Burley/Heyburn
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Burley/Heyburn clear sky chart from 2005-11-06 to 2024-04-10.

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	6% 7% 3 5% 5% 3 4 5% 6% 7% 49%	82812
	Night	7% 8% 3 6% 5% 3 5% 5% 6% 8% 46%	86039
Transparency	Day	35% 4 12% 23% 18% 9%	82522
	Night	37% 4 13% 23% 16% 8%	85851
Seeing	Day	10% 11% 24% 27% 21% 8%	13682
	Night	10% 8% 21% 37% 22% 3	23733

By Month

Percentage Cloud Cover SW (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% 16% 5% 10% 9% 4 4 6% 6% 6% 24%	2539
	11th to 20th	Day	9% 14% 6% 9% 8% 4 4 5% 4 7% 30%	2540
	21st to end	Day	10% 13% 4 8% 6% 4 5% 4 6% 8% 32%	3027
February	1st to 10th	Day	7% 12% 5% 9% 6% 3 5% 5% 6% 8% 35%	1710
	11th to 20th	Day	8% 13% 4 7% 7% 3 6% 4 6% 7% 37%	1797
	21st to end	Day	6% 11% 5% 9% 6% 4 5% 4 6% 9% 35%	1570
March	1st to 10th	Day	8% 13% 5% 8% 7% 3 4 5% 5% 8% 33%	3189
	11th to 20th	Day	6% 9% 3 5% 4 2 4 5% 5% 6% 52%	3490
	21st to end	Day	8% 10% 4 8% 8% 5% 7% 6% 7% 8% 30%	3825
April	1st to 10th	Day	8% 9% 4 6% 6% 3 4 5% 7% 8% 41%	2207
	11th to 20th	Day	7% 8% 3 5% 6% 3 5% 5% 6% 8% 44%	2260
	21st to end	Day	7% 5% 2 5% 5% 3 4 4 6% 8% 49%	2340
May	1st to 10th	Day	7% 4 2 5% 5% 4 5% 6% 6% 8% 48%	2340
	11th to 20th	Day	7% 5% 2 5% 6% 3 4 7% 6% 9% 46%	2301
	21st to end	Day	8% 6% 2 5% 6% 4 6% 6% 7% 9% 40%	2555
June	1st to 10th	Day	5% 3 2 3 4 3 5% 5% 7% 9% 52%	2520
	11th to 20th	Day	5% 3 2 4 3 2 5% 4 4 7% 61%	2520
	21st to end	Day	2 1 1 2 2 1 3 4 5% 6% 74%	2520
July	1st to 10th	Day	1 1 1 2 2 2 3 4 6% 8% 69%	2520
	11th to 20th	Day	2 2 1 2 2 2 3 4 4 5% 72%	2520
	21st to end	Day	2 2 1 3 4 3 4 4 5% 7% 66%	2617
August	1st to 10th	Day	4 3 1 3 4 3 3 6% 6% 7% 60%	2328
	11th to 20th	Day	2 2 1 2 2 2 3 3 4 6% 74%	2299
	21st to end	Day	2 2 1 3 3 2 3 3 5% 6% 70%	2525
September	1st to 10th	Day	3 2 1 1 2 2 3 4 5% 7% 71%	2066
	11th to 20th	Day	3 3 2 3 2 2 3 4 4 6% 68%	1980
	21st to end	Day	6% 4 1 3 4 2 3 3 4 4 66%	1980
October	1st to 10th	Day	9% 4 2 3 5% 2 4 5% 5% 7% 54%	1962
	11th to 20th	Day	6% 5% 2 4 4 3 4 3 5% 6% 59%	1800
	21st to end	Day	5% 5% 2 4 4 3 4 5% 5% 8% 55%	1810
November	1st to 10th	Day	8% 8% 2 6% 5% 3 5% 5% 5% 9% 45%	1674
	11th to 20th	Day	9% 6% 3 6% 5% 3 5% 6% 6% 8% 44%	1710
	21st to end	Day	6% 10% 4 5% 5% 4 4 6% 6% 9% 42%	1669
December	1st to 10th	Day	8% 11% 4 6% 7% 3 5% 5% 5% 6% 39%	1520
	11th to 20th	Day	10% 11% 4 7% 5% 4 6% 6% 8% 10% 30%	1788
	21st to end	Day	9% 12% 4 6% 5% 3 5% 5% 6% 8% 36%	2794
January	1st to 10th	Night	9% 14% 5% 9% 6% 4 5% 5% 7% 8% 29%	4406
	11th to 20th	Night	11% 14% 5% 10% 7% 4 6% 6% 5% 7% 26%	4420
	21st to end	Night	10% 13% 4 9% 6% 3 5% 5% 6% 7% 31%	4633
February	1st to 10th	Night	9% 10% 5% 7% 7% 4 5% 6% 7% 8% 33%	2470
	11th to 20th	Night	7% 10% 3 7% 6% 3 5% 4 5% 8% 43%	2267
	21st to end	Night	5% 8% 5% 7% 7% 3 5% 6% 8% 11% 37%	1884
March	1st to 10th	Night	7% 11% 3 7% 6% 4 5% 5% 6% 8% 38%	3685
	11th to 20th	Night	4 8% 2 5% 5% 3 4 5% 6% 7% 52%	3490
	21st to end	Night	7% 9% 3 7% 6% 3 6% 6% 7% 10% 37%	3828
April	1st to 10th	Night	6% 9% 3 6% 6% 3 5% 5% 6% 7% 45%	1960
	11th to 20th	Night	7% 8% 3 5% 5% 3 6% 4 5% 6% 48%	1647
	21st to end	Night	7% 5% 2 5% 4 3 4 4 6% 8% 54%	1620
May	1st to 10th	Night	5% 6% 2 6% 5% 4 4 5% 5% 7% 51%	1620
	11th to 20th	Night	5% 4 2 5% 7% 3 6% 7% 8% 8% 45%	1594
	21st to end	Night	10% 7% 1 4 4 3 5% 5% 7% 9% 44%	1717
June	1st to 10th	Night	4 3 1 4 4 3 5% 5% 7% 9% 54%	1440
	11th to 20th	Night	4 3 1 4 3 2 3 4 5% 9% 62%	1440
	21st to end	Night	3 2 1 2 3 1 3 3 4 6% 73%	1440
July	1st to 10th	Night	1 1 1 2 3 2 5% 5% 7% 10% 63%	1440
	11th to 20th	Night	1 1 1 1 2 1 4 4 6% 5% 73%	1440
	21st to end	Night	2 2 1 3 3 2 4 5% 5% 8% 65%	1697
August	1st to 10th	Night	3 3 1 4 3 2 4 5% 5% 9% 61%	1611
	11th to 20th	Night	2 3 1 2 3 2 3 4 5% 9% 66%	1602
	21st to end	Night	3 2 1 3 4 2 3 4 4 6% 70%	1827
September	1st to 10th	Night	2 2 1 2 2 1 3 3 4 7% 73%	1892
	11th to 20th	Night	4 2 1 4 3 2 3 4 4 7% 66%	1980
	21st to end	Night	6% 3 1 3 3 3 3 3 3 5% 68%	1980
October	1st to 10th	Night	7% 5% 2 4 4 3 4 4 3 6% 60%	1998
	11th to 20th	Night	7% 5% 2 3 3 2 4 5% 4 6% 59%	2160
	21st to end	Night	5% 5% 2 4 4 2 4 5% 6% 9% 54%	2542
November	1st to 10th	Night	9% 7% 2 5% 4 3 5% 4 5% 7% 47%	2405
	11th to 20th	Night	9% 6% 2 5% 6% 3 5% 5% 6% 9% 44%	2470
	21st to end	Night	6% 7% 3 5% 5% 3 5% 5% 7% 9% 45%	2486
December	1st to 10th	Night	9% 11% 4 7% 5% 3 5% 5% 6% 8% 36%	2660
	11th to 20th	Night	10% 11% 5% 8% 7% 3 5% 6% 6% 9% 29%	3426
	21st to end	Night	10% 10% 5% 9% 6% 4 4 5% 6% 8% 34%	4862

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	61% 3 16% 17% 2 1	2539
	11th to 20th	Day	56% 5% 19% 16% 4 1	2540
	21st to end	Day	51% 5% 22% 17% 5% 1	3027
February	1st to 10th	Day	50% 5% 19% 20% 5% 1	1710
	11th to 20th	Day	47% 4 16% 22% 9% 1	1807
	21st to end	Day	48% 5% 13% 22% 9% 2	1570
March	1st to 10th	Day	48% 6% 10% 27% 8% 1	3189
	11th to 20th	Day	34% 4 11% 34% 16% 1	3490
	21st to end	Day	52% 4 20% 17% 6% 1	3825
April	1st to 10th	Day	42% 4 13% 22% 14% 4	2207
	11th to 20th	Day	40% 4 10% 26% 16% 3	2263
	21st to end	Day	34% 3 13% 26% 21% 2	2340
May	1st to 10th	Day	33% 4 7% 31% 22% 2	2340
	11th to 20th	Day	33% 4 13% 30% 16% 3	2304
	21st to end	Day	39% 4 14% 28% 13% 2	2555
June	1st to 10th	Day	28% 5% 14% 31% 20% 3	2520
	11th to 20th	Day	24% 3 9% 25% 29% 10%	2520
	21st to end	Day	12% 2 5% 23% 37% 21%	2520
July	1st to 10th	Day	13% 3 3 20% 35% 25%	2451
	11th to 20th	Day	15% 2 3 11% 33% 36%	2445
	21st to end	Day	19% 2 3 13% 26% 37%	2471
August	1st to 10th	Day	23% 3 5% 18% 24% 27%	2313
	11th to 20th	Day	13% 2 3 19% 37% 26%	2299
	21st to end	Day	16% 2 4 19% 36% 23%	2525
September	1st to 10th	Day	15% 2 6% 16% 32% 30%	2066
	11th to 20th	Day	18% 2 7% 26% 27% 20%	1980
	21st to end	Day	23% 3 4 24% 35% 11%	1980
October	1st to 10th	Day	31% 3 10% 27% 21% 8%	1962
	11th to 20th	Day	29% 2 10% 33% 22% 4	1800
	21st to end	Day	30% 3 15% 32% 18% 3	1810
November	1st to 10th	Day	39% 5% 12% 26% 16% 3	1674
	11th to 20th	Day	39% 4 17% 30% 9% 1	1710
	21st to end	Day	41% 3 16% 27% 12% 1	1669
December	1st to 10th	Day	46% 6% 18% 20% 7% 3	1520
	11th to 20th	Day	50% 3 26% 17% 4	1787
	21st to end	Day	46% 3 20% 19% 11%	2794
January	1st to 10th	Night	53% 5% 15% 23% 3 1	4406
	11th to 20th	Night	60% 4 17% 15% 3 1	4420
	21st to end	Night	52% 5% 20% 17% 5% 1	4633
February	1st to 10th	Night	49% 6% 17% 23% 5% 1	2470
	11th to 20th	Night	41% 4 18% 24% 12% 1	2268
	21st to end	Night	42% 5% 17% 26% 10% 1	1884
March	1st to 10th	Night	43% 6% 13% 25% 11% 2	3685
	11th to 20th	Night	31% 3 15% 31% 18% 1	3490
	21st to end	Night	43% 4 18% 28% 7% 1	3828
April	1st to 10th	Night	39% 4 10% 26% 15% 6%	1960
	11th to 20th	Night	37% 5% 10% 26% 19% 2	1647
	21st to end	Night	30% 3 11% 29% 25% 2	1620
May	1st to 10th	Night	32% 5% 8% 24% 28% 4	1620
	11th to 20th	Night	32% 4 12% 28% 19% 5%	1595
	21st to end	Night	35% 4 15% 28% 15% 3	1717
June	1st to 10th	Night	25% 3 16% 27% 24% 5%	1440
	11th to 20th	Night	23% 3 7% 22% 32% 13%	1440
	21st to end	Night	15% 2 4 16% 33% 31%	1440
July	1st to 10th	Night	17% 3 2 15% 32% 31%	1400
	11th to 20th	Night	12% 3 2 10% 25% 48%	1392
	21st to end	Night	18% 2 3 12% 25% 41%	1603
August	1st to 10th	Night	21% 3 4 18% 22% 32%	1602
	11th to 20th	Night	16% 3 2 16% 33% 30%	1602
	21st to end	Night	17% 3 2 14% 33% 31%	1827
September	1st to 10th	Night	14% 2 4 15% 31% 35%	1892
	11th to 20th	Night	19% 3 4 22% 29% 24%	1980
	21st to end	Night	22% 2 4 20% 36% 16%	1980
October	1st to 10th	Night	29% 2 9% 22% 29% 10%	1998
	11th to 20th	Night	26% 3 7% 30% 28% 6%	2160
	21st to end	Night	27% 3 14% 32% 20% 4	2542
November	1st to 10th	Night	37% 4 13% 23% 18% 4	2405
	11th to 20th	Night	38% 3 15% 28% 15% 1	2470
	21st to end	Night	36% 4 16% 31% 12% 1	2486
December	1st to 10th	Night	47% 4 19% 20% 7% 2	2660
	11th to 20th	Night	51% 4 19% 22% 4	3427
	21st to end	Night	48% 4 17% 20% 11%	4862

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	17% 16% 22% 31% 14% 1	180
	11th to 20th	Day	12% 13% 21% 33% 14% 6%	180
	21st to end	Day	14% 10% 27% 25% 22% 1	265
February	1st to 10th	Day	21% 15% 30% 22% 12%	270
	11th to 20th	Day	15% 21% 32% 18% 13% 2	403
	21st to end	Day	15% 20% 30% 26% 8% 1	382
March	1st to 10th	Day	15% 18% 29% 26% 11%	460
	11th to 20th	Day	10% 15% 30% 27% 15% 2	460
	21st to end	Day	17% 21% 29% 23% 8% 2	506
April	1st to 10th	Day	16% 18% 28% 18% 14% 7%	457
	11th to 20th	Day	15% 19% 28% 23% 12% 4	412
	21st to end	Day	11% 17% 32% 20% 16% 5%	420
May	1st to 10th	Day	7% 16% 26% 28% 17% 6%	423
	11th to 20th	Day	13% 9% 24% 24% 21% 10%	448
	21st to end	Day	9% 9% 21% 22% 23% 15%	485
June	1st to 10th	Day	6% 9% 25% 25% 24% 12%	450
	11th to 20th	Day	7% 12% 29% 27% 20% 5%	450
	21st to end	Day	2 4 24% 35% 23% 11%	450
July	1st to 10th	Day	2 2 19% 34% 33% 11%	446
	11th to 20th	Day	2 3 21% 37% 30% 7%	444
	21st to end	Day	2 2 15% 34% 34% 13%	487
August	1st to 10th	Day	6% 3 19% 31% 29% 12%	447
	11th to 20th	Day	3 4 15% 28% 34% 16%	437
	21st to end	Day	3 4 19% 24% 36% 13%	495
September	1st to 10th	Day	4 5% 16% 30% 27% 19%	450
	11th to 20th	Day	5% 6% 18% 30% 27% 15%	450
	21st to end	Day	7% 8% 19% 28% 26% 12%	450
October	1st to 10th	Day	9% 7% 22% 26% 24% 12%	432
	11th to 20th	Day	7% 15% 19% 17% 31% 10%	270
	21st to end	Day	10% 9% 26% 28% 21% 5%	297
November	1st to 10th	Day	14% 13% 26% 24% 21% 3	270
	11th to 20th	Day	10% 10% 20% 34% 20% 5%	270
	21st to end	Day	14% 11% 17% 31% 23% 4	270
December	1st to 10th	Day	20% 9% 24% 27% 16% 4	270
	11th to 20th	Day	19% 16% 22% 27% 15% 3	198
	21st to end	Day	17% 16% 24% 27% 12% 4	198
January	1st to 10th	Night	14% 12% 22% 32% 19% 2	760
	11th to 20th	Night	13% 13% 19% 34% 19% 3	760
	21st to end	Night	16% 9% 18% 34% 21% 2	836
February	1st to 10th	Night	13% 11% 28% 32% 15% 1	760
	11th to 20th	Night	13% 9% 29% 33% 15% 1	744
	21st to end	Night	7% 13% 28% 36% 13% 1	628
March	1st to 10th	Night	9% 11% 26% 38% 14% 1	760
	11th to 20th	Night	8% 9% 25% 38% 19% 2	760
	21st to end	Night	12% 12% 28% 34% 14%	836
April	1st to 10th	Night	10% 13% 23% 36% 16% 2	760
	11th to 20th	Night	9% 13% 31% 32% 13% 2	579
	21st to end	Night	8% 10% 30% 33% 17% 2	540
May	1st to 10th	Night	8% 9% 27% 36% 19% 1	540
	11th to 20th	Night	8% 5% 21% 34% 28% 4	531
	21st to end	Night	13% 5% 20% 30% 28% 4	555
June	1st to 10th	Night	5% 6% 17% 43% 26% 4	360
	11th to 20th	Night	6% 7% 21% 46% 20% 1	360
	21st to end	Night	4 1 19% 45% 26% 5%	360
July	1st to 10th	Night	2 1 10% 51% 34% 3	350
	11th to 20th	Night	1 13% 55% 30% 1	348
	21st to end	Night	1 1 10% 46% 38% 3	515
August	1st to 10th	Night	3 2 13% 48% 33% 2	537
	11th to 20th	Night	3 1 13% 47% 33% 3	534
	21st to end	Night	4 2 16% 45% 31% 3	639
September	1st to 10th	Night	3 2 14% 41% 34% 6%	720
	11th to 20th	Night	5% 2 15% 37% 34% 7%	720
	21st to end	Night	7% 3 18% 35% 28% 9%	720
October	1st to 10th	Night	9% 5% 18% 36% 28% 4	720
	11th to 20th	Night	9% 6% 19% 33% 29% 4	720
	21st to end	Night	8% 8% 21% 36% 24% 3	792
November	1st to 10th	Night	12% 8% 23% 31% 23% 3	740
	11th to 20th	Night	12% 9% 21% 38% 18% 2	760
	21st to end	Night	10% 8% 22% 33% 23% 4	776
December	1st to 10th	Night	15% 9% 24% 36% 16% 1	950
	11th to 20th	Night	17% 9% 18% 39% 15% 2	927
	21st to end	Night	19% 12% 24% 32% 11% 2	836

Page generated at 2024-04-07 07:28:11. Version ac07

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