%
720
15%
1800
9%
720
70%
720
26%
1277
September11th to 20thNight
57%
720
15%
1800
10%
720
58%
720
19%
1403
September21st to endNight
53%
720
14%
2059
12%
720
54%
720
14%
1597
October1st to 10thNight
50%
720
9%
2160
8%
720
52%
720
13%
1693
October11th to 20thNight
45%
720
8%
2160
7%
720
47%
720
12%
1708
October21st to endNight
41%
792
7%
2474
6%
792
43%
792
10%
2002
November1st to 10thNight
32%
740
5%
2566
4%
740
36%
740
6%
2219
November11th to 20thNight
33%
760
4%
2660
4%
760
34%
760
6%
2290
November21st to endNight
34%
760
3%
2660
2%
760
36%
760
5%
2318
December1st to 10thNight
36%
760
5%
2660
3%
760
38%
760
6%
2265
December11th to 20thNight
24%
769
2%
3290
1%
768
25%
768
3%
2843
December21st to endNight
23%
924
2%
5173
1%
905
26%
905
2%
4418

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%9%47%7%45%5%5%7%32%
74846
Night
15%10%47%6%45%5%5%7%32%
74878
TransparencyDay
35%37%11%11%41
74538
Night
36%38%10%11%41
74704
SeeingDay
21%7%19%27%19%7%
14040
Night
25%7%16%28%21%4
22550

By Month

Percentage Cloud Cover NW (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
22%13%5%11%8%46%45%5%18%
1329
11th to 20thDay
16%11%5%10%9%45%7%6%7%20%
1407
21st to endDay
17%11%5%11%7%47%6%6%7%18%
1638
February1st to 10thDay
17%14%5%8%7%46%6%6%7%18%
1620
11th to 20thDay
14%13%49%8%46%5%7%8%22%
1575
21st to endDay
13%13%5%9%8%46%5%6%7%25%
1376
March1st to 10thDay
15%12%47%8%36%6%5%8%25%
1854
11th to 20thDay
18%11%48%7%46%6%5%7%24%
1980
21st to endDay
16%11%49%8%5%7%7%6%8%19%
2239
April1st to 10thDay
17%13%5%8%7%46%6%7%7%21%
2160
11th to 20thDay
18%9%49%7%5%5%5%5%8%25%
2171
21st to endDay
15%10%48%7%5%6%6%6%7%26%
2371
May1st to 10thDay
13%9%38%8%35%5%6%8%33%
2520
11th to 20thDay
15%9%36%6%35%5%6%7%33%
2477
21st to endDay
21%9%37%7%35%5%45%29%
2723
June1st to 10thDay
19%8%37%7%45%6%6%7%28%
2605
11th to 20thDay
20%10%47%7%47%6%6%6%22%
2700
21st to endDay
11%6%36%6%46%5%6%7%40%
2700
July1st to 10thDay
9%7%35%5%24447%49%
2700
11th to 20thDay
9%5%25%42445%7%52%
2626
21st to endDay
8%424423345%61%
2741
August1st to 10thDay
9%5%25%5%235%47%52%
2454
11th to 20thDay
7%42442345%7%55%
2298
21st to endDay
11%6%35%5%345%5%6%47%
2482
September1st to 10thDay
9%6%3443345%7%53%
2160
11th to 20thDay
11%7%36%6%445%6%7%42%
2160
21st to endDay
12%7%35%6%35%46%7%42%
1897
October1st to 10thDay
13%9%36%6%45%5%6%8%35%
1800
11th to 20thDay
15%9%37%5%46%6%6%8%31%
1800
21st to endDay
17%10%49%7%46%6%5%7%25%
1882
November1st to 10thDay
19%12%5%8%8%47%5%5%7%20%
1510
11th to 20thDay
18%12%5%7%7%46%5%5%8%23%
1520
21st to endDay
19%13%48%6%46%46%8%23%
1520
December1st to 10thDay
16%13%46%7%46%5%5%7%26%
1520
11th to 20thDay
18%13%7%10%10%5%7%6%5%7%13%
1889
21st to endDay
16%13%7%11%10%5%6%5%5%6%15%
2442
January1st to 10thNight
21%13%5%8%7%46%5%5%7%18%
2836
11th to 20thNight
17%12%5%10%7%35%5%5%7%23%
2588
21st to endNight
17%12%48%6%46%6%6%8%23%
2714
February1st to 10thNight
17%15%5%8%7%45%5%5%8%22%
2340
11th to 20thNight
14%12%48%7%35%5%6%7%28%
2272
21st to endNight
14%13%49%6%36%6%5%7%26%
1879
March1st to 10thNight
15%9%47%7%46%5%7%8%28%
2102
11th to 20thNight
15%12%37%6%46%5%6%9%27%
1979
21st to endNight
16%11%49%7%46%5%6%7%24%
2116
April1st to 10thNight
16%11%47%7%47%6%7%8%22%
1800
11th to 20thNight
15%9%47%6%47%5%7%8%29%
1736
21st to endNight
17%10%47%6%45%5%6%8%29%
1589
May1st to 10thNight
14%8%35%5%35%5%5%8%39%
1440
11th to 20thNight
13%6%36%6%47%5%6%7%39%
1416
21st to endNight
18%9%37%6%4445%7%32%
1552
June1st to 10thNight
17%8%37%5%35%5%6%6%34%
1350
11th to 20thNight
21%9%47%7%36%5%6%7%26%
1260
21st to endNight
9%5%25%6%345%6%8%46%
1260
July1st to 10thNight
11%6%24435%345%54%
1260
11th to 20thNight
8%325%413345%61%
1332
21st to endNight
7%42332234367%
1576
August1st to 10thNight
7%425%423345%60%
1481
11th to 20thNight
6%31431235%8%64%
1602
21st to endNight
9%5%25%5%2445%7%53%
1873
September1st to 10thNight
7%42443445%6%58%
1800
11th to 20thNight
12%7%35%6%45%35%6%44%
1800
21st to endNight
12%7%36%6%35%5%5%6%43%
2059
October1st to 10thNight
11%6%37%6%46%5%5%7%41%
2160
11th to 20thNight
15%9%37%5%36%45%7%37%
2160
21st to endNight
16%9%37%6%45%45%7%34%
2474
November1st to 10thNight
22%9%47%6%45%6%46%28%
2566
11th to 20thNight
18%10%47%7%46%5%6%6%26%
2660
21st to endNight
16%10%48%8%47%6%5%7%24%
2660
December1st to 10thNight
18%10%5%8%6%45%5%5%6%27%
2660
11th to 20thNight
17%13%411%8%46%6%5%7%18%
3312
21st to endNight
18%16%6%10%8%5%6%5%5%6%15%
5214

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
48%41%5%5%1
1329
11th to 20thDay
43%42%7%5%11
1407
21st to endDay
45%40%7%6%2
1638
February1st to 10thDay
42%41%8%7%2
1620
11th to 20thDay
40%40%9%7%5%
1584
21st to endDay
41%39%9%8%3
1376
March1st to 10thDay
44%38%9%7%2
1854
11th to 20thDay
43%37%10%8%2
1980
21st to endDay
44%38%10%8%1
2239
April1st to 10thDay
41%38%12%8%1
2160
11th to 20thDay
39%36%9%10%5%1
2171
21st to endDay
38%37%11%9%41
2371
May1st to 10thDay
36%37%13%11%3
2520
11th to 20thDay
30%38%14%14%5%
2480
21st to endDay
41%36%12%9%2
2724
June1st to 10thDay
38%37%14%7%31
2605
11th to 20thDay
40%37%14%8%1
2700
21st to endDay
26%38%18%11%5%2
2700
July1st to 10thDay
20%38%14%18%7%2
2626
11th to 20thDay
20%37%13%21%8%1
2545
21st to endDay
16%37%12%22%10%2
2589
August1st to 10thDay
22%36%17%17%7%1
2437
11th to 20thDay
18%36%16%18%9%3
2298
21st to endDay
24%36%14%19%6%1
2482
September1st to 10thDay
19%36%13%19%10%4
2160
11th to 20thDay
26%37%12%13%10%1
2160
21st to endDay
30%38%11%12%6%2
1897
October1st to 10thDay
32%38%11%15%5%
1800
11th to 20thDay
36%38%13%11%21
1800
21st to endDay
40%38%8%8%5%
1882
November1st to 10thDay
42%41%7%6%3
1510
11th to 20thDay
41%42%8%7%3
1520
21st to endDay
41%43%6%8%2
1520
December1st to 10thDay
40%41%8%7%4
1520
11th to 20thDay
52%34%7%6%1
1892
21st to endDay
58%25%11%5%1
2442
January1st to 10thNight
46%42%6%5%1
2836
11th to 20thNight
40%43%7%6%22
2588
21st to endNight
41%39%8%9%31
2714
February1st to 10thNight
42%38%9%9%2
2340
11th to 20thNight
37%40%10%8%6%
2274
21st to endNight
41%38%9%9%4
1879
March1st to 10thNight
38%38%11%10%3
2102
11th to 20thNight
40%38%9%9%3
1980
21st to endNight
42%38%10%8%1
2116
April1st to 10thNight
40%40%9%8%2
1800
11th to 20thNight
35%37%11%9%6%1
1736
21st to endNight
37%38%10%10%41
1589
May1st to 10thNight
35%37%10%13%5%
1440
11th to 20thNight
29%38%13%12%6%1
1416
21st to endNight
41%37%11%11%1
1552
June1st to 10thNight
39%37%12%8%32
1350
11th to 20thNight
41%37%13%8%1
1260
21st to endNight
25%36%18%13%5%3
1260
July1st to 10thNight
21%37%10%21%7%3
1225
11th to 20thNight
16%37%13%24%9%1
1290
21st to endNight
15%38%8%20%14%5%
1488
August1st to 10thNight
20%36%13%20%9%2
1473
11th to 20thNight
14%36%13%19%14%3
1602
21st to endNight
23%36%13%18%8%1
1873
September1st to 10thNight
16%36%12%21%10%5%
1800
11th to 20thNight
27%36%9%13%12%3
1800
21st to endNight
29%37%9%16%8%1
2059
October1st to 10thNight
31%37%9%16%8%
2160
11th to 20thNight
31%38%13%14%41
2160
21st to endNight
33%38%10%12%6%
2474
November1st to 10thNight
38%42%7%8%31
2566
11th to 20thNight
39%41%11%7%2
2660
21st to endNight
40%42%8%7%2
2660
December1st to 10thNight
39%40%9%8%3
2660
11th to 20thNight
47%36%11%5%1
3308
21st to endNight
56%26%9%7%2
5214

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%10%21%19%10%5%
180
11th to 20thDay
32%13%23%13%14%4
163
21st to endDay
36%12%20%18%10%4
230
February1st to 10thDay
38%10%20%22%9%1
340
11th to 20thDay
33%11%25%20%7%3
335
21st to endDay
29%10%25%23%11%3
300
March1st to 10thDay
27%14%25%22%9%3
420
11th to 20thDay
27%12%23%19%15%4
420
21st to endDay
30%10%25%22%11%2
462
April1st to 10thDay
25%11%24%23%13%4
420
11th to 20thDay
24%11%28%19%11%6%
412
21st to endDay
21%7%26%30%13%3
420
May1st to 10thDay
15%6%21%35%19%4
423
11th to 20thDay
19%5%16%30%21%9%
448
21st to endDay
20%5%14%30%20%10%
485
June1st to 10thDay
20%5%19%32%19%6%
535
11th to 20thDay
20%5%19%31%19%5%
630
21st to endDay
10%5%19%34%23%8%
630
July1st to 10thDay
13%313%31%29%10%
621
11th to 20thDay
6%315%31%33%11%
544
21st to endDay
6%38%32%36%15%
487
August1st to 10thDay
9%18%29%36%17%
447
11th to 20thDay
6%210%35%34%14%
437
21st to endDay
11%5%15%37%23%9%
495
September1st to 10thDay
12%5%19%36%24%4
450
11th to 20thDay
15%8%16%30%24%8%
450
21st to endDay
17%9%22%28%20%4
450
October1st to 10thDay
21%8%20%25%18%8%
450
11th to 20thDay
26%8%19%24%18%5%
450
21st to endDay
32%12%18%21%14%3
397
November1st to 10thDay
40%7%24%21%5%2
191
11th to 20thDay
34%15%17%17%9%7%
180
21st to endDay
33%11%22%18%10%7%
180
December1st to 10thDay
32%13%16%18%15%7%
180
11th to 20thDay
34%16%27%16%7%1
180
21st to endDay
32%12%20%27%7%3
198
January1st to 10thNight
38%7%20%19%14%2
850
11th to 20thNight
34%8%16%23%17%2
746
21st to endNight
31%7%17%27%15%3
792
February1st to 10thNight
34%9%19%25%11%2
720
11th to 20thNight
29%9%19%26%16%2
704
21st to endNight
30%7%20%28%12%3
592
March1st to 10thNight
26%9%21%27%15%2
720
11th to 20thNight
27%14%16%26%14%2
720
21st to endNight
26%9%22%29%12%2
792
April1st to 10thNight
25%7%19%29%18%2
720
11th to 20thNight
22%8%19%30%17%3
668
21st to endNight
26%6%16%33%17%3
509
May1st to 10thNight
19%8%15%34%22%2
360
11th to 20thNight
18%312%35%29%4
354
21st to endNight
21%5%10%33%26%6%
389
June1st to 10thNight
21%6%15%33%21%4
360
11th to 20thNight
24%6%13%35%19%3
360
21st to endNight
13%314%38%29%3
360
July1st to 10thNight
12%47%34%37%6%
350
11th to 20thNight
9%29%37%38%5%
348
21st to endNight
8%35%34%43%6%
394
August1st to 10thNight
10%2428%45%11%
407
11th to 20thNight
8%1428%46%12%
534
21st to endNight
13%28%34%36%6%
685
September1st to 10thNight
11%29%39%33%6%
720
11th to 20thNight
18%310%25%34%10%
720
21st to endNight
17%7%15%33%24%4
720
October1st to 10thNight
18%7%15%29%26%6%
720
11th to 20thNight
25%6%15%26%23%4
720
21st to endNight
28%8%17%28%17%2
792
November1st to 10thNight
34%9%18%27%11%
740
11th to 20thNight
32%8%20%23%14%2
760
21st to endNight
31%8%18%25%14%4
760
December1st to 10thNight
28%9%16%28%16%3
760
11th to 20thNight
35%11%19%21%13%1
769
21st to endNight
39%9%20%22%10%1
935
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