Hatcher Pass Lodge
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Hatcher Pass Lodge 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
31%
21626
9%
81937
6%
21518
35%
21518
12%
59224

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
39%
935
14%
5585
11%
906
46%
906
11%
3656
January11th to 20thNight
26%
914
13%
5147
7%
890
32%
890
10%
3113
January21st to endNight
30%
912
8%
5414
8%
902
36%
902
9%
3301
February1st to 10thNight
31%
850
18%
2907
10%
850
39%
850
19%
1910
February11th to 20thNight
24%
834
7%
2593
5%
830
25%
830
12%
2049
February21st to endNight
28%
618
14%
2113
8%
618
35%
618
14%
1506
March1st to 10thNight
34%
649
16%
2276
11%
649
42%
649
18%
1520
March11th to 20thNight
39%
620
18%
2114
13%
620
48%
620
22%
1320
March21st to endNight
37%
596
13%
1985
10%
596
43%
596
19%
1342
April1st to 10thNight
30%
540
6%
1744
3%
540
32%
540
11%
1366
April11th to 20thNight
43%
533
5%
1423
3%
533
44%
533
21%
1027
April21st to endNight
41%
540
0%
1389
0%
540
41%
540
19%
1028
May1st to 10thNight
32%
388
0%
1108
0%
388
32%
388
12%
906
May11th to 20thNight
43%
339
0%
1048
0%
339
43%
339
16%
787
May21st to endNight
41%
195
0%
859
0%
194
41%
194
13%
590
June1st to 10thNight
38%
180
0%
720
0%
180
38%
180
9%
548
June11th to 20thNight
38%
180
0%
720
0%
180
38%
180
8%
577
June21st to endNight
34%
180
0%
720
0%
180
34%
180
7%
586
July1st to 10thNight
39%
175
0%
700
0%
175
39%
175
7%
562
July11th to 20thNight
32%
200
0%
722
0%
200
32%
200
7%
613
July21st to endNight
35%
394
0%
1087
0%
372
34%
372
8%
918
August1st to 10thNight
33%
358
0%
1068
0%
356
33%
356
9%
907
August11th to 20thNight
24%
484
0%
1353
0%
484
24%
484
7%
1187
August21st to endNight
30%
594
1%
1584
0%
594
30%
594
9%
1352
September1st to 10thNight
23%
540
2%
1718
2%
540
24%
540
6%
1500
September11th to 20thNight
28%
540
5%
1804
6%
540
28%
540
8%
1504
September21st to endNight
29%
569
4%
2037
4%
569
31%
569
9%
1636
October1st to 10thNight
25%
657
7%
2187
6%
657
27%
657
10%
1792
October11th to 20thNight
34%
810
8%
2349
5%
810
36%
810
16%
1798
October21st to endNight
32%
891
11%
2830
7%
891
35%
891
15%
2091
November1st to 10thNight
31%
830
9%
2786
7%
830
33%
830
16%
1997
November11th to 20thNight
36%
850
18%
3059
14%
850
44%
850
18%
2013
November21st to endNight
29%
850
13%
3230
9%
850
36%
850
12%
2356
December1st to 10thNight
27%
922
11%
3382
9%
922
31%
922
11%
2586
December11th to 20thNight
31%
940
7%
4209
6%
939
36%
939
9%
3275
December21st to endNight
24%
1019
7%
5967
5%
1004
30%
1004
7%
4005

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
20%16%5%9%7%45%5%5%5%20%
76710
Night
12%17%6%10%7%45%445%27%
82860
TransparencyDay
61%6%14%12%6%1
76356
Night
56%6%11%14%10%3
82797
SeeingDay
25%8%18%25%19%5%
16878
Night
21%9%21%27%18%3
21675

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
215%5%9%7%5%6%6%6%7%32%
1269
11th to 20thDay
6%15%5%8%5%445%5%5%39%
1549
21st to endDay
417%5%11%7%5%5%445%34%
2090
February1st to 10thDay
416%8%9%6%245%5%5%36%
1270
11th to 20thDay
7%24%10%10%6%5%45%5%7%18%
1478
21st to endDay
5%14%7%10%10%45%5%5%5%31%
1341
March1st to 10thDay
6%15%8%11%7%34345%35%
1844
11th to 20thDay
313%5%9%8%5%6%6%5%7%34%
1844
21st to endDay
5%15%8%11%8%45%5%5%7%27%
2371
April1st to 10thDay
7%21%9%12%9%46%5%5%5%17%
2213
11th to 20thDay
6%17%6%10%7%46%6%6%7%27%
2486
21st to endDay
9%19%6%9%6%46%5%5%6%24%
2571
May1st to 10thDay
13%21%6%9%9%5%6%6%5%5%17%
2852
11th to 20thDay
14%18%5%8%7%35%5%5%6%24%
2847
21st to endDay
20%14%47%6%45%5%5%6%24%
3415
June1st to 10thDay
22%14%48%7%46%5%6%6%17%
3240
11th to 20thDay
29%13%47%7%46%6%5%6%14%
3240
21st to endDay
32%15%47%5%45%5%5%5%13%
3240
July1st to 10thDay
34%12%47%6%35%5%6%6%13%
3240
11th to 20thDay
35%12%48%7%45%45%5%11%
3212
21st to endDay
36%12%48%5%35%446%13%
3167
August1st to 10thDay
41%12%47%6%35%34410%
2865
11th to 20thDay
40%12%47%6%45%5%4411%
2545
21st to endDay
36%11%47%6%345%5%5%13%
2772
September1st to 10thDay
39%14%38%6%3443312%
2241
11th to 20thDay
35%17%47%6%3333414%
2156
21st to endDay
27%14%5%9%6%35%445%18%
1922
October1st to 10thDay
26%19%5%8%6%3444417%
1772
11th to 20thDay
17%19%5%8%7%44346%23%
1608
21st to endDay
12%19%5%8%7%345%5%5%27%
1526
November1st to 10thDay
9%20%6%10%6%35%6%6%5%24%
1291
11th to 20thDay
9%17%5%9%6%2334437%
1121
21st to endDay
10%19%6%12%6%35%5%45%25%
950
December1st to 10thDay
12%22%6%13%6%236%46%21%
798
11th to 20thDay
319%12%16%9%4345%5%20%
967
21st to endDay
315%8%9%9%46%46%5%31%
1397
January1st to 10thNight
316%6%10%8%5%5%5%5%7%30%
5686
11th to 20thNight
7%15%6%9%7%3444439%
5363
21st to endNight
5%15%5%9%7%45%5%45%37%
5577
February1st to 10thNight
417%8%10%6%2434438%
2907
11th to 20thNight
7%23%10%12%8%35%445%19%
2589
21st to endNight
6%13%7%14%9%5%445%5%27%
2113
March1st to 10thNight
6%13%8%10%7%35%445%34%
2276
11th to 20thNight
313%6%9%7%46%5%5%6%36%
2114
21st to endNight
5%15%8%11%6%33446%34%
1985
April1st to 10thNight
7%21%8%13%9%5%5%44420%
1744
11th to 20thNight
7%17%6%7%8%5%6%5%5%5%30%
1423
21st to endNight
10%20%6%8%6%3435%6%28%
1389
May1st to 10thNight
13%22%5%11%8%45%5%4417%
1108
11th to 20thNight
13%17%5%8%6%46%6%47%24%
1047
21st to endNight
18%14%5%7%5%35%46%6%26%
859
June1st to 10thNight
23%13%6%8%9%34446%20%
720
11th to 20thNight
28%13%49%5%345%6%6%18%
720
21st to endNight
31%13%6%8%6%35%446%16%
720
July1st to 10thNight
32%10%38%45%6%6%46%17%
720
11th to 20thNight
36%11%5%7%5%35%346%16%
746
21st to endNight
40%11%35%43335%6%17%
1151
August1st to 10thNight
35%9%47%7%345%6%6%14%
1074
11th to 20thNight
43%12%46%5%4333414%
1353
21st to endNight
37%12%46%5%3344417%
1584
September1st to 10thNight
37%15%47%6%4333314%
1718
11th to 20thNight
36%15%5%6%5%2444415%
1804
21st to endNight
28%16%5%7%6%35%5%4417%
2037
October1st to 10thNight
26%21%5%7%6%34325%18%
2187
11th to 20thNight
16%18%5%9%7%3445%5%24%
2349
21st to endNight
12%20%5%10%6%35%5%5%5%23%
2830
November1st to 10thNight
9%21%6%9%7%36%45%427%
2786
11th to 20thNight
8%17%5%9%6%35%445%35%
3059
21st to endNight
8%21%6%11%7%45%445%25%
3230
December1st to 10thNight
12%25%6%10%6%34445%21%
3382
11th to 20thNight
418%10%16%8%45%5%4421%
4240
21st to endNight
415%8%12%9%45%6%5%430%
6270

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
42%10%13%17%13%4
1269
11th to 20thDay
45%49%21%16%6%
1564
21st to endDay
50%6%7%13%18%6%
2090
February1st to 10thDay
46%5%12%14%16%7%
1270
11th to 20thDay
62%5%11%12%7%2
1485
21st to endDay
51%8%10%16%13%2
1341
March1st to 10thDay
50%310%16%15%6%
1844
11th to 20thDay
42%5%10%22%17%4
1844
21st to endDay
51%6%15%13%11%4
2371
April1st to 10thDay
63%6%11%13%5%1
2213
11th to 20thDay
51%6%14%20%9%
2486
21st to endDay
58%5%10%18%8%1
2571
May1st to 10thDay
65%8%14%11%3
2852
11th to 20thDay
57%5%14%19%5%
2850
21st to endDay
55%6%16%19%3
3416
June1st to 10thDay
62%7%18%12%1
3240
11th to 20thDay
65%9%15%9%3
3240
21st to endDay
68%8%18%5%
3240
July1st to 10thDay
66%8%17%9%1
3151
11th to 20thDay
70%8%19%3
3113
21st to endDay
67%8%19%6%
2991
August1st to 10thDay
74%6%15%41
2846
11th to 20thDay
73%7%12%7%1
2545
21st to endDay
69%7%14%7%2
2772
September1st to 10thDay
73%7%10%8%2
2241
11th to 20thDay
72%6%13%9%1
2156
21st to endDay
65%5%15%11%3
1922
October1st to 10thDay
68%415%9%31
1772
11th to 20thDay
59%5%15%15%42
1608
21st to endDay
53%6%14%17%7%2
1526
November1st to 10thDay
55%6%13%15%7%3
1291
11th to 20thDay
50%39%22%14%1
1121
21st to endDay
58%410%12%13%3
950
December1st to 10thDay
63%5%10%13%9%1
798
11th to 20thDay
63%5%10%14%6%1
970
21st to endDay
46%9%10%13%15%8%
1397
January1st to 10thNight
48%8%9%19%12%4
5686
11th to 20thNight
45%6%10%18%18%3
5411
21st to endNight
44%9%6%13%21%7%
5577
February1st to 10thNight
48%46%17%18%7%
2907
11th to 20thNight
64%48%12%9%2
2593
21st to endNight
53%6%9%16%12%2
2113
March1st to 10thNight
49%5%9%15%14%8%
2276
11th to 20thNight
43%5%9%19%21%4
2116
21st to endNight
48%6%14%15%13%4
1985
April1st to 10thNight
63%6%11%14%41
1744
11th to 20thNight
50%6%15%19%9%
1423
21st to endNight
54%416%18%7%
1389
May1st to 10thNight
66%5%15%13%1
1108
11th to 20thNight
57%6%13%20%5%
1048
21st to endNight
54%6%19%18%3
859
June1st to 10thNight
63%6%21%10%1
720
11th to 20thNight
64%9%16%8%2
720
21st to endNight
69%6%21%4
720
July1st to 10thNight
66%8%18%7%1
700
11th to 20thNight
70%9%18%4
722
21st to endNight
67%10%18%5%
1087
August1st to 10thNight
69%8%19%4
1068
11th to 20thNight
74%7%12%6%1
1353
21st to endNight
70%7%14%6%2
1584
September1st to 10thNight
75%7%10%6%2
1718
11th to 20thNight
71%5%13%10%1
1804
21st to endNight
67%5%13%11%4
2037
October1st to 10thNight
70%311%12%3
2187
11th to 20thNight
59%5%17%13%6%1
2349
21st to endNight
57%5%13%15%8%2
2830
November1st to 10thNight
56%414%15%9%2
2786
11th to 20thNight
49%411%23%14%
3059
21st to endNight
58%5%9%13%12%4
3230
December1st to 10thNight
63%5%9%13%10%1
3382
11th to 20thNight
62%7%9%13%8%1
4236
21st to endNight
50%9%8%12%14%7%
6270

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%14%27%27%16%11%
90
11th to 20thDay
15%18%21%28%12%7%
227
21st to endDay
20%10%16%28%18%6%
308
February1st to 10thDay
11%11%22%29%16%10%
280
11th to 20thDay
21%14%22%22%16%3
365
21st to endDay
14%13%25%26%15%6%
307
March1st to 10thDay
15%10%26%29%16%4
362
11th to 20thDay
11%8%27%31%16%7%
384
21st to endDay
11%12%25%24%24%5%
572
April1st to 10thDay
15%10%28%26%18%3
538
11th to 20thDay
16%7%19%32%22%4
590
21st to endDay
19%8%20%31%19%4
600
May1st to 10thDay
19%11%23%26%18%3
603
11th to 20thDay
21%8%19%27%20%4
625
21st to endDay
26%6%19%29%17%3
790
June1st to 10thDay
25%8%15%21%25%8%
810
11th to 20thDay
28%5%15%23%23%6%
810
21st to endDay
30%6%14%22%22%6%
810
July1st to 10thDay
29%412%28%21%6%
796
11th to 20thDay
31%5%12%28%20%5%
792
21st to endDay
32%5%11%26%21%5%
714
August1st to 10thDay
39%5%17%22%14%4
626
11th to 20thDay
37%8%16%20%15%3
615
21st to endDay
37%6%14%24%16%3
693
September1st to 10thDay
35%7%15%25%14%4
569
11th to 20thDay
41%5%13%19%17%6%
536
21st to endDay
32%9%14%23%18%5%
360
October1st to 10thDay
36%8%19%18%14%5%
360
11th to 20thDay
24%6%14%26%22%7%
360
21st to endDay
23%9%15%23%20%9%
396
November1st to 10thDay
20%11%18%23%19%10%
360
11th to 20thDay
16%7%15%28%21%12%
261
21st to endDay
18%12%14%28%16%12%
90
December1st to 10thDay
27%11%10%26%26%1
90
11th to 20thDay
20%10%29%24%10%7%
90
21st to endDay
16%13%29%21%15%5%
99
January1st to 10thNight
11%11%27%31%17%4
940
11th to 20thNight
16%15%28%24%13%4
920
21st to endNight
17%10%24%31%15%3
935
February1st to 10thNight
11%13%30%26%17%3
850
11th to 20thNight
19%14%29%27%11%1
834
21st to endNight
13%9%32%29%13%4
618
March1st to 10thNight
12%11%27%34%14%2
649
11th to 20thNight
9%10%25%33%18%5%
620
21st to endNight
12%7%25%27%26%3
596
April1st to 10thNight
16%8%20%31%21%3
540
11th to 20thNight
14%6%19%28%29%4
533
21st to endNight
18%6%15%33%26%2
540
May1st to 10thNight
20%8%16%31%23%2
388
11th to 20thNight
17%7%15%37%20%4
339
21st to endNight
23%415%32%25%1
195
June1st to 10thNight
26%411%28%26%5%
180
11th to 20thNight
30%47%23%32%3
180
21st to endNight
33%5%8%17%33%4
180
July1st to 10thNight
32%27%18%36%5%
175
11th to 20thNight
40%5%423%25%4
200
21st to endNight
38%7%5%20%24%6%
394
August1st to 10thNight
38%49%26%18%4
358
11th to 20thNight
45%6%12%18%17%2
484
21st to endNight
40%48%22%23%3
594
September1st to 10thNight
41%6%11%23%15%4
540
11th to 20thNight
43%48%21%21%3
540
21st to endNight
32%8%15%21%20%4
569
October1st to 10thNight
36%7%17%20%17%3
657
11th to 20thNight
22%7%16%29%22%5%
810
21st to endNight
24%8%18%27%21%2
891
November1st to 10thNight
19%7%26%29%16%2
830
11th to 20thNight
16%9%22%31%19%4
850
21st to endNight
20%13%22%26%15%5%
850
December1st to 10thNight
25%10%21%27%14%3
922
11th to 20thNight
13%9%26%31%16%5%
940
21st to endNight
15%15%26%26%13%4
1034
Page generated at 2024-03-05 03:23:58. Version ac07

Copyright © 2024 Attilla Danko.


Hatcher Pass Lodge Clear Sky Chart |Charts Home