Santa Teresa Spring
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Santa Teresa Spring clear sky chart from 2005-11-06 to 2024-07-31.

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	8% 5% 2 4 3 3 3 3 4 6% 59%	90001
	Night	9% 6% 2 5% 4 3 4 3 5% 6% 52%	89981
Transparency	Day	26% 6% 8% 20% 23% 16%	89720
	Night	31% 8% 9% 17% 20% 15%	89784
Seeing	Day	10% 10% 22% 32% 20% 6%	15041
	Night	10% 6% 14% 32% 30% 8%	24425

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	19% 9% 3 6% 4 3 3 3 5% 5% 41%	2678
	11th to 20th	Day	17% 7% 3 8% 4 5% 5% 4 5% 6% 35%	2860
	21st to end	Day	21% 9% 3 7% 5% 4 4 3 5% 7% 31%	3146
February	1st to 10th	Day	17% 8% 2 5% 3 3 3 3 5% 6% 45%	1710
	11th to 20th	Day	13% 6% 2 6% 5% 4 4 4 5% 7% 44%	1787
	21st to end	Day	16% 7% 2 6% 4 3 3 3 4 5% 47%	1570
March	1st to 10th	Day	12% 12% 3 10% 7% 7% 6% 4 5% 6% 26%	3343
	11th to 20th	Day	11% 5% 1 4 3 4 4 3 5% 7% 54%	3490
	21st to end	Day	13% 11% 3 8% 6% 5% 5% 5% 5% 7% 33%	3912
April	1st to 10th	Day	12% 7% 2 5% 5% 4 3 3 5% 7% 46%	2280
	11th to 20th	Day	10% 6% 2 5% 3 3 3 3 5% 7% 54%	2249
	21st to end	Day	5% 5% 2 4 3 4 4 3 5% 7% 59%	2280
May	1st to 10th	Day	6% 3 1 3 2 2 2 2 4 6% 69%	3826
	11th to 20th	Day	3 2 1 3 2 2 2 2 3 6% 73%	4190
	21st to end	Day	3 4 2 4 3 2 2 2 4 5% 69%	4813
June	1st to 10th	Day	3 4 2 4 2 2 3 3 5% 7% 63%	2660
	11th to 20th	Day	1 2 1 1 2 2 2 2 4 7% 76%	2660
	21st to end	Day	1 2 1 2 2 1 2 2 3 4 80%	2660
July	1st to 10th	Day	1 1 1 2 2 2 2 3 3 5% 81%	2660
	11th to 20th	Day	1 2 2 1 2 2 2 3 5% 80%	2503
	21st to end	Day	1 1 1 2 2 2 2 4 5% 81%	2679
August	1st to 10th	Day	1 2 1 3 2 2 3 2 4 6% 74%	2328
	11th to 20th	Day	1 1 2 2 2 3 3 4 82%	2148
	21st to end	Day	1 2 2 2 2 2 4 6% 79%	2376
September	1st to 10th	Day	1 2 1 1 1 1 1 2 2 5% 83%	2160
	11th to 20th	Day	1 2 1 4 2 2 3 3 5% 6% 71%	2160
	21st to end	Day	3 2 1 2 1 2 2 1 4 5% 78%	1927
October	1st to 10th	Day	3 3 1 3 2 3 2 2 5% 7% 69%	1800
	11th to 20th	Day	4 3 1 3 3 3 3 3 4 7% 67%	1800
	21st to end	Day	5% 4 1 4 3 3 3 3 4 5% 64%	1980
November	1st to 10th	Day	8% 4 2 5% 3 4 4 3 6% 7% 54%	1803
	11th to 20th	Day	8% 5% 2 5% 4 4 4 3 5% 6% 55%	1710
	21st to end	Day	12% 5% 2 3 2 2 4 3 5% 7% 55%	1611
December	1st to 10th	Day	11% 7% 2 7% 4 4 4 3 5% 7% 47%	1520
	11th to 20th	Day	27% 9% 3 5% 4 4 3 3 5% 5% 31%	1928
	21st to end	Day	15% 11% 3 7% 5% 4 4 4 6% 7% 34%	2794
January	1st to 10th	Night	12% 9% 3 7% 4 4 4 3 5% 5% 43%	4268
	11th to 20th	Night	18% 9% 3 6% 4 5% 5% 4 5% 7% 34%	4110
	21st to end	Night	21% 12% 3 6% 3 4 5% 4 4 6% 32%	4521
February	1st to 10th	Night	14% 8% 2 4 4 3 3 3 4 6% 49%	2470
	11th to 20th	Night	13% 6% 2 5% 3 4 4 4 7% 7% 44%	2279
	21st to end	Night	13% 7% 2 6% 4 2 3 3 4 7% 49%	1884
March	1st to 10th	Night	17% 15% 4 8% 5% 4 4 4 4 5% 31%	3529
	11th to 20th	Night	11% 6% 2 5% 4 3 3 2 3 5% 55%	3490
	21st to end	Night	14% 15% 3 7% 5% 4 4 3 4 6% 33%	3739
April	1st to 10th	Night	10% 7% 2 5% 4 4 5% 4 6% 6% 46%	1900
	11th to 20th	Night	9% 6% 2 6% 4 4 3 3 4 6% 54%	1879
	21st to end	Night	5% 5% 2 5% 4 3 4 3 5% 9% 54%	1900
May	1st to 10th	Night	2 5% 2 7% 5% 4 3 2 4 5% 62%	3149
	11th to 20th	Night	2 2 1 6% 4 4 6% 7% 9% 6% 54%	2707
	21st to end	Night	2 3 2 4 3 3 5% 4 5% 6% 63%	2762
June	1st to 10th	Night	2 4 1 4 4 2 4 5% 5% 8% 60%	1520
	11th to 20th	Night	2 1 2 3 4 4 3 5% 6% 68%	1520
	21st to end	Night	1 2 2 3 2 2 3 3 3 4 74%	1520
July	1st to 10th	Night	1 3 2 3 3 4 5% 6% 73%	1520
	11th to 20th	Night	1 1 2 2 3 3 4 5% 7% 73%	1671
	21st to end	Night	1 1 1 4 3 3 4 4 7% 8% 63%	1872
August	1st to 10th	Night	1 3 2 6% 4 4 4 3 5% 7% 61%	1611
	11th to 20th	Night	1 1 3 3 3 3 4 6% 8% 67%	1751
	21st to end	Night	1 1 3 3 4 4 4 4 6% 70%	1980
September	1st to 10th	Night	1 2 1 2 2 1 3 3 4 5% 76%	1800
	11th to 20th	Night	3 2 1 4 3 2 4 4 5% 5% 67%	1800
	21st to end	Night	2 2 1 3 2 2 3 2 3 5% 75%	2028
October	1st to 10th	Night	4 3 1 3 2 3 3 3 4 5% 70%	2160
	11th to 20th	Night	5% 4 2 4 2 3 3 3 4 6% 65%	2160
	21st to end	Night	5% 3 1 4 3 3 3 2 4 5% 66%	2376
November	1st to 10th	Night	7% 5% 1 4 3 3 3 3 4 7% 58%	2272
	11th to 20th	Night	7% 5% 2 5% 4 3 4 3 7% 9% 52%	2470
	21st to end	Night	8% 5% 2 5% 4 4 3 3 4 6% 57%	2565
December	1st to 10th	Night	13% 7% 2 6% 3 3 4 2 4 6% 49%	2660
	11th to 20th	Night	25% 10% 3 6% 4 3 3 3 5% 6% 33%	3276
	21st to end	Night	16% 8% 3 10% 5% 5% 5% 4 5% 5% 33%	4862

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	43% 5% 12% 28% 9% 3	2678
	11th to 20th	Day	47% 9% 10% 15% 11% 8%	2860
	21st to end	Day	52% 5% 8% 17% 13% 5%	3146
February	1st to 10th	Day	39% 4 7% 21% 18% 11%	1710
	11th to 20th	Day	38% 6% 9% 17% 22% 8%	1796
	21st to end	Day	39% 5% 7% 22% 20% 6%	1570
March	1st to 10th	Day	54% 9% 9% 12% 14% 3	3343
	11th to 20th	Day	29% 6% 11% 30% 13% 11%	3490
	21st to end	Day	46% 8% 14% 19% 10% 3	3912
April	1st to 10th	Day	37% 5% 12% 22% 19% 5%	2280
	11th to 20th	Day	29% 7% 15% 23% 20% 7%	2252
	21st to end	Day	25% 6% 11% 30% 23% 5%	2280
May	1st to 10th	Day	18% 4 10% 29% 27% 12%	3826
	11th to 20th	Day	12% 11% 5% 30% 34% 8%	4193
	21st to end	Day	18% 11% 8% 30% 30% 3	4814
June	1st to 10th	Day	21% 7% 11% 26% 26% 9%	2660
	11th to 20th	Day	12% 5% 8% 21% 36% 18%	2660
	21st to end	Day	13% 4 4 12% 31% 36%	2660
July	1st to 10th	Day	9% 4 4 10% 23% 50%	2591
	11th to 20th	Day	11% 4 6% 11% 22% 46%	2432
	21st to end	Day	9% 4 3 9% 32% 43%	2538
August	1st to 10th	Day	16% 5% 4 10% 30% 35%	2312
	11th to 20th	Day	9% 4 4 12% 32% 38%	2148
	21st to end	Day	11% 5% 4 10% 33% 37%	2376
September	1st to 10th	Day	10% 2 3 9% 30% 46%	2160
	11th to 20th	Day	15% 6% 5% 22% 33% 19%	2160
	21st to end	Day	12% 3 4 21% 36% 23%	1927
October	1st to 10th	Day	16% 4 8% 17% 27% 27%	1800
	11th to 20th	Day	19% 4 8% 19% 23% 27%	1800
	21st to end	Day	22% 5% 8% 18% 23% 23%	1980
November	1st to 10th	Day	28% 5% 8% 21% 24% 14%	1803
	11th to 20th	Day	29% 6% 10% 21% 26% 9%	1710
	21st to end	Day	28% 4 9% 17% 31% 11%	1611
December	1st to 10th	Day	35% 8% 10% 18% 18% 12%	1520
	11th to 20th	Day	54% 4 8% 15% 14% 6%	1928
	21st to end	Day	46% 6% 11% 21% 11% 4	2794
January	1st to 10th	Night	38% 8% 15% 23% 13% 4	4268
	11th to 20th	Night	47% 8% 13% 14% 10% 8%	4110
	21st to end	Night	51% 6% 10% 15% 12% 7%	4521
February	1st to 10th	Night	37% 3 8% 19% 20% 13%	2470
	11th to 20th	Night	36% 6% 11% 17% 22% 9%	2281
	21st to end	Night	33% 4 11% 27% 18% 6%	1884
March	1st to 10th	Night	52% 10% 10% 12% 13% 4	3529
	11th to 20th	Night	31% 9% 7% 23% 19% 11%	3490
	21st to end	Night	48% 7% 12% 19% 10% 4	3739
April	1st to 10th	Night	33% 8% 14% 21% 19% 6%	1900
	11th to 20th	Night	30% 7% 12% 26% 18% 7%	1879
	21st to end	Night	24% 8% 12% 27% 23% 6%	1900
May	1st to 10th	Night	21% 6% 11% 22% 25% 14%	3149
	11th to 20th	Night	18% 34% 7% 12% 21% 8%	2707
	21st to end	Night	17% 18% 10% 23% 29% 3	2762
June	1st to 10th	Night	21% 12% 11% 23% 22% 11%	1520
	11th to 20th	Night	19% 6% 9% 13% 30% 23%	1520
	21st to end	Night	17% 10% 3 12% 23% 35%	1520
July	1st to 10th	Night	14% 9% 8% 7% 17% 44%	1480
	11th to 20th	Night	15% 9% 8% 8% 19% 40%	1620
	21st to end	Night	23% 9% 8% 9% 19% 32%	1773
August	1st to 10th	Night	25% 10% 7% 9% 18% 30%	1602
	11th to 20th	Night	16% 9% 5% 9% 25% 35%	1751
	21st to end	Night	17% 10% 7% 6% 28% 32%	1980
September	1st to 10th	Night	12% 4 5% 8% 23% 47%	1800
	11th to 20th	Night	19% 9% 5% 17% 29% 21%	1800
	21st to end	Night	13% 6% 5% 15% 36% 25%	2028
October	1st to 10th	Night	18% 6% 8% 15% 24% 28%	2160
	11th to 20th	Night	22% 6% 6% 18% 22% 25%	2160
	21st to end	Night	21% 5% 6% 18% 25% 25%	2376
November	1st to 10th	Night	25% 5% 10% 21% 22% 18%	2272
	11th to 20th	Night	26% 6% 10% 21% 27% 10%	2470
	21st to end	Night	28% 4 9% 19% 25% 15%	2565
December	1st to 10th	Night	35% 6% 7% 19% 19% 14%	2660
	11th to 20th	Night	52% 4 9% 14% 16% 5%	3276
	21st to end	Night	48% 8% 13% 14% 12% 5%	4862

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	30% 15% 22% 20% 12% 1	267
	11th to 20th	Day	18% 14% 22% 28% 14% 4	370
	21st to end	Day	18% 11% 23% 26% 19% 3	407
February	1st to 10th	Day	21% 16% 23% 21% 14% 5%	370
	11th to 20th	Day	18% 19% 27% 23% 12%	425
	21st to end	Day	20% 16% 25% 27% 10% 2	382
March	1st to 10th	Day	23% 17% 27% 24% 7% 2	460
	11th to 20th	Day	23% 17% 19% 23% 14% 3	460
	21st to end	Day	19% 19% 31% 21% 9%	506
April	1st to 10th	Day	17% 18% 29% 22% 13% 1	460
	11th to 20th	Day	16% 18% 28% 23% 14% 2	452
	21st to end	Day	7% 18% 29% 28% 12% 6%	460
May	1st to 10th	Day	11% 16% 31% 27% 12% 3	463
	11th to 20th	Day	9% 12% 30% 29% 16% 5%	488
	21st to end	Day	7% 12% 26% 31% 18% 6%	529
June	1st to 10th	Day	6% 11% 28% 28% 18% 9%	490
	11th to 20th	Day	3 11% 29% 37% 15% 6%	490
	21st to end	Day	1 4 23% 41% 22% 8%	490
July	1st to 10th	Day	1 2 16% 41% 33% 7%	486
	11th to 20th	Day	1 1 12% 42% 35% 11%	484
	21st to end	Day	1 1 12% 44% 29% 15%	528
August	1st to 10th	Day	2 3 18% 38% 30% 9%	447
	11th to 20th	Day	1 17% 40% 27% 13%	437
	21st to end	Day	1 1 13% 41% 33% 11%	495
September	1st to 10th	Day	2 4 14% 41% 30% 9%	450
	11th to 20th	Day	2 6% 23% 40% 22% 7%	450
	21st to end	Day	4 8% 16% 41% 26% 5%	450
October	1st to 10th	Day	4 10% 24% 33% 24% 5%	450
	11th to 20th	Day	7% 8% 22% 32% 24% 7%	450
	21st to end	Day	9% 5% 25% 34% 22% 5%	495
November	1st to 10th	Day	9% 12% 19% 26% 27% 7%	399
	11th to 20th	Day	7% 9% 21% 30% 24% 10%	270
	21st to end	Day	11% 10% 22% 32% 21% 5%	223
December	1st to 10th	Day	15% 16% 16% 27% 19% 7%	180
	11th to 20th	Day	19% 16% 16% 28% 14% 8%	180
	21st to end	Day	21% 17% 20% 21% 16% 6%	198
January	1st to 10th	Night	18% 8% 16% 30% 20% 8%	760
	11th to 20th	Night	14% 6% 14% 34% 22% 9%	760
	21st to end	Night	19% 7% 14% 32% 23% 6%	836
February	1st to 10th	Night	20% 8% 13% 31% 21% 6%	760
	11th to 20th	Night	16% 10% 16% 32% 19% 6%	744
	21st to end	Night	17% 9% 18% 35% 17% 4	628
March	1st to 10th	Night	19% 11% 15% 32% 19% 4	760
	11th to 20th	Night	19% 9% 16% 26% 24% 5%	760
	21st to end	Night	16% 11% 20% 31% 19% 3	836
April	1st to 10th	Night	14% 10% 20% 32% 21% 4	760
	11th to 20th	Night	11% 12% 18% 33% 21% 5%	751
	21st to end	Night	7% 9% 26% 29% 22% 8%	760
May	1st to 10th	Night	6% 6% 24% 34% 24% 6%	742
	11th to 20th	Night	6% 4 13% 34% 36% 7%	487
	21st to end	Night	4 5% 17% 37% 31% 6%	411
June	1st to 10th	Night	4 4 15% 38% 32% 7%	380
	11th to 20th	Night	1 4 15% 43% 33% 4	380
	21st to end	Night	2 1 9% 37% 46% 6%	380
July	1st to 10th	Night	1 6% 34% 52% 8%	370
	11th to 20th	Night	1 2 28% 53% 16%	516
	21st to end	Night	1 1 3 27% 52% 16%	624
August	1st to 10th	Night	2 5% 32% 48% 12%	537
	11th to 20th	Night	1 6% 36% 45% 12%	683
	21st to end	Night	1 4 30% 52% 13%	792
September	1st to 10th	Night	2 2 6% 33% 45% 13%	720
	11th to 20th	Night	4 2 9% 34% 40% 10%	720
	21st to end	Night	3 3 11% 33% 38% 13%	720
October	1st to 10th	Night	5% 3 11% 36% 34% 11%	720
	11th to 20th	Night	8% 4 11% 33% 35% 11%	720
	21st to end	Night	7% 4 12% 32% 28% 17%	792
November	1st to 10th	Night	9% 6% 13% 32% 29% 11%	740
	11th to 20th	Night	11% 3 15% 35% 29% 8%	760
	21st to end	Night	10% 6% 16% 37% 24% 8%	760
December	1st to 10th	Night	17% 7% 15% 32% 23% 7%	760
	11th to 20th	Night	22% 7% 15% 30% 21% 5%	760
	21st to end	Night	19% 10% 19% 30% 18% 4	836

Page generated at 2024-07-28 06:52:15. Version ac07

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