Wyrd Works
Clear Sky Chart
History

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

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
42%
23471
12%
74617
9%
23445
46%
23445
20%
50812

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
36%
946
12%
2836
7%
946
40%
946
17%
2096
January11th to 20thNight
36%
905
14%
2713
9%
905
41%
905
17%
1977
January21st to endNight
37%
846
16%
2826
11%
846
45%
846
15%
2014
February1st to 10thNight
40%
720
13%
2520
12%
720
44%
720
16%
1767
February11th to 20thNight
36%
701
12%
2273
9%
700
41%
700
15%
1685
February21st to endNight
48%
592
15%
1857
15%
592
52%
592
20%
1282
March1st to 10thNight
42%
720
13%
2160
11%
720
46%
720
18%
1591
March11th to 20thNight
42%
720
16%
1984
11%
720
46%
720
23%
1403
March21st to endNight
37%
792
9%
2173
4%
792
40%
792
17%
1670
April1st to 10thNight
39%
640
12%
1720
4%
640
44%
640
19%
1265
April11th to 20thNight
35%
533
13%
1601
8%
533
39%
533
18%
1144
April21st to endNight
40%
540
10%
1620
9%
540
43%
540
19%
1141
May1st to 10thNight
38%
460
9%
1443
7%
460
41%
460
18%
1020
May11th to 20thNight
47%
354
11%
1239
10%
354
50%
354
21%
808
May21st to endNight
42%
388
4%
1358
2%
388
43%
388
18%
932
June1st to 10thNight
42%
360
0%
1260
0%
360
42%
360
16%
903
June11th to 20thNight
38%
360
0%
1260
0%
360
38%
360
13%
942
June21st to endNight
52%
360
0%
1260
0%
360
52%
360
22%
802
July1st to 10thNight
60%
350
0%
1225
0%
350
60%
350
24%
750
July11th to 20thNight
55%
348
3%
1218
1%
348
55%
348
22%
784
July21st to endNight
65%
394
9%
1302
10%
372
67%
372
31%
709
August1st to 10thNight
58%
358
10%
1415
14%
356
60%
356
20%
857
August11th to 20thNight
58%
513
13%
1581
13%
513
60%
513
28%
983
August21st to endNight
58%
594
18%
1782
16%
594
60%
594
33%
1067
September1st to 10thNight
53%
586
17%
1697
13%
586
55%
586
31%
1046
September11th to 20thNight
51%
720
17%
1980
11%
720
54%
720
29%
1301
September21st to endNight
50%
720
21%
1980
14%
720
56%
720
34%
1227
October1st to 10thNight
46%
720
18%
2085
11%
720
52%
720
26%
1377
October11th to 20thNight
43%
720
15%
2272
10%
720
50%
720
24%
1478
October21st to endNight
38%
792
15%
2574
10%
792
46%
792
19%
1767
November1st to 10thNight
35%
893
16%
2558
10%
893
40%
893
19%
1846
November11th to 20thNight
35%
950
15%
2728
9%
950
41%
950
19%
1955
November21st to endNight
39%
950
11%
2850
6%
950
43%
950
20%
1989
December1st to 10thNight
38%
950
14%
2850
9%
950
43%
950
17%
2067
December11th to 20thNight
37%
949
12%
3480
7%
949
42%
949
14%
2492
December21st to endNight
36%
1027
11%
4937
8%
1026
42%
1026
15%
2675

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
10%8%47%6%45%5%6%9%35%
74620
Night
8%9%48%7%46%5%6%9%34%
75084
TransparencyDay
44%9%16%22%8%1
74301
Night
45%8%15%21%9%2
74921
SeeingDay
13%6%25%32%19%6%
14263
Night
12%5%28%37%16%2
23498

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
6%11%5%10%7%5%8%6%7%8%28%
1329
11th to 20thDay
8%13%5%8%8%5%6%6%7%8%27%
1260
21st to endDay
6%11%5%11%9%47%5%6%8%25%
1547
February1st to 10thDay
7%13%5%9%7%5%7%5%6%7%28%
1440
11th to 20thDay
7%12%7%9%9%5%6%7%6%8%25%
1575
21st to endDay
5%11%6%11%11%5%8%5%5%8%25%
1396
March1st to 10thDay
6%12%7%11%11%5%7%5%6%6%24%
1800
11th to 20thDay
7%8%5%9%8%5%6%6%7%8%31%
1974
21st to endDay
9%13%7%9%6%46%5%6%8%26%
2182
April1st to 10thDay
8%10%49%7%46%6%6%10%31%
2240
11th to 20thDay
12%12%48%6%36%6%7%8%28%
2310
21st to endDay
12%9%39%7%45%5%5%9%32%
2340
May1st to 10thDay
13%11%37%7%45%6%7%9%29%
2513
11th to 20thDay
9%6%26%7%46%6%7%8%40%
2654
21st to endDay
18%7%37%6%345%6%8%33%
2917
June1st to 10thDay
16%6%25%6%46%6%8%9%32%
2700
11th to 20thDay
19%7%37%7%45%6%6%8%26%
2700
21st to endDay
8%426%6%46%6%7%10%40%
2700
July1st to 10thDay
8%6%25%5%35%6%7%10%41%
2700
11th to 20thDay
10%5%25%5%35%5%7%10%43%
2700
21st to endDay
6%4244345%7%10%51%
2938
August1st to 10thDay
10%5%245%35%5%7%11%44%
2516
11th to 20thDay
8%4244345%6%10%49%
2319
21st to endDay
10%415%4346%6%8%47%
2574
September1st to 10thDay
11%6%245%345%6%8%45%
2260
11th to 20thDay
15%8%35%42445%8%42%
1980
21st to endDay
8%9%35%425%5%5%9%45%
1980
October1st to 10thDay
13%11%36%5%2436%7%40%
1875
11th to 20thDay
9%8%47%7%45%5%6%8%37%
1684
21st to endDay
7%12%37%7%46%6%6%7%34%
1782
November1st to 10thDay
10%15%7%10%6%35%5%6%9%24%
1502
11th to 20thDay
7%13%49%7%45%45%7%34%
1449
21st to endDay
6%11%5%10%8%5%5%5%6%8%31%
1330
December1st to 10thDay
7%11%6%10%8%7%7%6%5%6%27%
1330
11th to 20thDay
411%6%12%9%5%6%6%7%8%26%
1682
21st to endDay
48%39%7%345%6%9%41%
2442
January1st to 10thNight
5%11%6%11%9%5%6%6%8%8%25%
2836
11th to 20thNight
7%11%7%9%8%5%5%5%6%9%28%
2713
21st to endNight
6%12%6%9%7%47%7%7%9%27%
2826
February1st to 10thNight
7%10%6%10%8%46%6%6%8%29%
2520
11th to 20thNight
6%13%5%10%9%6%7%6%7%7%24%
2272
21st to endNight
5%9%49%9%46%6%8%9%30%
1857
March1st to 10thNight
5%10%5%10%10%6%6%5%6%8%28%
2160
11th to 20thNight
6%9%5%9%8%36%6%7%9%30%
1984
21st to endNight
8%14%5%9%7%5%6%6%7%9%23%
2173
April1st to 10thNight
9%8%47%10%46%6%6%8%30%
1720
11th to 20thNight
9%11%5%10%8%46%5%6%8%28%
1601
21st to endNight
10%10%48%6%46%6%6%8%32%
1620
May1st to 10thNight
12%11%48%7%445%6%9%29%
1443
11th to 20thNight
8%7%37%7%46%5%5%8%39%
1239
21st to endNight
19%6%46%7%4446%9%33%
1358
June1st to 10thNight
15%8%47%7%45%6%8%9%28%
1260
11th to 20thNight
18%8%37%8%47%7%7%7%24%
1260
21st to endNight
10%5%26%7%35%7%7%8%39%
1260
July1st to 10thNight
9%5%26%6%35%6%9%10%42%
1260
11th to 20thNight
10%5%25%5%5%5%7%8%11%37%
1260
21st to endNight
6%424425%5%7%10%50%
1379
August1st to 10thNight
9%5%25%6%45%6%6%10%42%
1422
11th to 20thNight
7%5%46%5%345%7%8%44%
1581
21st to endNight
8%426%5%35%46%10%47%
1782
September1st to 10thNight
10%5%25%44446%8%46%
1697
11th to 20thNight
13%6%25%6%345%5%7%43%
1980
21st to endNight
8%6%35%5%345%7%8%47%
1980
October1st to 10thNight
11%10%35%5%346%5%7%40%
2085
11th to 20thNight
9%8%48%6%36%46%9%38%
2272
21st to endNight
7%9%48%7%46%6%6%9%34%
2574
November1st to 10thNight
11%13%5%8%5%46%46%8%31%
2558
11th to 20thNight
5%9%5%10%8%5%7%6%7%8%31%
2728
21st to endNight
5%9%410%8%5%6%5%7%10%32%
2850
December1st to 10thNight
6%11%6%11%8%5%5%45%9%30%
2850
11th to 20thNight
39%5%11%10%5%8%6%6%9%29%
3510
21st to endNight
48%47%6%45%5%6%9%43%
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
50%8%14%19%7%1
1329
11th to 20thDay
51%7%13%21%6%2
1260
21st to endDay
53%8%15%14%9%1
1547
February1st to 10thDay
52%6%15%17%9%1
1440
11th to 20thDay
55%9%13%15%7%1
1584
21st to endDay
56%7%10%18%9%
1396
March1st to 10thDay
58%9%13%14%6%
1800
11th to 20thDay
47%9%12%22%9%
1975
21st to endDay
55%8%16%14%6%
2182
April1st to 10thDay
47%10%17%18%8%1
2240
11th to 20thDay
50%7%14%21%8%1
2310
21st to endDay
49%7%15%22%6%2
2340
May1st to 10thDay
49%9%15%20%7%
2513
11th to 20thDay
38%9%15%26%11%1
2658
21st to endDay
48%8%15%21%8%1
2918
June1st to 10thDay
45%10%17%21%8%
2700
11th to 20thDay
53%10%13%19%41
2700
21st to endDay
35%12%20%26%6%1
2700
July1st to 10thDay
35%11%21%25%7%1
2626
11th to 20thDay
36%10%21%28%5%
2619
21st to endDay
26%10%23%30%9%
2775
August1st to 10thDay
33%11%22%27%7%1
2498
11th to 20thDay
30%10%25%25%9%1
2319
21st to endDay
31%10%21%26%11%1
2574
September1st to 10thDay
35%9%18%26%9%3
2260
11th to 20thDay
40%6%14%29%9%1
1980
21st to endDay
35%8%18%25%11%3
1980
October1st to 10thDay
43%6%17%23%9%1
1875
11th to 20thDay
43%7%18%22%10%1
1684
21st to endDay
46%8%13%21%11%1
1782
November1st to 10thDay
55%7%14%16%6%1
1502
11th to 20thDay
49%8%13%21%8%1
1449
21st to endDay
49%8%16%18%8%1
1330
December1st to 10thDay
56%7%13%14%8%2
1330
11th to 20thDay
52%10%14%19%41
1684
21st to endDay
38%6%13%24%16%4
2442
January1st to 10thNight
52%9%13%16%8%3
2836
11th to 20thNight
51%8%14%19%5%3
2713
21st to endNight
51%8%14%16%10%1
2826
February1st to 10thNight
51%7%12%19%11%1
2520
11th to 20thNight
55%8%13%15%9%1
2273
21st to endNight
46%9%13%19%12%1
1857
March1st to 10thNight
52%8%14%20%6%1
2160
11th to 20thNight
47%7%15%21%9%1
1984
21st to endNight
54%9%14%16%6%1
2173
April1st to 10thNight
48%10%13%17%11%
1720
11th to 20thNight
51%7%13%22%7%1
1601
21st to endNight
47%9%13%22%7%2
1620
May1st to 10thNight
49%7%14%20%9%1
1443
11th to 20thNight
42%8%12%22%16%
1239
21st to endNight
48%8%14%22%7%1
1358
June1st to 10thNight
49%10%14%18%9%
1260
11th to 20thNight
56%9%13%15%5%1
1260
21st to endNight
38%11%18%24%7%1
1260
July1st to 10thNight
33%13%22%25%6%1
1225
11th to 20thNight
36%14%21%20%8%
1218
21st to endNight
26%10%23%29%10%1
1302
August1st to 10thNight
35%13%20%24%7%1
1415
11th to 20thNight
35%9%18%28%9%1
1581
21st to endNight
31%8%19%28%11%2
1782
September1st to 10thNight
33%8%17%25%12%4
1697
11th to 20thNight
39%8%14%25%10%4
1980
21st to endNight
33%7%17%27%14%2
1980
October1st to 10thNight
42%7%15%25%11%1
2085
11th to 20thNight
42%6%17%22%9%2
2272
21st to endNight
45%10%15%21%8%1
2574
November1st to 10thNight
50%7%12%21%8%1
2558
11th to 20thNight
48%9%14%18%10%1
2728
21st to endNight
46%9%18%18%7%2
2850
December1st to 10thNight
52%7%10%20%9%2
2850
11th to 20thNight
50%10%16%18%6%
3507
21st to endNight
37%7%13%24%16%4
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
6%427%36%19%9%
180
11th to 20thDay
9%433%29%21%3
160
21st to endDay
6%7%31%30%19%7%
176
February1st to 10thDay
11%9%26%36%13%6%
160
11th to 20thDay
13%6%26%36%16%3
240
21st to endDay
8%5%23%39%19%6%
262
March1st to 10thDay
9%6%30%33%16%5%
420
11th to 20thDay
8%427%36%18%7%
420
21st to endDay
13%5%28%30%18%7%
462
April1st to 10thDay
9%12%29%31%13%6%
420
11th to 20thDay
15%8%30%28%15%5%
412
21st to endDay
17%9%27%31%13%3
420
May1st to 10thDay
16%10%23%27%17%6%
519
11th to 20thDay
13%6%21%35%21%4
625
21st to endDay
18%5%21%27%22%7%
679
June1st to 10thDay
16%6%26%35%14%3
630
11th to 20thDay
20%7%25%30%14%4
630
21st to endDay
9%423%30%26%8%
630
July1st to 10thDay
11%419%36%23%8%
621
11th to 20thDay
12%5%19%35%23%6%
618
21st to endDay
6%219%36%27%10%
684
August1st to 10thDay
9%5%25%31%20%10%
456
11th to 20thDay
8%6%21%31%29%5%
437
21st to endDay
10%7%22%29%23%9%
495
September1st to 10thDay
15%6%29%29%18%3
450
11th to 20thDay
18%6%22%29%20%4
450
21st to endDay
13%12%28%29%14%5%
450
October1st to 10thDay
20%6%22%28%17%6%
345
11th to 20thDay
11%10%34%26%16%4
270
21st to endDay
14%13%33%27%13%
297
November1st to 10thDay
20%7%25%33%12%3
270
11th to 20thDay
16%7%30%31%14%2
237
21st to endDay
8%6%30%33%16%7%
180
December1st to 10thDay
11%228%34%21%4
180
11th to 20thDay
6%6%34%37%14%3
180
21st to endDay
10%321%38%22%7%
198
January1st to 10thNight
12%6%31%34%15%2
950
11th to 20thNight
12%6%30%36%15%1
905
21st to endNight
12%8%30%37%11%2
846
February1st to 10thNight
12%6%27%35%18%3
720
11th to 20thNight
12%5%32%36%14%1
704
21st to endNight
8%322%42%20%5%
592
March1st to 10thNight
9%427%40%16%4
720
11th to 20thNight
9%5%29%38%16%3
720
21st to endNight
13%5%27%34%19%3
792
April1st to 10thNight
12%6%29%33%18%2
640
11th to 20thNight
15%6%31%36%11%1
533
21st to endNight
15%9%27%34%14%1
540
May1st to 10thNight
16%7%26%36%13%1
460
11th to 20thNight
12%5%27%39%16%2
354
21st to endNight
19%6%23%32%18%1
389
June1st to 10thNight
17%7%24%35%14%3
360
11th to 20thNight
20%428%31%17%1
360
21st to endNight
13%322%39%21%2
360
July1st to 10thNight
11%317%45%23%1
350
11th to 20thNight
14%319%42%20%2
348
21st to endNight
7%320%41%27%3
394
August1st to 10thNight
13%218%38%26%3
358
11th to 20thNight
9%5%17%43%24%1
513
21st to endNight
8%5%19%44%23%
594
September1st to 10thNight
12%324%41%19%2
586
11th to 20thNight
14%5%22%39%20%1
720
21st to endNight
11%427%38%17%2
720
October1st to 10thNight
15%5%25%36%18%2
720
11th to 20thNight
11%5%31%35%16%2
720
21st to endNight
13%7%31%35%13%1
792
November1st to 10thNight
16%8%29%35%10%1
893
11th to 20thNight
8%7%38%34%10%2
950
21st to endNight
9%5%35%38%13%2
950
December1st to 10thNight
11%6%29%35%16%2
950
11th to 20thNight
9%5%34%37%12%2
950
21st to endNight
11%430%37%15%2
1045
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