Huntington
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Huntington clear sky chart from 2005-11-06 to 2026-08-15.

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	14% 9% 4 8% 5% 5% 5% 4 5% 7% 35%	143272
	Night	15% 10% 4 8% 5% 4 4 3 5% 6% 35%	138829
Transparency	Day	48% 4 11% 23% 13% 1	146855
	Night	49% 4 10% 22% 14% 2	143321
Seeing	Day	18% 11% 27% 23% 15% 6%	18082
	Night	19% 10% 28% 29% 13% 1	27841

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	15% 15% 8% 17% 6% 4 4 3 4 5% 18%	4691
	11th to 20th	Day	11% 14% 9% 13% 8% 8% 7% 5% 4 4 18%	4710
	21st to end	Day	19% 16% 7% 13% 7% 5% 4 4 4 4 17%	5400
February	1st to 10th	Day	16% 14% 6% 13% 7% 5% 4 3 4 5% 21%	2016
	11th to 20th	Day	15% 13% 5% 11% 8% 5% 4 4 4 6% 25%	2048
	21st to end	Day	17% 15% 6% 10% 5% 4 3 3 4 6% 28%	1730
March	1st to 10th	Day	19% 15% 7% 9% 4 4 3 2 3 4 30%	4580
	11th to 20th	Day	11% 12% 4 6% 4 4 4 3 6% 8% 40%	4987
	21st to end	Day	18% 14% 5% 9% 5% 5% 5% 3 5% 6% 24%	5723
April	1st to 10th	Day	17% 12% 4 7% 5% 5% 5% 4 5% 7% 30%	2520
	11th to 20th	Day	16% 9% 3 7% 5% 4 4 3 5% 8% 34%	2525
	21st to end	Day	19% 8% 3 6% 5% 4 4 4 5% 7% 35%	2730
May	1st to 10th	Day	20% 8% 2 7% 5% 5% 5% 4 5% 7% 31%	7616
	11th to 20th	Day	16% 6% 2 6% 4 5% 4 4 6% 8% 38%	7626
	21st to end	Day	15% 6% 2 7% 5% 5% 5% 5% 6% 8% 36%	8621
June	1st to 10th	Day	11% 5% 3 6% 5% 5% 4 4 7% 8% 41%	2940
	11th to 20th	Day	10% 5% 2 6% 5% 4 5% 4 6% 9% 44%	2940
	21st to end	Day	10% 5% 2 7% 6% 4 6% 5% 7% 9% 39%	2940
July	1st to 10th	Day	11% 5% 2 6% 5% 5% 5% 4 7% 10% 40%	8280
	11th to 20th	Day	9% 4 2 5% 4 5% 5% 4 7% 11% 45%	8280
	21st to end	Day	10% 6% 3 7% 5% 5% 5% 5% 6% 9% 41%	8736
August	1st to 10th	Day	9% 5% 2 5% 5% 4 5% 4 7% 11% 44%	4364
	11th to 20th	Day	11% 4 2 6% 4 4 5% 4 6% 8% 45%	4198
	21st to end	Day	8% 4 2 6% 3 4 4 4 6% 9% 50%	4312
September	1st to 10th	Day	11% 6% 1 6% 5% 5% 5% 3 5% 7% 48%	2344
	11th to 20th	Day	10% 5% 2 5% 4 4 4 4 6% 9% 48%	2200
	21st to end	Day	14% 7% 3 5% 5% 4 4 3 5% 7% 44%	2200
October	1st to 10th	Day	12% 5% 2 6% 4 4 5% 3 6% 7% 45%	2200
	11th to 20th	Day	15% 6% 3 6% 5% 5% 4 4 5% 7% 41%	2016
	21st to end	Day	19% 9% 3 9% 5% 4 5% 4 5% 6% 32%	1980
November	1st to 10th	Day	10% 8% 2 6% 4 4 4 3 6% 7% 47%	1852
	11th to 20th	Day	17% 13% 3 8% 5% 4 4 3 5% 7% 31%	1890
	21st to end	Day	20% 14% 4 9% 4 4 4 3 4 5% 28%	1890
December	1st to 10th	Day	12% 13% 4 11% 5% 4 4 3 5% 6% 32%	3020
	11th to 20th	Day	17% 17% 6% 10% 5% 5% 4 3 4 5% 23%	3097
	21st to end	Day	28% 19% 7% 11% 5% 5% 4 3 3 4 11%	4070
January	1st to 10th	Night	15% 15% 7% 14% 6% 5% 4 4 4 5% 21%	8232
	11th to 20th	Night	10% 17% 8% 17% 7% 6% 5% 4 4 4 19%	8280
	21st to end	Night	18% 12% 6% 9% 5% 5% 5% 4 5% 5% 26%	8787
February	1st to 10th	Night	18% 14% 5% 11% 6% 4 4 3 4 5% 25%	2599
	11th to 20th	Night	13% 14% 4 9% 6% 5% 5% 3 4 7% 31%	2458
	21st to end	Night	18% 13% 4 10% 4 4 4 4 5% 6% 30%	2076
March	1st to 10th	Night	18% 12% 4 6% 4 4 3 3 4 6% 36%	5493
	11th to 20th	Night	12% 7% 2 5% 4 5% 5% 4 6% 7% 43%	5191
	21st to end	Night	17% 10% 3 8% 5% 4 4 3 5% 6% 35%	5477
April	1st to 10th	Night	16% 10% 3 6% 4 5% 4 3 5% 8% 35%	2100
	11th to 20th	Night	17% 7% 2 7% 5% 4 5% 3 5% 6% 39%	2044
	21st to end	Night	18% 9% 3 6% 4 4 4 2 6% 6% 38%	1890
May	1st to 10th	Night	21% 9% 3 8% 5% 5% 4 3 4 6% 32%	5237
	11th to 20th	Night	16% 6% 2 6% 4 3 4 3 5% 8% 43%	5234
	21st to end	Night	14% 6% 2 7% 4 4 4 4 6% 8% 39%	5538
June	1st to 10th	Night	10% 5% 3 6% 4 4 4 4 5% 8% 47%	1680
	11th to 20th	Night	9% 5% 2 6% 5% 4 4 4 6% 9% 46%	1680
	21st to end	Night	11% 4 2 6% 5% 4 5% 4 5% 9% 45%	1680
July	1st to 10th	Night	10% 4 2 5% 4 4 4 4 6% 9% 47%	4708
	11th to 20th	Night	8% 5% 2 6% 4 4 4 3 5% 9% 51%	4707
	21st to end	Night	10% 5% 2 7% 5% 4 4 4 6% 9% 44%	5357
August	1st to 10th	Night	12% 5% 2 6% 4 4 4 4 5% 8% 45%	3005
	11th to 20th	Night	10% 5% 2 6% 4 5% 4 3 6% 6% 49%	2935
	21st to end	Night	7% 4 2 6% 4 4 5% 3 6% 8% 51%	3586
September	1st to 10th	Night	10% 5% 2 5% 5% 3 4 3 5% 7% 52%	2035
	11th to 20th	Night	9% 4 1 4 3 4 3 3 5% 7% 57%	2200
	21st to end	Night	13% 6% 2 5% 4 4 4 3 5% 6% 48%	2200
October	1st to 10th	Night	10% 5% 2 4 3 4 4 4 4 7% 53%	2200
	11th to 20th	Night	17% 8% 2 6% 4 4 3 3 4 6% 44%	2378
	21st to end	Night	18% 9% 2 6% 4 3 4 4 5% 6% 38%	2860
November	1st to 10th	Night	12% 8% 3 6% 4 3 3 3 5% 6% 46%	2666
	11th to 20th	Night	15% 12% 3 7% 4 4 3 4 5% 7% 36%	2730
	21st to end	Night	19% 13% 5% 8% 5% 4 3 3 5% 6% 28%	2730
December	1st to 10th	Night	14% 10% 4 8% 5% 5% 6% 4 6% 7% 32%	4380
	11th to 20th	Night	19% 16% 9% 11% 5% 4 4 3 4 5% 21%	5326
	21st to end	Night	28% 18% 7% 11% 5% 5% 4 3 4 4 12%	7150

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	70% 3 10% 14% 3	4692
	11th to 20th	Day	71% 3 8% 8% 9% 1	4710
	21st to end	Day	72% 3 8% 12% 5%	5400
February	1st to 10th	Day	67% 2 9% 13% 7% 1	2016
	11th to 20th	Day	61% 3 9% 19% 7% 1	2058
	21st to end	Day	58% 3 12% 18% 8% 1	1730
March	1st to 10th	Day	61% 2 5% 22% 10%	4580
	11th to 20th	Day	44% 2 10% 34% 9% 1	4987
	21st to end	Day	61% 2 14% 17% 5% 1	5725
April	1st to 10th	Day	55% 3 10% 20% 12%	2520
	11th to 20th	Day	50% 4 10% 22% 12% 2	2525
	21st to end	Day	49% 3 12% 23% 11% 3	2730
May	1st to 10th	Day	53% 4 10% 21% 12%	7651
	11th to 20th	Day	45% 4 12% 23% 15% 1	7630
	21st to end	Day	45% 4 8% 24% 14% 5%	8635
June	1st to 10th	Day	39% 5% 11% 25% 18% 2	2940
	11th to 20th	Day	37% 4 12% 25% 19% 3	2940
	21st to end	Day	40% 5% 14% 22% 15% 3	2940
July	1st to 10th	Day	37% 6% 12% 27% 16% 2	8211
	11th to 20th	Day	32% 6% 13% 31% 17% 1	8205
	21st to end	Day	39% 6% 11% 24% 18% 2	8543
August	1st to 10th	Day	33% 7% 16% 28% 15% 1	4351
	11th to 20th	Day	35% 5% 13% 30% 16% 1	4237
	21st to end	Day	30% 5% 13% 30% 18% 3	4311
September	1st to 10th	Day	36% 4 12% 25% 19% 3	2344
	11th to 20th	Day	34% 4 9% 29% 23% 2	2200
	21st to end	Day	40% 3 9% 25% 22% 1	2200
October	1st to 10th	Day	28% 3 11% 33% 24% 1	3590
	11th to 20th	Day	36% 4 11% 23% 25% 1	3258
	21st to end	Day	44% 4 9% 27% 15% 1	3180
November	1st to 10th	Day	37% 4 11% 28% 18% 1	1852
	11th to 20th	Day	54% 2 11% 19% 11% 2	1890
	21st to end	Day	59% 3 10% 19% 7% 1	1890
December	1st to 10th	Day	54% 3 16% 22% 5%	3020
	11th to 20th	Day	65% 2 11% 17% 4	3094
	21st to end	Day	79% 3 6% 8% 4	4070
January	1st to 10th	Night	66% 4 9% 16% 6%	8233
	11th to 20th	Night	70% 2 7% 11% 9%	8280
	21st to end	Night	61% 3 11% 17% 7%	8787
February	1st to 10th	Night	63% 3 10% 16% 8% 1	2599
	11th to 20th	Night	55% 3 10% 22% 10% 1	2459
	21st to end	Night	56% 3 11% 18% 10% 2	2076
March	1st to 10th	Night	51% 2 8% 28% 10% 1	5493
	11th to 20th	Night	41% 3 10% 29% 15% 2	5191
	21st to end	Night	52% 2 10% 26% 10% 1	5477
April	1st to 10th	Night	48% 4 10% 22% 14% 1	2100
	11th to 20th	Night	47% 3 9% 22% 16% 3	2044
	21st to end	Night	48% 3 9% 24% 12% 3	1890
May	1st to 10th	Night	55% 3 8% 19% 13% 2	5264
	11th to 20th	Night	41% 4 11% 27% 16% 1	5235
	21st to end	Night	42% 4 11% 21% 17% 5%	5548
June	1st to 10th	Night	36% 4 10% 26% 22% 2	1680
	11th to 20th	Night	34% 5% 12% 25% 21% 3	1680
	21st to end	Night	36% 6% 16% 23% 16% 4	1680
July	1st to 10th	Night	33% 6% 11% 27% 19% 4	4670
	11th to 20th	Night	31% 5% 13% 28% 22% 1	4662
	21st to end	Night	36% 6% 13% 23% 20% 3	5237
August	1st to 10th	Night	37% 5% 14% 30% 14% 1	2994
	11th to 20th	Night	34% 5% 12% 31% 17% 1	2962
	21st to end	Night	31% 5% 12% 28% 21% 3	3586
September	1st to 10th	Night	33% 4 12% 26% 20% 6%	2035
	11th to 20th	Night	28% 3 8% 32% 27% 2	2200
	21st to end	Night	37% 4 10% 24% 22% 2	2200
October	1st to 10th	Night	22% 3 7% 33% 34% 1	3590
	11th to 20th	Night	34% 3 8% 24% 30% 1	3875
	21st to end	Night	35% 3 8% 32% 20% 2	4610
November	1st to 10th	Night	40% 3 9% 27% 20% 1	2666
	11th to 20th	Night	48% 3 11% 22% 14% 2	2730
	21st to end	Night	58% 3 11% 20% 8%	2730
December	1st to 10th	Night	51% 4 13% 25% 6% 1	4380
	11th to 20th	Night	67% 3 10% 12% 7% 1	5328
	21st to end	Night	77% 3 8% 9% 3	7150

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% 17% 39% 15% 5% 1	330
	11th to 20th	Day	24% 20% 38% 14% 3 1	330
	21st to end	Day	26% 18% 34% 16% 5% 1	363
February	1st to 10th	Day	26% 18% 35% 17% 4	330
	11th to 20th	Day	26% 19% 36% 15% 4	330
	21st to end	Day	26% 21% 38% 13% 2	273
March	1st to 10th	Day	23% 24% 38% 13% 2 1	330
	11th to 20th	Day	29% 15% 30% 19% 7% 1	489
	21st to end	Day	30% 17% 29% 17% 5% 1	594
April	1st to 10th	Day	24% 13% 34% 19% 8% 1	540
	11th to 20th	Day	22% 20% 27% 19% 9% 3	532
	21st to end	Day	22% 15% 31% 20% 9% 2	540
May	1st to 10th	Day	24% 14% 29% 21% 8% 3	543
	11th to 20th	Day	22% 8% 28% 24% 12% 5%	567
	21st to end	Day	12% 7% 29% 26% 18% 8%	691
June	1st to 10th	Day	12% 8% 29% 28% 17% 6%	780
	11th to 20th	Day	12% 8% 28% 28% 18% 5%	780
	21st to end	Day	12% 7% 27% 28% 19% 7%	780
July	1st to 10th	Day	11% 3 18% 32% 23% 13%	771
	11th to 20th	Day	8% 4 21% 32% 23% 12%	768
	21st to end	Day	9% 4 18% 32% 27% 11%	760
August	1st to 10th	Day	9% 3 14% 30% 27% 17%	566
	11th to 20th	Day	11% 5% 18% 26% 28% 12%	535
	21st to end	Day	8% 4 13% 29% 32% 14%	583
September	1st to 10th	Day	12% 6% 17% 26% 27% 12%	530
	11th to 20th	Day	9% 3 13% 24% 33% 18%	530
	21st to end	Day	18% 9% 19% 24% 22% 7%	530
October	1st to 10th	Day	12% 6% 25% 28% 21% 8%	530
	11th to 20th	Day	17% 16% 28% 27% 10% 2	481
	21st to end	Day	25% 16% 33% 22% 2 1	363
November	1st to 10th	Day	13% 15% 36% 23% 9% 3	330
	11th to 20th	Day	26% 19% 29% 16% 8% 1	330
	21st to end	Day	32% 15% 32% 18% 3	330
December	1st to 10th	Day	22% 22% 34% 17% 6%	330
	11th to 20th	Day	24% 17% 40% 14% 5%	330
	21st to end	Day	30% 21% 32% 15% 2	363
January	1st to 10th	Night	24% 15% 35% 21% 5%	1050
	11th to 20th	Night	23% 17% 37% 20% 4	1050
	21st to end	Night	23% 15% 36% 22% 4	1065
February	1st to 10th	Night	26% 13% 32% 25% 4	840
	11th to 20th	Night	21% 14% 39% 22% 3	823
	21st to end	Night	26% 15% 37% 20% 3	692
March	1st to 10th	Night	23% 14% 33% 24% 6%	840
	11th to 20th	Night	20% 13% 35% 25% 7% 1	840
	21st to end	Night	24% 11% 33% 26% 5%	877
April	1st to 10th	Night	21% 11% 34% 27% 6% 1	630
	11th to 20th	Night	19% 12% 34% 27% 7% 1	623
	21st to end	Night	21% 9% 35% 26% 8% 1	630
May	1st to 10th	Night	23% 8% 33% 30% 7%	630
	11th to 20th	Night	20% 5% 26% 32% 15% 1	621
	21st to end	Night	12% 4 24% 42% 16% 2	683
June	1st to 10th	Night	11% 3 23% 47% 17%	630
	11th to 20th	Night	10% 5% 25% 40% 19% 1	630
	21st to end	Night	11% 3 23% 39% 23% 1	630
July	1st to 10th	Night	9% 2 14% 42% 28% 4	615
	11th to 20th	Night	8% 3 14% 39% 33% 3	612
	21st to end	Night	7% 5% 12% 43% 31% 1	690
August	1st to 10th	Night	8% 2 12% 41% 32% 5%	627
	11th to 20th	Night	10% 3 13% 40% 31% 3	606
	21st to end	Night	7% 2 15% 36% 36% 4	660
September	1st to 10th	Night	11% 3 15% 34% 33% 4	635
	11th to 20th	Night	11% 2 14% 37% 33% 4	800
	21st to end	Night	15% 7% 21% 34% 20% 3	800
October	1st to 10th	Night	14% 5% 23% 34% 21% 4	800
	11th to 20th	Night	21% 12% 26% 29% 11% 1	800
	21st to end	Night	23% 12% 32% 26% 7%	880
November	1st to 10th	Night	17% 11% 35% 25% 11%	820
	11th to 20th	Night	20% 15% 33% 26% 6%	840
	21st to end	Night	27% 13% 28% 25% 7%	840
December	1st to 10th	Night	24% 14% 34% 23% 5%	840
	11th to 20th	Night	25% 13% 33% 23% 5%	1037
	21st to end	Night	33% 13% 31% 20% 3	1155

Page generated at 2026-08-12 03:37:15. Version ac07

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