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 2026-05-02.

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	6% 4 1 4 3 3 3 3 4 6% 63%	140340
	Night	8% 6% 2 6% 3 3 4 4 4 6% 55%	139652
Transparency	Day	24% 4 7% 18% 26% 21%	135294
	Night	31% 6% 8% 16% 22% 17%	135683
Seeing	Day	10% 11% 23% 31% 20% 6%	17322
	Night	10% 6% 14% 33% 29% 8%	26819

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	17% 7% 2 5% 3 3 3 3 4 6% 47%	5001
	11th to 20th	Day	9% 4 2 5% 2 3 3 3 4 5% 60%	5340
	21st to end	Day	13% 7% 2 6% 4 4 4 3 5% 7% 44%	5843
February	1st to 10th	Day	17% 7% 2 4 3 3 3 3 4 6% 46%	1890
	11th to 20th	Day	14% 6% 2 6% 5% 4 4 4 5% 7% 42%	1981
	21st to end	Day	15% 7% 2 6% 4 4 4 3 5% 5% 46%	1730
March	1st to 10th	Day	11% 10% 3 9% 6% 6% 6% 5% 6% 6% 32%	4920
	11th to 20th	Day	13% 5% 2 5% 3 4 4 3 6% 7% 48%	5110
	21st to end	Day	11% 9% 3 7% 5% 5% 5% 5% 6% 9% 34%	5736
April	1st to 10th	Day	12% 7% 2 5% 5% 4 3 3 5% 7% 47%	2520
	11th to 20th	Day	9% 6% 2 5% 3 3 4 4 5% 7% 53%	2489
	21st to end	Day	6% 5% 2 4 3 4 4 3 5% 7% 57%	2520
May	1st to 10th	Day	4 3 1 2 2 2 2 2 4 6% 73%	5492
	11th to 20th	Day	3 2 1 3 2 2 2 3 4 6% 73%	6012
	21st to end	Day	2 3 1 4 2 2 2 2 3 5% 73%	6902
June	1st to 10th	Day	3 4 2 4 2 2 3 3 5% 7% 64%	2800
	11th to 20th	Day	1 2 1 1 2 2 2 2 4 7% 77%	2800
	21st to end	Day	1 2 1 2 2 1 2 2 3 4 81%	2800
July	1st to 10th	Day	1 1 1 1 2 2 4 88%	6319
	11th to 20th	Day	1 1 1 1 1 2 2 3 4 83%	5951
	21st to end	Day	1 4 2 2 2 2 3 5% 78%	6402
August	1st to 10th	Day	1 1 1 2 1 2 2 3 4 5% 79%	5777
	11th to 20th	Day	1 1 2 1 1 2 2 2 4 85%	5415
	21st to end	Day	1 2 1 2 2 2 3 5% 81%	5984
September	1st to 10th	Day	1 2 1 2 1 2 2 2 2 4 82%	2400
	11th to 20th	Day	2 2 1 4 2 2 3 3 5% 6% 70%	2400
	21st to end	Day	3 2 1 2 1 2 2 1 4 5% 77%	2140
October	1st to 10th	Day	2 2 1 2 2 2 2 2 4 6% 74%	3280
	11th to 20th	Day	3 2 1 4 3 2 2 2 3 5% 73%	3261
	21st to end	Day	3 3 1 4 3 4 3 3 5% 7% 64%	3558
November	1st to 10th	Day	7% 4 2 4 3 4 4 3 6% 6% 56%	1997
	11th to 20th	Day	8% 5% 2 5% 4 4 4 3 5% 6% 52%	1890
	21st to end	Day	12% 5% 2 3 2 2 3 3 5% 7% 56%	1780
December	1st to 10th	Day	7% 4 1 5% 3 3 4 3 5% 8% 56%	2700
	11th to 20th	Day	21% 8% 3 6% 4 4 4 4 6% 7% 34%	3108
	21st to end	Day	19% 12% 4 8% 5% 3 4 4 6% 6% 29%	4092
January	1st to 10th	Night	14% 8% 3 7% 4 3 3 3 4 6% 44%	7904
	11th to 20th	Night	10% 5% 2 4 3 3 4 3 4 6% 56%	7650
	21st to end	Night	13% 9% 3 7% 3 4 4 4 4 7% 43%	8371
February	1st to 10th	Night	15% 8% 2 4 4 3 3 3 3 6% 49%	2730
	11th to 20th	Night	14% 7% 2 6% 3 5% 4 3 6% 7% 42%	2525
	21st to end	Night	12% 7% 3 6% 4 3 3 3 4 7% 49%	2076
March	1st to 10th	Night	15% 14% 4 9% 5% 4 4 4 4 4 33%	5191
	11th to 20th	Night	14% 8% 3 6% 4 3 3 2 4 5% 47%	5110
	21st to end	Night	14% 14% 3 9% 4 4 4 3 4 6% 35%	5479
April	1st to 10th	Night	10% 8% 2 5% 4 4 5% 4 6% 7% 47%	2100
	11th to 20th	Night	8% 6% 2 6% 4 4 3 3 4 6% 52%	2079
	21st to end	Night	5% 6% 2 6% 4 3 4 3 5% 8% 53%	2100
May	1st to 10th	Night	3 4 2 6% 4 3 3 4 3 5% 64%	4525
	11th to 20th	Night	2 3 1 6% 4 4 5% 6% 7% 6% 56%	3891
	21st to end	Night	1 3 2 5% 2 2 4 4 4 5% 67%	3972
June	1st to 10th	Night	2 4 1 4 4 3 4 6% 6% 8% 60%	1600
	11th to 20th	Night	2 1 2 3 4 4 3 5% 6% 70%	1600
	21st to end	Night	1 2 2 3 2 2 3 3 4 4 75%	1600
July	1st to 10th	Night	2 1 1 3 3 3 4 83%	3640
	11th to 20th	Night	1 3 2 2 4 6% 5% 5% 72%	4007
	21st to end	Night	2 5% 12% 3 3 8% 4 5% 6% 53%	4472
August	1st to 10th	Night	1 1 1 4 2 2 3 4 5% 6% 71%	4035
	11th to 20th	Night	1 4 2 2 3 4 4 5% 75%	4450
	21st to end	Night	1 1 1 4 3 3 3 4 4 5% 72%	5015
September	1st to 10th	Night	1 2 1 3 2 1 3 3 4 5% 76%	2000
	11th to 20th	Night	3 3 2 5% 3 2 4 4 5% 5% 65%	2000
	21st to end	Night	2 3 1 3 2 2 3 2 3 5% 74%	2255
October	1st to 10th	Night	2 2 1 2 2 2 2 2 3 5% 76%	3920
	11th to 20th	Night	3 3 2 9% 3 2 2 3 4 5% 65%	3897
	21st to end	Night	4 4 2 5% 3 3 3 3 4 5% 64%	4253
November	1st to 10th	Night	7% 5% 1 4 3 3 3 3 4 7% 59%	2518
	11th to 20th	Night	8% 5% 2 5% 4 3 4 3 6% 8% 51%	2730
	21st to end	Night	8% 5% 2 5% 4 4 4 3 4 7% 56%	2835
December	1st to 10th	Night	7% 4 1 4 3 3 4 3 5% 6% 59%	4700
	11th to 20th	Night	19% 9% 3 6% 4 3 4 4 7% 9% 31%	5316
	21st to end	Night	21% 10% 4 11% 5% 6% 5% 3 5% 5% 26%	7106

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	38% 3 16% 24% 16% 4	5002
	11th to 20th	Day	27% 5% 5% 11% 25% 27%	5340
	21st to end	Day	40% 3 6% 16% 23% 12%	5843
February	1st to 10th	Day	38% 4 6% 21% 18% 12%	1890
	11th to 20th	Day	40% 5% 10% 17% 20% 7%	1990
	21st to end	Day	40% 5% 8% 23% 19% 6%	1730
March	1st to 10th	Day	48% 6% 7% 15% 21% 2	4920
	11th to 20th	Day	33% 4 12% 30% 12% 8%	5110
	21st to end	Day	44% 7% 14% 22% 11% 2	5736
April	1st to 10th	Day	36% 5% 12% 23% 20% 5%	2520
	11th to 20th	Day	30% 6% 14% 23% 19% 7%	2492
	21st to end	Day	27% 5% 11% 30% 22% 5%	2520
May	1st to 10th	Day	15% 2 7% 29% 32% 14%	5492
	11th to 20th	Day	14% 8% 5% 34% 34% 5%	6015
	21st to end	Day	16% 7% 6% 27% 39% 5%	6904
June	1st to 10th	Day	20% 7% 10% 27% 27% 9%	2800
	11th to 20th	Day	11% 5% 8% 20% 37% 20%	2800
	21st to end	Day	12% 4 3 12% 32% 37%	2800
July	1st to 10th	Day	7% 2 2 5% 21% 63%	6251
	11th to 20th	Day	11% 2 2 4 16% 65%	5880
	21st to end	Day	15% 2 2 16% 32% 34%	6217
August	1st to 10th	Day	13% 3 2 8% 33% 41%	4206
	11th to 20th	Day	8% 2 2 7% 40% 40%	3919
	21st to end	Day	11% 3 4 8% 35% 39%	4311
September	1st to 10th	Day	11% 2 3 10% 30% 45%	2400
	11th to 20th	Day	17% 6% 4 22% 33% 17%	2400
	21st to end	Day	13% 3 4 21% 36% 24%	2140
October	1st to 10th	Day	14% 2 5% 11% 27% 41%	3280
	11th to 20th	Day	17% 2 5% 24% 32% 20%	3261
	21st to end	Day	20% 3 5% 19% 33% 19%	3558
November	1st to 10th	Day	26% 4 9% 22% 25% 13%	1997
	11th to 20th	Day	31% 5% 10% 21% 24% 8%	1890
	21st to end	Day	28% 4 9% 18% 31% 10%	1780
December	1st to 10th	Day	27% 4 5% 22% 34% 8%	2700
	11th to 20th	Day	49% 3 8% 18% 15% 7%	3108
	21st to end	Day	53% 5% 11% 18% 10% 3	4092
January	1st to 10th	Night	39% 5% 15% 20% 17% 4	7904
	11th to 20th	Night	29% 4 7% 13% 28% 19%	7650
	21st to end	Night	42% 3 6% 17% 19% 13%	8371
February	1st to 10th	Night	38% 3 7% 19% 20% 14%	2730
	11th to 20th	Night	39% 5% 11% 17% 20% 8%	2527
	21st to end	Night	34% 4 11% 27% 17% 7%	2076
March	1st to 10th	Night	50% 7% 7% 15% 17% 3	5191
	11th to 20th	Night	38% 6% 9% 23% 16% 8%	5110
	21st to end	Night	48% 6% 11% 20% 13% 3	5479
April	1st to 10th	Night	32% 7% 14% 23% 19% 6%	2100
	11th to 20th	Night	32% 6% 12% 26% 17% 7%	2079
	21st to end	Night	26% 7% 12% 27% 21% 6%	2100
May	1st to 10th	Night	22% 4 8% 23% 28% 14%	4522
	11th to 20th	Night	20% 24% 7% 19% 25% 6%	3891
	21st to end	Night	18% 13% 7% 21% 37% 4	3972
June	1st to 10th	Night	22% 11% 10% 24% 22% 11%	1600
	11th to 20th	Night	18% 6% 9% 13% 30% 25%	1600
	21st to end	Night	17% 9% 3 11% 25% 35%	1600
July	1st to 10th	Night	11% 4 3 5% 16% 61%	3600
	11th to 20th	Night	21% 4 3 3 17% 52%	3956
	21st to end	Night	38% 4 4 8% 20% 27%	4345
August	1st to 10th	Night	19% 6% 4 6% 26% 39%	2929
	11th to 20th	Night	14% 5% 3 6% 31% 41%	3213
	21st to end	Night	19% 6% 5% 6% 32% 32%	3608
September	1st to 10th	Night	13% 4 5% 9% 23% 46%	2000
	11th to 20th	Night	22% 9% 5% 17% 28% 20%	2000
	21st to end	Night	16% 5% 5% 15% 35% 24%	2255
October	1st to 10th	Night	13% 3 4 11% 21% 48%	3920
	11th to 20th	Night	24% 4 5% 22% 25% 20%	3897
	21st to end	Night	23% 3 4 20% 28% 21%	4253
November	1st to 10th	Night	24% 5% 10% 22% 23% 17%	2518
	11th to 20th	Night	28% 6% 10% 21% 25% 9%	2730
	21st to end	Night	29% 4 8% 20% 24% 15%	2835
December	1st to 10th	Night	26% 3 5% 26% 27% 13%	4700
	11th to 20th	Night	48% 3 9% 15% 19% 6%	5316
	21st to end	Night	58% 6% 11% 13% 9% 4	7106

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	28% 16% 22% 21% 11% 1	317
	11th to 20th	Day	16% 13% 21% 29% 16% 6%	430
	21st to end	Day	16% 11% 24% 26% 19% 3	473
February	1st to 10th	Day	22% 15% 23% 22% 13% 5%	430
	11th to 20th	Day	20% 19% 28% 22% 10%	499
	21st to end	Day	18% 15% 28% 28% 9% 1	446
March	1st to 10th	Day	22% 18% 27% 24% 7% 1	540
	11th to 20th	Day	22% 16% 21% 24% 15% 3	540
	21st to end	Day	19% 18% 32% 21% 10% 1	594
April	1st to 10th	Day	16% 18% 28% 24% 13% 2	540
	11th to 20th	Day	16% 18% 28% 23% 14% 3	532
	21st to end	Day	8% 17% 29% 28% 12% 6%	540
May	1st to 10th	Day	10% 16% 31% 28% 12% 3	508
	11th to 20th	Day	9% 13% 30% 28% 15% 4	528
	21st to end	Day	6% 12% 27% 32% 17% 5%	573
June	1st to 10th	Day	5% 10% 27% 29% 20% 8%	530
	11th to 20th	Day	2 11% 30% 37% 15% 5%	530
	21st to end	Day	2 5% 23% 39% 23% 9%	530
July	1st to 10th	Day	1 3 18% 40% 32% 7%	526
	11th to 20th	Day	1 1 11% 41% 35% 11%	524
	21st to end	Day	1 1 11% 43% 31% 14%	575
August	1st to 10th	Day	2 3 19% 37% 29% 10%	527
	11th to 20th	Day	1 3 19% 38% 26% 12%	517
	21st to end	Day	1 2 13% 40% 32% 12%	583
September	1st to 10th	Day	2 4 17% 41% 28% 8%	530
	11th to 20th	Day	3 8% 23% 38% 22% 6%	530
	21st to end	Day	4 7% 20% 40% 25% 5%	530
October	1st to 10th	Day	4 10% 24% 33% 24% 5%	530
	11th to 20th	Day	7% 9% 22% 31% 23% 7%	530
	21st to end	Day	8% 6% 25% 35% 20% 5%	583
November	1st to 10th	Day	9% 12% 20% 27% 25% 8%	473
	11th to 20th	Day	11% 11% 23% 28% 20% 8%	330
	21st to end	Day	12% 9% 23% 32% 20% 4	272
December	1st to 10th	Day	12% 13% 18% 29% 21% 7%	220
	11th to 20th	Day	18% 14% 17% 26% 17% 7%	220
	21st to end	Day	25% 16% 20% 20% 14% 5%	242
January	1st to 10th	Night	19% 8% 16% 30% 19% 7%	840
	11th to 20th	Night	13% 6% 15% 36% 22% 8%	840
	21st to end	Night	18% 6% 15% 33% 22% 6%	924
February	1st to 10th	Night	21% 8% 14% 32% 19% 6%	840
	11th to 20th	Night	18% 10% 17% 32% 17% 6%	824
	21st to end	Night	16% 9% 21% 35% 16% 3	692
March	1st to 10th	Night	19% 10% 17% 32% 18% 4	840
	11th to 20th	Night	20% 8% 16% 27% 24% 5%	840
	21st to end	Night	15% 10% 22% 32% 19% 3	924
April	1st to 10th	Night	13% 10% 20% 33% 21% 3	840
	11th to 20th	Night	11% 12% 20% 33% 20% 4	831
	21st to end	Night	8% 9% 26% 29% 21% 7%	840
May	1st to 10th	Night	5% 6% 24% 34% 24% 7%	785
	11th to 20th	Night	6% 4 14% 34% 35% 7%	513
	21st to end	Night	4 5% 17% 37% 31% 6%	433
June	1st to 10th	Night	4 4 15% 38% 33% 6%	400
	11th to 20th	Night	1 4 15% 45% 32% 4	400
	21st to end	Night	2 1 9% 37% 45% 6%	400
July	1st to 10th	Night	1 7% 35% 51% 7%	390
	11th to 20th	Night	1 1 27% 53% 17%	544
	21st to end	Night	1 1 2 28% 52% 16%	657
August	1st to 10th	Night	2 5% 32% 49% 12%	597
	11th to 20th	Night	1 7% 37% 43% 11%	761
	21st to end	Night	1 1 5% 30% 51% 12%	880
September	1st to 10th	Night	2 2 8% 35% 43% 11%	800
	11th to 20th	Night	4 3 11% 33% 39% 10%	800
	21st to end	Night	3 3 11% 36% 36% 12%	800
October	1st to 10th	Night	4 3 11% 37% 34% 10%	800
	11th to 20th	Night	8% 4 11% 33% 34% 10%	800
	21st to end	Night	7% 4 14% 33% 28% 15%	880
November	1st to 10th	Night	9% 7% 13% 31% 30% 11%	820
	11th to 20th	Night	12% 4 18% 33% 26% 7%	840
	21st to end	Night	10% 6% 16% 37% 23% 7%	840
December	1st to 10th	Night	15% 7% 15% 33% 23% 6%	840
	11th to 20th	Night	22% 6% 15% 31% 21% 5%	840
	21st to end	Night	21% 10% 20% 28% 17% 4	924

Page generated at 2026-04-28 23:21:48. Version ac07

Copyright © 2026 Attilla Danko.