Payette
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Payette clear sky chart from 2005-11-06 to 2024-03-08.

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	9% 7% 3 5% 5% 3 4 4 5% 7% 48%	78489
	Night	12% 8% 3 6% 6% 3 5% 5% 5% 6% 41%	81090
Transparency	Day	36% 7% 12% 19% 17% 10%	78193
	Night	41% 8% 12% 17% 14% 8%	80907
Seeing	Day	10% 5% 16% 26% 28% 15%	13510
	Night	13% 3 18% 39% 24% 3	22947

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	14% 16% 5% 11% 9% 4 7% 5% 5% 6% 19%	2539
	11th to 20th	Day	19% 17% 5% 11% 7% 4 5% 5% 4 5% 19%	2540
	21st to end	Day	25% 15% 7% 10% 7% 4 5% 4 4 5% 14%	2794
February	1st to 10th	Day	14% 12% 4 8% 7% 3 5% 5% 4 6% 31%	1643
	11th to 20th	Day	12% 9% 3 7% 8% 4 6% 6% 5% 7% 33%	1850
	21st to end	Day	10% 8% 4 7% 7% 4 5% 5% 6% 8% 35%	1570
March	1st to 10th	Day	11% 11% 4 7% 6% 3 5% 5% 6% 8% 33%	1871
	11th to 20th	Day	13% 9% 4 6% 6% 3 6% 5% 5% 7% 37%	1870
	21st to end	Day	12% 9% 3 5% 6% 4 6% 6% 6% 7% 36%	2322
April	1st to 10th	Day	10% 7% 3 7% 5% 3 5% 5% 6% 8% 41%	2160
	11th to 20th	Day	7% 6% 3 6% 5% 3 5% 5% 5% 8% 46%	2147
	21st to end	Day	8% 6% 3 5% 5% 3 4 4 5% 8% 49%	2340
May	1st to 10th	Day	5% 5% 2 3 4 3 5% 4 5% 8% 55%	2340
	11th to 20th	Day	10% 5% 2 5% 4 3 4 4 6% 9% 48%	2439
	21st to end	Day	6% 7% 2 6% 6% 3 5% 5% 7% 10% 44%	2723
June	1st to 10th	Day	8% 5% 3 4 5% 3 5% 6% 7% 9% 45%	2520
	11th to 20th	Day	7% 3 2 3 4 2 4 4 6% 7% 58%	2520
	21st to end	Day	2 3 1 2 3 2 3 3 4 6% 71%	2520
July	1st to 10th	Day	3 2 1 2 3 2 2 3 4 5% 74%	2520
	11th to 20th	Day	2 1 1 1 2 1 1 2 3 4 81%	2520
	21st to end	Day	2 2 1 2 2 1 3 3 4 5% 77%	2741
August	1st to 10th	Day	4 3 1 3 3 2 3 3 4 6% 67%	2464
	11th to 20th	Day	2 1 1 1 3 2 2 2 4 5% 77%	2278
	21st to end	Day	2 2 1 2 3 1 2 3 3 5% 75%	2376
September	1st to 10th	Day	3 2 1 2 2 2 3 3 3 5% 75%	2160
	11th to 20th	Day	4 3 1 3 2 2 4 5% 4 7% 65%	2026
	21st to end	Day	5% 3 2 4 4 2 4 4 4 6% 63%	1980
October	1st to 10th	Day	7% 5% 1 5% 4 3 4 3 4 7% 56%	1976
	11th to 20th	Day	7% 5% 2 4 4 3 4 4 5% 7% 55%	1721
	21st to end	Day	9% 7% 2 6% 6% 3 4 5% 5% 6% 46%	1782
November	1st to 10th	Day	15% 6% 3 5% 6% 3 5% 5% 7% 7% 39%	1674
	11th to 20th	Day	13% 8% 4 6% 7% 4 4 5% 5% 8% 35%	1710
	21st to end	Day	11% 9% 4 8% 7% 5% 7% 6% 6% 7% 29%	1611
December	1st to 10th	Day	18% 12% 6% 7% 6% 3 5% 5% 6% 6% 25%	1520
	11th to 20th	Day	18% 14% 6% 13% 10% 5% 5% 3 5% 4 17%	1928
	21st to end	Day	13% 13% 5% 11% 10% 5% 5% 6% 5% 5% 22%	2794
January	1st to 10th	Night	17% 16% 5% 11% 9% 4 6% 5% 6% 6% 15%	4406
	11th to 20th	Night	23% 15% 5% 10% 8% 4 5% 5% 4 5% 16%	4420
	21st to end	Night	25% 16% 6% 9% 6% 3 4 4 4 5% 17%	4862
February	1st to 10th	Night	15% 11% 4 7% 7% 5% 6% 6% 6% 6% 28%	2530
	11th to 20th	Night	13% 9% 4 7% 6% 4 6% 6% 6% 7% 33%	2218
	21st to end	Night	11% 11% 4 6% 7% 5% 6% 6% 7% 8% 29%	1884
March	1st to 10th	Night	13% 9% 4 7% 7% 4 6% 5% 5% 7% 34%	2249
	11th to 20th	Night	12% 8% 4 5% 6% 3 5% 6% 6% 9% 36%	2089
	21st to end	Night	12% 8% 4 7% 7% 5% 5% 5% 5% 7% 34%	2030
April	1st to 10th	Night	11% 7% 3 6% 5% 3 4 5% 6% 6% 44%	1800
	11th to 20th	Night	10% 6% 3 6% 5% 3 6% 5% 5% 6% 45%	1761
	21st to end	Night	8% 5% 2 4 4 2 5% 5% 6% 7% 51%	1620
May	1st to 10th	Night	6% 4 1 3 4 3 4 6% 6% 8% 55%	1620
	11th to 20th	Night	7% 4 2 6% 6% 2 5% 5% 8% 9% 46%	1452
	21st to end	Night	8% 5% 4 7% 7% 3 4 5% 7% 9% 41%	1552
June	1st to 10th	Night	8% 5% 2 6% 5% 4 5% 5% 5% 8% 47%	1440
	11th to 20th	Night	7% 4 2 4 4 3 3 4 5% 6% 59%	1440
	21st to end	Night	3 2 2 3 3 2 3 5% 5% 7% 65%	1440
July	1st to 10th	Night	1 2 1 2 3 2 3 3 3 8% 72%	1440
	11th to 20th	Night	1 1 1 3 2 2 2 4 5% 80%	1440
	21st to end	Night	2 2 1 3 2 1 3 3 3 5% 74%	1576
August	1st to 10th	Night	4 2 1 3 4 2 3 3 6% 8% 64%	1475
	11th to 20th	Night	1 1 1 1 2 2 2 3 5% 6% 76%	1620
	21st to end	Night	2 2 1 2 2 2 3 3 4 4 74%	1980
September	1st to 10th	Night	3 3 1 2 2 1 2 3 3 5% 76%	1800
	11th to 20th	Night	4 3 2 3 3 2 3 4 4 6% 66%	1934
	21st to end	Night	7% 3 1 3 3 2 3 4 3 5% 66%	1980
October	1st to 10th	Night	8% 4 2 4 3 3 3 4 3 7% 59%	1982
	11th to 20th	Night	8% 4 1 4 3 3 4 4 5% 6% 57%	2238
	21st to end	Night	8% 5% 2 5% 4 3 5% 6% 6% 7% 48%	2574
November	1st to 10th	Night	14% 7% 2 5% 5% 2 4 5% 5% 6% 42%	2405
	11th to 20th	Night	17% 7% 2 6% 6% 3 5% 6% 5% 6% 36%	2470
	21st to end	Night	13% 8% 3 6% 5% 4 6% 6% 5% 7% 36%	2565
December	1st to 10th	Night	17% 11% 4 8% 6% 3 6% 5% 5% 6% 29%	2660
	11th to 20th	Night	20% 11% 5% 9% 8% 4 7% 5% 4 6% 21%	3276
	21st to end	Night	15% 12% 4 9% 9% 5% 8% 7% 6% 6% 19%	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% 11% 16% 10% 1	2539
	11th to 20th	Day	66% 11% 14% 9% 1	2540
	21st to end	Day	71% 12% 11% 5% 1	2794
February	1st to 10th	Day	54% 9% 19% 14% 3	1643
	11th to 20th	Day	48% 10% 16% 19% 6%	1860
	21st to end	Day	45% 8% 18% 18% 9% 1	1570
March	1st to 10th	Day	48% 9% 15% 19% 7% 1	1871
	11th to 20th	Day	45% 7% 14% 24% 10%	1870
	21st to end	Day	46% 7% 17% 20% 9% 1	2322
April	1st to 10th	Day	40% 6% 16% 21% 14% 3	2160
	11th to 20th	Day	35% 6% 13% 26% 16% 4	2150
	21st to end	Day	33% 6% 13% 26% 19% 3	2340
May	1st to 10th	Day	27% 5% 11% 29% 24% 5%	2340
	11th to 20th	Day	32% 6% 11% 27% 18% 5%	2442
	21st to end	Day	34% 8% 15% 23% 17% 3	2724
June	1st to 10th	Day	33% 8% 12% 24% 21% 2	2520
	11th to 20th	Day	24% 5% 10% 25% 26% 10%	2520
	21st to end	Day	16% 3 7% 20% 32% 22%	2520
July	1st to 10th	Day	14% 3 5% 15% 28% 35%	2451
	11th to 20th	Day	9% 2 4 10% 28% 48%	2445
	21st to end	Day	11% 2 4 9% 29% 46%	2589
August	1st to 10th	Day	19% 3 8% 14% 28% 29%	2447
	11th to 20th	Day	11% 2 5% 17% 35% 30%	2278
	21st to end	Day	14% 2 6% 17% 37% 24%	2376
September	1st to 10th	Day	14% 3 5% 19% 31% 28%	2160
	11th to 20th	Day	19% 4 9% 23% 31% 13%	2026
	21st to end	Day	23% 4 9% 28% 29% 7%	1980
October	1st to 10th	Day	29% 5% 13% 28% 22% 3	1976
	11th to 20th	Day	28% 6% 14% 32% 18% 2	1721
	21st to end	Day	37% 7% 16% 27% 11% 1	1782
November	1st to 10th	Day	43% 9% 17% 23% 8%	1674
	11th to 20th	Day	47% 9% 19% 18% 6% 1	1710
	21st to end	Day	50% 11% 17% 15% 6%	1611
December	1st to 10th	Day	58% 11% 16% 12% 4	1520
	11th to 20th	Day	69% 10% 11% 7% 3	1928
	21st to end	Day	58% 12% 16% 10% 3	2794
January	1st to 10th	Night	63% 13% 15% 7% 2	4406
	11th to 20th	Night	66% 9% 12% 10% 2	4420
	21st to end	Night	65% 11% 13% 9% 2	4862
February	1st to 10th	Night	52% 10% 16% 17% 4 1	2530
	11th to 20th	Night	46% 9% 18% 19% 8%	2219
	21st to end	Night	48% 9% 15% 19% 8% 2	1884
March	1st to 10th	Night	48% 6% 12% 22% 9% 2	2249
	11th to 20th	Night	42% 7% 14% 27% 10%	2089
	21st to end	Night	48% 7% 14% 21% 9%	2030
April	1st to 10th	Night	39% 7% 11% 23% 18% 2	1800
	11th to 20th	Night	39% 6% 10% 24% 17% 4	1761
	21st to end	Night	30% 6% 12% 25% 24% 3	1620
May	1st to 10th	Night	26% 7% 9% 25% 29% 4	1620
	11th to 20th	Night	32% 6% 12% 23% 21% 6%	1452
	21st to end	Night	39% 6% 12% 25% 14% 4	1552
June	1st to 10th	Night	35% 6% 13% 24% 20% 2	1440
	11th to 20th	Night	27% 5% 8% 21% 30% 8%	1440
	21st to end	Night	18% 4 7% 18% 32% 21%	1440
July	1st to 10th	Night	14% 3 5% 16% 27% 35%	1400
	11th to 20th	Night	9% 2 5% 13% 26% 46%	1392
	21st to end	Night	14% 2 4 9% 24% 48%	1488
August	1st to 10th	Night	18% 4 9% 13% 26% 30%	1467
	11th to 20th	Night	11% 2 7% 13% 29% 39%	1620
	21st to end	Night	15% 2 6% 13% 32% 32%	1980
September	1st to 10th	Night	14% 3 4 14% 29% 36%	1800
	11th to 20th	Night	20% 3 7% 19% 27% 23%	1934
	21st to end	Night	22% 3 5% 22% 33% 15%	1980
October	1st to 10th	Night	27% 4 9% 27% 26% 7%	1982
	11th to 20th	Night	27% 4 10% 29% 25% 4	2238
	21st to end	Night	34% 7% 14% 25% 19% 2	2574
November	1st to 10th	Night	40% 7% 13% 25% 14% 1	2405
	11th to 20th	Night	46% 7% 15% 22% 8%	2470
	21st to end	Night	43% 9% 18% 21% 9% 1	2565
December	1st to 10th	Night	53% 10% 16% 14% 6%	2660
	11th to 20th	Night	60% 11% 16% 11% 3	3276
	21st to end	Night	53% 15% 17% 11% 5%	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	21% 6% 12% 33% 23% 7%	180
	11th to 20th	Day	23% 4 15% 27% 19% 11%	180
	21st to end	Day	21% 4 12% 31% 25% 9%	198
February	1st to 10th	Day	18% 5% 24% 28% 20% 6%	281
	11th to 20th	Day	17% 5% 19% 31% 22% 7%	455
	21st to end	Day	14% 6% 26% 29% 19% 6%	382
March	1st to 10th	Day	18% 9% 21% 33% 17% 2	449
	11th to 20th	Day	15% 6% 18% 32% 23% 5%	420
	21st to end	Day	15% 11% 20% 30% 19% 5%	462
April	1st to 10th	Day	14% 14% 19% 20% 21% 12%	420
	11th to 20th	Day	9% 12% 25% 27% 17% 10%	412
	21st to end	Day	9% 9% 25% 25% 22% 9%	420
May	1st to 10th	Day	6% 11% 23% 25% 23% 11%	423
	11th to 20th	Day	16% 8% 15% 24% 23% 14%	448
	21st to end	Day	9% 4 16% 21% 29% 19%	485
June	1st to 10th	Day	9% 4 16% 27% 25% 19%	450
	11th to 20th	Day	9% 6% 21% 27% 26% 11%	450
	21st to end	Day	3 2 15% 29% 32% 19%	450
July	1st to 10th	Day	3 1 10% 28% 37% 21%	446
	11th to 20th	Day	2 2 9% 31% 39% 18%	444
	21st to end	Day	3 1 6% 26% 42% 22%	487
August	1st to 10th	Day	5% 2 7% 25% 39% 22%	447
	11th to 20th	Day	2 1 7% 21% 35% 34%	437
	21st to end	Day	4 2 10% 21% 35% 28%	495
September	1st to 10th	Day	6% 1 9% 18% 36% 30%	450
	11th to 20th	Day	6% 2 12% 21% 32% 27%	450
	21st to end	Day	6% 3 14% 26% 29% 23%	450
October	1st to 10th	Day	9% 4 14% 21% 28% 24%	450
	11th to 20th	Day	9% 3 15% 28% 25% 20%	371
	21st to end	Day	12% 6% 18% 26% 28% 11%	297
November	1st to 10th	Day	17% 4 16% 27% 31% 6%	270
	11th to 20th	Day	14% 3 18% 27% 29% 9%	270
	21st to end	Day	17% 2 12% 26% 35% 9%	223
December	1st to 10th	Day	23% 3 13% 28% 21% 13%	180
	11th to 20th	Day	24% 4 21% 28% 19% 4	180
	21st to end	Day	18% 4 17% 32% 21% 8%	198
January	1st to 10th	Night	21% 4 17% 34% 19% 4	760
	11th to 20th	Night	21% 4 17% 32% 22% 4	760
	21st to end	Night	20% 3 13% 38% 23% 4	836
February	1st to 10th	Night	21% 2 20% 37% 18% 2	760
	11th to 20th	Night	17% 2 19% 39% 21% 2	744
	21st to end	Night	15% 4 25% 37% 17% 2	628
March	1st to 10th	Night	15% 6% 23% 38% 15% 3	750
	11th to 20th	Night	15% 5% 20% 40% 20% 1	720
	21st to end	Night	16% 6% 22% 39% 17% 1	792
April	1st to 10th	Night	12% 5% 22% 37% 22% 1	720
	11th to 20th	Night	13% 6% 25% 35% 20% 2	693
	21st to end	Night	9% 5% 27% 39% 18% 2	540
May	1st to 10th	Night	7% 6% 23% 42% 20% 1	540
	11th to 20th	Night	8% 5% 20% 36% 27% 4	390
	21st to end	Night	9% 5% 18% 38% 25% 5%	389
June	1st to 10th	Night	9% 4 22% 36% 25% 4	360
	11th to 20th	Night	9% 5% 28% 33% 23% 2	360
	21st to end	Night	3 2 24% 44% 27% 1	360
July	1st to 10th	Night	2 3 18% 49% 27% 1	350
	11th to 20th	Night	1 21% 58% 20%	348
	21st to end	Night	3 1 15% 53% 27% 2	394
August	1st to 10th	Night	4 14% 48% 31% 2	401
	11th to 20th	Night	1 1 13% 46% 36% 3	552
	21st to end	Night	4 2 13% 41% 36% 4	792
September	1st to 10th	Night	4 1 12% 42% 37% 5%	720
	11th to 20th	Night	5% 2 12% 34% 42% 6%	720
	21st to end	Night	8% 2 14% 36% 33% 7%	720
October	1st to 10th	Night	10% 1 16% 40% 29% 4	720
	11th to 20th	Night	9% 3 15% 37% 29% 6%	720
	21st to end	Night	11% 2 17% 39% 27% 4	792
November	1st to 10th	Night	17% 3 15% 39% 24% 2	740
	11th to 20th	Night	20% 2 16% 38% 21% 2	760
	21st to end	Night	17% 4 16% 36% 24% 4	760
December	1st to 10th	Night	21% 2 17% 38% 19% 2	760
	11th to 20th	Night	24% 2 15% 39% 17% 2	760
	21st to end	Night	26% 4 18% 37% 12% 2	836

Page generated at 2024-03-05 05:24:00. Version ac07

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