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 2024-11-02.

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	7% 6% 2 6% 4 4 4 3 5% 6% 52%	101327
	Night	11% 8% 3 7% 4 4 5% 4 5% 6% 44%	97767
Transparency	Day	32% 6% 10% 19% 19% 14%	101071
	Night	38% 7% 11% 18% 16% 11%	97612
Seeing	Day	10% 5% 16% 26% 27% 16%	14448
	Night	13% 3 18% 39% 24% 3	23691

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% 4 13% 7% 6% 6% 4 5% 6% 19%	2539
	11th to 20th	Day	18% 17% 5% 12% 6% 5% 5% 4 4 5% 19%	2540
	21st to end	Day	25% 15% 7% 11% 6% 6% 5% 3 4 5% 14%	2794
February	1st to 10th	Day	14% 13% 4 10% 6% 5% 4 4 5% 6% 31%	1643
	11th to 20th	Day	12% 9% 3 8% 7% 6% 5% 4 5% 7% 33%	1850
	21st to end	Day	9% 10% 3 8% 7% 6% 5% 4 6% 8% 35%	1570
March	1st to 10th	Day	8% 13% 4 9% 6% 5% 5% 4 6% 9% 31%	3138
	11th to 20th	Day	8% 7% 2 5% 3 3 3 3 4 5% 57%	3302
	21st to end	Day	9% 8% 2 8% 6% 6% 6% 6% 7% 9% 33%	4072
April	1st to 10th	Day	10% 8% 3 7% 5% 4 5% 4 6% 7% 41%	2280
	11th to 20th	Day	6% 7% 2 7% 4 4 5% 4 6% 8% 47%	2268
	21st to end	Day	8% 6% 2 6% 4 4 5% 3 6% 8% 49%	2470
May	1st to 10th	Day	8% 7% 2 4 4 4 5% 3 5% 7% 52%	4110
	11th to 20th	Day	6% 3 1 3 2 2 2 2 4 6% 67%	4313
	21st to end	Day	5% 5% 2 5% 4 4 4 4 6% 8% 54%	4813
June	1st to 10th	Day	8% 6% 2 5% 4 4 5% 5% 7% 8% 45%	2660
	11th to 20th	Day	7% 4 1 3 4 3 4 3 6% 7% 59%	2660
	21st to end	Day	2 3 1 3 2 3 3 3 4 6% 71%	2660
July	1st to 10th	Day	1 1 1 2 2 2 1 2 3 3 82%	4420
	11th to 20th	Day	2 2 1 2 2 1 2 2 3 4 80%	4420
	21st to end	Day	1 2 1 2 2 2 2 2 4 5% 77%	4790
August	1st to 10th	Day	4 4 2 5% 3 3 3 3 4 6% 64%	4318
	11th to 20th	Day	2 1 1 2 2 2 2 2 4 5% 79%	3981
	21st to end	Day	2 2 1 2 3 2 2 2 3 4 77%	4180
September	1st to 10th	Day	3 2 1 2 2 3 2 3 4 5% 74%	2280
	11th to 20th	Day	4 3 1 4 2 3 4 4 4 7% 63%	2138
	21st to end	Day	4 3 1 4 3 3 4 2 4 6% 64%	2090
October	1st to 10th	Day	7% 5% 1 5% 4 3 4 3 4 6% 57%	2085
	11th to 20th	Day	7% 5% 2 5% 4 4 4 3 5% 8% 55%	1816
	21st to end	Day	9% 7% 2 7% 4 4 5% 3 5% 7% 46%	1881
November	1st to 10th	Day	15% 7% 3 6% 5% 4 5% 3 7% 7% 39%	1683
	11th to 20th	Day	13% 9% 3 8% 6% 5% 5% 4 5% 7% 35%	1710
	21st to end	Day	10% 10% 4 9% 7% 6% 7% 4 6% 7% 29%	1611
December	1st to 10th	Day	17% 13% 6% 8% 6% 4 5% 3 6% 6% 25%	1520
	11th to 20th	Day	18% 15% 6% 16% 7% 6% 5% 3 5% 4 16%	1928
	21st to end	Day	13% 13% 5% 13% 7% 6% 5% 5% 5% 5% 22%	2794
January	1st to 10th	Night	16% 16% 5% 13% 7% 6% 6% 4 6% 6% 15%	4406
	11th to 20th	Night	23% 16% 5% 11% 6% 5% 5% 4 4 5% 16%	4420
	21st to end	Night	25% 16% 6% 11% 5% 4 4 3 4 5% 17%	4862
February	1st to 10th	Night	14% 12% 4 8% 6% 6% 6% 5% 6% 6% 28%	2530
	11th to 20th	Night	13% 10% 3 8% 5% 5% 6% 4 6% 7% 32%	2218
	21st to end	Night	11% 12% 3 8% 6% 6% 6% 5% 8% 7% 29%	1884
March	1st to 10th	Night	10% 11% 4 9% 6% 8% 8% 4 6% 6% 28%	3736
	11th to 20th	Night	9% 9% 2 5% 4 3 3 3 4 6% 52%	3677
	21st to end	Night	10% 8% 3 8% 7% 6% 6% 5% 7% 9% 32%	3564
April	1st to 10th	Night	11% 8% 2 7% 4 4 4 4 6% 5% 45%	1900
	11th to 20th	Night	10% 7% 2 6% 4 4 5% 3 6% 6% 46%	1860
	21st to end	Night	8% 5% 2 5% 3 3 5% 4 6% 7% 51%	1710
May	1st to 10th	Night	11% 5% 2 5% 4 4 4 5% 6% 7% 48%	2860
	11th to 20th	Night	4 3 1 4 3 3 3 3 7% 6% 63%	2566
	21st to end	Night	8% 6% 2 6% 5% 4 4 3 5% 8% 50%	2762
June	1st to 10th	Night	8% 6% 2 7% 4 5% 4 4 5% 8% 47%	1520
	11th to 20th	Night	7% 4 2 4 4 3 3 3 4 6% 59%	1520
	21st to end	Night	3 3 2 3 2 2 4 3 5% 7% 66%	1520
July	1st to 10th	Night	1 1 2 2 2 2 2 2 4 82%	2540
	11th to 20th	Night	1 1 1 2 2 2 2 4 5% 80%	2540
	21st to end	Night	3 3 1 3 3 3 3 3 4 5% 70%	2761
August	1st to 10th	Night	3 4 2 4 4 4 4 4 6% 6% 60%	2614
	11th to 20th	Night	1 2 1 2 2 2 3 2 4 5% 76%	2843
	21st to end	Night	4 3 1 2 1 2 2 2 3 3 77%	3498
September	1st to 10th	Night	3 3 1 2 2 2 2 2 3 5% 75%	1900
	11th to 20th	Night	4 4 1 4 3 3 3 3 4 6% 64%	2042
	21st to end	Night	7% 3 1 4 2 2 3 3 3 5% 67%	2090
October	1st to 10th	Night	8% 4 2 5% 3 3 3 3 3 6% 60%	2093
	11th to 20th	Night	7% 4 1 5% 2 4 3 3 5% 7% 57%	2363
	21st to end	Night	8% 5% 2 6% 4 5% 5% 4 6% 7% 47%	2717
November	1st to 10th	Night	14% 8% 2 6% 4 3 4 4 5% 6% 42%	2418
	11th to 20th	Night	17% 7% 2 7% 5% 4 5% 5% 6% 6% 36%	2470
	21st to end	Night	13% 9% 3 7% 5% 5% 6% 4 5% 7% 36%	2565
December	1st to 10th	Night	17% 12% 4 9% 5% 4 6% 4 5% 7% 28%	2660
	11th to 20th	Night	19% 12% 5% 10% 6% 6% 7% 4 4 6% 21%	3276
	21st to end	Night	15% 12% 3 10% 8% 7% 8% 5% 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	46% 9% 15% 20% 9% 1	3138
	11th to 20th	Day	30% 6% 13% 35% 15%	3302
	21st to end	Day	42% 9% 17% 20% 9% 3	4072
April	1st to 10th	Day	40% 6% 16% 22% 14% 3	2280
	11th to 20th	Day	34% 6% 14% 25% 17% 4	2271
	21st to end	Day	33% 6% 13% 27% 19% 3	2470
May	1st to 10th	Day	31% 5% 9% 23% 27% 5%	4110
	11th to 20th	Day	19% 4 8% 26% 29% 14%	4316
	21st to end	Day	25% 6% 13% 32% 19% 3	4814
June	1st to 10th	Day	33% 7% 12% 24% 21% 2	2660
	11th to 20th	Day	23% 4 10% 25% 27% 11%	2660
	21st to end	Day	16% 3 7% 19% 33% 22%	2660
July	1st to 10th	Day	9% 2 3 8% 21% 57%	4351
	11th to 20th	Day	11% 1 2 6% 20% 59%	4345
	21st to end	Day	11% 1 2 7% 31% 47%	4639
August	1st to 10th	Day	23% 2 4 9% 27% 35%	4302
	11th to 20th	Day	11% 1 3 17% 36% 31%	4020
	21st to end	Day	14% 1 4 21% 35% 24%	4179
September	1st to 10th	Day	14% 2 5% 19% 32% 28%	2280
	11th to 20th	Day	21% 4 10% 23% 30% 13%	2138
	21st to end	Day	22% 4 9% 28% 30% 8%	2090
October	1st to 10th	Day	28% 5% 12% 27% 24% 4	2085
	11th to 20th	Day	28% 6% 14% 32% 18% 3	1816
	21st to end	Day	38% 6% 16% 27% 12% 1	1881
November	1st to 10th	Day	43% 9% 17% 23% 8%	1683
	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	45% 10% 13% 22% 9% 1	3736
	11th to 20th	Night	33% 5% 10% 35% 17%	3677
	21st to end	Night	44% 10% 16% 22% 8% 1	3564
April	1st to 10th	Night	39% 7% 12% 23% 17% 2	1900
	11th to 20th	Night	37% 6% 10% 25% 18% 4	1860
	21st to end	Night	30% 6% 12% 25% 24% 3	1710
May	1st to 10th	Night	31% 6% 11% 23% 25% 4	2860
	11th to 20th	Night	20% 4 9% 24% 34% 9%	2566
	21st to end	Night	33% 5% 10% 31% 19% 2	2762
June	1st to 10th	Night	35% 6% 13% 23% 20% 2	1520
	11th to 20th	Night	27% 5% 8% 21% 30% 9%	1520
	21st to end	Night	18% 4 7% 18% 32% 22%	1520
July	1st to 10th	Night	9% 1 3 9% 18% 59%	2500
	11th to 20th	Night	9% 1 3 7% 20% 60%	2492
	21st to end	Night	18% 2 2 6% 27% 45%	2674
August	1st to 10th	Night	25% 3 5% 8% 24% 35%	2606
	11th to 20th	Night	13% 1 4 12% 28% 42%	2870
	21st to end	Night	15% 1 3 14% 33% 33%	3498
September	1st to 10th	Night	14% 3 4 14% 30% 35%	1900
	11th to 20th	Night	22% 3 7% 19% 26% 22%	2042
	21st to end	Night	21% 3 5% 22% 33% 16%	2090
October	1st to 10th	Night	26% 4 9% 26% 27% 9%	2093
	11th to 20th	Night	27% 4 11% 29% 25% 4	2363
	21st to end	Night	34% 6% 14% 25% 19% 2	2717
November	1st to 10th	Night	40% 7% 13% 25% 14% 1	2418
	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% 10% 21% 32% 17% 2	460
	11th to 20th	Day	14% 7% 18% 31% 22% 9%	460
	21st to end	Day	14% 11% 20% 30% 20% 6%	506
April	1st to 10th	Day	14% 13% 18% 22% 20% 12%	460
	11th to 20th	Day	8% 12% 25% 27% 19% 10%	452
	21st to end	Day	8% 8% 26% 26% 23% 8%	460
May	1st to 10th	Day	7% 12% 23% 25% 22% 11%	463
	11th to 20th	Day	15% 9% 16% 25% 22% 14%	488
	21st to end	Day	8% 5% 16% 22% 30% 19%	529
June	1st to 10th	Day	9% 4 16% 27% 25% 19%	490
	11th to 20th	Day	8% 6% 22% 27% 26% 12%	490
	21st to end	Day	3 2 16% 29% 31% 19%	490
July	1st to 10th	Day	3 1 11% 28% 36% 21%	486
	11th to 20th	Day	2 1 9% 30% 39% 18%	484
	21st to end	Day	3 1 6% 26% 42% 22%	531
August	1st to 10th	Day	6% 1 7% 26% 38% 22%	487
	11th to 20th	Day	2 1 7% 24% 35% 31%	477
	21st to end	Day	4 2 11% 22% 33% 28%	539
September	1st to 10th	Day	5% 1 9% 18% 35% 31%	490
	11th to 20th	Day	6% 2 11% 22% 31% 26%	490
	21st to end	Day	5% 3 14% 25% 29% 24%	490
October	1st to 10th	Day	8% 4 13% 21% 28% 25%	490
	11th to 20th	Day	9% 3 15% 26% 28% 20%	406
	21st to end	Day	12% 5% 18% 26% 28% 11%	330
November	1st to 10th	Day	17% 4 16% 27% 31% 6%	273
	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% 5% 23% 39% 15% 3	760
	11th to 20th	Night	14% 5% 20% 39% 20% 2	760
	21st to end	Night	15% 6% 22% 39% 17% 1	836
April	1st to 10th	Night	12% 5% 22% 37% 21% 1	760
	11th to 20th	Night	12% 6% 26% 35% 19% 2	732
	21st to end	Night	9% 5% 27% 40% 18% 2	570
May	1st to 10th	Night	8% 7% 23% 42% 19% 1	570
	11th to 20th	Night	8% 5% 21% 35% 27% 4	411
	21st to end	Night	9% 5% 18% 38% 25% 5%	411
June	1st to 10th	Night	9% 5% 23% 36% 24% 4	380
	11th to 20th	Night	9% 4 28% 34% 22% 2	380
	21st to end	Night	3 2 24% 44% 26% 1	380
July	1st to 10th	Night	2 3 18% 50% 26% 1	370
	11th to 20th	Night	1 1 20% 58% 20%	368
	21st to end	Night	3 1 15% 52% 28% 2	416
August	1st to 10th	Night	5% 14% 47% 31% 2	424
	11th to 20th	Night	2 1 14% 47% 34% 3	583
	21st to end	Night	4 2 13% 41% 35% 4	836
September	1st to 10th	Night	4 1 11% 42% 37% 5%	760
	11th to 20th	Night	5% 2 12% 35% 40% 6%	760
	21st to end	Night	8% 3 13% 37% 33% 7%	760
October	1st to 10th	Night	10% 1 16% 40% 29% 5%	760
	11th to 20th	Night	9% 3 15% 37% 30% 6%	760
	21st to end	Night	11% 2 17% 40% 26% 3	836
November	1st to 10th	Night	17% 3 15% 39% 24% 2	744
	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 2024-10-29 23:22:59. Version ac07

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