Bella Vista
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Bella Vista clear sky chart from 2005-11-06 to 2024-01-15.

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	13% 7% 3 5% 5% 3 4 4 5% 7% 44%	74555
	Night	12% 6% 3 5% 4 2 4 4 5% 7% 50%	75228
Transparency	Day	26% 37% 7% 16% 12% 2	74279
	Night	24% 37% 6% 16% 14% 3	75024
Seeing	Day	16% 12% 28% 26% 15% 3	14331
	Night	16% 11% 31% 28% 13% 1	24294

By Month

Percentage Cloud Cover SE (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	14% 8% 3 5% 4 2 3 3 4 6% 47%	1707
	11th to 20th	Day	14% 9% 3 5% 3 3 4 4 4 6% 45%	1656
	21st to end	Day	15% 9% 3 5% 4 1 3 3 4 6% 46%	1782
February	1st to 10th	Day	16% 11% 4 7% 5% 2 4 3 3 5% 40%	1620
	11th to 20th	Day	14% 9% 5% 6% 5% 2 3 3 4 6% 43%	1576
	21st to end	Day	18% 9% 3 5% 4 3 4 4 4 5% 40%	1606
March	1st to 10th	Day	15% 8% 3 5% 5% 3 4 4 4 6% 44%	1980
	11th to 20th	Day	20% 9% 3 5% 5% 2 4 4 4 5% 39%	1980
	21st to end	Day	21% 8% 4 6% 5% 3 4 4 4 6% 34%	2178
April	1st to 10th	Day	14% 7% 2 5% 5% 3 4 3 5% 8% 43%	2078
	11th to 20th	Day	18% 7% 3 6% 5% 3 4 4 5% 6% 39%	2134
	21st to end	Day	21% 8% 3 6% 5% 3 4 4 4 5% 38%	2173
May	1st to 10th	Day	19% 8% 3 6% 5% 3 5% 4 4 6% 38%	2340
	11th to 20th	Day	15% 7% 3 6% 6% 3 5% 4 5% 7% 39%	2302
	21st to end	Day	12% 5% 3 7% 6% 4 6% 5% 6% 9% 36%	2531
June	1st to 10th	Day	9% 4 2 5% 5% 3 4 6% 7% 10% 45%	2340
	11th to 20th	Day	8% 4 3 5% 5% 3 6% 6% 6% 9% 46%	2340
	21st to end	Day	5% 3 2 3 4 3 5% 5% 6% 9% 55%	2340
July	1st to 10th	Day	10% 4 2 5% 5% 4 5% 7% 8% 11% 38%	2340
	11th to 20th	Day	4 3 2 3 5% 4 5% 6% 7% 9% 51%	2340
	21st to end	Day	8% 4 2 5% 6% 3 5% 6% 8% 11% 42%	2546
August	1st to 10th	Day	8% 4 2 5% 5% 4 6% 7% 7% 10% 44%	2328
	11th to 20th	Day	9% 4 2 5% 6% 4 5% 6% 7% 8% 44%	2283
	21st to end	Day	6% 5% 2 4 4 3 5% 5% 5% 8% 52%	2376
September	1st to 10th	Day	11% 5% 2 5% 4 2 4 4 4 6% 51%	2160
	11th to 20th	Day	11% 6% 2 5% 5% 3 4 4 5% 8% 46%	2008
	21st to end	Day	7% 5% 2 4 4 2 4 5% 5% 7% 55%	1957
October	1st to 10th	Day	10% 4 2 4 5% 3 3 4 5% 7% 53%	1800
	11th to 20th	Day	14% 5% 2 4 3 2 3 3 3 6% 56%	1800
	21st to end	Day	19% 6% 2 4 4 2 2 3 3 5% 49%	1980
November	1st to 10th	Day	10% 6% 2 3 3 2 3 3 3 7% 56%	1858
	11th to 20th	Day	13% 8% 2 5% 4 2 3 4 4 5% 51%	1838
	21st to end	Day	17% 8% 3 4 3 2 2 3 3 6% 48%	1596
December	1st to 10th	Day	14% 8% 3 6% 5% 2 3 4 4 5% 45%	1520
	11th to 20th	Day	14% 11% 3 6% 5% 3 4 3 3 4 43%	2027
	21st to end	Day	16% 16% 6% 6% 5% 4 4 3 4 6% 30%	3135
January	1st to 10th	Night	14% 6% 3 4 5% 2 4 3 4 6% 48%	2458
	11th to 20th	Night	14% 7% 3 5% 4 3 3 3 4 5% 49%	2393
	21st to end	Night	13% 7% 4 5% 3 2 3 3 4 5% 50%	2574
February	1st to 10th	Night	15% 10% 4 5% 4 2 3 3 5% 6% 42%	2340
	11th to 20th	Night	14% 8% 4 5% 4 2 4 3 3 5% 46%	2273
	21st to end	Night	17% 9% 3 5% 4 3 4 3 4 5% 45%	1662
March	1st to 10th	Night	12% 8% 3 5% 5% 2 3 4 5% 5% 46%	1980
	11th to 20th	Night	17% 9% 2 5% 5% 2 4 4 4 6% 42%	1980
	21st to end	Night	17% 8% 3 6% 5% 3 4 4 5% 6% 41%	2178
April	1st to 10th	Night	12% 6% 1 4 4 2 4 4 4 5% 52%	1882
	11th to 20th	Night	13% 6% 2 5% 4 2 4 4 5% 7% 47%	1775
	21st to end	Night	18% 6% 3 5% 4 3 3 4 4 6% 44%	1782
May	1st to 10th	Night	13% 6% 2 4 5% 3 5% 4 4 7% 47%	1620
	11th to 20th	Night	13% 5% 2 5% 5% 3 3 4 5% 7% 48%	1593
	21st to end	Night	10% 5% 2 5% 4 3 6% 5% 7% 10% 43%	1745
June	1st to 10th	Night	6% 3 2 4 5% 2 4 4 6% 9% 56%	1620
	11th to 20th	Night	5% 3 2 3 4 3 4 4 5% 11% 56%	1620
	21st to end	Night	2 2 2 4 3 2 4 5% 5% 7% 64%	1620
July	1st to 10th	Night	5% 3 2 4 4 2 5% 5% 6% 12% 52%	1620
	11th to 20th	Night	4 2 1 3 3 2 4 5% 5% 9% 60%	1620
	21st to end	Night	4 3 2 5% 5% 4 4 5% 6% 10% 53%	1772
August	1st to 10th	Night	4 2 1 3 4 4 4 5% 8% 12% 51%	1611
	11th to 20th	Night	7% 2 2 4 4 3 4 5% 7% 9% 53%	1617
	21st to end	Night	4 3 2 3 4 3 4 6% 5% 8% 58%	1980
September	1st to 10th	Night	9% 3 2 3 4 2 4 3 5% 8% 58%	1800
	11th to 20th	Night	9% 5% 2 5% 4 2 4 3 5% 8% 53%	1948
	21st to end	Night	8% 3 2 4 3 2 3 3 5% 8% 58%	1984
October	1st to 10th	Night	7% 3 1 4 3 3 3 4 5% 8% 60%	2160
	11th to 20th	Night	14% 5% 2 4 3 2 3 4 4 5% 56%	2160
	21st to end	Night	17% 7% 2 4 3 2 3 3 3 4 51%	2376
November	1st to 10th	Night	11% 4 1 3 2 2 3 3 3 5% 61%	2220
	11th to 20th	Night	10% 7% 2 4 3 2 3 3 4 5% 56%	2340
	21st to end	Night	15% 7% 2 4 3 2 3 3 4 5% 52%	2577
December	1st to 10th	Night	14% 8% 3 6% 4 2 3 3 4 6% 47%	2660
	11th to 20th	Night	15% 9% 4 6% 4 2 4 3 4 4 44%	3156
	21st to end	Night	17% 15% 7% 6% 5% 2 3 3 3 4 35%	4532

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	23% 38% 6% 17% 13% 2	1708
	11th to 20th	Day	25% 40% 6% 16% 11% 1	1656
	21st to end	Day	30% 36% 6% 17% 9% 1	1782
February	1st to 10th	Day	34% 36% 6% 15% 8% 2	1620
	11th to 20th	Day	30% 36% 5% 15% 11% 3	1585
	21st to end	Day	31% 35% 5% 14% 10% 5%	1606
March	1st to 10th	Day	27% 36% 5% 14% 14% 4	1980
	11th to 20th	Day	35% 36% 5% 13% 8% 3	1980
	21st to end	Day	36% 36% 6% 14% 6% 1	2178
April	1st to 10th	Day	26% 37% 7% 16% 13% 3	2078
	11th to 20th	Day	30% 36% 7% 12% 13% 3	2134
	21st to end	Day	34% 37% 5% 14% 9% 1	2173
May	1st to 10th	Day	35% 37% 6% 13% 9%	2340
	11th to 20th	Day	29% 39% 8% 15% 9% 1	2306
	21st to end	Day	27% 39% 10% 17% 6%	2531
June	1st to 10th	Day	21% 38% 11% 20% 9% 1	2340
	11th to 20th	Day	21% 39% 8% 20% 11% 1	2340
	21st to end	Day	16% 38% 11% 18% 13% 4	2340
July	1st to 10th	Day	22% 41% 9% 16% 12% 1	2276
	11th to 20th	Day	18% 40% 11% 17% 12% 2	2271
	21st to end	Day	22% 41% 10% 20% 7%	2405
August	1st to 10th	Day	21% 40% 11% 18% 9% 2	2314
	11th to 20th	Day	23% 38% 7% 18% 13% 1	2283
	21st to end	Day	18% 37% 8% 18% 14% 6%	2376
September	1st to 10th	Day	23% 37% 4 15% 13% 7%	2160
	11th to 20th	Day	24% 37% 6% 13% 17% 3	2008
	21st to end	Day	17% 36% 6% 17% 20% 4	1957
October	1st to 10th	Day	18% 37% 7% 18% 18% 4	1800
	11th to 20th	Day	21% 36% 5% 18% 16% 5%	1800
	21st to end	Day	27% 37% 4 18% 11% 3	1980
November	1st to 10th	Day	17% 40% 6% 20% 14% 4	1858
	11th to 20th	Day	24% 38% 4 15% 13% 6%	1838
	21st to end	Day	24% 39% 6% 13% 16% 2	1596
December	1st to 10th	Day	25% 39% 6% 18% 11% 2	1520
	11th to 20th	Day	32% 31% 4 14% 18% 1	2025
	21st to end	Day	46% 25% 5% 14% 8% 1	3135
January	1st to 10th	Night	23% 39% 5% 18% 13% 2	2458
	11th to 20th	Night	22% 40% 6% 18% 13% 1	2393
	21st to end	Night	27% 36% 5% 18% 12% 2	2574
February	1st to 10th	Night	31% 36% 6% 14% 11% 2	2340
	11th to 20th	Night	28% 36% 4 16% 12% 3	2274
	21st to end	Night	29% 36% 6% 14% 12% 4	1662
March	1st to 10th	Night	24% 36% 5% 14% 14% 6%	1980
	11th to 20th	Night	31% 38% 6% 13% 11% 2	1980
	21st to end	Night	33% 37% 5% 15% 9% 1	2178
April	1st to 10th	Night	24% 35% 5% 17% 14% 5%	1882
	11th to 20th	Night	24% 36% 4 14% 17% 5%	1775
	21st to end	Night	28% 38% 7% 16% 11% 1	1782
May	1st to 10th	Night	28% 37% 7% 15% 11% 2	1620
	11th to 20th	Night	24% 39% 11% 14% 12% 1	1594
	21st to end	Night	25% 38% 10% 19% 7% 1	1746
June	1st to 10th	Night	16% 39% 10% 22% 11% 2	1620
	11th to 20th	Night	16% 38% 10% 21% 14% 2	1620
	21st to end	Night	13% 37% 9% 19% 16% 6%	1620
July	1st to 10th	Night	15% 39% 9% 21% 15% 1	1575
	11th to 20th	Night	15% 39% 10% 17% 16% 3	1566
	21st to end	Night	18% 40% 8% 22% 11% 1	1673
August	1st to 10th	Night	16% 39% 11% 22% 12%	1601
	11th to 20th	Night	18% 38% 8% 18% 17% 3	1617
	21st to end	Night	14% 38% 8% 16% 19% 6%	1980
September	1st to 10th	Night	20% 37% 5% 16% 15% 8%	1800
	11th to 20th	Night	23% 36% 5% 14% 17% 4	1948
	21st to end	Night	15% 36% 5% 15% 25% 5%	1984
October	1st to 10th	Night	13% 37% 7% 15% 21% 6%	2160
	11th to 20th	Night	20% 36% 4 15% 19% 6%	2160
	21st to end	Night	26% 37% 4 15% 14% 4	2376
November	1st to 10th	Night	15% 40% 6% 19% 16% 4	2220
	11th to 20th	Night	21% 39% 4 17% 16% 4	2340
	21st to end	Night	21% 39% 5% 13% 17% 4	2577
December	1st to 10th	Night	24% 40% 8% 15% 12% 2	2660
	11th to 20th	Night	31% 33% 4 16% 15% 1	3157
	21st to end	Night	44% 25% 6% 14% 9% 3	4532

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	26% 19% 39% 13% 3	270
	11th to 20th	Day	25% 25% 39% 10% 2	252
	21st to end	Day	22% 28% 35% 12% 4	264
February	1st to 10th	Day	28% 25% 36% 10% 1	240
	11th to 20th	Day	32% 28% 29% 10% 1	240
	21st to end	Day	36% 27% 28% 8% 1	198
March	1st to 10th	Day	27% 28% 29% 14% 2	240
	11th to 20th	Day	34% 18% 35% 13%	240
	21st to end	Day	31% 27% 32% 7% 2	264
April	1st to 10th	Day	22% 25% 34% 14% 5%	338
	11th to 20th	Day	27% 19% 33% 16% 4	412
	21st to end	Day	26% 20% 32% 17% 5%	433
May	1st to 10th	Day	21% 15% 39% 19% 5%	603
	11th to 20th	Day	18% 12% 34% 25% 9% 2	625
	21st to end	Day	14% 11% 34% 23% 14% 4	679
June	1st to 10th	Day	8% 4 24% 38% 22% 5%	630
	11th to 20th	Day	9% 4 25% 39% 20% 3	630
	21st to end	Day	4 4 32% 35% 21% 3	630
July	1st to 10th	Day	10% 3 16% 32% 31% 8%	621
	11th to 20th	Day	5% 2 17% 40% 29% 6%	618
	21st to end	Day	8% 1 13% 36% 32% 9%	684
August	1st to 10th	Day	10% 2 18% 40% 27% 4	626
	11th to 20th	Day	10% 3 16% 35% 31% 4	597
	21st to end	Day	9% 1 15% 36% 30% 10%	495
September	1st to 10th	Day	10% 2 16% 36% 28% 6%	450
	11th to 20th	Day	9% 1 21% 45% 18% 6%	298
	21st to end	Day	8% 9% 30% 33% 17% 3	270
October	1st to 10th	Day	10% 11% 36% 26% 13% 4	270
	11th to 20th	Day	17% 16% 43% 18% 6%	270
	21st to end	Day	31% 17% 33% 14% 4 1	297
November	1st to 10th	Day	16% 17% 40% 20% 6% 1	270
	11th to 20th	Day	21% 19% 35% 18% 5% 2	270
	21st to end	Day	30% 17% 32% 16% 4	270
December	1st to 10th	Day	23% 21% 35% 14% 5% 1	270
	11th to 20th	Day	24% 24% 34% 14% 4	270
	21st to end	Day	27% 24% 38% 9% 2	297
January	1st to 10th	Night	20% 20% 33% 23% 4	950
	11th to 20th	Night	20% 21% 37% 17% 4	921
	21st to end	Night	17% 21% 36% 21% 4	990
February	1st to 10th	Night	22% 17% 40% 17% 3	900
	11th to 20th	Night	22% 20% 40% 17% 2	879
	21st to end	Night	26% 19% 33% 20% 2	478
March	1st to 10th	Night	20% 14% 40% 23% 3	540
	11th to 20th	Night	24% 15% 34% 24% 3	540
	21st to end	Night	23% 17% 37% 18% 5%	594
April	1st to 10th	Night	17% 17% 39% 24% 4	540
	11th to 20th	Night	17% 15% 35% 26% 7%	533
	21st to end	Night	23% 11% 41% 17% 8%	540
May	1st to 10th	Night	16% 7% 40% 30% 7%	540
	11th to 20th	Night	17% 5% 33% 31% 13% 2	531
	21st to end	Night	12% 7% 33% 28% 18% 1	584
June	1st to 10th	Night	8% 4 17% 42% 30%	540
	11th to 20th	Night	6% 3 28% 43% 20% 1	540
	21st to end	Night	3 1 26% 46% 22% 2	540
July	1st to 10th	Night	6% 1 13% 39% 35% 4	525
	11th to 20th	Night	5% 1 13% 42% 34% 6%	522
	21st to end	Night	5% 2 11% 45% 33% 5%	591
August	1st to 10th	Night	5% 2 14% 42% 35% 2	537
	11th to 20th	Night	8% 2 14% 44% 28% 4	534
	21st to end	Night	4 2 16% 38% 36% 5%	594
September	1st to 10th	Night	9% 1 17% 41% 29% 2	540
	11th to 20th	Night	13% 1 15% 41% 26% 3	540
	21st to end	Night	10% 3 25% 36% 23% 3	544
October	1st to 10th	Night	8% 4 31% 33% 21% 4	720
	11th to 20th	Night	17% 8% 37% 28% 9%	720
	21st to end	Night	22% 10% 33% 24% 9% 1	792
November	1st to 10th	Night	14% 11% 41% 23% 10% 1	740
	11th to 20th	Night	17% 13% 36% 26% 8%	820
	21st to end	Night	21% 15% 35% 21% 8%	950
December	1st to 10th	Night	20% 15% 37% 23% 4	950
	11th to 20th	Night	24% 15% 33% 25% 3	950
	21st to end	Night	22% 20% 36% 19% 3	1045

Page generated at 2024-01-11 21:33:50. Version ac07

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