Rancho Caņada del Oro
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Rancho Caņada del Oro clear sky chart from 2005-11-06 to 2025-09-19.

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 Type	Minimum conditions for hour to be usable				Out of hours
	Clear of Clouds	Transparency	Seeing	Sky Brightness
Planetary:	50%	(no limit)	Average	(no limit)	Nighttime Hours
Deep Sky:	70%	Average	(no limit)	5.9	Nighttime Hours
CCD Imaging:	70%	Below Average	Poor	(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

By Month

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 Forecast	Data Points
Cloud Cover	Day	5% 4 1 4 3 3 3 3 4 7% 63%	134676
	Night	7% 5% 2 6% 4 4 3 3 4 7% 54%	131827
Transparency	Day	24% 4 8% 19% 25% 20%	129618
	Night	30% 6% 10% 17% 21% 16%	127871
Seeing	Day	7% 10% 23% 31% 22% 7%	16583
	Night	9% 5% 15% 34% 31% 7%	25941

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	11% 7% 2 6% 4 3 3 3 4 7% 50%	3887
	11th to 20th	Day	11% 5% 3 6% 4 4 4 3 4 5% 54%	4100
	21st to end	Day	15% 7% 2 7% 5% 4 4 3 5% 6% 42%	4510
February	1st to 10th	Day	16% 8% 2 5% 3 4 4 3 5% 5% 46%	1800
	11th to 20th	Day	12% 7% 2 5% 4 4 4 4 6% 7% 44%	1881
	21st to end	Day	14% 7% 2 6% 4 4 4 3 5% 5% 46%	1650
March	1st to 10th	Day	11% 8% 3 7% 6% 7% 7% 5% 6% 7% 33%	4820
	11th to 20th	Day	10% 7% 1 5% 3 4 4 4 6% 8% 46%	5000
	21st to end	Day	11% 8% 2 7% 6% 5% 5% 5% 7% 10% 35%	5608
April	1st to 10th	Day	11% 7% 2 5% 5% 4 4 3 5% 7% 48%	2400
	11th to 20th	Day	8% 6% 2 4 3 3 4 3 6% 7% 54%	2369
	21st to end	Day	6% 5% 2 4 4 3 4 3 5% 9% 56%	2400
May	1st to 10th	Day	4 3 1 2 1 1 2 2 4 6% 73%	5481
	11th to 20th	Day	2 2 1 3 2 2 2 3 3 6% 72%	5988
	21st to end	Day	1 3 1 4 2 2 2 2 4 7% 71%	6902
June	1st to 10th	Day	3 4 2 4 3 2 2 4 4 8% 63%	2800
	11th to 20th	Day	1 3 1 2 2 2 3 2 3 7% 75%	2800
	21st to end	Day	1 2 1 3 2 2 2 2 3 5% 77%	2800
July	1st to 10th	Day	1 2 1 1 2 1 2 4 85%	6319
	11th to 20th	Day	1 1 2 1 1 2 2 3 6% 81%	5911
	21st to end	Day	1 1 3 2 2 2 2 4 8% 75%	6402
August	1st to 10th	Day	1 1 1 2 2 2 2 2 4 6% 77%	5777
	11th to 20th	Day	1 1 1 1 1 2 1 3 6% 82%	5432
	21st to end	Day	1 1 2 1 2 2 2 3 7% 79%	5984
September	1st to 10th	Day	2 2 1 2 1 2 1 1 3 5% 80%	2400
	11th to 20th	Day	2 4 1 4 2 3 4 3 4 8% 65%	2377
	21st to end	Day	3 2 3 2 2 2 2 3 5% 77%	2031
October	1st to 10th	Day	2 2 1 2 2 2 3 2 4 6% 74%	3180
	11th to 20th	Day	2 3 1 3 2 3 3 2 3 5% 73%	3161
	21st to end	Day	3 2 1 3 3 4 4 3 6% 7% 64%	3448
November	1st to 10th	Day	7% 4 2 5% 3 3 4 3 5% 7% 56%	1911
	11th to 20th	Day	8% 5% 2 6% 5% 3 4 3 5% 7% 53%	1800
	21st to end	Day	9% 5% 1 4 3 3 4 3 5% 7% 55%	1695
December	1st to 10th	Day	7% 4 1 4 4 4 4 3 5% 8% 55%	2620
	11th to 20th	Day	18% 6% 2 6% 5% 5% 5% 4 6% 8% 36%	3028
	21st to end	Day	14% 10% 3 9% 6% 5% 6% 4 6% 7% 30%	4004
January	1st to 10th	Night	8% 7% 3 7% 4 3 4 3 5% 7% 49%	6064
	11th to 20th	Night	11% 6% 2 8% 5% 4 4 3 4 4 50%	5880
	21st to end	Night	13% 9% 3 9% 4 3 4 3 4 5% 43%	6468
February	1st to 10th	Night	13% 8% 2 5% 4 3 4 3 4 5% 48%	2600
	11th to 20th	Night	12% 5% 3 6% 4 4 4 4 6% 7% 45%	2406
	21st to end	Night	11% 8% 2 6% 3 2 3 3 5% 7% 51%	1980
March	1st to 10th	Night	13% 11% 4 8% 5% 5% 5% 3 5% 6% 34%	5069
	11th to 20th	Night	11% 7% 2 8% 5% 5% 4 3 4 8% 44%	5000
	21st to end	Night	11% 10% 3 9% 6% 5% 5% 3 5% 6% 36%	5365
April	1st to 10th	Night	9% 6% 2 6% 4 4 4 4 5% 7% 47%	2000
	11th to 20th	Night	8% 6% 2 7% 4 3 3 3 4 7% 53%	1979
	21st to end	Night	5% 5% 2 5% 3 3 4 3 5% 10% 55%	2000
May	1st to 10th	Night	2 4 1 5% 3 3 3 2 4 6% 66%	4500
	11th to 20th	Night	1 2 3 11% 6% 6% 3 3 5% 9% 51%	3902
	21st to end	Night	1 4 3 5% 3 2 3 2 4 9% 63%	3972
June	1st to 10th	Night	2 3 2 6% 5% 3 3 3 5% 9% 58%	1600
	11th to 20th	Night	3 1 4 4 3 4 3 4 7% 65%	1600
	21st to end	Night	1 3 2 5% 3 3 3 3 4 8% 67%	1600
July	1st to 10th	Night	1 1 4 3 3 2 2 3 6% 76%	3640
	11th to 20th	Night	1 2 6% 5% 4 3 3 4 8% 65%	4049
	21st to end	Night	9% 4 7% 4 3 4 2 5% 11% 50%	4472
August	1st to 10th	Night	1 2 1 5% 5% 3 3 2 4 9% 66%	4035
	11th to 20th	Night	2 1 4 4 2 2 2 3 6% 73%	4435
	21st to end	Night	1 1 1 4 3 3 3 2 3 7% 71%	5015
September	1st to 10th	Night	1 3 1 4 2 2 2 3 4 7% 71%	2000
	11th to 20th	Night	2 4 2 7% 3 3 4 3 4 8% 59%	1980
	21st to end	Night	2 4 1 3 2 2 2 2 4 6% 72%	2145
October	1st to 10th	Night	2 2 1 2 2 2 3 2 3 6% 74%	3800
	11th to 20th	Night	2 5% 2 5% 3 3 2 2 4 7% 63%	3777
	21st to end	Night	3 3 2 5% 4 3 3 3 4 7% 63%	4121
November	1st to 10th	Night	6% 4 2 5% 4 3 3 3 5% 7% 59%	2385
	11th to 20th	Night	7% 5% 2 5% 3 3 4 4 5% 8% 53%	2600
	21st to end	Night	7% 5% 2 6% 4 3 4 3 4 7% 55%	2700
December	1st to 10th	Night	8% 4 2 4 3 4 4 3 5% 6% 58%	4560
	11th to 20th	Night	17% 7% 3 6% 5% 5% 4 4 7% 9% 33%	5176
	21st to end	Night	15% 11% 4 12% 6% 5% 5% 4 5% 6% 27%	6952

Transparency (when cloud cover <= 30%)
Color Meanings: Too cloudy to forecast Poor Below Average Average Above average Transparent
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	32% 6% 16% 25% 16% 5%	3887
	11th to 20th	Day	33% 5% 9% 13% 20% 21%	4100
	21st to end	Day	41% 5% 6% 12% 19% 16%	4510
February	1st to 10th	Day	39% 4 7% 20% 18% 11%	1800
	11th to 20th	Day	38% 5% 11% 18% 21% 8%	1890
	21st to end	Day	39% 5% 8% 22% 18% 7%	1650
March	1st to 10th	Day	46% 9% 8% 16% 19% 2	4820
	11th to 20th	Day	34% 7% 11% 30% 10% 8%	5000
	21st to end	Day	40% 11% 15% 21% 11% 2	5608
April	1st to 10th	Day	35% 6% 12% 23% 20% 4	2400
	11th to 20th	Day	30% 6% 13% 25% 20% 7%	2372
	21st to end	Day	26% 6% 13% 28% 22% 5%	2400
May	1st to 10th	Day	14% 4 8% 29% 32% 14%	5481
	11th to 20th	Day	17% 4 12% 30% 31% 6%	5991
	21st to end	Day	18% 5% 8% 28% 37% 3	6904
June	1st to 10th	Day	23% 5% 11% 27% 27% 7%	2800
	11th to 20th	Day	13% 4 9% 23% 35% 16%	2800
	21st to end	Day	16% 2 5% 13% 32% 32%	2800
July	1st to 10th	Day	7% 2 5% 6% 20% 59%	6251
	11th to 20th	Day	9% 1 8% 6% 14% 62%	5841
	21st to end	Day	11% 3 6% 18% 30% 33%	6217
August	1st to 10th	Day	15% 2 3 10% 32% 38%	4206
	11th to 20th	Day	8% 2 6% 9% 41% 35%	3924
	21st to end	Day	12% 2 6% 10% 34% 36%	4311
September	1st to 10th	Day	12% 2 3 11% 30% 42%	2400
	11th to 20th	Day	20% 4 7% 20% 32% 16%	2377
	21st to end	Day	12% 2 6% 21% 35% 24%	2031
October	1st to 10th	Day	14% 2 5% 11% 28% 41%	3180
	11th to 20th	Day	16% 4 6% 23% 31% 19%	3161
	21st to end	Day	20% 5% 6% 19% 30% 20%	3448
November	1st to 10th	Day	26% 5% 8% 23% 25% 13%	1911
	11th to 20th	Day	29% 5% 10% 22% 25% 8%	1800
	21st to end	Day	30% 3 10% 17% 30% 11%	1695
December	1st to 10th	Day	28% 4 8% 18% 35% 9%	2620
	11th to 20th	Day	47% 5% 8% 17% 15% 8%	3028
	21st to end	Day	50% 7% 12% 19% 10% 3	4004
January	1st to 10th	Night	29% 7% 17% 24% 17% 5%	6064
	11th to 20th	Night	35% 5% 10% 14% 23% 13%	5880
	21st to end	Night	40% 6% 8% 12% 16% 17%	6468
February	1st to 10th	Night	38% 3 8% 18% 20% 12%	2600
	11th to 20th	Night	36% 5% 12% 19% 21% 8%	2408
	21st to end	Night	32% 4 10% 29% 18% 7%	1980
March	1st to 10th	Night	46% 9% 10% 14% 17% 3	5069
	11th to 20th	Night	37% 7% 11% 22% 15% 8%	5000
	21st to end	Night	41% 10% 12% 23% 12% 3	5365
April	1st to 10th	Night	32% 7% 14% 22% 19% 6%	2000
	11th to 20th	Night	31% 6% 12% 27% 17% 7%	1979
	21st to end	Night	25% 9% 13% 28% 21% 6%	2000
May	1st to 10th	Night	19% 9% 10% 22% 26% 14%	4497
	11th to 20th	Night	37% 6% 10% 19% 23% 5%	3903
	21st to end	Night	20% 8% 13% 20% 37% 3	3972
June	1st to 10th	Night	25% 9% 11% 24% 22% 9%	1600
	11th to 20th	Night	21% 5% 7% 15% 30% 21%	1600
	21st to end	Night	25% 3 5% 14% 24% 30%	1600
July	1st to 10th	Night	15% 4 11% 5% 15% 51%	3600
	11th to 20th	Night	21% 2 18% 6% 11% 42%	3997
	21st to end	Night	33% 6% 15% 9% 16% 22%	4345
August	1st to 10th	Night	25% 2 7% 8% 25% 33%	2929
	11th to 20th	Night	16% 2 11% 8% 28% 36%	3211
	21st to end	Night	20% 3 8% 9% 32% 28%	3608
September	1st to 10th	Night	16% 4 6% 10% 24% 41%	2000
	11th to 20th	Night	26% 5% 6% 18% 29% 17%	1980
	21st to end	Night	17% 3 6% 15% 36% 23%	2145
October	1st to 10th	Night	15% 3 6% 9% 21% 47%	3800
	11th to 20th	Night	23% 5% 7% 22% 24% 20%	3777
	21st to end	Night	22% 3 5% 21% 27% 22%	4121
November	1st to 10th	Night	25% 5% 8% 23% 24% 15%	2385
	11th to 20th	Night	28% 4 10% 22% 27% 9%	2600
	21st to end	Night	30% 4 9% 19% 24% 15%	2700
December	1st to 10th	Night	26% 4 6% 23% 28% 13%	4560
	11th to 20th	Night	45% 6% 9% 15% 19% 5%	5176
	21st to end	Night	51% 9% 12% 15% 9% 4	6952

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
Month	Days in Month		Occurrence of each Forecast	Data Points
January	1st to 10th	Day	25% 15% 21% 24% 12% 3	305
	11th to 20th	Day	14% 12% 24% 31% 16% 5%	400
	21st to end	Day	14% 11% 24% 26% 22% 4	440
February	1st to 10th	Day	18% 17% 25% 19% 16% 6%	400
	11th to 20th	Day	15% 18% 28% 25% 12% 2	460
	21st to end	Day	14% 15% 28% 28% 13% 1	414
March	1st to 10th	Day	18% 19% 29% 23% 10% 1	500
	11th to 20th	Day	18% 17% 24% 23% 14% 3	500
	21st to end	Day	15% 19% 31% 22% 11% 2	550
April	1st to 10th	Day	14% 14% 30% 27% 14% 2	500
	11th to 20th	Day	11% 17% 29% 25% 14% 4	492
	21st to end	Day	6% 15% 28% 28% 16% 6%	500
May	1st to 10th	Day	6% 15% 33% 28% 13% 5%	503
	11th to 20th	Day	8% 11% 30% 29% 17% 5%	528
	21st to end	Day	5% 10% 27% 34% 17% 6%	573
June	1st to 10th	Day	5% 8% 27% 31% 20% 9%	530
	11th to 20th	Day	2 9% 29% 38% 18% 5%	530
	21st to end	Day	1 4 20% 41% 24% 10%	530
July	1st to 10th	Day	1 1 17% 39% 33% 9%	526
	11th to 20th	Day	1 10% 41% 36% 11%	524
	21st to end	Day	1 9% 42% 34% 15%	575
August	1st to 10th	Day	2 2 17% 39% 31% 10%	527
	11th to 20th	Day	2 17% 40% 27% 14%	517
	21st to end	Day	1 1 12% 38% 36% 11%	583
September	1st to 10th	Day	1 4 14% 39% 30% 11%	530
	11th to 20th	Day	2 6% 23% 39% 20% 11%	523
	21st to end	Day	3 6% 17% 37% 30% 8%	490
October	1st to 10th	Day	2 9% 23% 30% 27% 9%	490
	11th to 20th	Day	6% 9% 19% 30% 27% 10%	490
	21st to end	Day	7% 6% 23% 32% 24% 8%	539
November	1st to 10th	Day	7% 12% 18% 25% 29% 9%	447
	11th to 20th	Day	8% 8% 20% 28% 26% 9%	300
	21st to end	Day	10% 7% 22% 33% 23% 4	247
December	1st to 10th	Day	10% 13% 22% 27% 21% 8%	200
	11th to 20th	Day	15% 15% 19% 25% 19% 10%	200
	21st to end	Day	15% 18% 23% 25% 15% 5%	220
January	1st to 10th	Night	17% 6% 17% 32% 23% 6%	800
	11th to 20th	Night	14% 6% 15% 35% 22% 8%	800
	21st to end	Night	17% 5% 14% 34% 24% 5%	880
February	1st to 10th	Night	16% 10% 15% 32% 22% 6%	800
	11th to 20th	Night	15% 8% 19% 34% 19% 5%	784
	21st to end	Night	15% 7% 20% 38% 18% 3	660
March	1st to 10th	Night	15% 10% 21% 31% 20% 4	800
	11th to 20th	Night	16% 9% 18% 29% 24% 5%	800
	21st to end	Night	13% 9% 24% 33% 19% 3	880
April	1st to 10th	Night	11% 7% 22% 35% 23% 3	800
	11th to 20th	Night	10% 10% 20% 35% 20% 5%	791
	21st to end	Night	6% 7% 24% 33% 23% 7%	800
May	1st to 10th	Night	5% 4 24% 37% 25% 5%	779
	11th to 20th	Night	5% 2 14% 36% 36% 7%	524
	21st to end	Night	4 4 18% 39% 30% 5%	433
June	1st to 10th	Night	4 4 13% 41% 33% 6%	400
	11th to 20th	Night	1 3 16% 46% 33% 3	400
	21st to end	Night	1 2 8% 36% 48% 5%	400
July	1st to 10th	Night	1 5% 34% 55% 5%	390
	11th to 20th	Night	1 2 26% 55% 17%	559
	21st to end	Night	1 5% 27% 51% 15%	657
August	1st to 10th	Night	3 7% 33% 48% 9%	597
	11th to 20th	Night	1 1 9% 36% 44% 9%	759
	21st to end	Night	1 1 5% 31% 51% 11%	880
September	1st to 10th	Night	2 1 9% 31% 46% 12%	800
	11th to 20th	Night	3 2 10% 35% 40% 10%	792
	21st to end	Night	3 2 11% 32% 41% 12%	760
October	1st to 10th	Night	4 3 11% 35% 36% 12%	760
	11th to 20th	Night	7% 3 12% 32% 35% 11%	760
	21st to end	Night	6% 4 12% 34% 29% 16%	836
November	1st to 10th	Night	6% 5% 16% 30% 32% 11%	780
	11th to 20th	Night	9% 4 15% 36% 30% 7%	800
	21st to end	Night	9% 4 16% 37% 26% 8%	800
December	1st to 10th	Night	13% 7% 15% 34% 25% 6%	800
	11th to 20th	Night	18% 7% 17% 34% 21% 4	800
	21st to end	Night	16% 9% 22% 32% 17% 4	880

Page generated at 2025-09-15 22:49:15. Version ac07

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