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 2025-01-07.

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 4 3 3 3 3 4 6% 62%	108656
	Night	9% 6% 2 5% 3 3 4 3 5% 6% 54%	109127
Transparency	Day	25% 5% 7% 18% 24% 21%	108412
	Night	31% 7% 8% 16% 20% 18%	108961
Seeing	Day	10% 10% 23% 32% 20% 6%	15579
	Night	10% 6% 14% 33% 30% 8%	25050

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	18% 9% 3 6% 4 3 3 3 5% 5% 41%	2728
	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 1 2 2 3 88%	4420
	11th to 20th	Day	1 1 2 1 2 2 2 3 4 80%	4155
	21st to end	Day	2 2 2 2 2 3 4 83%	4455
August	1st to 10th	Day	1 1 1 2 2 2 2 3 5% 6% 75%	4091
	11th to 20th	Day	1 1 1 2 2 3 4 86%	3762
	21st to end	Day	1 2 2 2 2 2 3 5% 81%	4180
September	1st to 10th	Day	1 2 1 1 1 1 1 2 2 4 83%	2280
	11th to 20th	Day	2 2 1 4 2 2 3 3 5% 6% 71%	2280
	21st to end	Day	3 2 1 2 1 2 2 1 4 4 78%	2033
October	1st to 10th	Day	2 2 1 2 2 2 2 2 4 6% 74%	3180
	11th to 20th	Day	2 2 1 4 3 2 2 2 3 5% 73%	3161
	21st to end	Day	3 3 1 4 3 4 3 4 5% 7% 64%	3448
November	1st to 10th	Day	8% 4 2 4 3 4 4 3 6% 7% 55%	1900
	11th to 20th	Day	8% 5% 2 5% 4 4 4 3 5% 6% 54%	1800
	21st to end	Day	12% 5% 2 3 2 2 4 3 5% 7% 54%	1695
December	1st to 10th	Day	7% 4 1 5% 3 4 4 3 5% 8% 55%	2620
	11th to 20th	Day	22% 8% 3 6% 4 4 4 4 6% 6% 34%	3028
	21st to end	Day	19% 12% 4 8% 5% 4 4 4 6% 6% 29%	4004
January	1st to 10th	Night	12% 9% 3 7% 4 4 4 3 5% 5% 43%	4351
	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 2 1 2 2 3 3 4 83%	2540
	11th to 20th	Night	1 3 2 3 4 5% 5% 5% 71%	2795
	21st to end	Night	1 3 8% 3 3 7% 4 5% 6% 60%	3109
August	1st to 10th	Night	1 2 1 4 3 3 3 3 5% 7% 68%	2848
	11th to 20th	Night	1 3 2 2 2 3 4 5% 76%	3084
	21st to end	Night	1 2 1 5% 3 3 3 4 3 4 72%	3498
September	1st to 10th	Night	1 1 1 2 2 1 3 3 4 4 77%	1900
	11th to 20th	Night	3 3 2 5% 3 2 4 4 5% 5% 66%	1900
	21st to end	Night	2 2 1 3 2 2 3 2 3 5% 75%	2142
October	1st to 10th	Night	2 2 1 2 2 2 2 2 3 6% 77%	3800
	11th to 20th	Night	3 3 2 9% 3 2 2 3 4 5% 65%	3777
	21st to end	Night	4 4 2 4 3 3 3 3 4 5% 64%	4121
November	1st to 10th	Night	7% 5% 1 4 3 3 3 3 4 7% 59%	2395
	11th to 20th	Night	7% 5% 2 5% 4 3 4 3 6% 8% 53%	2600
	21st to end	Night	8% 5% 2 5% 4 4 4 3 4 7% 55%	2700
December	1st to 10th	Night	8% 4 1 4 3 3 4 3 5% 6% 59%	4560
	11th to 20th	Night	20% 10% 3 6% 4 3 4 4 7% 9% 31%	5176
	21st to end	Night	20% 10% 4 11% 5% 6% 5% 3 5% 5% 26%	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	43% 5% 12% 28% 8% 3	2728
	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	6% 3 2 6% 14% 70%	4351
	11th to 20th	Day	12% 3 3 6% 14% 61%	4084
	21st to end	Day	10% 2 2 6% 32% 48%	4315
August	1st to 10th	Day	13% 3 2 8% 32% 42%	4076
	11th to 20th	Day	7% 3 2 7% 41% 41%	3798
	21st to end	Day	10% 3 4 8% 35% 40%	4179
September	1st to 10th	Day	10% 2 3 8% 30% 47%	2280
	11th to 20th	Day	16% 6% 5% 23% 33% 18%	2280
	21st to end	Day	12% 3 4 21% 37% 24%	2033
October	1st to 10th	Day	13% 2 5% 10% 27% 42%	3180
	11th to 20th	Day	17% 2 5% 23% 32% 20%	3161
	21st to end	Day	20% 3 5% 19% 32% 20%	3448
November	1st to 10th	Day	27% 5% 9% 22% 24% 14%	1900
	11th to 20th	Day	29% 5% 10% 22% 25% 9%	1800
	21st to end	Day	29% 4 9% 17% 31% 10%	1695
December	1st to 10th	Day	28% 4 6% 20% 35% 8%	2620
	11th to 20th	Day	49% 3 8% 18% 15% 7%	3028
	21st to end	Day	53% 5% 11% 18% 10% 3	4004
January	1st to 10th	Night	38% 8% 15% 23% 12% 4	4351
	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	9% 6% 4 4 10% 66%	2500
	11th to 20th	Night	20% 6% 5% 4 14% 51%	2744
	21st to end	Night	29% 5% 5% 6% 19% 35%	3011
August	1st to 10th	Night	19% 6% 4 6% 24% 40%	2839
	11th to 20th	Night	14% 5% 3 5% 31% 42%	3114
	21st to end	Night	19% 6% 5% 6% 32% 33%	3498
September	1st to 10th	Night	12% 4 5% 7% 23% 48%	1900
	11th to 20th	Night	21% 9% 5% 17% 29% 20%	1900
	21st to end	Night	14% 5% 5% 15% 36% 25%	2142
October	1st to 10th	Night	12% 4 4 10% 21% 49%	3800
	11th to 20th	Night	24% 4 5% 22% 25% 20%	3777
	21st to end	Night	22% 3 4 20% 28% 22%	4121
November	1st to 10th	Night	25% 5% 10% 21% 23% 17%	2395
	11th to 20th	Night	27% 6% 11% 21% 26% 9%	2600
	21st to end	Night	30% 4 9% 18% 24% 15%	2700
December	1st to 10th	Night	26% 4 5% 24% 28% 13%	4560
	11th to 20th	Night	49% 3 9% 15% 19% 5%	5176
	21st to end	Night	57% 6% 11% 13% 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	29% 15% 23% 20% 11% 1	281
	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 11% 44% 29% 15%	531
August	1st to 10th	Day	2 3 18% 39% 29% 10%	487
	11th to 20th	Day	1 3 19% 40% 25% 12%	477
	21st to end	Day	1 2 13% 41% 32% 11%	539
September	1st to 10th	Day	2 3 16% 41% 30% 9%	490
	11th to 20th	Day	3 8% 23% 39% 21% 6%	490
	21st to end	Day	4 7% 17% 41% 26% 6%	490
October	1st to 10th	Day	4 10% 23% 33% 25% 6%	490
	11th to 20th	Day	6% 9% 22% 32% 24% 7%	490
	21st to end	Day	9% 6% 25% 34% 21% 5%	539
November	1st to 10th	Day	9% 12% 20% 27% 25% 7%	436
	11th to 20th	Day	8% 10% 23% 28% 22% 9%	300
	21st to end	Day	13% 10% 22% 32% 19% 4	247
December	1st to 10th	Day	14% 14% 18% 28% 20% 8%	200
	11th to 20th	Day	19% 15% 18% 27% 15% 8%	200
	21st to end	Day	22% 16% 21% 20% 15% 5%	220
January	1st to 10th	Night	18% 8% 16% 31% 20% 8%	784
	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 28% 52% 16%	624
August	1st to 10th	Night	2 5% 32% 49% 11%	567
	11th to 20th	Night	1 7% 37% 43% 12%	722
	21st to end	Night	1 1 5% 30% 51% 12%	836
September	1st to 10th	Night	2 1 6% 34% 44% 12%	760
	11th to 20th	Night	4 2 10% 34% 40% 10%	760
	21st to end	Night	3 3 10% 34% 37% 13%	760
October	1st to 10th	Night	4 3 11% 37% 34% 11%	760
	11th to 20th	Night	7% 4 11% 33% 34% 11%	760
	21st to end	Night	7% 4 14% 32% 27% 16%	836
November	1st to 10th	Night	9% 7% 13% 31% 29% 11%	780
	11th to 20th	Night	11% 4 17% 34% 27% 7%	800
	21st to end	Night	11% 6% 17% 36% 23% 8%	800
December	1st to 10th	Night	16% 7% 15% 32% 23% 7%	800
	11th to 20th	Night	23% 7% 15% 31% 20% 5%	800
	21st to end	Night	20% 11% 20% 28% 17% 4	880

Page generated at 2025-01-04 00:23:58. Version ac07

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