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 2024-01-17.

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	7% 4 2 3 3 2 3 4 4 6% 61%	74732
	Night	9% 5% 2 4 4 2 4 4 5% 7% 55%	75104
Transparency	Day	25% 5% 8% 18% 24% 18%	74451
	Night	30% 7% 9% 17% 21% 16%	74907
Seeing	Day	10% 11% 22% 32% 20% 6%	14286
	Night	10% 6% 13% 32% 30% 8%	23781

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% 7% 2 6% 4 3 4 4 5% 6% 39%	1606
	11th to 20th	Day	12% 4 2 5% 4 2 4 5% 5% 6% 51%	1675
	21st to end	Day	15% 7% 3 5% 5% 3 3 4 5% 6% 43%	1782
February	1st to 10th	Day	17% 6% 2 4 3 3 3 4 5% 6% 47%	1620
	11th to 20th	Day	13% 6% 2 5% 5% 3 3 5% 5% 7% 46%	1691
	21st to end	Day	16% 7% 2 6% 4 2 4 3 4 5% 46%	1480
March	1st to 10th	Day	15% 9% 3 6% 6% 3 5% 4 6% 8% 34%	1915
	11th to 20th	Day	17% 7% 2 5% 6% 4 5% 5% 6% 8% 36%	1980
	21st to end	Day	13% 6% 3 5% 4 3 4 6% 4 7% 44%	2227
April	1st to 10th	Day	13% 6% 3 5% 4 3 4 3 5% 7% 46%	2160
	11th to 20th	Day	10% 6% 2 4 4 2 3 4 5% 7% 55%	2129
	21st to end	Day	6% 4 2 3 3 3 4 4 5% 7% 59%	2160
May	1st to 10th	Day	4 5% 2 4 3 2 3 3 5% 8% 61%	2173
	11th to 20th	Day	5% 4 1 3 3 2 3 3 3 7% 65%	2368
	21st to end	Day	5% 4 2 5% 4 2 4 4 5% 7% 60%	2723
June	1st to 10th	Day	4 4 2 4 3 2 3 4 5% 8% 64%	2520
	11th to 20th	Day	1 2 1 1 2 2 2 2 4 7% 76%	2520
	21st to end	Day	1 2 1 2 2 1 2 3 3 4 79%	2520
July	1st to 10th	Day	1 1 1 2 2 1 2 3 3 5% 80%	2520
	11th to 20th	Day	1 1 1 1 2 1 2 2 3 5% 80%	2372
	21st to end	Day	1 1 2 1 2 2 3 5% 81%	2546
August	1st to 10th	Day	1 2 1 2 3 2 3 3 4 6% 74%	2328
	11th to 20th	Day	1 1 2 1 2 3 3 5% 82%	2148
	21st to end	Day	1 2 2 2 2 2 3 6% 79%	2376
September	1st to 10th	Day	1 2 1 1 1 1 2 2 2 4 83%	2160
	11th to 20th	Day	1 2 1 3 3 2 3 3 5% 6% 72%	2160
	21st to end	Day	3 2 1 1 2 1 2 2 4 5% 78%	1927
October	1st to 10th	Day	3 3 2 3 3 2 3 3 5% 7% 69%	1800
	11th to 20th	Day	4 3 1 2 3 2 3 3 4 7% 68%	1800
	21st to end	Day	5% 4 1 3 3 2 3 4 4 5% 64%	1980
November	1st to 10th	Day	8% 4 2 4 3 3 4 4 6% 7% 54%	1803
	11th to 20th	Day	8% 4 2 4 5% 3 5% 4 5% 6% 55%	1710
	21st to end	Day	12% 4 2 3 2 2 3 4 5% 7% 56%	1611
December	1st to 10th	Day	11% 7% 2 6% 4 3 4 4 5% 7% 47%	1520
	11th to 20th	Day	28% 8% 3 5% 4 3 3 3 5% 5% 31%	1928
	21st to end	Day	15% 11% 3 6% 6% 3 4 5% 6% 7% 35%	2794
January	1st to 10th	Night	14% 7% 2 6% 5% 3 4 5% 6% 6% 41%	2556
	11th to 20th	Night	11% 7% 2 4 4 3 5% 5% 5% 7% 46%	2429
	21st to end	Night	15% 6% 2 4 3 3 4 5% 5% 7% 45%	2574
February	1st to 10th	Night	14% 7% 2 4 4 2 4 3 3 6% 51%	2340
	11th to 20th	Night	12% 6% 2 5% 4 3 4 5% 6% 8% 45%	2155
	21st to end	Night	14% 6% 3 5% 4 2 3 3 4 7% 49%	1776
March	1st to 10th	Night	16% 9% 3 6% 5% 3 5% 5% 4 6% 38%	2043
	11th to 20th	Night	16% 7% 3 5% 5% 3 4 4 5% 8% 42%	1980
	21st to end	Night	12% 7% 3 4 5% 3 5% 4 5% 7% 46%	2127
April	1st to 10th	Night	11% 6% 2 5% 4 3 5% 5% 5% 7% 45%	1800
	11th to 20th	Night	9% 5% 3 6% 4 2 4 3 4 6% 55%	1779
	21st to end	Night	5% 4 2 4 4 2 4 4 5% 9% 56%	1800
May	1st to 10th	Night	3 5% 3 5% 5% 3 3 4 5% 7% 58%	1783
	11th to 20th	Night	4 4 2 4 4 3 4 5% 5% 8% 58%	1523
	21st to end	Night	4 4 3 5% 5% 3 5% 5% 5% 7% 55%	1552
June	1st to 10th	Night	3 4 1 3 4 2 4 6% 4 8% 61%	1440
	11th to 20th	Night	2 1 2 3 3 4 5% 5% 6% 68%	1440
	21st to end	Night	1 2 2 3 3 2 3 4 3 5% 74%	1440
July	1st to 10th	Night	1 3 2 2 3 5% 5% 6% 72%	1440
	11th to 20th	Night	1 1 1 1 2 2 4 4 5% 7% 74%	1583
	21st to end	Night	1 1 1 3 3 3 3 6% 7% 9% 64%	1773
August	1st to 10th	Night	1 3 2 5% 5% 3 4 4 5% 7% 61%	1611
	11th to 20th	Night	1 1 3 3 3 3 5% 6% 8% 68%	1751
	21st to end	Night	1 1 2 4 3 4 5% 4 6% 71%	1980
September	1st to 10th	Night	1 2 1 2 2 1 2 4 4 5% 77%	1800
	11th to 20th	Night	3 2 1 3 4 2 2 5% 4 5% 68%	1800
	21st to end	Night	2 2 1 2 2 2 3 2 3 5% 75%	2028
October	1st to 10th	Night	4 3 2 2 2 2 3 3 4 5% 70%	2160
	11th to 20th	Night	5% 4 2 3 3 2 3 3 4 6% 65%	2160
	21st to end	Night	5% 3 1 3 3 2 3 3 3 5% 66%	2376
November	1st to 10th	Night	8% 5% 2 4 3 2 4 3 4 7% 59%	2272
	11th to 20th	Night	7% 5% 2 4 4 2 4 4 6% 9% 53%	2470
	21st to end	Night	8% 4 2 4 4 2 4 4 4 7% 57%	2565
December	1st to 10th	Night	13% 6% 2 5% 4 2 4 3 4 6% 49%	2660
	11th to 20th	Night	25% 9% 3 5% 5% 2 4 4 5% 6% 33%	3276
	21st to end	Night	16% 8% 4 8% 6% 4 5% 5% 5% 6% 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% 6% 12% 21% 12% 6%	1606
	11th to 20th	Day	33% 7% 10% 18% 17% 14%	1675
	21st to end	Day	40% 5% 9% 14% 23% 9%	1782
February	1st to 10th	Day	37% 4 7% 21% 19% 12%	1620
	11th to 20th	Day	37% 6% 9% 17% 23% 8%	1700
	21st to end	Day	39% 5% 7% 21% 20% 6%	1480
March	1st to 10th	Day	46% 6% 11% 18% 16% 4	1915
	11th to 20th	Day	42% 6% 10% 19% 17% 4	1980
	21st to end	Day	38% 7% 14% 20% 16% 4	2227
April	1st to 10th	Day	38% 5% 12% 20% 20% 5%	2160
	11th to 20th	Day	29% 7% 14% 22% 20% 7%	2132
	21st to end	Day	25% 5% 11% 30% 23% 5%	2160
May	1st to 10th	Day	23% 5% 11% 24% 29% 7%	2173
	11th to 20th	Day	21% 5% 8% 30% 27% 8%	2371
	21st to end	Day	26% 7% 12% 27% 23% 4	2724
June	1st to 10th	Day	21% 7% 11% 26% 26% 10%	2520
	11th to 20th	Day	12% 5% 9% 22% 35% 18%	2520
	21st to end	Day	13% 5% 4 12% 32% 34%	2520
July	1st to 10th	Day	10% 5% 4 10% 24% 47%	2451
	11th to 20th	Day	11% 5% 6% 11% 24% 44%	2301
	21st to end	Day	9% 4 3 9% 33% 42%	2405
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	40% 7% 11% 21% 15% 6%	2556
	11th to 20th	Night	36% 6% 11% 17% 15% 14%	2429
	21st to end	Night	37% 7% 12% 13% 19% 11%	2574
February	1st to 10th	Night	36% 3 8% 20% 21% 13%	2340
	11th to 20th	Night	34% 5% 11% 17% 23% 9%	2157
	21st to end	Night	34% 3 12% 26% 18% 7%	1776
March	1st to 10th	Night	44% 7% 12% 16% 14% 6%	2043
	11th to 20th	Night	40% 6% 8% 20% 18% 7%	1980
	21st to end	Night	37% 5% 13% 20% 17% 7%	2127
April	1st to 10th	Night	34% 7% 14% 20% 19% 6%	1800
	11th to 20th	Night	31% 6% 12% 25% 19% 7%	1779
	21st to end	Night	23% 8% 12% 27% 23% 6%	1800
May	1st to 10th	Night	28% 7% 11% 19% 24% 11%	1783
	11th to 20th	Night	26% 11% 11% 19% 26% 7%	1523
	21st to end	Night	28% 11% 13% 20% 24% 4	1552
June	1st to 10th	Night	22% 11% 11% 23% 22% 12%	1440
	11th to 20th	Night	19% 6% 10% 13% 28% 23%	1440
	21st to end	Night	18% 10% 3 12% 24% 33%	1440
July	1st to 10th	Night	14% 10% 8% 8% 18% 42%	1400
	11th to 20th	Night	15% 10% 8% 8% 20% 39%	1532
	21st to end	Night	22% 9% 9% 9% 20% 32%	1674
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	359
	21st to end	Day	18% 10% 23% 26% 20% 3	374
February	1st to 10th	Day	20% 16% 22% 21% 15% 6%	340
	11th to 20th	Day	17% 19% 28% 24% 12% 1	389
	21st to end	Day	21% 17% 24% 26% 10% 1	346
March	1st to 10th	Day	23% 17% 26% 25% 7% 2	420
	11th to 20th	Day	24% 17% 19% 23% 13% 3	420
	21st to end	Day	18% 19% 32% 22% 10%	462
April	1st to 10th	Day	17% 19% 28% 23% 13% 1	420
	11th to 20th	Day	17% 19% 29% 21% 14% 1	412
	21st to end	Day	7% 20% 28% 27% 12% 6%	420
May	1st to 10th	Day	11% 17% 29% 28% 12% 3	423
	11th to 20th	Day	10% 13% 31% 28% 14% 4	448
	21st to end	Day	7% 13% 26% 31% 17% 5%	485
June	1st to 10th	Day	6% 12% 27% 27% 19% 9%	450
	11th to 20th	Day	3 11% 28% 37% 16% 6%	450
	21st to end	Day	1 4 23% 39% 23% 9%	450
July	1st to 10th	Day	1 2 16% 43% 31% 7%	446
	11th to 20th	Day	1 1 11% 42% 34% 11%	444
	21st to end	Day	1 12% 43% 29% 15%	487
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% 15% 34% 22% 9%	748
	21st to end	Night	18% 6% 14% 32% 23% 7%	792
February	1st to 10th	Night	19% 8% 12% 32% 22% 7%	720
	11th to 20th	Night	15% 11% 16% 32% 19% 7%	704
	21st to end	Night	17% 10% 18% 33% 18% 4	592
March	1st to 10th	Night	19% 11% 15% 32% 20% 4	720
	11th to 20th	Night	19% 8% 17% 26% 25% 5%	720
	21st to end	Night	15% 10% 20% 31% 20% 3	792
April	1st to 10th	Night	14% 9% 20% 33% 21% 4	720
	11th to 20th	Night	11% 13% 19% 32% 21% 5%	711
	21st to end	Night	7% 9% 25% 29% 22% 8%	720
May	1st to 10th	Night	6% 6% 22% 34% 25% 7%	703
	11th to 20th	Night	7% 4 13% 34% 35% 7%	461
	21st to end	Night	4 6% 16% 36% 31% 6%	389
June	1st to 10th	Night	5% 5% 15% 36% 33% 7%	360
	11th to 20th	Night	1 4 14% 43% 34% 4	360
	21st to end	Night	2 1 9% 36% 46% 7%	360
July	1st to 10th	Night	1 7% 33% 51% 8%	350
	11th to 20th	Night	1 2 27% 53% 17%	488
	21st to end	Night	1 1 2 27% 52% 17%	591
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 2024-01-14 06:55:04. Version ac07

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