Venetie
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Venetie clear sky chart from 2005-11-06 to 2026-02-16.

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	9% 10% 4 10% 6% 6% 6% 5% 7% 8% 31%	134884
	Night	6% 13% 5% 12% 7% 6% 5% 4 6% 6% 30%	137538
Transparency	Day	48% 7% 19% 20% 6%	134449
	Night	53% 6% 14% 16% 10% 1	137556
Seeing	Day	11% 4 13% 27% 28% 17%	20890
	Night	12% 4 14% 32% 29% 9%	24472

By Month

Percentage Cloud Cover NW (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	3 15% 4 14% 9% 9% 6% 4 4 5% 28%	658
	11th to 20th	Day	3 11% 5% 14% 6% 5% 6% 5% 6% 8% 31%	1496
	21st to end	Day	5% 14% 4 12% 9% 8% 6% 6% 7% 8% 22%	2591
February	1st to 10th	Day	2 9% 4 12% 8% 7% 7% 3 6% 7% 34%	1218
	11th to 20th	Day	3 11% 5% 13% 8% 6% 7% 6% 6% 7% 28%	1368
	21st to end	Day	3 9% 6% 11% 7% 6% 8% 6% 8% 7% 30%	1320
March	1st to 10th	Day	2 10% 6% 16% 9% 8% 7% 4 6% 6% 25%	4213
	11th to 20th	Day	2 12% 5% 13% 8% 6% 6% 4 5% 6% 34%	4656
	21st to end	Day	3 13% 6% 10% 8% 6% 6% 5% 7% 7% 30%	5918
April	1st to 10th	Day	3 12% 5% 12% 7% 6% 6% 5% 6% 9% 29%	2626
	11th to 20th	Day	3 9% 3 11% 7% 5% 5% 4 6% 8% 40%	2846
	21st to end	Day	3 6% 3 8% 6% 6% 6% 4 7% 9% 42%	3115
May	1st to 10th	Day	15% 19% 5% 9% 5% 4 4 3 5% 7% 24%	7726
	11th to 20th	Day	3 5% 3 6% 5% 5% 5% 4 7% 9% 48%	8351
	21st to end	Day	12% 10% 4 10% 7% 7% 7% 6% 8% 7% 23%	9901
June	1st to 10th	Day	8% 8% 3 8% 8% 6% 7% 6% 7% 8% 32%	4517
	11th to 20th	Day	7% 6% 2 7% 5% 6% 6% 5% 9% 10% 36%	4800
	21st to end	Day	8% 5% 2 7% 7% 6% 6% 6% 8% 9% 35%	4800
July	1st to 10th	Day	12% 8% 3 7% 5% 5% 5% 5% 7% 8% 34%	10370
	11th to 20th	Day	9% 7% 3 7% 5% 5% 6% 5% 8% 11% 35%	9158
	21st to end	Day	11% 8% 3 9% 6% 6% 6% 5% 7% 8% 30%	9127
August	1st to 10th	Day	11% 8% 3 8% 6% 6% 6% 5% 8% 9% 30%	5604
	11th to 20th	Day	17% 8% 3 10% 5% 6% 6% 5% 6% 8% 25%	5079
	21st to end	Day	14% 9% 4 9% 6% 6% 6% 5% 6% 7% 29%	5176
September	1st to 10th	Day	12% 9% 4 9% 5% 6% 6% 4 6% 7% 31%	2653
	11th to 20th	Day	16% 13% 4 9% 5% 6% 4 4 6% 7% 25%	2373
	21st to end	Day	15% 14% 4 9% 6% 4 4 4 5% 6% 28%	2183
October	1st to 10th	Day	10% 14% 5% 12% 7% 6% 5% 4 6% 5% 26%	3014
	11th to 20th	Day	11% 17% 5% 13% 7% 5% 5% 3 5% 7% 22%	2717
	21st to end	Day	8% 16% 6% 15% 10% 6% 4 3 5% 5% 22%	2484
November	1st to 10th	Day	8% 22% 6% 15% 8% 5% 5% 3 5% 4 19%	1082
	11th to 20th	Day	3 11% 7% 14% 8% 7% 6% 4 4 6% 29%	850
	21st to end	Day	7% 15% 4 12% 7% 6% 5% 6% 6% 6% 24%	583
December	1st to 10th	Day	6% 19% 5% 8% 7% 4 6% 5% 5% 5% 31%	311
	January	1st to 10th	Night	4 11% 5% 12% 6% 5% 6% 6% 6% 5% 36%	12257
11th to 20th		Night	4 11% 4 10% 6% 6% 5% 5% 7% 8% 35%	11491
21st to end		Night	6% 13% 5% 13% 8% 8% 7% 4 7% 8% 21%	11622
February	1st to 10th	Night	2 9% 4 11% 8% 6% 6% 5% 8% 8% 33%	3401
	11th to 20th	Night	4 10% 6% 12% 6% 5% 6% 5% 6% 8% 32%	3028
	21st to end	Night	4 11% 4 10% 7% 5% 5% 4 6% 7% 36%	2310
March	1st to 10th	Night	1 7% 6% 15% 7% 6% 7% 5% 6% 7% 32%	5648
	11th to 20th	Night	3 10% 6% 12% 6% 5% 5% 3 5% 7% 39%	5302
	21st to end	Night	4 14% 5% 13% 6% 5% 5% 3 5% 6% 33%	5013
April	1st to 10th	Night	4 10% 4 13% 8% 6% 5% 4 7% 8% 31%	1771
	11th to 20th	Night	4 11% 4 10% 5% 4 6% 5% 6% 7% 39%	1503
	21st to end	Night	3 6% 3 8% 6% 6% 6% 5% 8% 8% 41%	1284
May	1st to 10th	Night	16% 18% 5% 8% 5% 4 3 3 3 5% 29%	2234
	11th to 20th	Night	3 6% 2 6% 5% 6% 5% 4 8% 10% 45%	1564
	21st to end	Night	13% 9% 3 6% 6% 6% 7% 6% 10% 9% 25%	982
June	1st to 10th	Night	11% 7% 11% 9% 5% 5% 11% 11% 5% 24%	55
	July	1st to 10th	Night	34% 13% 8% 18% 16% 3 3 3 3	38
11th to 20th		Night	10% 5% 2 8% 4 5% 6% 5% 7% 11% 36%	820
21st to end		Night	15% 8% 3 9% 6% 6% 5% 5% 7% 9% 27%	1724
August	1st to 10th	Night	10% 9% 4 10% 5% 5% 6% 4 8% 9% 29%	1549
	11th to 20th	Night	19% 10% 4 10% 6% 4 5% 4 7% 8% 22%	1979
	21st to end	Night	13% 9% 3 9% 6% 6% 6% 6% 7% 6% 29%	2731
September	1st to 10th	Night	12% 9% 3 9% 4 4 5% 4 7% 7% 35%	1747
	11th to 20th	Night	20% 11% 4 8% 6% 4 4 4 6% 6% 26%	2025
	21st to end	Night	15% 18% 5% 9% 5% 5% 4 4 4 5% 28%	2215
October	1st to 10th	Night	9% 15% 5% 10% 5% 4 4 4 6% 8% 29%	4174
	11th to 20th	Night	11% 17% 8% 15% 5% 4 4 3 4 5% 27%	4429
	21st to end	Night	8% 14% 7% 18% 8% 6% 5% 3 4 5% 22%	5317
November	1st to 10th	Night	9% 21% 6% 14% 7% 6% 4 4 4 4 21%	3433
	11th to 20th	Night	5% 12% 5% 14% 9% 8% 7% 4 5% 6% 26%	3747
	21st to end	Night	7% 15% 6% 13% 8% 6% 7% 4 5% 6% 23%	4034
December	1st to 10th	Night	7% 18% 6% 13% 6% 5% 4 3 5% 5% 29%	7098
	11th to 20th	Night	3 11% 5% 11% 6% 6% 5% 4 6% 6% 38%	9059
	21st to end	Night	5% 16% 7% 16% 7% 5% 6% 3 4 5% 25%	11954

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	58% 5% 7% 15% 11% 4	658
	11th to 20th	Day	51% 6% 15% 18% 9% 1	1502
	21st to end	Day	59% 6% 7% 13% 16%	2592
February	1st to 10th	Day	49% 6% 8% 20% 14% 3	1218
	11th to 20th	Day	53% 7% 13% 19% 7% 1	1374
	21st to end	Day	50% 7% 14% 20% 8%	1320
March	1st to 10th	Day	58% 6% 13% 17% 5% 1	4213
	11th to 20th	Day	49% 4 10% 16% 18% 3	4656
	21st to end	Day	49% 7% 16% 15% 13% 1	5918
April	1st to 10th	Day	50% 6% 17% 20% 6% 1	2626
	11th to 20th	Day	40% 6% 21% 24% 8%	2846
	21st to end	Day	35% 8% 22% 27% 8%	3115
May	1st to 10th	Day	58% 6% 12% 21% 4	7726
	11th to 20th	Day	30% 5% 16% 31% 17%	8355
	21st to end	Day	51% 9% 15% 19% 5%	9902
June	1st to 10th	Day	44% 7% 17% 23% 9%	4517
	11th to 20th	Day	38% 7% 16% 31% 9%	4800
	21st to end	Day	39% 9% 19% 26% 6%	4800
July	1st to 10th	Day	43% 8% 18% 19% 12%	10261
	11th to 20th	Day	39% 9% 29% 21% 2	9044
	21st to end	Day	47% 10% 24% 19%	8871
August	1st to 10th	Day	46% 9% 29% 15% 1	5583
	11th to 20th	Day	54% 9% 25% 12%	5127
	21st to end	Day	52% 8% 23% 17%	5175
September	1st to 10th	Day	49% 10% 25% 13% 3	2653
	11th to 20th	Day	57% 6% 24% 12% 1	2373
	21st to end	Day	56% 6% 20% 17% 1	2183
October	1st to 10th	Day	57% 6% 18% 16% 2	3014
	11th to 20th	Day	60% 7% 18% 14% 1	2717
	21st to end	Day	63% 5% 17% 14% 1	2484
November	1st to 10th	Day	69% 7% 11% 11% 2	1082
	11th to 20th	Day	59% 5% 18% 13% 4	850
	21st to end	Day	60% 6% 12% 17% 4	583
December	1st to 10th	Day	56% 6% 10% 13% 14% 1	311
	January	1st to 10th	Night	48% 6% 8% 16% 20% 1	12258
11th to 20th		Night	46% 7% 14% 19% 10% 4	11547
21st to end		Night	61% 5% 6% 11% 18%	11622
February	1st to 10th	Night	47% 6% 13% 19% 13% 3	3401
	11th to 20th	Night	49% 7% 14% 19% 11% 1	3033
	21st to end	Night	46% 6% 14% 23% 11%	2310
March	1st to 10th	Night	48% 6% 18% 21% 6%	5648
	11th to 20th	Night	44% 3 11% 17% 22% 3	5304
	21st to end	Night	50% 5% 15% 16% 13% 1	5013
April	1st to 10th	Night	49% 6% 17% 20% 7% 2	1771
	11th to 20th	Night	42% 7% 21% 24% 7% 1	1503
	21st to end	Night	36% 7% 22% 27% 8%	1284
May	1st to 10th	Night	57% 6% 12% 23% 2	2231
	11th to 20th	Night	29% 6% 18% 30% 16%	1564
	21st to end	Night	47% 8% 20% 21% 4	982
June	1st to 10th	Night	49% 11% 13% 15% 13%	55
	July	1st to 10th	Night	92% 3 3 3	38
11th to 20th		Night	38% 9% 28% 24% 1	811
21st to end		Night	50% 10% 23% 16% 1	1676
August	1st to 10th	Night	50% 7% 24% 17% 2	1545
	11th to 20th	Night	57% 7% 25% 11% 1	1997
	21st to end	Night	51% 8% 22% 17% 1	2731
September	1st to 10th	Night	46% 9% 27% 15% 3	1747
	11th to 20th	Night	56% 6% 23% 14% 1	2025
	21st to end	Night	59% 7% 17% 16% 2	2215
October	1st to 10th	Night	52% 6% 21% 19% 2	4174
	11th to 20th	Night	61% 5% 18% 15% 1	4429
	21st to end	Night	63% 6% 17% 12% 1	5317
November	1st to 10th	Night	67% 5% 12% 13% 2	3433
	11th to 20th	Night	59% 6% 18% 14% 3	3747
	21st to end	Night	62% 5% 13% 17% 4	4034
December	1st to 10th	Night	58% 6% 11% 12% 12%	7098
	11th to 20th	Night	46% 6% 15% 17% 15%	9059
	21st to end	Night	61% 5% 9% 15% 9%	11954

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	6% 6% 15% 33% 33% 8%	80
	11th to 20th	Day	11% 5% 15% 31% 29% 9%	110
	21st to end	Day	10% 2 13% 35% 32% 7%	121
February	1st to 10th	Day	4 5% 12% 30% 28% 21%	287
	11th to 20th	Day	8% 3 13% 33% 25% 18%	353
	21st to end	Day	6% 3 11% 29% 32% 19%	331
March	1st to 10th	Day	6% 2 10% 28% 32% 23%	400
	11th to 20th	Day	7% 3 13% 31% 28% 18%	400
	21st to end	Day	7% 4 15% 28% 30% 17%	635
April	1st to 10th	Day	8% 3 14% 31% 31% 13%	690
	11th to 20th	Day	6% 4 16% 28% 30% 16%	690
	21st to end	Day	3 2 11% 27% 33% 23%	700
May	1st to 10th	Day	11% 5% 17% 25% 24% 18%	713
	11th to 20th	Day	8% 4 18% 31% 27% 12%	1023
	21st to end	Day	10% 5% 14% 29% 30% 13%	1222
June	1st to 10th	Day	9% 4 15% 31% 28% 14%	1215
	11th to 20th	Day	8% 4 10% 27% 34% 17%	1330
	21st to end	Day	9% 2 8% 31% 34% 17%	1330
July	1st to 10th	Day	10% 4 8% 25% 32% 21%	1211
	11th to 20th	Day	12% 3 12% 26% 28% 20%	1106
	21st to end	Day	10% 4 13% 24% 28% 22%	1106
August	1st to 10th	Day	14% 5% 13% 28% 24% 16%	812
	11th to 20th	Day	20% 5% 13% 23% 22% 17%	715
	21st to end	Day	23% 4 13% 19% 23% 18%	803
September	1st to 10th	Day	15% 4 13% 23% 24% 20%	730
	11th to 20th	Day	22% 3 13% 25% 24% 13%	582
	21st to end	Day	22% 6% 10% 22% 19% 20%	420
October	1st to 10th	Day	21% 6% 16% 25% 18% 14%	420
	11th to 20th	Day	21% 5% 15% 23% 20% 16%	420
	21st to end	Day	19% 6% 11% 19% 26% 19%	462
November	1st to 10th	Day	17% 7% 13% 23% 28% 13%	151
	11th to 20th	Day	6% 5% 15% 22% 26% 25%	110
	21st to end	Day	15% 5% 10% 30% 27% 14%	110
December	1st to 10th	Day	12% 8% 12% 31% 31% 6%	102
	January	1st to 10th	Night	7% 4 15% 30% 31% 12%	1270
11th to 20th		Night	12% 3 13% 35% 30% 7%	1254
21st to end		Night	9% 3 14% 36% 28% 10%	1166
February	1st to 10th	Night	5% 4 16% 29% 32% 14%	955
	11th to 20th	Night	9% 4 15% 36% 29% 7%	909
	21st to end	Night	9% 2 14% 34% 34% 7%	743
March	1st to 10th	Night	5% 3 10% 39% 31% 12%	780
	11th to 20th	Night	6% 2 17% 37% 29% 10%	670
	21st to end	Night	6% 4 14% 34% 31% 12%	660
April	1st to 10th	Night	10% 2 15% 33% 32% 8%	600
	11th to 20th	Night	9% 3 13% 40% 31% 6%	593
	21st to end	Night	5% 2 17% 35% 35% 6%	484
May	1st to 10th	Night	12% 3 15% 36% 30% 3	210
	11th to 20th	Night	5% 6% 21% 37% 29% 2	197
	21st to end	Night	12% 4 21% 30% 32% 2	217
June	1st to 10th	Night	13% 2 16% 35% 25% 9%	55
	July	1st to 10th	Night	17% 17% 50% 17%	12
11th to 20th		Night	13% 3 16% 24% 35% 8%	194
21st to end		Night	11% 3 11% 35% 32% 7%	219
August	1st to 10th	Night	16% 6% 12% 32% 26% 6%	231
	11th to 20th	Night	18% 3 14% 30% 28% 5%	419
	21st to end	Night	16% 3 12% 28% 30% 11%	660
September	1st to 10th	Night	13% 4 14% 28% 31% 10%	600
	11th to 20th	Night	24% 3 11% 30% 26% 6%	600
	21st to end	Night	25% 5% 12% 30% 24% 5%	608
October	1st to 10th	Night	20% 6% 17% 29% 22% 7%	860
	11th to 20th	Night	21% 5% 11% 30% 26% 6%	910
	21st to end	Night	19% 5% 10% 26% 29% 11%	1001
November	1st to 10th	Night	19% 5% 17% 28% 24% 7%	930
	11th to 20th	Night	10% 4 11% 23% 32% 19%	1081
	21st to end	Night	13% 2 12% 29% 32% 12%	1270
December	1st to 10th	Night	14% 6% 14% 33% 27% 6%	1270
	11th to 20th	Night	11% 5% 14% 28% 30% 11%	1358
	21st to end	Night	8% 4 13% 33% 30% 12%	1486

Page generated at 2026-02-12 21:42:13. Version ac07

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