Auroraville
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Auroraville 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% 8% 3 7% 5% 4 5% 4 5% 7% 38%	101473
	Night	14% 10% 4 8% 5% 4 4 4 5% 6% 38%	97630
Transparency	Day	43% 7% 12% 25% 12% 1	104990
	Night	45% 6% 11% 23% 13% 1	102253
Seeing	Day	16% 9% 28% 27% 15% 5%	15956
	Night	17% 8% 30% 31% 12% 1	25809

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	11% 14% 7% 12% 6% 4 5% 3 4 4 29%	2527
	11th to 20th	Day	11% 13% 5% 13% 5% 5% 10% 5% 6% 5% 22%	2530
	21st to end	Day	16% 18% 7% 13% 6% 5% 3 3 5% 5% 21%	2819
February	1st to 10th	Day	11% 12% 4 9% 6% 5% 5% 4 6% 6% 32%	1710
	11th to 20th	Day	11% 11% 3 8% 5% 5% 5% 4 5% 6% 37%	1781
	21st to end	Day	12% 11% 5% 8% 6% 5% 4 4 6% 6% 33%	1570
March	1st to 10th	Day	13% 8% 3 6% 3 3 4 3 5% 6% 47%	3120
	11th to 20th	Day	9% 8% 3 8% 4 4 4 3 5% 8% 44%	3311
	21st to end	Day	22% 11% 4 10% 5% 4 4 2 4 6% 30%	4151
April	1st to 10th	Day	17% 13% 3 7% 5% 5% 4 5% 5% 6% 32%	2280
	11th to 20th	Day	20% 10% 3 7% 5% 5% 4 4 5% 5% 34%	2254
	21st to end	Day	20% 9% 3 8% 5% 4 4 4 5% 6% 33%	2389
May	1st to 10th	Day	14% 7% 3 6% 4 4 5% 4 6% 7% 40%	4241
	11th to 20th	Day	14% 6% 2 6% 4 4 4 3 5% 7% 46%	4399
	21st to end	Day	14% 7% 2 7% 5% 5% 5% 4 6% 7% 39%	4824
June	1st to 10th	Day	12% 5% 2 6% 4 4 4 4 5% 8% 46%	2660
	11th to 20th	Day	14% 5% 3 5% 4 5% 5% 4 7% 9% 41%	2660
	21st to end	Day	12% 6% 2 6% 4 4 4 4 6% 9% 42%	2660
July	1st to 10th	Day	13% 5% 2 7% 5% 5% 5% 5% 7% 9% 36%	4440
	11th to 20th	Day	5% 3 1 4 3 4 5% 4 8% 10% 52%	4440
	21st to end	Day	9% 6% 2 6% 5% 5% 5% 4 6% 8% 45%	4813
August	1st to 10th	Day	9% 5% 2 6% 5% 5% 5% 4 6% 8% 43%	4423
	11th to 20th	Day	12% 5% 1 5% 3 4 5% 4 6% 8% 45%	3864
	21st to end	Day	12% 5% 2 7% 5% 5% 6% 4 5% 8% 42%	4180
September	1st to 10th	Day	13% 5% 2 7% 4 4 4 3 5% 7% 46%	2280
	11th to 20th	Day	12% 4 2 5% 4 4 4 4 5% 8% 49%	2204
	21st to end	Day	14% 6% 3 6% 4 5% 4 4 6% 7% 42%	2090
October	1st to 10th	Day	14% 7% 3 6% 4 3 4 3 5% 7% 45%	1957
	11th to 20th	Day	19% 10% 3 7% 4 5% 4 3 6% 7% 33%	1895
	21st to end	Day	17% 10% 3 7% 4 3 4 4 4 5% 38%	1881
November	1st to 10th	Day	13% 7% 2 7% 4 5% 5% 3 5% 6% 43%	1699
	11th to 20th	Day	14% 12% 4 9% 5% 5% 5% 3 6% 6% 31%	1680
	21st to end	Day	15% 11% 3 8% 5% 4 4 3 4 6% 36%	1520
December	1st to 10th	Day	13% 12% 5% 11% 6% 4 5% 4 5% 7% 30%	1520
	11th to 20th	Day	13% 13% 5% 10% 6% 6% 5% 4 4 7% 27%	1918
	21st to end	Day	20% 19% 7% 12% 6% 4 4 3 4 5% 17%	2783
January	1st to 10th	Night	13% 15% 8% 11% 5% 4 3 2 3 4 33%	4428
	11th to 20th	Night	12% 13% 6% 13% 6% 5% 7% 6% 6% 5% 20%	4440
	21st to end	Night	15% 19% 8% 11% 5% 4 4 3 4 4 24%	4848
February	1st to 10th	Night	10% 13% 5% 9% 6% 5% 4 4 4 4 35%	2470
	11th to 20th	Night	10% 10% 4 8% 6% 5% 5% 4 5% 5% 40%	2285
	21st to end	Night	16% 11% 4 9% 4 4 4 3 4 6% 36%	1884
March	1st to 10th	Night	15% 7% 3 6% 3 4 4 3 5% 6% 44%	3733
	11th to 20th	Night	11% 7% 3 6% 6% 5% 5% 3 5% 7% 42%	3677
	21st to end	Night	20% 11% 4 10% 5% 4 4 3 4 5% 31%	3480
April	1st to 10th	Night	20% 10% 3 7% 4 4 4 3 4 6% 36%	1900
	11th to 20th	Night	21% 7% 3 7% 3 4 5% 3 5% 6% 37%	1875
	21st to end	Night	18% 8% 3 7% 4 3 4 4 5% 7% 38%	1791
May	1st to 10th	Night	16% 7% 3 8% 5% 5% 5% 4 6% 7% 36%	2644
	11th to 20th	Night	12% 6% 2 6% 5% 3 6% 4 6% 7% 44%	2506
	21st to end	Night	15% 7% 2 7% 5% 5% 4 4 5% 6% 40%	2743
June	1st to 10th	Night	9% 6% 2 6% 4 4 4 5% 6% 7% 47%	1520
	11th to 20th	Night	11% 6% 2 6% 4 4 4 4 6% 8% 45%	1520
	21st to end	Night	9% 4 2 5% 4 4 4 4 6% 9% 49%	1520
July	1st to 10th	Night	14% 7% 2 6% 3 3 3 4 6% 8% 44%	2530
	11th to 20th	Night	5% 3 1 4 3 4 4 5% 6% 8% 56%	2530
	21st to end	Night	8% 5% 2 6% 4 4 4 4 6% 7% 50%	2750
August	1st to 10th	Night	11% 5% 2 5% 4 3 4 4 4 8% 49%	2517
	11th to 20th	Night	10% 7% 2 6% 5% 4 5% 3 6% 7% 44%	2963
	21st to end	Night	10% 5% 2 6% 4 4 4 3 6% 8% 48%	3476
September	1st to 10th	Night	10% 5% 2 4 3 3 3 3 6% 7% 53%	1900
	11th to 20th	Night	13% 5% 2 4 3 3 4 3 5% 5% 53%	1956
	21st to end	Night	11% 5% 2 6% 5% 3 4 4 5% 7% 49%	2090
October	1st to 10th	Night	12% 6% 2 7% 3 4 4 3 5% 6% 48%	2219
	11th to 20th	Night	16% 8% 3 6% 4 5% 4 4 5% 6% 40%	2285
	21st to end	Night	19% 9% 2 7% 5% 4 5% 4 4 6% 35%	2717
November	1st to 10th	Night	13% 8% 3 4 4 4 4 3 5% 6% 45%	2452
	11th to 20th	Night	15% 11% 4 9% 5% 5% 4 4 4 5% 34%	2498
	21st to end	Night	15% 11% 3 8% 5% 4 4 3 5% 6% 37%	2660
December	1st to 10th	Night	13% 13% 4 8% 6% 5% 4 4 5% 6% 31%	2660
	11th to 20th	Night	13% 15% 5% 10% 7% 5% 4 3 4 5% 29%	3279
	21st to end	Night	22% 17% 5% 10% 5% 4 3 3 4 5% 21%	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	59% 6% 14% 15% 6%	2528
	11th to 20th	Day	60% 9% 11% 15% 5%	2530
	21st to end	Day	66% 6% 10% 14% 4	2819
February	1st to 10th	Day	51% 6% 13% 20% 9% 1	1710
	11th to 20th	Day	46% 7% 12% 23% 10% 2	1790
	21st to end	Day	52% 7% 11% 18% 10% 2	1570
March	1st to 10th	Day	38% 5% 12% 27% 15% 3	3120
	11th to 20th	Day	37% 7% 12% 28% 14% 1	3311
	21st to end	Day	57% 6% 9% 20% 7% 1	4151
April	1st to 10th	Day	52% 7% 12% 18% 11%	2280
	11th to 20th	Day	50% 7% 8% 21% 12% 2	2254
	21st to end	Day	50% 7% 11% 19% 11% 2	2389
May	1st to 10th	Day	41% 8% 11% 23% 16% 1	4279
	11th to 20th	Day	35% 8% 11% 32% 14% 1	4403
	21st to end	Day	42% 8% 10% 22% 16% 2	4837
June	1st to 10th	Day	37% 7% 14% 26% 16% 1	2660
	11th to 20th	Day	38% 9% 13% 25% 15% 1	2660
	21st to end	Day	37% 8% 15% 25% 13% 2	2660
July	1st to 10th	Day	41% 8% 15% 26% 9% 1	4371
	11th to 20th	Day	24% 8% 16% 35% 16% 1	4365
	21st to end	Day	35% 8% 13% 22% 19% 3	4662
August	1st to 10th	Day	37% 7% 16% 28% 12% 1	4408
	11th to 20th	Day	34% 7% 12% 35% 12%	3903
	21st to end	Day	39% 7% 12% 27% 14% 1	4179
September	1st to 10th	Day	36% 7% 12% 26% 17% 1	2280
	11th to 20th	Day	33% 7% 16% 31% 12% 1	2204
	21st to end	Day	40% 6% 12% 29% 12%	2090
October	1st to 10th	Day	24% 4 7% 39% 25% 1	3256
	11th to 20th	Day	41% 5% 9% 28% 17% 1	3123
	21st to end	Day	42% 5% 13% 28% 12% 1	3081
November	1st to 10th	Day	41% 6% 14% 23% 14% 2	1699
	11th to 20th	Day	54% 6% 13% 19% 8% 1	1680
	21st to end	Day	50% 6% 14% 22% 7%	1520
December	1st to 10th	Day	55% 6% 14% 18% 6% 1	1520
	11th to 20th	Day	56% 5% 15% 16% 6% 2	1915
	21st to end	Day	71% 7% 8% 10% 4	2783
January	1st to 10th	Night	57% 5% 9% 20% 8% 1	4428
	11th to 20th	Night	63% 7% 10% 13% 7%	4440
	21st to end	Night	64% 5% 9% 16% 5%	4848
February	1st to 10th	Night	52% 6% 10% 21% 10% 1	2470
	11th to 20th	Night	46% 6% 11% 24% 10% 2	2286
	21st to end	Night	51% 5% 12% 19% 11% 2	1884
March	1st to 10th	Night	41% 6% 13% 27% 10% 4	3733
	11th to 20th	Night	38% 6% 12% 25% 17% 2	3677
	21st to end	Night	56% 5% 7% 20% 10% 2	3480
April	1st to 10th	Night	50% 6% 9% 18% 16% 2	1900
	11th to 20th	Night	47% 5% 9% 21% 15% 3	1875
	21st to end	Night	44% 8% 12% 22% 14% 1	1791
May	1st to 10th	Night	43% 9% 14% 16% 17%	2671
	11th to 20th	Night	36% 10% 11% 27% 15% 1	2507
	21st to end	Night	42% 8% 10% 19% 17% 3	2751
June	1st to 10th	Night	34% 7% 14% 27% 17% 1	1520
	11th to 20th	Night	36% 7% 11% 27% 19% 2	1520
	21st to end	Night	31% 8% 16% 28% 14% 3	1520
July	1st to 10th	Night	38% 6% 16% 22% 13% 4	2490
	11th to 20th	Night	23% 7% 17% 34% 18% 2	2482
	21st to end	Night	30% 9% 15% 22% 21% 3	2662
August	1st to 10th	Night	33% 7% 14% 26% 18% 2	2508
	11th to 20th	Night	37% 7% 12% 29% 14%	2990
	21st to end	Night	33% 6% 14% 24% 20% 2	3476
September	1st to 10th	Night	30% 7% 12% 27% 23% 1	1900
	11th to 20th	Night	32% 7% 11% 34% 15% 1	1956
	21st to end	Night	35% 6% 12% 31% 16% 1	2090
October	1st to 10th	Night	27% 4 6% 36% 24% 2	3700
	11th to 20th	Night	33% 4 11% 32% 17% 2	3796
	21st to end	Night	45% 5% 9% 24% 16%	4467
November	1st to 10th	Night	40% 6% 12% 25% 15% 2	2452
	11th to 20th	Night	52% 7% 13% 17% 11% 1	2498
	21st to end	Night	48% 5% 16% 24% 7% 1	2660
December	1st to 10th	Night	54% 6% 13% 20% 6% 1	2660
	11th to 20th	Night	59% 6% 11% 17% 7% 1	3281
	21st to end	Night	66% 6% 9% 14% 4	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	16% 9% 32% 30% 10% 2	270
	11th to 20th	Day	21% 10% 33% 28% 7% 1	270
	21st to end	Day	19% 8% 31% 32% 9%	297
February	1st to 10th	Day	11% 13% 43% 24% 7% 1	270
	11th to 20th	Day	15% 16% 40% 19% 9% 1	270
	21st to end	Day	16% 14% 44% 24% 2	225
March	1st to 10th	Day	21% 12% 39% 19% 9% 1	270
	11th to 20th	Day	20% 15% 33% 21% 8% 3	270
	21st to end	Day	27% 9% 28% 25% 10% 1	492
April	1st to 10th	Day	24% 11% 33% 24% 7%	460
	11th to 20th	Day	26% 13% 29% 18% 11% 3	452
	21st to end	Day	21% 12% 28% 25% 12% 3	460
May	1st to 10th	Day	18% 11% 34% 25% 11% 2	557
	11th to 20th	Day	19% 10% 27% 27% 12% 5%	675
	21st to end	Day	18% 7% 25% 27% 16% 7%	734
June	1st to 10th	Day	10% 8% 28% 31% 17% 5%	680
	11th to 20th	Day	18% 6% 28% 29% 15% 5%	680
	21st to end	Day	13% 8% 26% 30% 17% 6%	680
July	1st to 10th	Day	9% 3 19% 28% 27% 14%	671
	11th to 20th	Day	8% 6% 23% 30% 23% 10%	668
	21st to end	Day	9% 4 23% 33% 22% 9%	739
August	1st to 10th	Day	9% 5% 21% 30% 24% 10%	676
	11th to 20th	Day	13% 5% 16% 26% 27% 14%	538
	21st to end	Day	12% 6% 20% 31% 21% 11%	539
September	1st to 10th	Day	14% 7% 21% 29% 21% 8%	490
	11th to 20th	Day	13% 3 18% 34% 23% 9%	490
	21st to end	Day	17% 9% 25% 24% 19% 6%	490
October	1st to 10th	Day	17% 9% 27% 24% 18% 5%	357
	11th to 20th	Day	18% 15% 34% 23% 9% 1	300
	21st to end	Day	23% 12% 36% 22% 7% 1	330
November	1st to 10th	Day	15% 13% 33% 26% 11% 2	279
	11th to 20th	Day	14% 19% 37% 20% 8% 1	270
	21st to end	Day	21% 13% 38% 21% 6%	270
December	1st to 10th	Day	16% 16% 39% 22% 7% 1	270
	11th to 20th	Day	20% 16% 36% 21% 7% 1	270
	21st to end	Day	26% 13% 39% 18% 4	297
January	1st to 10th	Night	17% 12% 35% 27% 8% 1	950
	11th to 20th	Night	20% 11% 35% 28% 6% 1	950
	21st to end	Night	20% 9% 32% 30% 8%	1045
February	1st to 10th	Night	17% 10% 37% 27% 8%	950
	11th to 20th	Night	15% 12% 39% 25% 8%	810
	21st to end	Night	22% 10% 35% 28% 5%	628
March	1st to 10th	Night	19% 9% 32% 29% 10% 1	760
	11th to 20th	Night	17% 9% 35% 31% 8% 1	689
	21st to end	Night	21% 7% 29% 33% 9% 1	627
April	1st to 10th	Night	24% 9% 34% 27% 5%	570
	11th to 20th	Night	23% 9% 30% 30% 6% 1	563
	21st to end	Night	20% 9% 29% 34% 8% 1	570
May	1st to 10th	Night	20% 8% 32% 33% 7% 1	570
	11th to 20th	Night	18% 7% 30% 35% 9% 1	561
	21st to end	Night	14% 6% 24% 37% 18% 1	617
June	1st to 10th	Night	11% 7% 23% 42% 16% 1	570
	11th to 20th	Night	15% 4 29% 39% 12% 1	570
	21st to end	Night	11% 4 23% 45% 16% 1	570
July	1st to 10th	Night	8% 2 19% 42% 26% 2	555
	11th to 20th	Night	9% 3 20% 42% 24% 2	552
	21st to end	Night	7% 2 17% 48% 25% 2	624
August	1st to 10th	Night	8% 3 16% 47% 24% 2	567
	11th to 20th	Night	10% 4 16% 39% 28% 4	564
	21st to end	Night	12% 2 18% 42% 24% 2	627
September	1st to 10th	Night	11% 3 24% 37% 20% 4	570
	11th to 20th	Night	15% 3 23% 32% 24% 4	626
	21st to end	Night	13% 8% 24% 33% 20% 2	760
October	1st to 10th	Night	15% 8% 26% 31% 19% 1	760
	11th to 20th	Night	20% 11% 33% 28% 8%	760
	21st to end	Night	25% 10% 29% 28% 8% 1	836
November	1st to 10th	Night	17% 8% 36% 27% 10% 1	755
	11th to 20th	Night	20% 14% 38% 22% 5%	788
	21st to end	Night	20% 12% 36% 25% 7%	950
December	1st to 10th	Night	20% 11% 40% 22% 7%	950
	11th to 20th	Night	23% 11% 34% 24% 7% 1	950
	21st to end	Night	28% 12% 31% 25% 4	1045

Page generated at 2024-11-01 21:47:51. Version ac07

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