Cypress Hills Dark-Sky Preserve - CHICO
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Cypress Hills Dark-Sky Preserve - CHICO clear sky chart from 2005-11-06 to 2024-01-16.

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
38%
23839
15%
74598
9%
23807
45%
23807
25%
45753

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
30%
948
14%
2836
7%
946
36%
946
22%
1864
January11th to 20thNight
29%
930
17%
2790
8%
930
38%
930
21%
1811
January21st to endNight
27%
882
16%
2836
7%
882
38%
882
19%
1808
February1st to 10thNight
35%
720
14%
2340
11%
720
40%
720
20%
1528
February11th to 20thNight
28%
700
14%
2273
9%
700
35%
700
21%
1467
February21st to endNight
37%
592
15%
1924
8%
592
46%
592
20%
1278
March1st to 10thNight
36%
720
14%
2074
8%
720
42%
720
23%
1405
March11th to 20thNight
36%
720
17%
1980
9%
720
43%
720
25%
1317
March21st to endNight
35%
792
13%
2178
4%
792
42%
792
21%
1541
April1st to 10thNight
35%
559
14%
1793
8%
559
41%
559
20%
1196
April11th to 20thNight
38%
533
17%
1601
10%
533
43%
533
23%
1072
April21st to endNight
37%
540
14%
1620
10%
540
41%
540
23%
1068
May1st to 10thNight
49%
540
12%
1472
10%
540
50%
540
28%
964
May11th to 20thNight
48%
515
16%
1401
11%
515
52%
515
32%
876
May21st to endNight
41%
389
9%
1358
7%
388
44%
388
18%
907
June1st to 10thNight
44%
360
7%
1260
5%
360
47%
360
23%
784
June11th to 20thNight
37%
360
6%
1260
4%
360
40%
360
23%
764
June21st to endNight
58%
360
8%
1260
6%
360
61%
360
38%
642
July1st to 10thNight
60%
350
9%
1225
8%
350
64%
350
40%
600
July11th to 20thNight
50%
348
14%
1218
11%
348
55%
348
38%
607
July21st to endNight
67%
394
24%
1302
23%
372
75%
372
49%
574
August1st to 10thNight
59%
537
18%
1540
14%
534
65%
534
42%
839
August11th to 20thNight
64%
534
21%
1602
16%
534
68%
534
41%
875
August21st to endNight
56%
594
26%
1782
18%
594
62%
594
38%
989
September1st to 10thNight
51%
540
22%
1770
17%
540
56%
540
36%
968
September11th to 20thNight
51%
648
22%
1908
17%
648
57%
648
33%
1144
September21st to endNight
46%
720
24%
1989
15%
720
54%
720
37%
1169
October1st to 10thNight
44%
720
20%
2160
11%
720
53%
720
28%
1325
October11th to 20thNight
38%
720
21%
2160
9%
720
49%
720
29%
1275
October21st to endNight
30%
821
16%
2548
7%
821
39%
821
21%
1633
November1st to 10thNight
29%
925
16%
2590
7%
925
37%
925
22%
1805
November11th to 20thNight
28%
950
18%
2660
7%
950
38%
950
26%
1695
November21st to endNight
28%
950
14%
2660
6%
950
35%
950
26%
1733
December1st to 10thNight
33%
950
14%
2850
7%
950
38%
950
23%
1870
December11th to 20thNight
30%
948
13%
3432
6%
948
38%
948
19%
2052
December21st to endNight
29%
1030
11%
4946
6%
1026
36%
1026
16%
2308

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
7%7%37%6%46%6%6%8%40%
74708
Night
5%7%37%7%46%6%7%9%40%
75101
TransparencyDay
39%6%17%25%12%2
74390
Night
37%6%18%24%12%2
74942
SeeingDay
11%11%30%29%16%4
14416
Night
9%11%33%32%14%2
23862

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
38%5%9%6%48%6%6%9%35%
1329
11th to 20thDay
27%49%7%5%8%7%7%10%34%
1298
21st to endDay
26%5%8%11%7%8%8%8%9%29%
1532
February1st to 10thDay
5%8%5%9%9%5%7%8%7%8%29%
1620
11th to 20thDay
39%5%8%8%6%7%8%10%10%26%
1575
21st to endDay
48%7%10%8%5%6%7%7%8%29%
1332
March1st to 10thDay
38%410%7%6%7%6%7%9%34%
1882
11th to 20thDay
48%47%7%5%7%7%8%9%35%
1980
21st to endDay
6%9%49%9%5%7%6%6%9%29%
2178
April1st to 10thDay
6%9%38%8%5%7%6%8%8%32%
2165
11th to 20thDay
10%12%5%10%7%46%5%5%7%29%
2307
21st to endDay
11%10%48%7%445%5%8%34%
2340
May1st to 10thDay
10%12%48%7%46%5%6%7%32%
2488
11th to 20thDay
9%7%37%7%46%6%6%8%38%
2491
21st to endDay
20%9%46%5%35%5%5%7%31%
2917
June1st to 10thDay
14%7%37%6%35%6%6%8%34%
2700
11th to 20thDay
16%8%36%7%46%6%6%7%30%
2700
21st to endDay
8%425%6%36%6%7%8%46%
2700
July1st to 10thDay
43245%35%6%7%11%49%
2700
11th to 20thDay
6%4244346%7%9%52%
2700
21st to endDay
42134345%6%7%61%
2937
August1st to 10thDay
6%41443446%7%56%
2388
11th to 20thDay
6%6%24425%6%6%9%51%
2299
21st to endDay
7%42343446%8%54%
2574
September1st to 10thDay
11%6%245%2446%6%50%
2189
11th to 20thDay
12%6%25%4345%5%8%47%
2048
21st to endDay
10%5%343245%6%8%50%
1971
October1st to 10thDay
8%8%37%7%445%7%8%40%
1800
11th to 20thDay
6%7%48%6%35%6%6%7%43%
1800
21st to endDay
5%9%5%8%8%445%6%8%39%
1787
November1st to 10thDay
8%12%5%9%8%45%5%6%6%32%
1488
11th to 20thDay
36%47%9%5%6%5%6%9%39%
1520
21st to endDay
47%5%8%7%5%7%7%7%7%36%
1516
December1st to 10thDay
310%49%10%5%8%7%7%8%31%
1330
11th to 20thDay
28%47%8%5%8%7%8%11%34%
1685
21st to endDay
27%36%7%46%5%6%8%47%
2442
January1st to 10thNight
37%48%7%45%7%9%10%35%
2836
11th to 20thNight
26%39%9%5%7%6%7%9%36%
2790
21st to endNight
26%47%9%6%8%9%9%10%29%
2836
February1st to 10thNight
48%5%9%8%5%8%8%8%9%29%
2340
11th to 20thNight
37%5%8%8%5%8%7%8%11%30%
2272
21st to endNight
37%5%10%10%5%7%7%8%9%30%
1924
March1st to 10thNight
46%48%8%5%8%8%8%9%31%
2074
11th to 20thNight
5%9%37%8%47%6%7%9%35%
1980
21st to endNight
6%9%49%9%47%6%8%10%29%
2178
April1st to 10thNight
6%9%49%7%5%7%6%6%8%32%
1793
11th to 20thNight
9%8%48%9%5%5%6%7%8%32%
1601
21st to endNight
8%9%48%7%45%6%6%8%35%
1620
May1st to 10thNight
8%10%37%5%45%6%6%7%39%
1472
11th to 20thNight
8%6%36%6%45%6%5%7%45%
1401
21st to endNight
15%8%48%7%345%48%33%
1358
June1st to 10thNight
14%5%37%5%245%5%8%40%
1260
11th to 20thNight
10%8%36%5%35%5%6%7%41%
1260
21st to endNight
6%415%3245%8%8%52%
1260
July1st to 10thNight
4415%4345%6%9%55%
1260
11th to 20thNight
5%4135%25%5%6%7%56%
1260
21st to endNight
32132345%6%7%63%
1379
August1st to 10thNight
5%325%5%2446%7%56%
1548
11th to 20thNight
6%4244345%7%10%51%
1602
21st to endNight
8%5%24425%45%8%53%
1782
September1st to 10thNight
9%6%144345%5%6%53%
1770
11th to 20thNight
9%6%26%5%3445%7%48%
1908
21st to endNight
6%6%36%5%3445%8%51%
1989
October1st to 10thNight
8%8%36%5%25%6%6%8%43%
2160
11th to 20thNight
5%6%36%7%45%6%8%9%42%
2160
21st to endNight
5%8%47%8%46%6%6%8%37%
2548
November1st to 10thNight
9%8%38%8%47%6%5%8%34%
2590
11th to 20thNight
36%36%8%5%8%7%8%8%37%
2660
21st to endNight
37%48%7%46%7%7%10%37%
2660
December1st to 10thNight
27%48%8%7%7%7%8%10%33%
2850
11th to 20thNight
27%47%7%5%7%7%8%10%36%
3506
21st to endNight
35%35%5%36%6%6%8%50%
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
41%8%21%23%5%2
1329
11th to 20thDay
43%8%18%21%8%1
1298
21st to endDay
44%8%21%21%6%1
1532
February1st to 10thDay
47%7%19%18%9%
1620
11th to 20thDay
46%8%19%21%6%1
1584
21st to endDay
50%6%15%17%10%1
1332
March1st to 10thDay
42%9%20%21%7%
1882
11th to 20thDay
40%8%21%22%8%1
1980
21st to endDay
49%6%20%17%7%1
2178
April1st to 10thDay
45%7%16%25%7%
2165
11th to 20thDay
52%5%12%24%7%1
2310
21st to endDay
47%5%16%24%6%1
2340
May1st to 10thDay
50%416%21%9%
2488
11th to 20thDay
42%6%15%28%8%1
2495
21st to endDay
52%5%15%21%7%
2918
June1st to 10thDay
46%5%17%22%9%1
2700
11th to 20thDay
48%5%14%22%10%1
2700
21st to endDay
32%7%20%28%12%1
2700
July1st to 10thDay
26%6%18%31%16%3
2626
11th to 20thDay
27%5%14%27%22%5%
2619
21st to endDay
19%6%13%30%26%6%
2774
August1st to 10thDay
26%5%14%30%20%5%
2372
11th to 20thDay
28%6%16%32%16%2
2299
21st to endDay
26%313%29%25%3
2574
September1st to 10thDay
33%313%25%19%6%
2189
11th to 20thDay
35%6%13%30%13%3
2048
21st to endDay
31%415%32%15%2
1971
October1st to 10thDay
40%6%18%25%11%1
1800
11th to 20thDay
38%5%18%26%11%2
1800
21st to endDay
42%6%17%25%11%
1787
November1st to 10thDay
51%6%14%20%9%1
1488
11th to 20thDay
38%7%22%24%8%1
1520
21st to endDay
42%7%20%21%9%1
1516
December1st to 10thDay
47%8%19%18%6%2
1330
11th to 20thDay
42%7%24%22%5%1
1684
21st to endDay
35%5%15%25%13%7%
2442
January1st to 10thNight
39%9%22%21%7%2
2836
11th to 20thNight
39%8%20%23%8%2
2790
21st to endNight
39%8%21%19%11%1
2836
February1st to 10thNight
44%6%20%18%10%2
2340
11th to 20thNight
43%6%20%20%11%1
2273
21st to endNight
45%6%14%22%9%3
1924
March1st to 10thNight
42%9%19%22%7%
2074
11th to 20thNight
41%6%20%22%10%1
1980
21st to endNight
47%7%17%21%7%2
2178
April1st to 10thNight
46%6%16%23%9%
1793
11th to 20thNight
45%5%13%23%13%1
1601
21st to endNight
44%6%15%27%7%1
1620
May1st to 10thNight
41%414%27%13%1
1472
11th to 20thNight
36%5%13%30%14%1
1402
21st to endNight
49%415%22%9%1
1358
June1st to 10thNight
41%5%19%25%9%1
1260
11th to 20thNight
40%5%14%25%14%1
1260
21st to endNight
25%6%19%34%14%2
1260
July1st to 10thNight
23%5%13%36%19%3
1225
11th to 20thNight
25%5%13%26%24%6%
1218
21st to endNight
17%5%12%31%28%7%
1302
August1st to 10thNight
26%5%13%32%17%6%
1540
11th to 20thNight
27%5%16%29%19%4
1602
21st to endNight
30%49%25%28%5%
1782
September1st to 10thNight
31%413%27%17%8%
1770
11th to 20thNight
35%412%31%13%4
1908
21st to endNight
31%5%15%31%17%2
1989
October1st to 10thNight
36%6%17%26%14%2
2160
11th to 20thNight
33%6%18%29%13%1
2160
21st to endNight
41%7%17%26%9%1
2548
November1st to 10thNight
46%7%16%21%9%2
2590
11th to 20thNight
36%7%25%20%12%
2660
21st to endNight
39%7%25%19%9%1
2660
December1st to 10thNight
41%8%20%20%9%1
2850
11th to 20thNight
37%7%29%21%5%1
3507
21st to endNight
31%5%16%26%15%8%
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
7%17%33%22%16%6%
180
11th to 20thDay
6%13%33%32%13%4
171
21st to endDay
319%37%31%8%2
188
February1st to 10thDay
11%18%37%26%6%2
240
11th to 20thDay
8%15%38%25%11%3
240
21st to endDay
410%38%32%14%3
198
March1st to 10thDay
9%12%38%28%11%2
394
11th to 20thDay
8%10%36%27%14%5%
420
21st to endDay
10%13%33%27%14%4
462
April1st to 10thDay
8%16%32%32%11%1
420
11th to 20thDay
13%14%34%27%11%1
412
21st to endDay
17%12%30%27%12%2
420
May1st to 10thDay
13%9%22%30%20%6%
571
11th to 20thDay
13%8%22%30%20%6%
625
21st to endDay
19%9%21%24%20%6%
679
June1st to 10thDay
16%11%23%30%18%3
630
11th to 20thDay
18%13%32%23%12%2
630
21st to endDay
11%6%27%28%23%5%
630
July1st to 10thDay
5%5%26%39%21%5%
621
11th to 20thDay
7%6%30%35%19%3
618
21st to endDay
5%5%26%36%22%6%
684
August1st to 10thDay
8%5%24%38%21%4
507
11th to 20thDay
8%6%22%38%20%6%
437
21st to endDay
6%8%27%34%19%5%
495
September1st to 10thDay
12%9%33%30%14%1
450
11th to 20thDay
12%10%28%30%15%4
450
21st to endDay
14%13%33%26%11%4
441
October1st to 10thDay
14%11%30%20%21%5%
270
11th to 20thDay
6%17%32%29%14%2
270
21st to endDay
14%16%35%25%9%1
297
November1st to 10thDay
17%15%36%21%10%1
270
11th to 20thDay
8%21%41%22%8%1
270
21st to endDay
5%20%37%22%13%3
268
December1st to 10thDay
8%17%41%22%9%3
180
11th to 20thDay
6%23%36%27%7%2
180
21st to endDay
9%11%26%38%13%4
198
January1st to 10thNight
7%17%38%27%10%1
950
11th to 20thNight
5%18%37%30%10%1
930
21st to endNight
5%20%40%24%9%2
882
February1st to 10thNight
8%14%31%29%15%3
720
11th to 20thNight
5%13%44%27%11%1
704
21st to endNight
6%10%32%31%16%5%
592
March1st to 10thNight
7%10%38%32%12%1
720
11th to 20thNight
9%11%34%32%11%3
720
21st to endNight
11%10%33%28%14%3
792
April1st to 10thNight
10%12%33%32%12%2
559
11th to 20thNight
13%7%35%32%12%1
533
21st to endNight
14%8%31%34%13%
540
May1st to 10thNight
12%8%22%34%21%2
540
11th to 20thNight
10%6%25%36%19%3
515
21st to endNight
19%8%21%28%21%3
389
June1st to 10thNight
17%10%22%31%18%2
360
11th to 20thNight
14%10%32%32%11%
360
21st to endNight
9%6%24%36%21%4
360
July1st to 10thNight
7%5%22%44%20%1
350
11th to 20thNight
8%5%31%41%13%1
348
21st to endNight
45%21%44%25%2
394
August1st to 10thNight
6%324%42%22%2
537
11th to 20thNight
9%319%41%27%1
534
21st to endNight
11%5%22%40%22%1
594
September1st to 10thNight
13%428%38%14%3
540
11th to 20thNight
12%7%24%37%18%2
648
21st to endNight
9%8%31%33%15%4
720
October1st to 10thNight
13%10%27%32%18%1
720
11th to 20thNight
9%12%33%29%14%2
720
21st to endNight
8%18%35%29%9%
821
November1st to 10thNight
14%13%37%29%7%
925
11th to 20thNight
8%17%41%25%7%1
950
21st to endNight
6%13%43%30%7%
950
December1st to 10thNight
6%14%37%29%12%2
950
11th to 20thNight
5%16%38%29%10%2
950
21st to endNight
9%14%36%29%10%2
1045
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Copyright 2024 Attilla Danko


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