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 2024-03-01.

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	15% 9% 4 7% 6% 3 5% 5% 5% 7% 34%	78490
	Night	16% 10% 4 7% 5% 3 4 4 5% 6% 34%	80956
Transparency	Day	50% 4 11% 21% 12% 2	78197
	Night	51% 3 10% 21% 13% 2	80770
Seeing	Day	18% 10% 26% 24% 15% 6%	14616
	Night	19% 9% 28% 29% 13% 1	24627

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	17% 14% 11% 11% 7% 3 4 4 4 5% 20%	2527
	11th to 20th	Day	16% 15% 10% 11% 8% 5% 6% 8% 5% 4 13%	2530
	21st to end	Day	27% 20% 11% 10% 5% 3 3 2 3 3 13%	2910
February	1st to 10th	Day	17% 14% 6% 11% 9% 3 5% 4 4 5% 22%	1824
	11th to 20th	Day	16% 11% 5% 10% 8% 4 4 5% 5% 6% 26%	1848
	21st to end	Day	18% 14% 6% 9% 5% 3 3 4 4 6% 27%	1570
March	1st to 10th	Day	17% 13% 6% 7% 7% 3 5% 4 4 6% 29%	1800
	11th to 20th	Day	17% 11% 4 7% 6% 3 4 5% 5% 8% 30%	1935
	21st to end	Day	22% 12% 4 7% 7% 3 5% 4 3 6% 26%	2232
April	1st to 10th	Day	16% 11% 5% 7% 6% 3 4 4 4 7% 32%	2160
	11th to 20th	Day	18% 9% 4 6% 5% 3 5% 4 5% 8% 34%	2160
	21st to end	Day	20% 9% 3 5% 6% 3 4 5% 5% 7% 33%	2340
May	1st to 10th	Day	18% 8% 3 6% 8% 4 5% 5% 6% 7% 31%	2340
	11th to 20th	Day	20% 7% 3 6% 5% 4 4 4 5% 7% 34%	2301
	21st to end	Day	11% 6% 2 6% 6% 4 5% 7% 6% 9% 38%	2593
June	1st to 10th	Day	11% 5% 3 5% 6% 4 5% 5% 7% 8% 41%	2520
	11th to 20th	Day	10% 5% 2 5% 6% 3 5% 5% 6% 9% 45%	2520
	21st to end	Day	10% 5% 2 6% 6% 3 6% 6% 7% 10% 38%	2520
July	1st to 10th	Day	9% 5% 2 5% 5% 3 6% 6% 6% 10% 43%	2520
	11th to 20th	Day	8% 4 2 5% 4 3 5% 5% 7% 10% 46%	2520
	21st to end	Day	7% 5% 2 5% 6% 4 6% 6% 7% 10% 42%	2667
August	1st to 10th	Day	7% 4 2 5% 5% 3 5% 5% 8% 11% 44%	2327
	11th to 20th	Day	9% 3 2 6% 5% 4 6% 6% 7% 9% 43%	2290
	21st to end	Day	9% 4 2 5% 4 3 4 6% 7% 9% 47%	2376
September	1st to 10th	Day	12% 6% 2 5% 6% 4 5% 4 5% 7% 45%	2110
	11th to 20th	Day	11% 5% 2 4 5% 3 5% 5% 5% 9% 46%	1980
	21st to end	Day	12% 6% 3 4 5% 3 4 4 5% 8% 46%	1980
October	1st to 10th	Day	13% 6% 2 5% 6% 3 4 4 6% 7% 43%	1980
	11th to 20th	Day	16% 6% 3 5% 5% 4 4 6% 5% 7% 39%	1816
	21st to end	Day	20% 9% 3 9% 6% 3 4 6% 5% 6% 30%	1782
November	1st to 10th	Day	11% 7% 3 5% 4 2 5% 3 5% 7% 49%	1672
	11th to 20th	Day	18% 11% 4 7% 6% 3 3 4 5% 7% 31%	1710
	21st to end	Day	20% 13% 4 8% 5% 3 4 4 4 6% 29%	1710
December	1st to 10th	Day	16% 15% 7% 10% 7% 3 4 4 4 6% 23%	1710
	11th to 20th	Day	15% 16% 6% 9% 6% 4 5% 4 5% 6% 24%	1927
	21st to end	Day	24% 21% 9% 10% 7% 3 4 3 3 4 11%	2783
January	1st to 10th	Night	18% 15% 9% 10% 6% 3 5% 4 4 5% 22%	4428
	11th to 20th	Night	14% 19% 8% 14% 8% 3 5% 5% 4 4 15%	4440
	21st to end	Night	27% 17% 8% 9% 5% 2 3 3 3 4 19%	4752
February	1st to 10th	Night	20% 13% 6% 9% 8% 3 5% 3 4 5% 26%	2352
	11th to 20th	Night	13% 13% 5% 8% 7% 3 5% 4 4 7% 31%	2218
	21st to end	Night	19% 12% 5% 8% 5% 3 3 4 4 6% 29%	1884
March	1st to 10th	Night	16% 10% 4 7% 7% 4 4 3 5% 5% 35%	2167
	11th to 20th	Night	14% 9% 4 5% 5% 3 5% 5% 6% 6% 37%	2023
	21st to end	Night	20% 11% 4 7% 5% 3 3 4 4 6% 34%	2138
April	1st to 10th	Night	15% 9% 3 6% 5% 3 5% 4 5% 9% 37%	1800
	11th to 20th	Night	18% 7% 3 5% 5% 3 5% 4 5% 6% 38%	1749
	21st to end	Night	20% 8% 3 5% 5% 3 4 4 5% 6% 37%	1620
May	1st to 10th	Night	18% 8% 4 7% 6% 4 5% 4 5% 7% 31%	1620
	11th to 20th	Night	20% 6% 3 5% 5% 2 4 4 5% 7% 39%	1592
	21st to end	Night	9% 5% 3 4 6% 3 5% 6% 8% 8% 44%	1677
June	1st to 10th	Night	8% 4 3 6% 4 3 4 5% 5% 8% 49%	1440
	11th to 20th	Night	9% 4 3 5% 5% 3 4 5% 6% 9% 48%	1440
	21st to end	Night	11% 4 2 5% 6% 3 6% 5% 5% 9% 45%	1440
July	1st to 10th	Night	7% 6% 2 5% 5% 3 4 5% 6% 9% 48%	1440
	11th to 20th	Night	8% 3 2 4 5% 3 4 4 6% 8% 53%	1440
	21st to end	Night	7% 5% 3 5% 4 3 4 5% 6% 10% 49%	1648
August	1st to 10th	Night	7% 4 2 6% 5% 3 4 5% 5% 9% 50%	1611
	11th to 20th	Night	8% 4 2 5% 5% 3 5% 4 6% 7% 51%	1607
	21st to end	Night	7% 4 2 5% 5% 3 4 4 6% 8% 53%	1980
September	1st to 10th	Night	11% 5% 2 4 6% 2 4 5% 5% 7% 50%	1831
	11th to 20th	Night	9% 4 1 4 3 3 4 4 5% 7% 55%	1980
	21st to end	Night	11% 6% 3 5% 4 3 4 4 5% 6% 50%	1980
October	1st to 10th	Night	11% 5% 2 4 4 3 4 5% 4 8% 50%	1980
	11th to 20th	Night	18% 8% 2 5% 5% 3 4 4 4 6% 41%	2139
	21st to end	Night	20% 9% 3 5% 5% 2 5% 4 5% 6% 36%	2574
November	1st to 10th	Night	12% 8% 3 5% 5% 2 4 4 5% 7% 45%	2406
	11th to 20th	Night	16% 11% 4 7% 5% 3 4 4 5% 7% 35%	2470
	21st to end	Night	19% 11% 5% 8% 6% 3 4 4 5% 6% 29%	2470
December	1st to 10th	Night	19% 13% 5% 8% 6% 3 5% 5% 5% 7% 26%	2470
	11th to 20th	Night	17% 14% 8% 10% 7% 3 4 4 5% 5% 24%	3266
	21st to end	Night	26% 17% 7% 10% 6% 4 4 4 4 5% 14%	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	69% 2 8% 16% 5%	2528
	11th to 20th	Day	75% 2 8% 8% 6%	2530
	21st to end	Day	79% 1 6% 11% 3	2910
February	1st to 10th	Day	67% 2 9% 14% 7% 1	1824
	11th to 20th	Day	60% 3 9% 20% 7% 1	1858
	21st to end	Day	59% 3 11% 18% 7% 1	1570
March	1st to 10th	Day	59% 3 9% 21% 8%	1800
	11th to 20th	Day	53% 3 13% 19% 11% 1	1935
	21st to end	Day	61% 3 11% 19% 5% 1	2232
April	1st to 10th	Day	53% 4 10% 21% 12%	2160
	11th to 20th	Day	50% 4 10% 21% 12% 3	2160
	21st to end	Day	51% 3 12% 20% 11% 3	2340
May	1st to 10th	Day	53% 4 12% 21% 9% 1	2340
	11th to 20th	Day	50% 5% 11% 20% 13% 1	2305
	21st to end	Day	42% 6% 12% 24% 14% 2	2593
June	1st to 10th	Day	39% 5% 11% 26% 16% 2	2520
	11th to 20th	Day	36% 4 13% 25% 20% 3	2520
	21st to end	Day	41% 5% 15% 22% 15% 3	2520
July	1st to 10th	Day	37% 5% 12% 24% 17% 4	2451
	11th to 20th	Day	32% 4 14% 29% 18% 2	2445
	21st to end	Day	36% 5% 13% 26% 16% 3	2519
August	1st to 10th	Day	32% 5% 16% 30% 15% 2	2314
	11th to 20th	Day	36% 5% 15% 27% 15% 2	2290
	21st to end	Day	33% 5% 12% 26% 19% 5%	2376
September	1st to 10th	Day	39% 4 13% 23% 18% 3	2110
	11th to 20th	Day	36% 4 9% 28% 21% 1	1980
	21st to end	Day	38% 3 9% 27% 21% 2	1980
October	1st to 10th	Day	40% 4 11% 26% 17% 2	1980
	11th to 20th	Day	44% 3 9% 24% 19% 1	1816
	21st to end	Day	55% 4 10% 20% 10% 1	1782
November	1st to 10th	Day	36% 4 12% 27% 18% 1	1672
	11th to 20th	Day	54% 2 12% 19% 12% 2	1710
	21st to end	Day	58% 3 11% 19% 8% 1	1710
December	1st to 10th	Day	65% 2 12% 14% 6%	1710
	11th to 20th	Day	64% 2 9% 21% 3	1924
	21st to end	Day	81% 3 5% 7% 5%	2783
January	1st to 10th	Night	66% 3 9% 14% 7%	4428
	11th to 20th	Night	75% 1 7% 13% 4	4440
	21st to end	Night	72% 2 7% 15% 5%	4752
February	1st to 10th	Night	63% 2 10% 16% 8% 1	2352
	11th to 20th	Night	54% 3 10% 22% 10% 1	2219
	21st to end	Night	57% 3 10% 18% 10% 2	1884
March	1st to 10th	Night	53% 2 11% 21% 12% 1	2167
	11th to 20th	Night	47% 4 10% 24% 13% 3	2023
	21st to end	Night	54% 3 8% 24% 10% 1	2138
April	1st to 10th	Night	46% 4 11% 23% 14% 1	1800
	11th to 20th	Night	47% 3 8% 22% 16% 3	1749
	21st to end	Night	49% 3 9% 23% 12% 4	1620
May	1st to 10th	Night	53% 4 11% 19% 10% 3	1620
	11th to 20th	Night	46% 4 12% 22% 14% 2	1593
	21st to end	Night	35% 7% 15% 23% 16% 3	1678
June	1st to 10th	Night	34% 4 11% 27% 21% 3	1440
	11th to 20th	Night	33% 5% 11% 26% 21% 3	1440
	21st to end	Night	36% 6% 16% 23% 15% 4	1440
July	1st to 10th	Night	34% 5% 14% 25% 19% 5%	1400
	11th to 20th	Night	29% 4 15% 29% 20% 3	1392
	21st to end	Night	31% 5% 15% 25% 19% 6%	1556
August	1st to 10th	Night	31% 4 13% 31% 19% 2	1600
	11th to 20th	Night	34% 4 14% 26% 21% 2	1607
	21st to end	Night	30% 5% 12% 24% 23% 5%	1980
September	1st to 10th	Night	35% 5% 13% 24% 18% 6%	1831
	11th to 20th	Night	30% 3 8% 31% 25% 2	1980
	21st to end	Night	35% 4 10% 26% 22% 3	1980
October	1st to 10th	Night	34% 4 10% 29% 21% 2	1980
	11th to 20th	Night	45% 3 7% 26% 17% 1	2139
	21st to end	Night	49% 3 9% 24% 14% 1	2574
November	1st to 10th	Night	40% 3 10% 25% 20% 2	2406
	11th to 20th	Night	49% 3 11% 21% 14% 2	2470
	21st to end	Night	57% 3 11% 21% 8%	2470
December	1st to 10th	Night	59% 3 11% 19% 8%	2470
	11th to 20th	Night	63% 3 10% 16% 7% 1	3268
	21st to end	Night	76% 2 9% 9% 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	22% 17% 40% 16% 5% 1	270
	11th to 20th	Day	26% 15% 39% 15% 4 1	270
	21st to end	Day	30% 15% 32% 17% 6% 1	297
February	1st to 10th	Day	29% 18% 33% 16% 3	270
	11th to 20th	Day	26% 18% 36% 17% 4	270
	21st to end	Day	28% 19% 38% 13% 3	225
March	1st to 10th	Day	23% 23% 36% 15% 2	240
	11th to 20th	Day	27% 11% 31% 21% 8% 1	375
	21st to end	Day	33% 15% 25% 18% 7% 1	462
April	1st to 10th	Day	22% 12% 34% 21% 10% 2	420
	11th to 20th	Day	22% 17% 28% 19% 11% 3	412
	21st to end	Day	25% 15% 29% 19% 10% 3	420
May	1st to 10th	Day	26% 13% 29% 21% 8% 3	423
	11th to 20th	Day	23% 6% 28% 25% 12% 6%	447
	21st to end	Day	12% 6% 27% 26% 18% 10%	547
June	1st to 10th	Day	12% 8% 28% 30% 17% 6%	630
	11th to 20th	Day	12% 7% 26% 28% 21% 6%	630
	21st to end	Day	12% 7% 28% 26% 20% 7%	630
July	1st to 10th	Day	11% 3 17% 31% 23% 15%	621
	11th to 20th	Day	7% 4 22% 32% 21% 14%	618
	21st to end	Day	9% 4 16% 31% 28% 11%	608
August	1st to 10th	Day	9% 2 11% 30% 27% 20%	446
	11th to 20th	Day	10% 4 17% 26% 29% 13%	439
	21st to end	Day	9% 4 14% 27% 31% 15%	495
September	1st to 10th	Day	14% 5% 16% 26% 27% 11%	450
	11th to 20th	Day	10% 3 15% 25% 31% 17%	450
	21st to end	Day	16% 10% 19% 24% 24% 7%	450
October	1st to 10th	Day	13% 6% 27% 26% 20% 8%	450
	11th to 20th	Day	19% 17% 30% 25% 9% 1	407
	21st to end	Day	28% 16% 33% 21% 1 1	297
November	1st to 10th	Day	11% 13% 37% 23% 11% 4	270
	11th to 20th	Day	25% 17% 29% 17% 10% 1	270
	21st to end	Day	30% 14% 32% 20% 3	270
December	1st to 10th	Day	22% 24% 33% 14% 7%	270
	11th to 20th	Day	22% 16% 41% 14% 6%	270
	21st to end	Day	30% 22% 30% 16% 2	297
January	1st to 10th	Night	24% 16% 34% 21% 5% 1	950
	11th to 20th	Night	24% 15% 35% 21% 4	950
	21st to end	Night	24% 13% 35% 23% 4	965
February	1st to 10th	Night	28% 12% 33% 25% 4	760
	11th to 20th	Night	22% 13% 39% 23% 4	743
	21st to end	Night	28% 13% 36% 20% 3	628
March	1st to 10th	Night	22% 14% 32% 26% 7%	723
	11th to 20th	Night	20% 11% 35% 26% 7% 1	720
	21st to end	Night	26% 10% 32% 27% 6% 1	752
April	1st to 10th	Night	19% 10% 34% 29% 7% 1	540
	11th to 20th	Night	19% 11% 33% 28% 8% 1	533
	21st to end	Night	22% 7% 36% 26% 8% 1	540
May	1st to 10th	Night	22% 7% 33% 29% 8%	540
	11th to 20th	Night	22% 5% 24% 32% 15% 2	531
	21st to end	Night	11% 3 23% 42% 18% 2	584
June	1st to 10th	Night	9% 3 22% 48% 17%	540
	11th to 20th	Night	10% 4 25% 39% 21% 1	540
	21st to end	Night	11% 3 23% 38% 24% 1	540
July	1st to 10th	Night	9% 2 14% 41% 29% 5%	525
	11th to 20th	Night	8% 3 13% 41% 32% 4	522
	21st to end	Night	7% 5% 12% 43% 31% 1	591
August	1st to 10th	Night	8% 2 12% 40% 33% 5%	537
	11th to 20th	Night	10% 3 12% 40% 32% 4	534
	21st to end	Night	7% 2 16% 34% 37% 5%	594
September	1st to 10th	Night	12% 3 14% 34% 32% 4	571
	11th to 20th	Night	12% 2 14% 35% 32% 4	720
	21st to end	Night	13% 6% 22% 35% 21% 3	720
October	1st to 10th	Night	15% 5% 23% 33% 20% 4	720
	11th to 20th	Night	22% 13% 26% 28% 10%	720
	21st to end	Night	25% 11% 32% 25% 7%	792
November	1st to 10th	Night	17% 10% 34% 25% 13% 1	740
	11th to 20th	Night	21% 14% 32% 26% 6%	760
	21st to end	Night	26% 11% 29% 26% 7%	760
December	1st to 10th	Night	25% 14% 33% 22% 6%	760
	11th to 20th	Night	25% 13% 33% 24% 5%	937
	21st to end	Night	32% 13% 31% 21% 3	1045

Page generated at 2024-02-27 06:30:12. Version ac07

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