Auburn City Recreation Complex
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Auburn City Recreation Complex clear sky chart from 2005-11-06 to 2026-07-16.

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	11% 7% 3 7% 4 4 4 3 5% 7% 45%	137704
	Night	10% 7% 2 6% 4 4 4 3 5% 7% 49%	135283
Transparency	Day	37% 5% 12% 26% 17% 3	141329
	Night	35% 5% 12% 26% 19% 3	139725
Seeing	Day	14% 10% 30% 29% 14% 3	18088
	Night	13% 9% 33% 33% 11% 1	27931

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	10% 11% 3 11% 6% 4 4 3 5% 6% 36%	5289
	11th to 20th	Day	5% 8% 3 8% 6% 7% 6% 4 5% 7% 41%	5310
	21st to end	Day	8% 12% 5% 10% 4 5% 4 3 5% 7% 38%	5812
February	1st to 10th	Day	9% 12% 4 8% 6% 5% 5% 3 5% 7% 36%	1890
	11th to 20th	Day	10% 9% 4 8% 5% 4 4 3 5% 7% 40%	1876
	21st to end	Day	9% 8% 3 7% 5% 3 4 2 5% 7% 47%	1730
March	1st to 10th	Day	14% 8% 2 5% 3 2 3 2 4 4 51%	5037
	11th to 20th	Day	11% 6% 2 5% 4 3 3 3 4 7% 51%	5090
	21st to end	Day	15% 10% 4 8% 4 4 4 4 5% 7% 34%	5583
April	1st to 10th	Day	16% 8% 2 5% 3 3 4 3 5% 5% 45%	2378
	11th to 20th	Day	15% 7% 2 6% 4 4 4 4 6% 7% 43%	2571
	21st to end	Day	20% 7% 3 5% 4 4 5% 3 4 6% 39%	2730
May	1st to 10th	Day	12% 7% 2 6% 4 4 4 3 5% 7% 46%	7617
	11th to 20th	Day	12% 6% 2 5% 4 4 4 3 5% 6% 50%	7627
	21st to end	Day	19% 7% 3 6% 4 4 4 4 5% 6% 38%	8511
June	1st to 10th	Day	8% 5% 1 5% 4 4 4 4 7% 9% 49%	2940
	11th to 20th	Day	8% 4 2 5% 5% 4 4 4 6% 9% 48%	2940
	21st to end	Day	8% 4 2 6% 6% 5% 6% 4 6% 8% 45%	2922
July	1st to 10th	Day	9% 5% 2 5% 4 4 5% 4 6% 9% 47%	6030
	11th to 20th	Day	8% 5% 2 6% 5% 4 5% 4 6% 9% 46%	5966
	21st to end	Day	7% 4 2 5% 4 4 4 4 6% 9% 51%	6422
August	1st to 10th	Day	6% 4 2 6% 4 4 5% 4 7% 10% 47%	4234
	11th to 20th	Day	12% 6% 2 6% 3 4 5% 4 6% 7% 45%	4171
	21st to end	Day	6% 4 2 6% 4 5% 5% 4 6% 8% 50%	4548
September	1st to 10th	Day	13% 4 2 4 3 3 4 3 5% 6% 53%	2336
	11th to 20th	Day	10% 5% 2 5% 4 4 3 4 5% 8% 52%	2200
	21st to end	Day	12% 4 2 5% 3 3 3 3 4 5% 58%	2200
October	1st to 10th	Day	13% 5% 2 4 3 3 2 3 5% 6% 53%	2036
	11th to 20th	Day	11% 6% 3 4 3 3 3 2 4 4 58%	2000
	21st to end	Day	13% 7% 2 6% 3 3 3 2 4 6% 49%	2200
November	1st to 10th	Day	9% 6% 2 4 3 2 4 3 5% 6% 56%	1923
	11th to 20th	Day	11% 6% 2 6% 3 4 3 3 5% 6% 52%	1843
	21st to end	Day	14% 9% 3 5% 4 4 4 4 5% 7% 44%	1680
December	1st to 10th	Day	5% 4 2 6% 4 4 4 3 5% 6% 55%	2690
	11th to 20th	Day	9% 8% 3 9% 5% 4 4 3 5% 7% 44%	3088
	21st to end	Day	18% 11% 5% 13% 4 4 4 3 4 5% 29%	4284
January	1st to 10th	Night	10% 9% 5% 15% 6% 5% 4 3 4 5% 34%	7634
	11th to 20th	Night	5% 6% 3 8% 4 4 6% 4 5% 7% 47%	7680
	21st to end	Night	10% 12% 4 9% 4 4 4 3 4 5% 41%	8402
February	1st to 10th	Night	11% 10% 4 7% 5% 4 5% 3 4 5% 41%	2730
	11th to 20th	Night	10% 9% 3 8% 5% 4 4 4 5% 7% 43%	2648
	21st to end	Night	9% 6% 3 6% 4 4 4 3 4 6% 51%	2076
March	1st to 10th	Night	13% 7% 2 5% 3 3 4 3 4 5% 52%	5037
	11th to 20th	Night	9% 6% 2 4 2 3 3 3 4 6% 57%	5090
	21st to end	Night	13% 9% 3 7% 4 4 4 3 5% 8% 39%	5588
April	1st to 10th	Night	14% 6% 1 6% 4 3 4 4 5% 6% 47%	2242
	11th to 20th	Night	11% 7% 2 6% 4 3 4 3 5% 8% 47%	1995
	21st to end	Night	17% 7% 2 5% 4 3 3 4 5% 7% 44%	1890
May	1st to 10th	Night	11% 6% 3 5% 4 3 4 3 4 6% 51%	5266
	11th to 20th	Night	14% 5% 2 5% 2 3 3 2 4 6% 55%	5265
	21st to end	Night	18% 6% 2 6% 4 4 3 3 4 7% 43%	5656
June	1st to 10th	Night	6% 4 2 5% 4 4 4 4 8% 8% 53%	1680
	11th to 20th	Night	7% 3 1 3 3 4 5% 4 8% 9% 53%	1680
	21st to end	Night	5% 4 1 3 3 3 4 4 5% 10% 57%	1691
July	1st to 10th	Night	7% 5% 2 6% 4 4 4 3 6% 7% 52%	4168
	11th to 20th	Night	5% 4 2 6% 4 5% 4 4 6% 8% 53%	4122
	21st to end	Night	6% 4 1 4 3 4 4 4 7% 10% 52%	4449
August	1st to 10th	Night	3 3 1 5% 4 4 4 3 6% 10% 59%	2926
	11th to 20th	Night	12% 5% 1 5% 2 4 3 3 5% 7% 52%	2888
	21st to end	Night	6% 4 2 5% 3 3 3 3 5% 8% 59%	3355
September	1st to 10th	Night	10% 4 2 4 2 3 3 2 4 7% 59%	2060
	11th to 20th	Night	9% 3 1 5% 3 4 5% 3 5% 7% 56%	2200
	21st to end	Night	9% 4 1 4 3 3 3 3 4 5% 62%	2200
October	1st to 10th	Night	12% 5% 2 5% 3 3 3 3 5% 7% 52%	2342
	11th to 20th	Night	11% 5% 2 4 3 3 3 3 4 5% 58%	2400
	21st to end	Night	14% 7% 2 5% 3 3 3 3 4 5% 52%	2640
November	1st to 10th	Night	8% 5% 1 4 4 3 3 2 5% 6% 59%	2595
	11th to 20th	Night	9% 6% 2 4 3 4 3 3 5% 6% 54%	2772
	21st to end	Night	13% 7% 2 5% 4 2 3 3 4 5% 51%	2940
December	1st to 10th	Night	5% 5% 2 5% 4 4 4 3 5% 6% 56%	4720
	11th to 20th	Night	10% 8% 3 7% 4 4 3 3 5% 7% 47%	5339
	21st to end	Night	18% 13% 5% 10% 4 3 3 3 4 5% 34%	6917

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	49% 5% 11% 23% 11% 1	5290
	11th to 20th	Day	43% 4 12% 20% 18% 2	5310
	21st to end	Day	46% 4 14% 22% 13%	5812
February	1st to 10th	Day	47% 6% 15% 20% 10% 2	1890
	11th to 20th	Day	44% 5% 11% 24% 13% 3	1885
	21st to end	Day	37% 5% 13% 26% 17% 3	1730
March	1st to 10th	Day	37% 4 8% 25% 19% 7%	5037
	11th to 20th	Day	34% 5% 8% 23% 25% 5%	5090
	21st to end	Day	48% 7% 18% 20% 5% 2	5585
April	1st to 10th	Day	40% 5% 11% 25% 15% 2	2378
	11th to 20th	Day	40% 6% 13% 23% 16% 2	2571
	21st to end	Day	46% 7% 10% 25% 12% 1	2730
May	1st to 10th	Day	37% 5% 9% 28% 18% 2	7655
	11th to 20th	Day	35% 6% 9% 24% 22% 3	7631
	21st to end	Day	45% 6% 10% 25% 14% 1	8525
June	1st to 10th	Day	29% 8% 14% 31% 16% 2	2940
	11th to 20th	Day	31% 7% 15% 27% 18% 2	2940
	21st to end	Day	34% 10% 12% 27% 13% 4	2922
July	1st to 10th	Day	33% 6% 13% 30% 17% 2	5966
	11th to 20th	Day	35% 6% 13% 26% 18% 2	5897
	21st to end	Day	28% 6% 15% 31% 15% 3	6240
August	1st to 10th	Day	29% 8% 16% 27% 19% 2	4220
	11th to 20th	Day	37% 6% 16% 24% 16%	4210
	21st to end	Day	30% 6% 16% 26% 16% 6%	4547
September	1st to 10th	Day	31% 5% 12% 28% 19% 5%	2336
	11th to 20th	Day	31% 6% 12% 29% 21% 1	2200
	21st to end	Day	30% 4 9% 29% 25% 2	2200
October	1st to 10th	Day	21% 3 7% 19% 46% 5%	3309
	11th to 20th	Day	20% 3 8% 29% 31% 8%	3240
	21st to end	Day	32% 3 10% 29% 23% 3	3538
November	1st to 10th	Day	30% 4 13% 29% 21% 3	1923
	11th to 20th	Day	33% 5% 11% 29% 20% 2	1843
	21st to end	Day	39% 5% 13% 26% 15% 1	1680
December	1st to 10th	Day	29% 5% 17% 31% 18% 1	2690
	11th to 20th	Day	40% 4 16% 30% 10%	3085
	21st to end	Day	59% 4 12% 18% 6% 1	4284
January	1st to 10th	Night	52% 5% 12% 19% 11% 2	7635
	11th to 20th	Night	35% 4 11% 28% 19% 3	7680
	21st to end	Night	47% 4 13% 18% 15% 3	8402
February	1st to 10th	Night	45% 5% 12% 21% 14% 3	2730
	11th to 20th	Night	40% 5% 13% 23% 15% 3	2649
	21st to end	Night	34% 5% 10% 25% 21% 6%	2076
March	1st to 10th	Night	35% 4 8% 26% 24% 3	5037
	11th to 20th	Night	29% 4 7% 26% 26% 9%	5090
	21st to end	Night	42% 6% 18% 25% 7% 1	5588
April	1st to 10th	Night	36% 6% 10% 25% 19% 3	2242
	11th to 20th	Night	36% 6% 10% 27% 17% 4	1995
	21st to end	Night	40% 7% 11% 24% 18% 1	1890
May	1st to 10th	Night	35% 5% 9% 27% 21% 3	5293
	11th to 20th	Night	33% 4 9% 23% 27% 5%	5266
	21st to end	Night	42% 6% 11% 24% 16% 1	5667
June	1st to 10th	Night	26% 8% 16% 30% 17% 3	1680
	11th to 20th	Night	24% 8% 15% 30% 19% 5%	1680
	21st to end	Night	21% 6% 16% 31% 22% 3	1691
July	1st to 10th	Night	31% 4 14% 25% 22% 3	4125
	11th to 20th	Night	28% 6% 15% 26% 22% 2	4071
	21st to end	Night	26% 7% 16% 28% 22% 1	4320
August	1st to 10th	Night	21% 6% 16% 31% 23% 3	2916
	11th to 20th	Night	32% 5% 13% 29% 18% 1	2915
	21st to end	Night	25% 4 16% 30% 18% 7%	3355
September	1st to 10th	Night	26% 5% 12% 27% 22% 7%	2060
	11th to 20th	Night	27% 5% 12% 32% 21% 3	2200
	21st to end	Night	25% 5% 9% 27% 31% 3	2200
October	1st to 10th	Night	20% 3 8% 18% 45% 6%	3836
	11th to 20th	Night	20% 3 6% 31% 28% 11%	3899
	21st to end	Night	34% 3 8% 28% 25% 2	4252
November	1st to 10th	Night	27% 4 13% 28% 24% 5%	2595
	11th to 20th	Night	31% 4 12% 30% 21% 3	2772
	21st to end	Night	36% 3 12% 27% 19% 2	2940
December	1st to 10th	Night	28% 5% 15% 35% 17% 1	4720
	11th to 20th	Night	38% 3 14% 30% 14% 1	5341
	21st to end	Night	54% 4 11% 23% 7% 1	6917

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	19% 15% 36% 24% 6% 1	330
	11th to 20th	Day	20% 18% 35% 20% 6%	330
	21st to end	Day	16% 11% 42% 26% 5%	363
February	1st to 10th	Day	16% 18% 43% 19% 4	330
	11th to 20th	Day	15% 16% 43% 19% 6% 1	330
	21st to end	Day	10% 21% 45% 20% 4	273
March	1st to 10th	Day	18% 16% 40% 22% 4	330
	11th to 20th	Day	28% 15% 30% 20% 6% 1	330
	21st to end	Day	25% 22% 34% 15% 3	363
April	1st to 10th	Day	23% 16% 38% 18% 5%	398
	11th to 20th	Day	18% 17% 37% 21% 6%	609
	21st to end	Day	23% 18% 30% 19% 8% 1	750
May	1st to 10th	Day	16% 12% 35% 25% 10% 1	753
	11th to 20th	Day	17% 11% 32% 27% 12% 2	775
	21st to end	Day	20% 7% 33% 27% 12% 2	844
June	1st to 10th	Day	7% 7% 22% 35% 24% 6%	780
	11th to 20th	Day	9% 5% 31% 35% 16% 4	780
	21st to end	Day	8% 8% 36% 32% 14% 2	780
July	1st to 10th	Day	8% 5% 17% 33% 30% 7%	771
	11th to 20th	Day	5% 2 22% 41% 22% 7%	744
	21st to end	Day	6% 3 15% 42% 29% 5%	794
August	1st to 10th	Day	8% 2 20% 41% 25% 4	726
	11th to 20th	Day	9% 4 19% 40% 23% 5%	715
	21st to end	Day	11% 3 19% 33% 29% 6%	728
September	1st to 10th	Day	12% 3 23% 37% 19% 6%	466
	11th to 20th	Day	8% 2 27% 34% 23% 6%	330
	21st to end	Day	17% 4 28% 30% 18% 3	330
October	1st to 10th	Day	20% 8% 23% 30% 15% 5%	330
	11th to 20th	Day	8% 16% 42% 25% 7% 2	330
	21st to end	Day	19% 19% 32% 21% 7% 2	363
November	1st to 10th	Day	16% 13% 39% 21% 9% 2	330
	11th to 20th	Day	16% 14% 38% 24% 7% 1	330
	21st to end	Day	23% 12% 34% 23% 7% 1	330
December	1st to 10th	Day	9% 15% 42% 28% 5% 2	330
	11th to 20th	Day	17% 15% 34% 26% 7%	330
	21st to end	Day	20% 16% 40% 21% 3 1	363
January	1st to 10th	Night	12% 12% 38% 30% 7%	1050
	11th to 20th	Night	14% 15% 38% 27% 6%	1050
	21st to end	Night	15% 9% 43% 28% 5%	1155
February	1st to 10th	Night	16% 11% 42% 27% 4	1050
	11th to 20th	Night	14% 13% 39% 30% 4	1014
	21st to end	Night	13% 12% 44% 25% 5%	692
March	1st to 10th	Night	13% 16% 37% 28% 6%	638
	11th to 20th	Night	19% 10% 39% 28% 4	630
	21st to end	Night	22% 13% 40% 21% 4	693
April	1st to 10th	Night	16% 15% 42% 22% 5%	630
	11th to 20th	Night	16% 15% 38% 27% 4	623
	21st to end	Night	20% 10% 37% 25% 7%	630
May	1st to 10th	Night	16% 10% 34% 33% 7%	630
	11th to 20th	Night	17% 7% 32% 34% 9% 1	621
	21st to end	Night	15% 6% 33% 33% 13%	683
June	1st to 10th	Night	7% 4 24% 45% 20%	630
	11th to 20th	Night	7% 3 31% 43% 15%	630
	21st to end	Night	6% 4 33% 43% 13%	630
July	1st to 10th	Night	6% 3 16% 44% 30% 1	615
	11th to 20th	Night	4 2 17% 49% 26% 1	597
	21st to end	Night	4 1 16% 51% 27% 1	657
August	1st to 10th	Night	5% 2 18% 50% 24% 2	597
	11th to 20th	Night	9% 2 16% 47% 25% 2	594
	21st to end	Night	7% 3 17% 46% 25% 2	660
September	1st to 10th	Night	11% 4 24% 37% 23% 2	600
	11th to 20th	Night	11% 2 24% 42% 21% 1	600
	21st to end	Night	9% 5% 27% 42% 16% 1	600
October	1st to 10th	Night	13% 8% 31% 33% 13% 2	742
	11th to 20th	Night	13% 10% 39% 31% 8%	800
	21st to end	Night	18% 10% 33% 31% 7%	880
November	1st to 10th	Night	10% 13% 31% 37% 9%	955
	11th to 20th	Night	12% 12% 40% 29% 7%	1050
	21st to end	Night	17% 11% 33% 29% 9%	1050
December	1st to 10th	Night	12% 13% 37% 32% 7%	1050
	11th to 20th	Night	17% 12% 34% 31% 6%	1050
	21st to end	Night	18% 13% 34% 29% 5%	1155

Page generated at 2026-07-13 02:14:53. Version ac07

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