Auburn
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Auburn clear sky chart from 2005-11-06 to 2024-11-04.

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% 9% 4 8% 5% 5% 5% 4 6% 7% 34%	101144
	Night	15% 10% 4 8% 5% 4 4 4 5% 7% 35%	97914
Transparency	Day	46% 6% 12% 22% 13% 1	104759
	Night	47% 6% 11% 21% 14% 2	102439
Seeing	Day	17% 10% 28% 24% 15% 6%	15663
	Night	18% 9% 29% 29% 13% 1	25480

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	16% 16% 9% 13% 6% 5% 4 3 4 5% 20%	2527
	11th to 20th	Day	15% 18% 7% 13% 7% 6% 6% 6% 6% 4 12%	2530
	21st to end	Day	26% 22% 10% 12% 5% 3 3 2 2 4 13%	2935
February	1st to 10th	Day	16% 14% 5% 12% 8% 6% 5% 3 5% 6% 21%	1784
	11th to 20th	Day	14% 13% 4 12% 8% 6% 4 4 5% 6% 24%	1848
	21st to end	Day	15% 15% 6% 10% 5% 4 4 4 5% 7% 25%	1570
March	1st to 10th	Day	18% 16% 4 9% 6% 4 4 3 4 5% 25%	3120
	11th to 20th	Day	13% 9% 3 8% 7% 5% 6% 3 6% 9% 33%	3439
	21st to end	Day	19% 11% 5% 10% 6% 5% 5% 4 5% 6% 24%	3868
April	1st to 10th	Day	16% 11% 4 9% 5% 5% 5% 4 6% 6% 30%	2280
	11th to 20th	Day	17% 9% 2 7% 5% 5% 4 4 6% 6% 35%	2311
	21st to end	Day	17% 10% 3 7% 5% 5% 4 3 6% 8% 33%	2470
May	1st to 10th	Day	18% 9% 3 8% 5% 5% 5% 4 6% 7% 30%	4082
	11th to 20th	Day	15% 7% 2 6% 5% 5% 4 4 6% 8% 37%	4081
	21st to end	Day	8% 6% 2 6% 5% 5% 5% 4 7% 9% 42%	4588
June	1st to 10th	Day	9% 6% 3 7% 5% 6% 5% 4 6% 7% 41%	2660
	11th to 20th	Day	9% 5% 2 6% 5% 5% 5% 4 6% 9% 43%	2660
	21st to end	Day	10% 6% 3 6% 6% 5% 5% 5% 7% 9% 38%	2660
July	1st to 10th	Day	12% 6% 3 8% 5% 5% 5% 4 6% 10% 37%	4440
	11th to 20th	Day	7% 4 2 5% 4 4 5% 4 7% 10% 48%	4440
	21st to end	Day	6% 6% 3 8% 6% 5% 6% 5% 7% 9% 41%	4661
August	1st to 10th	Day	8% 5% 2 6% 5% 5% 5% 4 6% 9% 44%	4104
	11th to 20th	Day	9% 5% 2 6% 4 5% 5% 4 7% 8% 45%	4044
	21st to end	Day	7% 5% 2 6% 4 4 4 4 6% 10% 48%	4226
September	1st to 10th	Day	11% 6% 2 6% 5% 4 5% 4 5% 7% 44%	2211
	11th to 20th	Day	9% 4 2 4 4 4 5% 4 7% 9% 47%	2090
	21st to end	Day	14% 7% 2 6% 4 4 4 3 6% 7% 42%	2090
October	1st to 10th	Day	12% 6% 2 7% 5% 4 4 4 5% 7% 44%	2090
	11th to 20th	Day	16% 6% 2 7% 4 5% 5% 4 5% 7% 38%	1909
	21st to end	Day	18% 9% 3 7% 6% 6% 5% 4 7% 6% 29%	1881
November	1st to 10th	Day	11% 8% 3 6% 4 4 4 5% 5% 7% 44%	1699
	11th to 20th	Day	16% 14% 4 8% 5% 5% 4 3 5% 7% 31%	1710
	21st to end	Day	20% 14% 4 10% 5% 4 4 3 5% 6% 26%	1710
December	1st to 10th	Day	15% 16% 7% 12% 7% 5% 5% 3 5% 4 20%	1710
	11th to 20th	Day	15% 14% 6% 12% 6% 5% 5% 4 6% 5% 22%	1933
	21st to end	Day	22% 22% 8% 13% 5% 4 4 2 3 5% 11%	2783
January	1st to 10th	Night	17% 15% 6% 12% 6% 5% 4 3 4 5% 22%	4428
	11th to 20th	Night	15% 18% 8% 14% 6% 5% 6% 4 5% 6% 14%	4440
	21st to end	Night	25% 18% 8% 11% 5% 4 4 3 3 5% 15%	4724
February	1st to 10th	Night	18% 14% 5% 10% 6% 5% 5% 3 4 6% 25%	2394
	11th to 20th	Night	13% 13% 4 9% 6% 6% 5% 3 5% 6% 29%	2218
	21st to end	Night	20% 12% 4 9% 5% 4 4 4 4 5% 29%	1884
March	1st to 10th	Night	17% 12% 4 8% 4 5% 4 3 4 5% 35%	3733
	11th to 20th	Night	10% 6% 2 6% 5% 5% 5% 4 5% 8% 44%	3521
	21st to end	Night	17% 9% 4 9% 5% 4 4 4 5% 6% 33%	3791
April	1st to 10th	Night	16% 9% 2 7% 4 4 5% 4 6% 7% 37%	1900
	11th to 20th	Night	18% 7% 4 7% 4 5% 4 4 5% 6% 37%	1817
	21st to end	Night	16% 9% 3 7% 6% 4 4 4 4 6% 37%	1710
May	1st to 10th	Night	15% 9% 3 8% 6% 5% 6% 5% 6% 8% 31%	2813
	11th to 20th	Night	19% 8% 3 6% 3 4 3 3 5% 6% 40%	2812
	21st to end	Night	12% 6% 2 5% 4 5% 5% 4 5% 8% 44%	2967
June	1st to 10th	Night	9% 6% 1 4 5% 4 4 4 7% 9% 47%	1520
	11th to 20th	Night	8% 6% 2 6% 4 5% 5% 5% 6% 8% 45%	1520
	21st to end	Night	8% 5% 2 5% 6% 5% 4 4 7% 9% 44%	1520
July	1st to 10th	Night	9% 4 1 6% 4 4 5% 4 5% 10% 46%	2530
	11th to 20th	Night	6% 4 1 5% 3 3 3 3 6% 10% 55%	2530
	21st to end	Night	7% 5% 2 6% 5% 4 5% 4 7% 11% 45%	2896
August	1st to 10th	Night	10% 6% 2 6% 4 4 5% 4 6% 10% 42%	2825
	11th to 20th	Night	7% 5% 2 6% 5% 4 5% 4 6% 9% 47%	2785
	21st to end	Night	9% 5% 2 6% 4 4 4 3 5% 8% 49%	3426
September	1st to 10th	Night	10% 5% 2 5% 4 4 4 3 4 6% 52%	1949
	11th to 20th	Night	10% 5% 1 4 4 3 4 2 4 7% 56%	2090
	21st to end	Night	13% 6% 3 6% 4 3 4 4 5% 6% 46%	2090
October	1st to 10th	Night	10% 6% 3 6% 4 3 4 3 6% 7% 50%	2090
	11th to 20th	Night	18% 9% 3 7% 4 4 4 3 5% 5% 39%	2267
	21st to end	Night	20% 9% 3 6% 4 3 4 3 5% 7% 37%	2717
November	1st to 10th	Night	12% 8% 3 6% 4 4 4 3 6% 6% 44%	2452
	11th to 20th	Night	16% 11% 3 8% 4 4 4 4 6% 7% 32%	2470
	21st to end	Night	19% 12% 4 9% 5% 4 4 4 5% 6% 28%	2470
December	1st to 10th	Night	17% 15% 5% 9% 6% 5% 5% 4 4 6% 23%	2470
	11th to 20th	Night	17% 14% 6% 11% 5% 4 5% 3 5% 6% 24%	3261
	21st to end	Night	26% 19% 7% 10% 5% 4 4 3 4 5% 13%	4884

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	67% 5% 10% 14% 4	2528
	11th to 20th	Day	71% 4 10% 8% 7%	2530
	21st to end	Day	78% 3 5% 10% 3	2935
February	1st to 10th	Day	63% 5% 10% 13% 8% 1	1784
	11th to 20th	Day	61% 5% 9% 17% 8% 1	1858
	21st to end	Day	59% 5% 13% 16% 6% 2	1570
March	1st to 10th	Day	61% 5% 9% 20% 6%	3120
	11th to 20th	Day	46% 5% 12% 27% 8% 1	3439
	21st to end	Day	60% 6% 13% 17% 4 1	3868
April	1st to 10th	Day	53% 6% 10% 19% 11%	2280
	11th to 20th	Day	49% 6% 10% 22% 12% 2	2311
	21st to end	Day	48% 6% 13% 18% 13% 2	2470
May	1st to 10th	Day	50% 8% 12% 21% 10%	4120
	11th to 20th	Day	43% 8% 15% 24% 10% 1	4085
	21st to end	Day	35% 8% 12% 20% 22% 2	4601
June	1st to 10th	Day	40% 7% 11% 24% 17% 2	2660
	11th to 20th	Day	36% 7% 12% 25% 18% 2	2660
	21st to end	Day	39% 9% 13% 21% 15% 3	2660
July	1st to 10th	Day	42% 6% 13% 21% 16% 3	4371
	11th to 20th	Day	29% 7% 14% 32% 18% 1	4365
	21st to end	Day	37% 8% 14% 18% 20% 3	4513
August	1st to 10th	Day	35% 8% 15% 26% 16% 1	4091
	11th to 20th	Day	34% 7% 12% 29% 17% 1	4083
	21st to end	Day	31% 7% 13% 31% 15% 3	4225
September	1st to 10th	Day	37% 8% 13% 21% 17% 3	2211
	11th to 20th	Day	32% 6% 12% 27% 21% 1	2090
	21st to end	Day	40% 5% 11% 24% 18% 1	2090
October	1st to 10th	Day	29% 4 10% 36% 19% 1	3480
	11th to 20th	Day	37% 5% 11% 23% 24%	3138
	21st to end	Day	44% 5% 12% 26% 12% 1	3081
November	1st to 10th	Day	38% 6% 12% 26% 16% 1	1699
	11th to 20th	Day	54% 5% 11% 18% 10% 1	1710
	21st to end	Day	60% 5% 11% 16% 7%	1710
December	1st to 10th	Day	66% 5% 12% 12% 5%	1710
	11th to 20th	Day	61% 7% 13% 15% 3	1930
	21st to end	Day	78% 4 7% 6% 5%	2783
January	1st to 10th	Night	63% 6% 10% 14% 7%	4428
	11th to 20th	Night	72% 5% 9% 11% 4	4440
	21st to end	Night	72% 4 8% 12% 3	4724
February	1st to 10th	Night	61% 5% 11% 14% 7% 2	2394
	11th to 20th	Night	55% 5% 9% 21% 9% 1	2219
	21st to end	Night	57% 4 11% 17% 10% 1	1884
March	1st to 10th	Night	52% 4 10% 23% 9%	3733
	11th to 20th	Night	36% 7% 11% 27% 17% 2	3521
	21st to end	Night	50% 6% 14% 22% 7% 1	3791
April	1st to 10th	Night	45% 7% 10% 22% 15% 1	1900
	11th to 20th	Night	47% 6% 9% 17% 18% 2	1817
	21st to end	Night	47% 7% 10% 19% 15% 3	1710
May	1st to 10th	Night	49% 8% 10% 20% 12% 2	2840
	11th to 20th	Night	44% 6% 10% 27% 11% 1	2813
	21st to end	Night	35% 8% 14% 20% 20% 3	2975
June	1st to 10th	Night	31% 6% 13% 28% 19% 3	1520
	11th to 20th	Night	35% 7% 12% 24% 19% 3	1520
	21st to end	Night	35% 8% 16% 23% 16% 3	1520
July	1st to 10th	Night	34% 6% 12% 24% 18% 6%	2490
	11th to 20th	Night	25% 6% 16% 28% 23% 2	2482
	21st to end	Night	32% 7% 16% 19% 21% 5%	2804
August	1st to 10th	Night	37% 6% 14% 28% 14% 2	2814
	11th to 20th	Night	32% 7% 12% 30% 16% 1	2812
	21st to end	Night	33% 6% 11% 29% 18% 2	3426
September	1st to 10th	Night	32% 7% 12% 23% 21% 5%	1949
	11th to 20th	Night	29% 5% 9% 30% 26% 2	2090
	21st to end	Night	37% 6% 11% 27% 18% 2	2090
October	1st to 10th	Night	22% 4 8% 32% 32% 1	3480
	11th to 20th	Night	38% 4 9% 23% 25% 1	3777
	21st to end	Night	36% 4 9% 32% 18% 1	4467
November	1st to 10th	Night	39% 5% 11% 26% 17% 1	2452
	11th to 20th	Night	51% 5% 12% 20% 11% 2	2470
	21st to end	Night	56% 6% 12% 18% 7%	2470
December	1st to 10th	Night	61% 6% 11% 15% 7%	2470
	11th to 20th	Night	61% 5% 13% 13% 7% 1	3263
	21st to end	Night	73% 6% 10% 8% 3	4884

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	23% 18% 35% 19% 5% 1	270
	11th to 20th	Day	27% 13% 41% 14% 4 1	270
	21st to end	Day	28% 15% 31% 20% 6%	297
February	1st to 10th	Day	24% 17% 35% 19% 5% 1	270
	11th to 20th	Day	23% 19% 33% 19% 6%	270
	21st to end	Day	24% 21% 40% 12% 3	225
March	1st to 10th	Day	23% 18% 38% 17% 4	270
	11th to 20th	Day	23% 13% 33% 23% 7% 1	432
	21st to end	Day	28% 13% 32% 20% 6% 1	506
April	1st to 10th	Day	20% 16% 32% 20% 9% 2	460
	11th to 20th	Day	22% 15% 33% 17% 10% 2	452
	21st to end	Day	22% 16% 30% 18% 11% 3	460
May	1st to 10th	Day	23% 11% 31% 21% 10% 3	463
	11th to 20th	Day	21% 8% 27% 23% 15% 6%	487
	21st to end	Day	12% 7% 26% 26% 18% 10%	589
June	1st to 10th	Day	11% 9% 28% 30% 17% 5%	680
	11th to 20th	Day	11% 6% 32% 25% 20% 6%	680
	21st to end	Day	13% 6% 28% 30% 16% 6%	680
July	1st to 10th	Day	11% 3 19% 31% 22% 15%	671
	11th to 20th	Day	8% 3 24% 30% 23% 11%	668
	21st to end	Day	8% 3 21% 29% 27% 12%	649
August	1st to 10th	Day	8% 3 17% 29% 25% 18%	486
	11th to 20th	Day	10% 4 20% 28% 26% 12%	479
	21st to end	Day	9% 2 17% 25% 31% 16%	539
September	1st to 10th	Day	12% 7% 19% 25% 25% 13%	490
	11th to 20th	Day	9% 3 13% 25% 32% 18%	490
	21st to end	Day	18% 9% 19% 25% 22% 7%	490
October	1st to 10th	Day	13% 8% 24% 30% 17% 9%	490
	11th to 20th	Day	18% 15% 28% 29% 8% 2	464
	21st to end	Day	26% 14% 36% 19% 5% 1	330
November	1st to 10th	Day	13% 13% 33% 25% 13% 3	279
	11th to 20th	Day	26% 16% 30% 18% 10%	270
	21st to end	Day	27% 13% 37% 18% 4	270
December	1st to 10th	Day	21% 23% 32% 16% 9%	270
	11th to 20th	Day	22% 15% 40% 18% 5%	270
	21st to end	Day	24% 22% 35% 16% 2	297
January	1st to 10th	Night	22% 15% 36% 21% 6%	950
	11th to 20th	Night	25% 12% 36% 21% 4 1	950
	21st to end	Night	22% 13% 37% 24% 4	950
February	1st to 10th	Night	25% 12% 36% 23% 3	760
	11th to 20th	Night	20% 14% 38% 26% 2	743
	21st to end	Night	28% 15% 35% 19% 3	628
March	1st to 10th	Night	20% 12% 36% 26% 6% 1	760
	11th to 20th	Night	17% 12% 38% 27% 5% 1	760
	21st to end	Night	23% 11% 32% 26% 7%	822
April	1st to 10th	Night	19% 12% 34% 27% 7% 1	570
	11th to 20th	Night	21% 10% 34% 27% 7% 1	563
	21st to end	Night	20% 9% 35% 26% 10% 1	570
May	1st to 10th	Night	19% 8% 34% 31% 8% 1	570
	11th to 20th	Night	22% 4 27% 31% 15% 1	561
	21st to end	Night	12% 4 24% 38% 19% 2	617
June	1st to 10th	Night	10% 4 26% 45% 15% 1	570
	11th to 20th	Night	11% 4 25% 40% 19% 1	570
	21st to end	Night	9% 4 26% 36% 23% 2	570
July	1st to 10th	Night	9% 3 16% 40% 27% 4	555
	11th to 20th	Night	8% 3 18% 38% 30% 3	552
	21st to end	Night	7% 1 17% 42% 33% 1	624
August	1st to 10th	Night	7% 2 14% 46% 27% 4	567
	11th to 20th	Night	8% 1 13% 43% 30% 4	564
	21st to end	Night	10% 1 16% 33% 38% 3	627
September	1st to 10th	Night	12% 3 16% 34% 31% 3	619
	11th to 20th	Night	11% 4 14% 35% 33% 3	760
	21st to end	Night	16% 5% 22% 34% 19% 3	760
October	1st to 10th	Night	13% 6% 25% 33% 20% 3	760
	11th to 20th	Night	20% 14% 26% 28% 11% 1	760
	21st to end	Night	23% 13% 32% 25% 7%	836
November	1st to 10th	Night	16% 12% 32% 28% 12% 1	755
	11th to 20th	Night	23% 14% 31% 25% 6% 1	760
	21st to end	Night	24% 12% 31% 27% 6%	760
December	1st to 10th	Night	26% 14% 34% 21% 5%	760
	11th to 20th	Night	26% 11% 36% 23% 4	932
	21st to end	Night	30% 14% 31% 23% 3	1045

Page generated at 2024-11-01 22:47:34. Version ac07

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