Eagle Plains
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Eagle Plains clear sky chart from 2005-11-06 to 2024-01-14.

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
46%
21998
7%
75009
7%
21970
47%
21970
12%
57347

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
50%
1126
10%
3815
10%
1126
52%
1126
12%
2907
January11th to 20thNight
43%
1078
10%
3485
11%
1078
44%
1078
11%
2756
January21st to endNight
47%
984
9%
3470
9%
984
49%
984
11%
2666
February1st to 10thNight
55%
800
14%
2948
16%
800
56%
800
15%
2067
February11th to 20thNight
54%
780
12%
2623
11%
780
55%
780
16%
1874
February21st to endNight
51%
658
9%
2028
8%
658
52%
658
16%
1537
March1st to 10thNight
58%
776
14%
2287
14%
776
59%
776
20%
1655
March11th to 20thNight
56%
630
10%
2068
12%
630
57%
630
17%
1499
March21st to endNight
58%
594
9%
2026
9%
594
59%
594
18%
1399
April1st to 10thNight
49%
540
3%
1600
3%
540
49%
540
13%
1262
April11th to 20thNight
53%
533
0%
1415
0%
533
53%
533
18%
1073
April21st to endNight
57%
401
0%
1121
0%
401
57%
401
20%
822
May1st to 10thNight
50%
288
0%
964
0%
288
50%
288
15%
700
May11th to 20thNight
51%
177
0%
708
0%
177
51%
177
16%
476
May21st to endNight
56%
194
0%
454
0%
194
56%
194
31%
317
June1st to 10thNight
52%
122
0%
198
0%
122
52%
122
32%
172
June11th to 20thNight00000
June21st to endNight00000
July1st to 10thNight
55%
121
0%
146
0%
121
55%
121
35%
135
July11th to 20thNight
48%
174
0%
402
0%
174
48%
174
14%
334
July21st to endNight
47%
197
0%
683
0%
186
45%
186
13%
506
August1st to 10thNight
47%
216
0%
910
0%
215
47%
215
9%
678
August11th to 20thNight
42%
400
0%
1112
0%
400
42%
400
12%
904
August21st to endNight
41%
594
0%
1526
0%
594
41%
594
12%
1268
September1st to 10thNight
46%
540
2%
1586
2%
540
46%
540
15%
1217
September11th to 20thNight
41%
540
6%
1800
5%
540
42%
540
12%
1404
September21st to endNight
31%
668
4%
2054
3%
668
32%
668
9%
1719
October1st to 10thNight
35%
720
5%
2191
5%
720
36%
720
10%
1809
October11th to 20thNight
31%
799
5%
2498
4%
799
31%
799
8%
2118
October21st to endNight
37%
891
7%
2956
7%
891
38%
891
10%
2406
November1st to 10thNight
43%
860
7%
2992
7%
860
44%
860
9%
2422
November11th to 20thNight
43%
1040
6%
3374
6%
1040
43%
1040
10%
2743
November21st to endNight
45%
1069
9%
3604
9%
1069
46%
1069
10%
2865
December1st to 10thNight
42%
1130
9%
3800
9%
1130
44%
1130
12%
2957
December11th to 20thNight
41%
1129
8%
4958
6%
1129
43%
1129
8%
3791
December21st to endNight
51%
1229
6%
7207
9%
1213
53%
1213
8%
4889

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
12%11%5%9%8%46%6%6%8%24%
74585
Night
7%13%6%11%10%5%7%7%7%8%20%
75514
TransparencyDay
58%8%16%15%4
74162
Night
59%7%12%15%7%1
75457
SeeingDay
17%5%17%29%23%9%
17298
Night
12%314%32%30%10%
22022

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
412%5%10%10%5%8%8%10%11%16%
349
11th to 20thDay
315%7%13%8%7%6%7%10%7%16%
548
21st to endDay
316%6%11%13%6%7%7%7%10%15%
903
February1st to 10thDay
18%5%10%9%7%8%9%7%13%23%
1009
11th to 20thDay
28%410%10%6%9%10%10%11%20%
1228
21st to endDay
27%416%12%7%9%8%6%7%22%
1228
March1st to 10thDay
19%6%12%9%6%9%7%8%8%25%
1673
11th to 20thDay
18%5%16%11%5%7%9%7%7%25%
1890
21st to endDay
29%6%14%9%5%8%8%7%8%24%
2330
April1st to 10thDay
311%6%14%13%6%7%6%5%7%22%
2360
11th to 20thDay
5%12%7%11%8%46%5%7%7%27%
2492
21st to endDay
411%6%9%7%45%6%7%10%32%
2839
May1st to 10thDay
9%14%5%10%7%46%5%5%7%26%
2996
11th to 20thDay
10%11%49%6%36%5%5%7%33%
3187
21st to endDay
11%10%37%6%345%5%8%37%
3818
June1st to 10thDay
14%7%37%8%46%6%6%8%31%
3761
11th to 20thDay
14%8%47%6%36%6%6%9%31%
4104
21st to endDay
16%7%47%7%5%7%7%7%8%26%
4150
July1st to 10thDay
15%8%37%7%5%6%7%7%9%26%
3808
11th to 20thDay
21%9%48%9%5%7%7%6%8%16%
3544
21st to endDay
17%10%49%8%6%7%6%7%8%19%
3594
August1st to 10thDay
21%10%48%7%46%5%5%8%22%
3025
11th to 20thDay
25%12%38%7%45%7%6%7%16%
2785
21st to endDay
22%15%49%7%46%5%6%7%15%
2830
September1st to 10thDay
18%14%5%7%6%45%6%5%7%24%
2373
11th to 20thDay
20%13%38%6%345%5%6%25%
2160
21st to endDay
19%22%6%11%7%44445%15%
1904
October1st to 10thDay
15%18%6%12%8%45%5%5%6%17%
1769
11th to 20thDay
12%20%8%12%9%5%6%45%6%14%
1459
21st to endDay
10%18%7%13%11%5%6%46%6%15%
1400
November1st to 10thDay
7%19%412%11%5%9%5%7%5%16%
1067
11th to 20thDay
6%13%7%16%15%6%8%6%7%5%12%
803
21st to endDay
6%12%7%15%11%6%8%9%9%6%11%
574
December1st to 10thDay
5%13%7%16%10%5%6%6%9%5%19%
380
11th to 20thDay
7%17%7%12%14%7%7%47%11%5%
81
21st to endDay
9%19%27%8%5%5%49%10%21%
164
January1st to 10thNight
6%12%6%11%9%6%8%8%8%10%17%
3815
11th to 20thNight
5%13%8%15%11%5%5%8%9%8%13%
3485
21st to endNight
314%7%12%10%6%7%7%7%9%16%
3470
February1st to 10thNight
28%5%12%11%6%8%7%8%11%22%
2948
11th to 20thNight
29%5%12%10%5%9%6%9%11%21%
2619
21st to endNight
29%414%13%6%7%7%7%7%24%
2028
March1st to 10thNight
28%5%9%11%7%7%8%6%8%28%
2287
11th to 20thNight
27%5%12%12%6%7%8%6%8%27%
2068
21st to endNight
28%6%12%9%5%6%5%7%9%32%
2026
April1st to 10thNight
412%6%12%11%7%7%5%6%8%22%
1600
11th to 20thNight
49%7%8%9%5%7%6%6%10%29%
1415
21st to endNight
48%5%11%9%46%5%9%11%30%
1121
May1st to 10thNight
7%13%7%6%8%5%5%6%6%6%30%
964
11th to 20thNight
10%8%411%6%35%5%7%8%32%
708
21st to endNight
11%6%28%5%3447%11%39%
454
June1st to 10thNight
14%11%26%5%5%5%6%5%8%35%
198
July1st to 10thNight
9%7%36%7%5%6%6%9%12%30%
152
11th to 20thNight
18%8%47%10%5%6%9%6%8%18%
414
21st to endNight
18%7%48%8%6%5%7%8%8%22%
723
August1st to 10thNight
16%10%47%9%5%7%5%7%7%23%
914
11th to 20thNight
21%11%5%8%7%5%6%6%6%8%18%
1112
21st to endNight
21%13%5%8%6%5%6%5%5%8%19%
1526
September1st to 10thNight
18%10%46%6%45%7%7%9%24%
1586
11th to 20thNight
18%13%48%8%46%5%5%5%25%
1800
21st to endNight
18%21%6%10%7%4445%6%16%
2054
October1st to 10thNight
15%18%6%10%7%45%5%5%7%19%
2191
11th to 20thNight
13%20%7%14%9%44445%16%
2498
21st to endNight
10%20%7%11%9%5%6%5%5%6%16%
2956
November1st to 10thNight
6%16%8%12%10%6%8%6%5%7%16%
2992
11th to 20thNight
5%13%7%16%13%6%8%6%6%6%14%
3374
21st to endNight
413%7%14%11%6%7%9%9%7%13%
3604
December1st to 10thNight
6%14%6%11%9%5%8%7%8%9%17%
3800
11th to 20thNight
411%6%14%11%6%7%8%10%10%13%
5112
21st to endNight
414%6%9%9%5%7%7%9%10%21%
7500

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
54%11%11%16%8%
349
11th to 20thDay
62%8%7%15%6%2
548
21st to endDay
62%5%11%12%9%1
903
February1st to 10thDay
47%8%11%19%12%2
1009
11th to 20thDay
49%11%13%19%7%1
1235
21st to endDay
58%9%14%9%8%1
1228
March1st to 10thDay
51%7%10%21%10%1
1673
11th to 20thDay
57%5%9%20%8%
1890
21st to endDay
55%9%13%15%7%
2330
April1st to 10thDay
62%8%14%10%6%1
2360
11th to 20thDay
55%8%16%16%5%
2492
21st to endDay
47%8%20%20%5%1
2839
May1st to 10thDay
58%7%18%13%5%
2996
11th to 20thDay
51%7%14%24%4
3191
21st to endDay
46%6%14%27%7%
3819
June1st to 10thDay
50%8%15%21%6%
3761
11th to 20thDay
49%7%17%24%3
4104
21st to endDay
53%9%19%17%3
4150
July1st to 10thDay
52%9%21%16%2
3705
11th to 20thDay
64%9%17%9%1
3433
21st to endDay
61%8%19%11%1
3394
August1st to 10thDay
60%8%18%13%1
3004
11th to 20thDay
67%9%17%7%
2785
21st to endDay
68%8%16%7%1
2830
September1st to 10thDay
60%6%20%11%1
2373
11th to 20thDay
60%8%17%13%2
2160
21st to endDay
74%5%11%9%1
1904
October1st to 10thDay
69%6%12%12%1
1769
11th to 20thDay
72%7%14%6%2
1459
21st to endDay
68%6%11%14%1
1400
November1st to 10thDay
68%6%13%10%2
1067
11th to 20thDay
71%7%10%10%3
803
21st to endDay
65%9%6%14%5%1
574
December1st to 10thDay
63%8%9%13%7%
380
11th to 20thDay
77%5%5%9%5%
81
21st to endDay
55%10%5%14%9%7%
164
January1st to 10thNight
58%9%11%16%7%
3815
11th to 20thNight
63%7%7%17%5%1
3485
21st to endNight
62%6%10%11%10%1
3470
February1st to 10thNight
52%7%9%19%11%2
2948
11th to 20thNight
52%8%10%19%11%
2623
21st to endNight
57%6%14%11%11%1
2028
March1st to 10thNight
51%7%9%23%10%
2287
11th to 20thNight
54%5%8%22%10%
2070
21st to endNight
47%9%14%21%9%1
2026
April1st to 10thNight
60%8%12%13%5%2
1600
11th to 20thNight
53%9%13%18%7%
1415
21st to endNight
50%8%16%20%5%1
1121
May1st to 10thNight
54%7%17%17%5%
964
11th to 20thNight
49%7%17%24%3
708
21st to endNight
41%7%15%29%7%
454
June1st to 10thNight
47%11%15%23%4
198
July1st to 10thNight
44%16%23%16%1
146
11th to 20thNight
61%10%21%7%1
402
21st to endNight
55%8%23%12%1
683
August1st to 10thNight
58%9%22%9%2
910
11th to 20thNight
62%10%22%6%
1112
21st to endNight
65%8%19%8%1
1526
September1st to 10thNight
57%8%22%12%1
1586
11th to 20thNight
61%7%17%13%2
1800
21st to endNight
69%7%12%11%1
2054
October1st to 10thNight
65%9%13%12%1
2191
11th to 20thNight
72%5%11%9%2
2498
21st to endNight
67%6%11%14%2
2956
November1st to 10thNight
66%7%13%12%2
2992
11th to 20thNight
68%5%12%11%4
3374
21st to endNight
62%8%9%14%6%
3604
December1st to 10thNight
61%7%12%14%6%
3800
11th to 20thNight
60%8%9%13%10%
5111
21st to endNight
52%8%7%17%16%1
7500

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
8%18%44%27%12%
90
11th to 20thDay
7%211%40%28%12%
83
21st to endDay
5%6%16%41%23%10%
88
February1st to 10thDay
3211%44%26%15%
131
11th to 20thDay
6%310%36%30%14%
335
21st to endDay
6%5%19%30%24%16%
280
March1st to 10thDay
4313%34%26%20%
340
11th to 20thDay
5%5%20%30%27%13%
340
21st to endDay
5%7%19%26%26%17%
442
April1st to 10thDay
8%417%35%26%10%
564
11th to 20thDay
8%420%30%25%13%
590
21st to endDay
7%5%18%33%25%12%
600
May1st to 10thDay
13%5%22%33%21%7%
647
11th to 20thDay
14%5%19%29%24%9%
802
21st to endDay
16%7%17%35%21%5%
1047
June1st to 10thDay
17%6%20%32%21%5%
990
11th to 20thDay
17%5%18%31%24%6%
1062
21st to endDay
19%414%30%25%8%
1085
July1st to 10thDay
17%5%16%27%27%8%
971
11th to 20thDay
22%415%22%25%11%
966
21st to endDay
21%5%15%22%27%10%
946
August1st to 10thDay
24%7%11%27%18%12%
644
11th to 20thDay
28%5%18%26%16%7%
615
21st to endDay
30%6%21%24%15%4
693
September1st to 10thDay
25%8%18%19%18%12%
586
11th to 20thDay
27%317%27%20%6%
450
21st to endDay
28%8%18%19%19%9%
385
October1st to 10thDay
22%6%24%28%13%7%
360
11th to 20thDay
21%6%16%24%21%13%
360
21st to endDay
19%213%27%26%12%
266
November1st to 10thDay
9%5%13%31%26%16%
180
11th to 20thDay
10%311%25%33%18%
111
21st to endDay
11%120%28%27%13%
90
December1st to 10thDay
13%317%33%24%9%
90
11th to 20thDay
14%5%18%27%27%9%
22
21st to endDay
9%6%15%30%23%17%
47
January1st to 10thNight
10%310%32%30%14%
1130
11th to 20thNight
9%312%35%30%10%
1078
21st to endNight
9%314%36%30%9%
984
February1st to 10thNight
6%29%36%33%14%
800
11th to 20thNight
6%212%34%34%11%
784
21st to endNight
7%416%35%29%9%
658
March1st to 10thNight
6%213%39%31%10%
776
11th to 20thNight
6%210%34%39%9%
630
21st to endNight
4314%35%32%12%
594
April1st to 10thNight
11%414%29%34%9%
540
11th to 20thNight
9%214%33%34%8%
533
21st to endNight
7%316%37%30%6%
401
May1st to 10thNight
12%414%39%30%2
288
11th to 20thNight
12%315%28%38%3
177
21st to endNight
12%5%15%36%30%1
195
June1st to 10thNight
16%5%20%36%24%
122
July1st to 10thNight
13%5%17%31%30%4
121
11th to 20thNight
20%313%34%29%2
174
21st to endNight
19%314%27%34%3
197
August1st to 10thNight
22%115%35%25%1
216
11th to 20thNight
25%5%13%29%27%2
400
21st to endNight
26%5%15%22%24%8%
594
September1st to 10thNight
22%6%15%23%27%7%
540
11th to 20thNight
25%416%31%20%4
540
21st to endNight
27%318%25%22%5%
668
October1st to 10thNight
24%418%28%20%5%
720
11th to 20thNight
24%314%23%27%9%
799
21st to endNight
18%414%26%27%11%
891
November1st to 10thNight
11%314%29%34%11%
860
11th to 20thNight
10%411%29%32%15%
1040
21st to endNight
9%313%30%28%18%
1069
December1st to 10thNight
11%417%38%23%7%
1130
11th to 20thNight
9%214%32%34%10%
1130
21st to endNight
6%413%30%33%14%
1243
Page generated at 2024-01-11 02:22:41. Version ac07

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