Camp Tres Ritos
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Camp Tres Ritos clear sky chart from 2005-11-06 to 2024-07-16.

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 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	3 5% 2 5% 4 4 4 4 6% 7% 56%	89747
	Night	2 4 2 4 3 3 4 3 6% 8% 61%	89892
Transparency	Day	24% 5% 10% 20% 26% 15%	89464
	Night	19% 4 13% 23% 27% 14%	89697
Seeing	Day	13% 22% 29% 23% 11% 2	14828
	Night	7% 19% 31% 28% 13% 2	24914

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	3 2 6% 2 4 4 3 5% 8% 61%	2643
	11th to 20th	Day	1 3 1 7% 4 3 3 3 4 7% 66%	2860
	21st to end	Day	1 8% 2 6% 3 4 4 3 7% 7% 53%	3146
February	1st to 10th	Day	4 2 7% 4 3 4 4 5% 9% 58%	1763
	11th to 20th	Day	4 2 6% 4 4 4 3 4 7% 63%	1849
	21st to end	Day	4 2 5% 3 5% 4 4 6% 7% 59%	1570
March	1st to 10th	Day	1 6% 3 4 2 3 3 2 4 8% 65%	3191
	11th to 20th	Day	2 14% 8% 7% 4 3 4 3 5% 6% 43%	3490
	21st to end	Day	1 6% 2 5% 3 4 5% 3 6% 7% 58%	4006
April	1st to 10th	Day	1 5% 1 4 4 3 3 4 6% 8% 60%	2280
	11th to 20th	Day	3 7% 2 5% 3 3 3 4 5% 7% 59%	2251
	21st to end	Day	3 6% 2 4 4 4 4 3 5% 9% 57%	2280
May	1st to 10th	Day	2 8% 2 3 3 3 3 3 5% 6% 62%	3800
	11th to 20th	Day	8% 6% 2 4 3 4 5% 4 6% 8% 49%	4039
	21st to end	Day	2 3 1 3 2 3 3 3 4 7% 70%	4825
June	1st to 10th	Day	2 4 2 5% 3 4 5% 5% 6% 9% 56%	2660
	11th to 20th	Day	2 2 1 3 3 3 4 4 5% 8% 63%	2660
	21st to end	Day	6% 4 2 5% 5% 5% 6% 5% 8% 8% 47%	2660
July	1st to 10th	Day	7% 5% 2 6% 6% 6% 6% 6% 9% 8% 40%	2660
	11th to 20th	Day	5% 6% 1 7% 6% 6% 7% 6% 9% 9% 37%	2497
	21st to end	Day	9% 7% 3 9% 8% 8% 8% 6% 9% 9% 25%	2545
August	1st to 10th	Day	8% 7% 3 7% 8% 7% 6% 4 7% 7% 35%	2244
	11th to 20th	Day	9% 6% 2 7% 6% 7% 6% 5% 6% 7% 39%	2123
	21st to end	Day	7% 6% 2 7% 5% 5% 5% 5% 6% 9% 42%	2376
September	1st to 10th	Day	8% 7% 2 7% 6% 4 6% 4 6% 7% 43%	2160
	11th to 20th	Day	7% 6% 2 5% 4 4 4 3 6% 7% 53%	2152
	21st to end	Day	5% 4 2 5% 3 3 3 2 5% 6% 63%	1980
October	1st to 10th	Day	8% 6% 2 5% 3 4 4 4 4 6% 55%	1810
	11th to 20th	Day	4 3 1 3 2 2 2 1 4 5% 73%	1800
	21st to end	Day	3 5% 2 3 2 2 3 2 3 4 71%	1980
November	1st to 10th	Day	1 2 1 2 2 3 2 3 6% 8% 70%	1730
	11th to 20th	Day	1 4 1 3 2 2 3 3 5% 8% 69%	1710
	21st to end	Day	1 5% 2 4 4 3 3 2 5% 7% 63%	1710
December	1st to 10th	Day	1 4 2 4 1 3 3 3 5% 9% 66%	1577
	11th to 20th	Day	1 4 2 5% 4 4 4 4 6% 10% 58%	1926
	21st to end	Day	4 2 5% 3 3 3 3 5% 7% 65%	2794
January	1st to 10th	Night	2 2 7% 3 5% 5% 3 5% 7% 61%	4339
	11th to 20th	Night	1 2 1 4 3 3 4 4 6% 7% 65%	4110
	21st to end	Night	4 2 5% 4 4 4 3 6% 10% 58%	4521
February	1st to 10th	Night	3 2 5% 4 3 4 3 5% 9% 62%	2414
	11th to 20th	Night	1 4 3 5% 3 2 4 4 5% 8% 62%	2218
	21st to end	Night	1 3 1 6% 2 3 3 3 5% 7% 66%	1884
March	1st to 10th	Night	4 1 3 2 3 3 2 4 8% 69%	3659
	11th to 20th	Night	1 11% 6% 7% 3 3 2 3 4 5% 55%	3490
	21st to end	Night	1 3 2 5% 3 4 4 3 5% 7% 62%	3640
April	1st to 10th	Night	1 3 2 3 3 3 3 3 5% 7% 67%	1900
	11th to 20th	Night	1 6% 2 4 3 3 3 3 5% 7% 63%	1877
	21st to end	Night	3 5% 1 4 3 3 3 3 4 8% 64%	1900
May	1st to 10th	Night	2 7% 1 2 2 2 3 2 4 5% 69%	3170
	11th to 20th	Night	5% 9% 1 4 3 3 3 3 6% 9% 52%	2845
	21st to end	Night	3 2 1 3 2 2 3 2 4 6% 71%	2762
June	1st to 10th	Night	2 4 1 4 4 5% 5% 5% 7% 10% 54%	1520
	11th to 20th	Night	1 2 1 2 3 3 4 4 7% 6% 67%	1520
	21st to end	Night	7% 4 1 4 3 5% 5% 5% 7% 9% 50%	1520
July	1st to 10th	Night	5% 4 2 7% 6% 5% 7% 5% 7% 9% 44%	1520
	11th to 20th	Night	2 3 1 5% 5% 4 6% 5% 9% 11% 47%	1580
	21st to end	Night	6% 6% 2 6% 5% 7% 5% 7% 9% 12% 36%	1773
August	1st to 10th	Night	5% 4 1 5% 5% 6% 6% 6% 9% 12% 42%	1693
	11th to 20th	Night	7% 4 2 7% 5% 6% 7% 5% 9% 11% 39%	1778
	21st to end	Night	4 4 2 5% 4 4 5% 5% 9% 11% 47%	1980
September	1st to 10th	Night	5% 4 2 5% 4 4 6% 4 6% 9% 52%	1800
	11th to 20th	Night	4 4 1 4 2 3 3 3 7% 8% 60%	1807
	21st to end	Night	4 3 1 3 2 2 3 3 6% 7% 65%	1980
October	1st to 10th	Night	5% 4 1 3 3 4 3 3 4 5% 64%	2146
	11th to 20th	Night	2 3 1 2 2 1 2 1 4 5% 77%	2160
	21st to end	Night	3 4 2 2 2 2 3 2 5% 6% 69%	2376
November	1st to 10th	Night	1 2 1 2 2 2 2 3 4 6% 75%	2328
	11th to 20th	Night	1 2 1 3 2 2 5% 8% 74%	2470
	21st to end	Night	1 4 2 4 3 3 3 3 6% 7% 64%	2470
December	1st to 10th	Night	1 4 2 3 3 3 2 3 4 8% 69%	2598
	11th to 20th	Night	1 3 2 5% 3 5% 4 3 6% 10% 57%	3271
	21st to end	Night	1 3 1 4 3 3 4 3 5% 8% 65%	4873

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	16% 3 11% 26% 33% 11%	2644
	11th to 20th	Day	13% 2 12% 35% 30% 7%	2860
	21st to end	Day	25% 4 12% 24% 26% 10%	3146
February	1st to 10th	Day	22% 4 13% 23% 24% 15%	1763
	11th to 20th	Day	20% 4 9% 27% 26% 16%	1859
	21st to end	Day	20% 2 9% 18% 32% 20%	1570
March	1st to 10th	Day	17% 3 5% 17% 35% 22%	3191
	11th to 20th	Day	36% 4 8% 20% 26% 6%	3490
	21st to end	Day	21% 4 9% 26% 34% 8%	4006
April	1st to 10th	Day	19% 3 10% 25% 26% 16%	2280
	11th to 20th	Day	23% 3 7% 23% 29% 16%	2254
	21st to end	Day	22% 4 9% 24% 30% 10%	2280
May	1st to 10th	Day	22% 3 9% 17% 28% 22%	3800
	11th to 20th	Day	30% 6% 10% 16% 25% 12%	4043
	21st to end	Day	15% 4 7% 13% 28% 33%	4825
June	1st to 10th	Day	23% 6% 13% 21% 23% 14%	2660
	11th to 20th	Day	18% 6% 7% 16% 24% 29%	2660
	21st to end	Day	31% 7% 11% 17% 18% 16%	2660
July	1st to 10th	Day	36% 10% 14% 13% 16% 11%	2591
	11th to 20th	Day	36% 11% 16% 20% 11% 6%	2423
	21st to end	Day	48% 12% 21% 15% 4 1	2404
August	1st to 10th	Day	43% 10% 15% 14% 11% 7%	2229
	11th to 20th	Day	40% 9% 13% 17% 15% 6%	2123
	21st to end	Day	35% 8% 14% 22% 17% 4	2376
September	1st to 10th	Day	36% 8% 12% 18% 18% 8%	2160
	11th to 20th	Day	28% 6% 10% 18% 23% 14%	2152
	21st to end	Day	22% 4 7% 21% 32% 13%	1980
October	1st to 10th	Day	28% 5% 8% 19% 25% 16%	1810
	11th to 20th	Day	15% 2 4 14% 38% 27%	1800
	21st to end	Day	19% 2 6% 21% 36% 16%	1980
November	1st to 10th	Day	11% 2 10% 21% 36% 20%	1730
	11th to 20th	Day	12% 3 9% 28% 35% 14%	1710
	21st to end	Day	19% 2 7% 21% 30% 21%	1710
December	1st to 10th	Day	15% 3 15% 27% 26% 14%	1577
	11th to 20th	Day	19% 3 13% 22% 27% 15%	1924
	21st to end	Day	17% 2 9% 19% 32% 20%	2794
January	1st to 10th	Night	20% 3 11% 24% 31% 11%	4339
	11th to 20th	Night	13% 2 18% 33% 27% 8%	4110
	21st to end	Night	20% 2 16% 25% 27% 10%	4521
February	1st to 10th	Night	18% 2 15% 25% 25% 15%	2414
	11th to 20th	Night	18% 4 11% 29% 25% 14%	2218
	21st to end	Night	16% 1 10% 20% 34% 19%	1884
March	1st to 10th	Night	14% 2 7% 19% 37% 21%	3659
	11th to 20th	Night	29% 4 9% 26% 24% 9%	3490
	21st to end	Night	19% 3 11% 30% 33% 5%	3640
April	1st to 10th	Night	14% 3 12% 27% 30% 15%	1900
	11th to 20th	Night	20% 3 9% 24% 30% 15%	1877
	21st to end	Night	18% 4 12% 29% 29% 9%	1900
May	1st to 10th	Night	19% 3 7% 19% 32% 20%	3170
	11th to 20th	Night	27% 4 13% 24% 21% 11%	2846
	21st to end	Night	13% 4 9% 13% 27% 35%	2762
June	1st to 10th	Night	21% 7% 17% 20% 20% 15%	1520
	11th to 20th	Night	14% 4 8% 18% 26% 29%	1520
	21st to end	Night	28% 7% 13% 17% 19% 15%	1520
July	1st to 10th	Night	31% 11% 15% 15% 14% 13%	1480
	11th to 20th	Night	24% 12% 23% 22% 11% 7%	1531
	21st to end	Night	35% 12% 33% 16% 5%	1674
August	1st to 10th	Night	29% 13% 24% 14% 12% 8%	1684
	11th to 20th	Night	34% 9% 19% 22% 12% 4	1778
	21st to end	Night	26% 8% 23% 24% 16% 4	1980
September	1st to 10th	Night	25% 8% 18% 25% 17% 8%	1800
	11th to 20th	Night	21% 6% 14% 18% 29% 12%	1807
	21st to end	Night	19% 4 11% 25% 31% 11%	1980
October	1st to 10th	Night	22% 4 12% 19% 28% 15%	2146
	11th to 20th	Night	11% 3 6% 18% 37% 25%	2160
	21st to end	Night	17% 2 7% 24% 35% 15%	2376
November	1st to 10th	Night	10% 2 7% 26% 38% 17%	2328
	11th to 20th	Night	9% 3 9% 29% 34% 16%	2470
	21st to end	Night	16% 2 10% 23% 28% 20%	2470
December	1st to 10th	Night	15% 3 14% 31% 26% 12%	2598
	11th to 20th	Night	19% 3 14% 23% 27% 15%	3272
	21st to end	Night	16% 3 13% 22% 29% 17%	4873

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	15% 37% 25% 16% 7%	270
	11th to 20th	Day	23% 32% 26% 15% 4 1	270
	21st to end	Day	9% 35% 34% 15% 6% 1	297
February	1st to 10th	Day	18% 38% 27% 14% 3	270
	11th to 20th	Day	14% 44% 24% 13% 3	270
	21st to end	Day	36% 30% 27% 5% 1	225
March	1st to 10th	Day	23% 33% 27% 15% 2	305
	11th to 20th	Day	23% 28% 32% 12% 3 1	460
	21st to end	Day	28% 38% 25% 8% 1	506
April	1st to 10th	Day	18% 40% 31% 9% 3	460
	11th to 20th	Day	24% 39% 27% 8% 1	452
	21st to end	Day	20% 38% 31% 9% 1	460
May	1st to 10th	Day	16% 36% 37% 8% 2 1	463
	11th to 20th	Day	11% 24% 34% 21% 7% 1	613
	21st to end	Day	10% 23% 34% 25% 8%	734
June	1st to 10th	Day	3 14% 33% 34% 15% 1	680
	11th to 20th	Day	6% 18% 34% 27% 14% 1	680
	21st to end	Day	7% 13% 29% 30% 18% 3	680
July	1st to 10th	Day	6% 6% 24% 36% 24% 3	671
	11th to 20th	Day	7% 2 17% 39% 27% 8%	550
	21st to end	Day	9% 2 13% 39% 31% 6%	487
August	1st to 10th	Day	10% 6% 22% 40% 17% 5%	447
	11th to 20th	Day	6% 5% 30% 37% 20% 2	437
	21st to end	Day	9% 5% 27% 35% 21% 3	495
September	1st to 10th	Day	9% 7% 26% 39% 16% 2	450
	11th to 20th	Day	9% 8% 37% 32% 13% 1	442
	21st to end	Day	7% 16% 31% 31% 11% 4	270
October	1st to 10th	Day	10% 26% 29% 22% 11% 3	270
	11th to 20th	Day	10% 26% 32% 21% 8% 3	270
	21st to end	Day	17% 22% 31% 22% 7% 1	297
November	1st to 10th	Day	14% 31% 28% 24% 4	270
	11th to 20th	Day	9% 28% 34% 21% 8%	270
	21st to end	Day	11% 34% 30% 14% 9% 1	270
December	1st to 10th	Day	19% 29% 31% 13% 8% 1	270
	11th to 20th	Day	17% 35% 27% 16% 4	270
	21st to end	Day	23% 37% 27% 10% 3	297
January	1st to 10th	Night	9% 25% 31% 23% 10% 1	898
	11th to 20th	Night	9% 26% 33% 24% 6% 2	760
	21st to end	Night	5% 27% 37% 20% 9% 2	836
February	1st to 10th	Night	8% 28% 41% 18% 5%	760
	11th to 20th	Night	7% 33% 39% 17% 5%	744
	21st to end	Night	12% 34% 41% 12% 1	628
March	1st to 10th	Night	9% 31% 35% 19% 5% 1	760
	11th to 20th	Night	10% 21% 33% 26% 9%	760
	21st to end	Night	12% 27% 40% 17% 3	725
April	1st to 10th	Night	11% 28% 41% 18% 2	570
	11th to 20th	Night	11% 29% 33% 23% 4	563
	21st to end	Night	9% 27% 37% 22% 3	570
May	1st to 10th	Night	9% 19% 40% 22% 9% 1	570
	11th to 20th	Night	8% 19% 30% 29% 13% 1	561
	21st to end	Night	7% 17% 37% 31% 8%	617
June	1st to 10th	Night	4 7% 29% 43% 17%	570
	11th to 20th	Night	2 9% 38% 40% 10% 1	570
	21st to end	Night	4 7% 27% 36% 24% 2	570
July	1st to 10th	Night	3 3 17% 43% 31% 3	555
	11th to 20th	Night	3 1 9% 41% 40% 6%	540
	21st to end	Night	6% 1 9% 32% 43% 10%	591
August	1st to 10th	Night	5% 2 9% 39% 36% 9%	537
	11th to 20th	Night	7% 2 14% 44% 30% 3	534
	21st to end	Night	3 2 14% 42% 35% 5%	594
September	1st to 10th	Night	6% 2 18% 44% 27% 3	540
	11th to 20th	Night	5% 4 20% 46% 23% 2	540
	21st to end	Night	6% 10% 24% 43% 16% 1	540
October	1st to 10th	Night	6% 13% 32% 35% 13% 1	706
	11th to 20th	Night	6% 18% 31% 31% 11% 3	720
	21st to end	Night	8% 20% 29% 26% 13% 4	792
November	1st to 10th	Night	5% 19% 33% 30% 11% 1	848
	11th to 20th	Night	5% 23% 33% 27% 10% 2	950
	21st to end	Night	7% 24% 32% 24% 12% 1	950
December	1st to 10th	Night	12% 24% 37% 19% 7% 1	950
	11th to 20th	Night	9% 30% 32% 22% 6% 1	950
	21st to end	Night	12% 28% 36% 20% 4 1	1045

Page generated at 2024-07-13 08:19:51. Version ac07

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